/*!
 * 小番茄图片混淆 · 全站样式
 * 设计语言：番茄红主导、白色留白、圆角与轻动效
 * 纯静态、无第三方字体与框架
 */

/* ══════════════════════════════════════════
   1. 设计变量
   ══════════════════════════════════════════ */
:root {
  --red: #e60012;
  --red-hover: #cc0010;
  --red-active: #b3000f;
  --red-disabled: #f08080;
  --red-soft: #fff0f1;
  --red-mist: #fff7f7;
  --red-line: #ffd2d5;
  --red-wash: #ffe4e6;

  --ink: #1e1e1e;
  --ink-2: #3d3d3d;
  --ink-3: #626262;
  --ink-4: #666666;
  --white: #ffffff;
  --black: #000000;
  --surface: #ebebeb;
  --surface-2: #f6f6f6;
  --surface-3: #faf7f5;
  --line: #e6e6e6;
  --line-strong: #cbcaca;

  --green: #1f7a4d;
  --green-soft: #e9f5ee;
  --amber: #8a5300;
  --amber-soft: #fff5df;

  --radius-sm: 4px;
  --radius-md: 16px;
  --radius-lg: 24px;
  --radius-xl: 32px;
  --radius-pill: 9999px;

  --shadow-sm: 0 2px 8px rgba(30, 30, 30, .05);
  --shadow-md: 0 14px 38px rgba(30, 30, 30, .09);
  --shadow-lg: 0 28px 70px rgba(30, 30, 30, .14);
  --shadow-red: 0 20px 50px rgba(230, 0, 18, .24);

  --wrap: 1200px;
  --wrap-narrow: 820px;
  --header-h: 76px;

  --font-sans: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei",
    "Source Han Sans SC", "Noto Sans CJK SC", system-ui, -apple-system,
    "Segoe UI", Roboto, Arial, sans-serif;
  --font-serif: "Rokkitt", "Georgia", "Times New Roman", "Songti SC",
    "Noto Serif CJK SC", serif;
  --font-mono: ui-monospace, "SFMono-Regular", Menlo, Consolas,
    "Liberation Mono", monospace;

  --ease: cubic-bezier(.22, .61, .36, 1);
  --ease-spring: cubic-bezier(.34, 1.56, .64, 1);
  --dur-fast: .3s;
  --dur-base: .5s;
}

/* ══════════════════════════════════════════
   2. 基础重置
   ══════════════════════════════════════════ */
*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-h) + 24px);
}

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.75;
  color: var(--ink);
  background: var(--white);
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

body.nav-open {
  overflow: hidden;
}

h1,
h2,
h3,
h4,
h5,
h6 {
  margin: 0 0 .6em;
  font-weight: 700;
  line-height: 1.3;
  letter-spacing: -.012em;
  color: var(--ink);
  text-wrap: balance;
}

h1 {
  font-size: clamp(2rem, 1.5rem + 2.1vw, 3.35rem);
}

h2 {
  font-size: clamp(1.6rem, 1.25rem + 1.2vw, 2.15rem);
}

h3 {
  font-size: clamp(1.1rem, 1rem + .35vw, 1.3rem);
}

h4 {
  font-size: 1.05rem;
}

p {
  margin: 0 0 1em;
  text-wrap: pretty;
}

a {
  color: var(--red);
  text-decoration: none;
  transition: color var(--dur-fast) var(--ease),
    background-color var(--dur-fast) var(--ease),
    border-color var(--dur-fast) var(--ease);
}

a:hover {
  color: var(--red-hover);
}

p a:not(.btn) {
  text-decoration: underline;
  text-underline-offset: 2px;
}

img,
svg,
canvas {
  max-width: 100%;
}

img {
  height: auto;
}

ul,
ol {
  margin: 0 0 1.1em;
  padding-left: 1.35em;
}

li {
  margin: .35em 0;
}

hr {
  border: 0;
  border-top: 1px solid var(--line);
  margin: 2.4rem 0;
}

strong,
b {
  font-weight: 700;
  color: var(--ink);
}

code,
kbd,
pre {
  font-family: var(--font-mono);
  font-size: .92em;
}

code {
  padding: .12em .42em;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--surface-2);
  color: var(--ink-2);
  word-break: break-word;
}

pre {
  margin: 1.4em 0;
  padding: 18px 20px;
  overflow-x: auto;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: #1e1e1e;
  color: #f5f5f5;
  line-height: 1.7;
}

pre code {
  padding: 0;
  border: 0;
  background: none;
  color: inherit;
}

blockquote {
  margin: 1.6em 0;
  padding: 18px 22px;
  border-left: 4px solid var(--red);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  background: var(--red-mist);
  color: var(--ink-2);
}

blockquote p:last-child {
  margin-bottom: 0;
}

::selection {
  background: var(--red);
  color: var(--white);
}

:focus-visible {
  outline: 3px solid rgba(230, 0, 18, .55);
  outline-offset: 3px;
}

[hidden] {
  display: none !important;
}

/* ══════════════════════════════════════════
   3. 通用布局
   ══════════════════════════════════════════ */
.wrap {
  width: min(var(--wrap), calc(100% - 48px));
  margin-inline: auto;
}

.wrap--narrow {
  width: min(var(--wrap-narrow), calc(100% - 48px));
  margin-inline: auto;
}

.section {
  padding: 76px 0;
}

.section--tight {
  padding: 48px 0;
}

.section--soft {
  background: var(--surface-3);
}

.section--mist {
  background: var(--red-mist);
}

.section--dark {
  background: #171313;
  color: #f4efee;
}

.section--dark h2,
.section--dark h3 {
  color: #fff;
}

.section--red {
  background: linear-gradient(135deg, var(--red) 0%, #c30010 100%);
  color: var(--white);
}

.section--red h2,
.section--red h3 {
  color: var(--white);
}

.section-head {
  max-width: 780px;
  margin-bottom: 36px;
}

.section-head--center {
  margin-inline: auto;
  text-align: center;
}

.section-head h2 {
  margin-bottom: 14px;
}

.section-head p {
  margin-bottom: 0;
  color: var(--ink-3);
  font-size: 17px;
  line-height: 1.85;
}

.section--red .section-head p,
.section--dark .section-head p {
  color: rgba(255, 255, 255, .84);
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 12px;
  color: var(--red);
  font-family: var(--font-sans);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: .16em;
  line-height: 1.4;
  text-transform: uppercase;
}

.eyebrow::before {
  width: 22px;
  height: 2px;
  background: currentColor;
  content: "";
}

.section--red .eyebrow,
.section--dark .eyebrow {
  color: #ffb3b9;
}

.eyebrow--light {
  color: rgba(255, 255, 255, .82);
}

.lead {
  font-size: clamp(1.05rem, 1rem + .35vw, 1.2rem);
  line-height: 1.85;
  color: var(--ink-3);
}

.muted {
  color: var(--ink-4);
}

.small {
  font-size: 14px;
}

.text-center {
  text-align: center;
}

.nowrap {
  white-space: nowrap;
}

.grid {
  display: grid;
  gap: 24px;
}

.grid--2 {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.grid--3 {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.grid--4 {
  grid-template-columns: repeat(4, minmax(0, 1fr));
}

.split {
  display: grid;
  grid-template-columns: minmax(0, 1.05fr) minmax(0, .95fr);
  gap: 48px;
  align-items: center;
}

.split > *,
.grid > *,
.page-layout > * {
  min-width: 0;
}

.stack > * + * {
  margin-top: 18px;
}

.skip-link {
  position: fixed;
  top: -100px;
  left: 16px;
  z-index: 10000;
  padding: 10px 18px;
  border-radius: var(--radius-pill);
  background: var(--ink);
  color: var(--white);
  font-size: 14px;
  font-weight: 700;
}

.skip-link:focus {
  top: 12px;
  color: var(--white);
}

/* ══════════════════════════════════════════
   4. 按钮、标签
   ══════════════════════════════════════════ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 46px;
  padding: 11px 24px;
  border: 1px solid transparent;
  border-radius: var(--radius-pill);
  background: transparent;
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: 15px;
  font-weight: 700;
  line-height: 1.2;
  text-align: center;
  text-decoration: none;
  cursor: pointer;
  transition: background-color var(--dur-fast) var(--ease),
    border-color var(--dur-fast) var(--ease),
    color var(--dur-fast) var(--ease),
    transform var(--dur-fast) var(--ease),
    box-shadow var(--dur-fast) var(--ease);
  -webkit-tap-highlight-color: transparent;
}

.btn:hover {
  text-decoration: none;
  transform: translateY(-1px);
}

.btn:active {
  transform: translateY(0);
}

.btn:disabled,
.btn[aria-disabled="true"] {
  cursor: not-allowed;
  transform: none;
  opacity: .62;
}

.btn svg {
  flex: 0 0 auto;
  width: 18px;
  height: 18px;
}

.btn--primary {
  background: var(--red);
  color: var(--white);
  box-shadow: 0 8px 20px rgba(230, 0, 18, .18);
}

.btn--primary:hover {
  background: var(--red-hover);
  color: var(--white);
}

.btn--primary:active {
  background: var(--red-active);
  color: var(--white);
}

.btn--secondary {
  border-color: var(--red);
  background: var(--white);
  color: var(--red);
}

.btn--secondary:hover {
  background: var(--red);
  color: var(--white);
}

.btn--secondary:active {
  border-color: var(--red-active);
  background: var(--red-active);
  color: var(--white);
}

.btn--ghost {
  border-color: transparent;
  background: transparent;
  color: var(--ink-2);
  font-weight: 500;
}

.btn--ghost:hover {
  background: var(--surface);
  color: var(--red);
}

.btn--dark {
  background: var(--ink);
  color: var(--white);
}

.btn--dark:hover {
  background: #000;
  color: var(--white);
}

.btn--white {
  background: var(--white);
  color: var(--red);
  box-shadow: 0 10px 28px rgba(0, 0, 0, .14);
}

.btn--white:hover {
  background: var(--red-soft);
  color: var(--red-hover);
}

.btn--outline-light {
  border-color: rgba(255, 255, 255, .62);
  color: var(--white);
}

.btn--outline-light:hover {
  border-color: var(--white);
  background: var(--white);
  color: var(--red);
}

.btn--sm {
  min-height: 40px;
  padding: 8px 18px;
  font-size: 14px;
}

.btn--lg {
  min-height: 54px;
  padding: 14px 30px;
  font-size: 16px;
}

.btn--block {
  width: 100%;
}

.badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 5px 10px;
  border-radius: var(--radius-sm);
  background: var(--surface);
  color: var(--ink-2);
  font-size: 11px;
  font-weight: 700;
  line-height: 1.4;
  white-space: nowrap;
}

.badge--red {
  background: var(--red);
  color: var(--white);
}

.badge--soft {
  background: var(--red-soft);
  color: var(--red-hover);
}

.badge--green {
  background: var(--green-soft);
  color: var(--green);
}

.badge--amber {
  background: var(--amber-soft);
  color: var(--amber);
}

.chip-row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.chip {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 7px 13px;
  border: 1px solid var(--line);
  border-radius: var(--radius-pill);
  background: var(--white);
  color: var(--ink-3);
  font-size: 13px;
  font-weight: 500;
  line-height: 1.4;
}

.chip::before {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--red);
  content: "";
}

.hero .chip {
  border-color: var(--red-line);
  background: var(--white);
  color: var(--ink-3);
}

.hero .chip::before {
  background: var(--red);
}

/* ══════════════════════════════════════════
   5. 顶部提示条与页头
   ══════════════════════════════════════════ */
.notice-bar {
  background: var(--ink);
  color: rgba(255, 255, 255, .9);
  font-size: 12px;
  line-height: 1.5;
}

.notice-bar__inner {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  min-height: 34px;
  padding: 6px 0;
  text-align: center;
}

.notice-bar__dot {
  display: inline-block;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: #ff5b67;
  box-shadow: 0 0 0 4px rgba(255, 91, 103, .16);
}

.notice-bar a {
  color: #fff;
  text-decoration: underline;
  text-underline-offset: 3px;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 999;
  border-bottom: 1px solid var(--line);
  background: rgba(255, 255, 255, .96);
  backdrop-filter: saturate(180%) blur(12px);
  transition: box-shadow var(--dur-fast) var(--ease);
}

.site-header.is-scrolled {
  box-shadow: 0 6px 24px rgba(30, 30, 30, .08);
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  min-height: var(--header-h);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 11px;
  flex: 0 0 auto;
  color: var(--ink);
  text-decoration: none;
}

.brand:hover {
  color: var(--ink);
  text-decoration: none;
}

.brand__mark {
  display: block;
  width: 38px;
  height: 38px;
  flex: 0 0 auto;
}

.brand__text {
  display: flex;
  flex-direction: column;
  line-height: 1.15;
}

.brand__name {
  font-size: 18px;
  font-weight: 800;
  letter-spacing: -.02em;
}

.brand__en {
  margin-top: 3px;
  color: var(--ink-4);
  font-family: var(--font-serif);
  font-size: 10px;
  font-weight: 400;
  letter-spacing: .1em;
  line-height: 1.2;
  text-transform: none;
}

.nav {
  display: flex;
  align-items: center;
  gap: 2px;
  margin-left: auto;
}

.nav__link {
  padding: 9px 13px;
  border-radius: var(--radius-pill);
  color: var(--ink-2);
  font-size: 14.5px;
  font-weight: 500;
  line-height: 1.4;
  white-space: nowrap;
}

.nav__link:hover {
  background: var(--surface-2);
  color: var(--red);
  text-decoration: none;
}

.nav__link[aria-current="page"] {
  background: var(--red-soft);
  color: var(--red-hover);
  font-weight: 700;
}

.header__cta {
  margin-left: 10px;
  flex: 0 0 auto;
}

.nav-toggle {
  display: none;
  width: 46px;
  height: 46px;
  padding: 0;
  border: 1px solid var(--line);
  border-radius: 50%;
  background: var(--white);
  color: var(--ink);
  cursor: pointer;
}

.nav-toggle__box {
  display: grid;
  place-content: center;
  gap: 5px;
  width: 100%;
  height: 100%;
}

.nav-toggle__bar {
  display: block;
  width: 20px;
  height: 2px;
  border-radius: 2px;
  background: currentColor;
  transition: transform var(--dur-fast) var(--ease),
    opacity var(--dur-fast) var(--ease);
}

.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(2) {
  opacity: 0;
}

.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

.nav-drawer {
  position: fixed;
  top: calc(var(--header-h) + 35px);
  right: 0;
  bottom: 0;
  left: 0;
  z-index: 998;
  overflow-y: auto;
  border-top: 1px solid var(--line);
  background: var(--white);
  opacity: 0;
  visibility: hidden;
  transform: translateY(-10px);
  transition: opacity var(--dur-fast) var(--ease),
    visibility var(--dur-fast) var(--ease),
    transform var(--dur-fast) var(--ease);
}

.nav-drawer[data-open="true"] {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.nav-drawer__inner {
  padding: 22px 24px 40px;
}

.nav-drawer__group + .nav-drawer__group {
  margin-top: 18px;
  padding-top: 18px;
  border-top: 1px solid var(--line);
}

.nav-drawer__label {
  margin: 0 0 6px;
  color: var(--ink-4);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: .12em;
  text-transform: uppercase;
}

.nav-drawer__link {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 46px;
  padding: 8px 2px;
  color: var(--ink-2);
  font-size: 16px;
  font-weight: 500;
}

.nav-drawer__link::after {
  color: var(--red);
  font-size: 18px;
  content: "→";
}

.nav-drawer__link[aria-current="page"] {
  color: var(--red);
  font-weight: 700;
}

.nav-drawer__note {
  margin: 24px 0 0;
  padding: 14px 16px;
  border-radius: var(--radius-md);
  background: var(--red-mist);
  color: var(--ink-3);
  font-size: 13px;
  line-height: 1.7;
}

/* ══════════════════════════════════════════
   6. 首页 Hero 与工具
   ══════════════════════════════════════════ */
.hero {
  position: relative;
  overflow: hidden;
  padding: 58px 0 70px;
  border-bottom: 1px solid var(--line);
  background:
    radial-gradient(circle at 88% 8%, rgba(230, 0, 18, .1) 0, rgba(230, 0, 18, 0) 28%),
    radial-gradient(circle at 4% 94%, rgba(230, 0, 18, .06) 0, rgba(230, 0, 18, 0) 34%),
    linear-gradient(180deg, #fff8f8 0%, #ffffff 68%, #ffffff 100%);
  color: var(--ink);
}

.hero::before,
.hero::after {
  position: absolute;
  border: 1px solid rgba(230, 0, 18, .12);
  border-radius: 50%;
  content: "";
  pointer-events: none;
}

.hero::before {
  top: -180px;
  right: -120px;
  width: 520px;
  height: 520px;
}

.hero::after {
  bottom: -260px;
  left: -180px;
  width: 620px;
  height: 620px;
}

.hero__inner {
  position: relative;
  z-index: 1;
}

.hero__title {
  max-width: 900px;
  margin: 0 0 16px;
  color: var(--ink);
  font-size: clamp(2.35rem, 1.5rem + 3vw, 4.35rem);
  font-weight: 800;
  letter-spacing: -.035em;
  line-height: 1.12;
}

.hero__lead {
  max-width: 790px;
  margin: 0 0 32px;
  color: var(--ink-3);
  font-size: clamp(1rem, .94rem + .32vw, 1.19rem);
  line-height: 1.85;
}

.hero__lead strong {
  color: var(--ink);
  font-weight: 700;
}

.hero__meta {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 0 0 30px;
  padding: 0;
  list-style: none;
}

.hero__meta li {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  margin: 0;
  padding: 6px 12px;
  border: 1px solid var(--red-line);
  border-radius: var(--radius-pill);
  background: rgba(255, 255, 255, .72);
  color: var(--ink-3);
  font-size: 12.5px;
  line-height: 1.4;
}

.hero__meta li::before {
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--red);
  content: "";
}

/* 工具卡片 */
.tool-card {
  position: relative;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--white);
  color: var(--ink);
  box-shadow: 0 22px 60px rgba(30, 30, 30, .1), 0 4px 14px rgba(230, 0, 18, .04);
}

.tool-card__top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 18px 24px;
  border-bottom: 1px solid var(--line);
  background: var(--white);
}

.tool-card__status {
  display: flex;
  align-items: center;
  gap: 9px;
  min-width: 0;
  color: var(--ink-2);
  font-size: 13.5px;
  font-weight: 600;
}

.status-dot {
  position: relative;
  display: inline-block;
  width: 8px;
  height: 8px;
  flex: 0 0 auto;
  border-radius: 50%;
  background: var(--red);
}

.status-dot::after {
  position: absolute;
  inset: -4px;
  border: 1px solid rgba(230, 0, 18, .3);
  border-radius: 50%;
  content: "";
}

.tool-card__state {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.tool-card__body {
  padding: 24px;
}

.dropzone {
  position: relative;
  display: grid;
  place-items: center;
  min-height: 300px;
  padding: 24px;
  border: 2px dashed var(--red-line);
  border-radius: var(--radius-md);
  background:
    linear-gradient(var(--red-mist), var(--red-mist)) padding-box,
    repeating-linear-gradient(45deg, rgba(230, 0, 18, .035) 0 8px, transparent 8px 16px);
  cursor: pointer;
  transition: border-color var(--dur-fast) var(--ease),
    background-color var(--dur-fast) var(--ease),
    transform var(--dur-fast) var(--ease);
}

.dropzone:hover,
.dropzone.is-dragover {
  border-color: var(--red);
  background-color: var(--red-soft);
}

.dropzone.is-dragover {
  transform: scale(.995);
}

.dropzone__empty {
  display: flex;
  flex-direction: column;
  align-items: center;
  max-width: 470px;
  text-align: center;
  pointer-events: none;
}

.dropzone__icon {
  display: grid;
  place-items: center;
  width: 72px;
  height: 72px;
  margin-bottom: 18px;
  border-radius: 50%;
  background: var(--white);
  color: var(--red);
  box-shadow: 0 8px 22px rgba(230, 0, 18, .13);
}

.dropzone__icon svg {
  width: 32px;
  height: 32px;
}

.dropzone__title {
  margin: 0 0 6px;
  color: var(--ink);
  font-size: 19px;
  font-weight: 700;
}

.dropzone__desc {
  margin: 0;
  color: var(--ink-3);
  font-size: 14px;
  line-height: 1.7;
}

.dropzone__formats {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 6px;
  margin-top: 16px;
}

.dropzone__formats span {
  padding: 3px 8px;
  border: 1px solid var(--red-line);
  border-radius: var(--radius-sm);
  background: var(--white);
  color: var(--red);
  font-size: 10.5px;
  font-weight: 700;
  letter-spacing: .04em;
  line-height: 1.5;
}

.preview {
  position: relative;
  display: grid;
  place-items: center;
  width: 100%;
  min-height: 260px;
  overflow: hidden;
  border-radius: 10px;
  background-color: #fff;
  background-image:
    linear-gradient(45deg, #f0f0f0 25%, transparent 25%),
    linear-gradient(-45deg, #f0f0f0 25%, transparent 25%),
    linear-gradient(45deg, transparent 75%, #f0f0f0 75%),
    linear-gradient(-45deg, transparent 75%, #f0f0f0 75%);
  background-position: 0 0, 0 10px, 10px -10px, -10px 0;
  background-size: 20px 20px;
}

.preview img {
  display: block;
  max-width: 100%;
  max-height: 480px;
  object-fit: contain;
}

.processing {
  position: absolute;
  inset: 0;
  z-index: 2;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(255, 255, 255, .9);
  backdrop-filter: blur(4px);
}

.processing__toast {
  display: inline-flex;
  align-items: center;
  gap: 11px;
  padding: 13px 20px;
  border: 1px solid var(--line);
  border-radius: var(--radius-pill);
  background: var(--white);
  color: var(--ink-2);
  font-size: 14px;
  font-weight: 600;
  box-shadow: var(--shadow-md);
}

.spinner {
  width: 19px;
  height: 19px;
  border: 2px solid var(--red-line);
  border-top-color: var(--red);
  border-radius: 50%;
  animation: spin .8s linear infinite;
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

.tool-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 18px;
  margin: 14px 0 0;
  padding: 0;
  list-style: none;
  color: var(--ink-4);
  font-size: 12.5px;
  line-height: 1.6;
}

.tool-meta li {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  min-width: 0;
  margin: 0;
}

.tool-meta b {
  display: inline-block;
  max-width: 240px;
  overflow: hidden;
  color: var(--ink-2);
  font-weight: 600;
  text-overflow: ellipsis;
  vertical-align: bottom;
  white-space: nowrap;
}

@media (max-width: 480px) {
  .tool-meta b {
    max-width: 150px;
  }
}

.tool-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 18px;
}

.tool-actions .btn {
  flex: 0 0 auto;
}

.tool-hint {
  display: flex;
  align-items: flex-start;
  gap: 8px;
  min-height: 24px;
  margin: 16px 0 0;
  color: var(--ink-3);
  font-size: 13px;
  line-height: 1.7;
}

.tool-hint::before {
  flex: 0 0 auto;
  width: 15px;
  height: 15px;
  margin-top: 2px;
  border: 1px solid var(--red-line);
  border-radius: 50%;
  color: var(--red);
  font-size: 10px;
  font-weight: 700;
  line-height: 13px;
  text-align: center;
  content: "i";
}

.tool-hint.is-error {
  color: var(--red);
}

.tool-hint.is-error::before {
  border-color: var(--red);
  content: "!";
}

.tool-hint.is-ok {
  color: var(--green);
}

.tool-hint.is-ok::before {
  border-color: var(--green);
  color: var(--green);
  content: "✓";
}

.tool-notes {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
  margin-top: 18px;
  padding-top: 18px;
  border-top: 1px solid var(--line);
}

.tool-note {
  display: flex;
  align-items: flex-start;
  gap: 9px;
  color: var(--ink-4);
  font-size: 12px;
  line-height: 1.6;
}

.tool-note svg {
  flex: 0 0 auto;
  width: 15px;
  height: 15px;
  margin-top: 2px;
  color: var(--red);
}

.hero__chips {
  margin: 18px 0 0;
  justify-content: center;
}

.hero__below {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-top: 22px;
  color: var(--ink-4);
  font-size: 12.5px;
}

.hero__below a {
  color: var(--red);
  text-decoration: underline;
  text-underline-offset: 3px;
}

/* ══════════════════════════════════════════
   7. 信任条
   ══════════════════════════════════════════ */
.trust-strip {
  border-bottom: 1px solid var(--line);
  background: var(--white);
}

.trust-strip__inner {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 0;
}

.trust-item {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 26px 28px;
}

.trust-item + .trust-item {
  border-left: 1px solid var(--line);
}

.trust-item__icon {
  display: grid;
  place-items: center;
  width: 44px;
  height: 44px;
  flex: 0 0 auto;
  border-radius: 50%;
  background: var(--red-mist);
  color: var(--red);
  line-height: 1;
}

.trust-item__icon svg {
  display: block;
  width: 21px;
  height: 21px;
}

.trust-item strong {
  display: block;
  margin-bottom: 2px;
  font-size: 15px;
  line-height: 1.4;
}

.trust-item > div > span {
  display: block;
  color: var(--ink-4);
  font-size: 12.5px;
  line-height: 1.5;
}

/* ══════════════════════════════════════════
   8. 卡片与内容模块
   ══════════════════════════════════════════ */
.card {
  position: relative;
  padding: 28px;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: var(--white);
  transition: transform var(--dur-base) var(--ease),
    box-shadow var(--dur-base) var(--ease),
    border-color var(--dur-base) var(--ease);
}

.card--hover:hover {
  transform: translateY(-4px);
  border-color: var(--red-line);
  box-shadow: var(--shadow-md);
}

.card--soft {
  border-color: transparent;
  background: var(--red-mist);
}

.card--red {
  border-color: transparent;
  background: var(--red);
  color: var(--white);
}

.card--red h3,
.card--red h4 {
  color: var(--white);
}

.card--red p {
  color: rgba(255, 255, 255, .84);
}

.card__icon {
  display: grid;
  place-items: center;
  width: 48px;
  height: 48px;
  margin-bottom: 18px;
  border-radius: 14px;
  background: var(--red-soft);
  color: var(--red);
}

.card__icon svg {
  width: 23px;
  height: 23px;
}

.card--red .card__icon {
  background: rgba(255, 255, 255, .16);
  color: #fff;
}

.card__index {
  display: block;
  margin-bottom: 12px;
  color: var(--red);
  font-family: var(--font-serif);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: .16em;
}

.card h3 {
  margin-bottom: 8px;
}

.card p:last-child {
  margin-bottom: 0;
}

.card__link {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  margin-top: 14px;
  font-size: 13.5px;
  font-weight: 700;
}

.card__link::after {
  content: "→";
  transition: transform var(--dur-fast) var(--ease);
}

.card__link:hover::after {
  transform: translateX(3px);
}

/* 数字步骤 */
.steps {
  counter-reset: step;
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 20px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.step {
  position: relative;
  padding: 26px 24px 24px;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: var(--white);
}

.step::before {
  counter-increment: step;
  content: "0" counter(step);
  display: block;
  margin-bottom: 14px;
  color: var(--red);
  font-family: var(--font-serif);
  font-size: 30px;
  font-weight: 700;
  letter-spacing: .02em;
  line-height: 1;
}

.step h3 {
  margin-bottom: 8px;
  font-size: 17px;
}

.step p {
  margin: 0;
  color: var(--ink-3);
  font-size: 14px;
  line-height: 1.75;
}

.step__tag {
  display: inline-block;
  margin-top: 14px;
  color: var(--red);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: .04em;
}

/* 前后对比演示 */
.compare-visual {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 44px minmax(0, 1fr);
  gap: 14px;
  align-items: center;
}

.compare-panel {
  margin: 0;
}

.compare-panel__frame {
  position: relative;
  display: grid;
  place-items: center;
  aspect-ratio: 4 / 3;
  overflow: hidden;
  border-radius: var(--radius-md);
}

.compare-panel__frame--original {
  background:
    radial-gradient(circle at 28% 26%, #ffd8dc 0 13%, transparent 13.5%),
    radial-gradient(circle at 70% 66%, #ffc1c7 0 9%, transparent 9.5%),
    linear-gradient(145deg, #fff7f7, #ffe3e6);
}

.compare-panel__frame--noise {
  background-color: #171313;
  background-image:
    radial-gradient(circle at 10% 20%, #ff4757 0 2px, transparent 2.5px),
    radial-gradient(circle at 34% 68%, #ffd166 0 2px, transparent 2.5px),
    radial-gradient(circle at 62% 34%, #4ecdc4 0 2px, transparent 2.5px),
    radial-gradient(circle at 82% 78%, #a78bfa 0 2px, transparent 2.5px),
    radial-gradient(circle at 48% 88%, #fff 0 1.5px, transparent 2px),
    radial-gradient(circle at 76% 14%, #ff8fa3 0 1.5px, transparent 2px);
  background-size: 46px 46px, 58px 58px, 38px 38px, 64px 64px, 52px 52px, 42px 42px;
}

.compare-panel__frame svg {
  width: 46%;
  height: auto;
  filter: drop-shadow(0 12px 20px rgba(230, 0, 18, .18));
}

.compare-panel figcaption {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  margin-top: 10px;
  color: var(--ink-3);
  font-size: 12.5px;
}

.compare-panel figcaption b {
  color: var(--ink);
}

.compare-arrow {
  display: grid;
  place-items: center;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--red);
  color: #fff;
  font-size: 19px;
  font-weight: 700;
}

/* 功能清单 */
.check-list {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px 20px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.check-list li {
  position: relative;
  margin: 0;
  padding: 10px 0 10px 28px;
  border-bottom: 1px solid var(--line);
  color: var(--ink-2);
  font-size: 14.5px;
  line-height: 1.7;
}

.check-list li::before {
  position: absolute;
  top: 13px;
  left: 0;
  display: grid;
  place-items: center;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--red-soft);
  color: var(--red);
  font-size: 10px;
  font-weight: 700;
  content: "✓";
}

.check-list--no li::before {
  background: var(--surface);
  color: var(--ink-4);
  content: "×";
}

/* 表格 */
.table-wrap {
  overflow-x: auto;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: var(--white);
  -webkit-overflow-scrolling: touch;
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 14px;
  line-height: 1.65;
}

caption {
  padding: 16px 20px 0;
  color: var(--ink-4);
  font-size: 12.5px;
  text-align: left;
}

th,
td {
  padding: 14px 18px;
  border-bottom: 1px solid var(--line);
  text-align: left;
  vertical-align: top;
}

th {
  background: var(--surface-2);
  color: var(--ink);
  font-size: 12.5px;
  font-weight: 700;
  letter-spacing: .02em;
  white-space: nowrap;
}

tbody tr:last-child td {
  border-bottom: 0;
}

tbody tr:hover td {
  background: var(--red-mist);
}

td strong {
  color: var(--red);
}

.table-note {
  margin: 12px 0 0;
  color: var(--ink-4);
  font-size: 12.5px;
}

/* 提示框 */
.callout {
  display: flex;
  gap: 14px;
  padding: 18px 20px;
  border: 1px solid var(--red-line);
  border-radius: var(--radius-md);
  background: var(--red-mist);
}

.callout__icon {
  display: grid;
  place-items: center;
  width: 34px;
  height: 34px;
  flex: 0 0 auto;
  border-radius: 50%;
  background: var(--red);
  color: #fff;
  font-size: 15px;
  font-weight: 800;
}

.callout h2,
.callout h3,
.callout h4 {
  margin-bottom: 4px;
  font-size: 15px;
}

.callout p:last-child {
  margin-bottom: 0;
}

.callout p {
  color: var(--ink-3);
  font-size: 13.5px;
  line-height: 1.75;
}

.callout--amber {
  border-color: #f0d9a8;
  background: var(--amber-soft);
}

.callout--amber .callout__icon {
  background: var(--amber);
}

/* FAQ */
.faq-list {
  display: grid;
  gap: 12px;
  max-width: 900px;
  margin: 0 auto;
}

.faq-item {
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: var(--white);
  transition: border-color var(--dur-fast) var(--ease),
    box-shadow var(--dur-fast) var(--ease);
}

.faq-item[open] {
  border-color: var(--red-line);
  box-shadow: var(--shadow-sm);
}

.faq-item summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  min-height: 58px;
  padding: 16px 20px;
  color: var(--ink);
  font-size: 15.5px;
  font-weight: 700;
  line-height: 1.55;
  list-style: none;
  cursor: pointer;
}

.faq-item summary::-webkit-details-marker {
  display: none;
}

.faq-item summary::after {
  display: grid;
  place-items: center;
  width: 28px;
  height: 28px;
  flex: 0 0 auto;
  border-radius: 50%;
  background: var(--red-soft);
  color: var(--red);
  font-size: 18px;
  font-weight: 400;
  line-height: 1;
  content: "+";
  transition: transform var(--dur-fast) var(--ease);
}

.faq-item[open] summary::after {
  transform: rotate(45deg);
}

.faq-item__body {
  padding: 0 20px 20px;
  color: var(--ink-3);
  font-size: 14.5px;
  line-height: 1.85;
}

.faq-item__body p:last-child {
  margin-bottom: 0;
}

/* 链接卡 */
.link-card {
  display: flex;
  flex-direction: column;
  min-height: 100%;
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: var(--white);
  color: var(--ink);
  transition: transform var(--dur-base) var(--ease),
    border-color var(--dur-base) var(--ease),
    box-shadow var(--dur-base) var(--ease);
}

.link-card:hover {
  transform: translateY(-4px);
  border-color: var(--red-line);
  color: var(--ink);
  box-shadow: var(--shadow-md);
  text-decoration: none;
}

.link-card__kicker {
  margin-bottom: 10px;
  color: var(--red);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: .12em;
  text-transform: uppercase;
}

.link-card h3 {
  margin-bottom: 8px;
  font-size: 18px;
}

.link-card p {
  margin: 0 0 18px;
  color: var(--ink-3);
  font-size: 13.5px;
  line-height: 1.75;
}

.link-card__arrow {
  margin-top: auto;
  color: var(--red);
  font-size: 13px;
  font-weight: 700;
}

.link-card__arrow::after {
  margin-left: 5px;
  content: "→";
}

/* CTA 区块 */
.cta-band {
  position: relative;
  overflow: hidden;
  padding: 58px 0;
  background:
    radial-gradient(circle at 92% 12%, rgba(255, 255, 255, .14) 0, transparent 28%),
    linear-gradient(132deg, #ed0013, #c50010);
  color: #fff;
}

.cta-band::after {
  position: absolute;
  right: -90px;
  bottom: -140px;
  width: 360px;
  height: 360px;
  border: 1px solid rgba(255, 255, 255, .18);
  border-radius: 50%;
  content: "";
}

.cta-band__inner {
  position: relative;
  z-index: 1;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 32px;
}

.cta-band h2 {
  margin-bottom: 6px;
  color: #fff;
}

.cta-band p {
  margin: 0;
  color: rgba(255, 255, 255, .86);
  font-size: 15px;
}

.cta-band__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  flex: 0 0 auto;
}

/* 数字统计 */
.stat-row {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 24px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.stat {
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: var(--white);
  text-align: center;
}

.stat b {
  display: block;
  margin-bottom: 4px;
  color: var(--red);
  font-family: var(--font-serif);
  font-size: 38px;
  font-weight: 700;
  line-height: 1.1;
}

.stat span {
  color: var(--ink-3);
  font-size: 13px;
}

/* ══════════════════════════════════════════
   9. 内页 Hero、面包屑
   ══════════════════════════════════════════ */
.page-hero {
  position: relative;
  overflow: hidden;
  padding: 46px 0 54px;
  border-bottom: 1px solid var(--line);
  background:
    radial-gradient(circle at 90% 0, rgba(230, 0, 18, .08) 0, transparent 34%),
    linear-gradient(180deg, var(--red-mist) 0%, var(--white) 100%);
}

.page-hero::after {
  position: absolute;
  top: -120px;
  right: -80px;
  width: 360px;
  height: 360px;
  border: 1px solid rgba(230, 0, 18, .1);
  border-radius: 50%;
  content: "";
  pointer-events: none;
}

.page-hero__inner {
  position: relative;
  z-index: 1;
}

.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 7px;
  margin: 0 0 22px;
  padding: 0;
  list-style: none;
  color: var(--ink-4);
  font-size: 12.5px;
  line-height: 1.5;
}

.breadcrumb li {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  margin: 0;
}

.breadcrumb li + li::before {
  color: var(--line-strong);
  content: "/";
}

.breadcrumb a {
  color: var(--ink-3);
}

.breadcrumb a:hover {
  color: var(--red);
}

.breadcrumb [aria-current="page"] {
  color: var(--red);
  font-weight: 600;
}

.page-hero h1 {
  max-width: 960px;
  margin-bottom: 14px;
  font-size: clamp(2rem, 1.55rem + 1.8vw, 3rem);
  letter-spacing: -.025em;
  line-height: 1.2;
}

.page-hero__lead {
  max-width: 820px;
  margin-bottom: 0;
  color: var(--ink-3);
  font-size: 17px;
  line-height: 1.85;
}

.page-hero__meta {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 20px 0 0;
  padding: 0;
  list-style: none;
}

.page-hero__meta li {
  margin: 0;
}

.page-hero__meta span {
  display: inline-flex;
  align-items: center;
  padding: 5px 10px;
  border: 1px solid var(--red-line);
  border-radius: var(--radius-pill);
  background: rgba(255, 255, 255, .7);
  color: var(--red);
  font-size: 11.5px;
  font-weight: 600;
  line-height: 1.5;
}

/* 内页布局与正文 */
.page-layout {
  display: grid;
  grid-template-columns: 250px minmax(0, 1fr);
  gap: 56px;
  align-items: start;
  padding: 56px 0 76px;
}

.page-layout--single {
  display: block;
  max-width: var(--wrap-narrow);
  margin-inline: auto;
}

.toc {
  position: sticky;
  top: calc(var(--header-h) + 24px);
  padding: 20px;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: var(--white);
}

.toc__title {
  margin: 0 0 10px;
  color: var(--ink-4);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: .12em;
  text-transform: uppercase;
}

.toc ol {
  margin: 0;
  padding: 0;
  list-style: none;
  counter-reset: toc;
}

.toc li {
  counter-increment: toc;
  margin: 0;
}

.toc a {
  display: flex;
  gap: 9px;
  padding: 7px 0;
  color: var(--ink-3);
  font-size: 13px;
  line-height: 1.55;
}

.toc a::before {
  color: var(--red);
  font-family: var(--font-serif);
  font-size: 11px;
  font-weight: 700;
  content: counter(toc, decimal-leading-zero);
}

.toc a:hover {
  color: var(--red);
  text-decoration: none;
}

.prose {
  min-width: 0;
  color: var(--ink-2);
  font-size: 16px;
  line-height: 1.9;
}

.prose > :first-child {
  margin-top: 0;
}

.prose h2 {
  margin: 2.2em 0 .7em;
  padding-top: .2em;
  font-size: clamp(1.45rem, 1.25rem + .7vw, 1.85rem);
  scroll-margin-top: calc(var(--header-h) + 24px);
}

.prose h2:first-child {
  margin-top: 0;
}

.prose h3 {
  margin: 1.7em 0 .55em;
  font-size: 1.16rem;
  scroll-margin-top: calc(var(--header-h) + 24px);
}

.prose p,
.prose li {
  color: var(--ink-2);
}

.prose ul,
.prose ol {
  padding-left: 1.5em;
}

.prose li + li {
  margin-top: .4em;
}

.prose a {
  color: var(--red);
  text-decoration: underline;
  text-underline-offset: 3px;
  text-decoration-thickness: 1px;
}

.prose a:hover {
  color: var(--red-hover);
}

.prose strong {
  color: var(--ink);
}

.prose h2 + p,
.prose h3 + p {
  margin-top: 0;
}

.prose .anchor-offset {
  display: block;
  position: relative;
  top: calc(-1 * var(--header-h) - 24px);
  visibility: hidden;
}

.prose figure {
  margin: 1.8em 0;
}

.prose figure img {
  display: block;
  width: 100%;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
}

.prose figcaption {
  margin-top: 8px;
  color: var(--ink-4);
  font-size: 12.5px;
  line-height: 1.6;
  text-align: center;
}

.prose .table-wrap {
  margin: 1.6em 0;
}

.prose blockquote {
  font-size: 15px;
}

.prose .callout {
  margin: 1.6em 0;
}

.prose hr {
  margin: 2.6rem 0;
}

.prose .lead {
  color: var(--ink-3);
}

/* 文内小卡片 */
.mini-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
  margin: 1.6em 0;
}

.mini-card {
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: var(--white);
}

.mini-card h3,
.mini-card h4 {
  margin-bottom: 4px;
  font-size: 14.5px;
}

.mini-card p {
  margin: 0;
  color: var(--ink-3);
  font-size: 13px;
  line-height: 1.7;
}

/* 文章头部 */
.article-hero {
  padding: 46px 0 42px;
}

.article-hero h1 {
  max-width: 900px;
}

.article-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px 18px;
  margin-top: 20px;
  color: var(--ink-4);
  font-size: 12.5px;
}

.article-meta span {
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.article-meta span + span::before {
  width: 3px;
  height: 3px;
  border-radius: 50%;
  background: var(--line-strong);
  content: "";
}

.article-footer {
  margin-top: 44px;
  padding-top: 26px;
  border-top: 1px solid var(--line);
}

.author-box {
  display: flex;
  gap: 16px;
  align-items: flex-start;
  padding: 20px;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: var(--surface-3);
}

.author-box__mark {
  width: 48px;
  height: 48px;
  flex: 0 0 auto;
}

.author-box h3 {
  margin-bottom: 4px;
  font-size: 15px;
}

.author-box p {
  margin: 0;
  color: var(--ink-4);
  font-size: 13px;
  line-height: 1.7;
}

.related-links {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
  margin: 24px 0 0;
  padding: 0;
  list-style: none;
}

.related-links li {
  margin: 0;
}

.related-links a {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  min-height: 54px;
  padding: 12px 16px;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: var(--white);
  color: var(--ink-2);
  font-size: 13.5px;
  font-weight: 600;
  line-height: 1.5;
  text-decoration: none;
}

.related-links a::after {
  flex: 0 0 auto;
  color: var(--red);
  content: "→";
}

.related-links a:hover {
  border-color: var(--red-line);
  background: var(--red-mist);
  color: var(--red);
  text-decoration: none;
}

/* 文章卡片列表 */
.article-list {
  display: grid;
  gap: 16px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.article-card {
  display: grid;
  grid-template-columns: 110px minmax(0, 1fr) auto;
  gap: 24px;
  align-items: center;
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: var(--white);
  transition: transform var(--dur-base) var(--ease),
    border-color var(--dur-base) var(--ease),
    box-shadow var(--dur-base) var(--ease);
}

.article-card:hover {
  transform: translateY(-3px);
  border-color: var(--red-line);
  box-shadow: var(--shadow-md);
}

.article-card__date {
  color: var(--red);
  font-family: var(--font-serif);
  font-size: 14px;
  font-weight: 700;
  line-height: 1.4;
}

.article-card__date span {
  display: block;
  margin-top: 4px;
  color: var(--ink-4);
  font-family: var(--font-sans);
  font-size: 11px;
  font-weight: 400;
}

.article-card h2,
.article-card h3 {
  margin-bottom: 5px;
  font-size: 19px;
}

.article-card h2 a,
.article-card h3 a {
  color: var(--ink);
}

.article-card h2 a:hover,
.article-card h3 a:hover {
  color: var(--red);
  text-decoration: none;
}

.article-card p {
  margin: 0;
  color: var(--ink-3);
  font-size: 13.5px;
  line-height: 1.7;
}

.article-card__arrow {
  display: grid;
  place-items: center;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--red-soft);
  color: var(--red);
  font-size: 17px;
}

/* 算法演示 */
.curve-demo {
  margin: 1.8em 0;
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: var(--white);
}

.curve-demo__head {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-end;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 18px;
}

.curve-demo__head h3 {
  margin: 0;
  font-size: 16px;
}

.curve-demo__head span {
  color: var(--ink-4);
  font-size: 12px;
}

.curve-demo__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 34px minmax(0, 1fr);
  gap: 12px;
  align-items: center;
}

.curve-demo__panel {
  min-width: 0;
}

.curve-demo__panel canvas {
  display: block;
  width: 100%;
  height: auto;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: #fff;
  image-rendering: pixelated;
}

.curve-demo__panel p {
  margin: 7px 0 0;
  color: var(--ink-4);
  font-size: 11.5px;
  text-align: center;
}

.curve-demo__arrow {
  display: grid;
  place-items: center;
  width: 34px;
  height: 34px;
  border-radius: 50%;
  background: var(--red-soft);
  color: var(--red);
  font-size: 16px;
}

.curve-demo__controls {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px;
  margin-top: 18px;
  padding-top: 18px;
  border-top: 1px solid var(--line);
}

.curve-demo__controls label {
  display: flex;
  flex: 1 1 260px;
  align-items: center;
  gap: 12px;
  color: var(--ink-3);
  font-size: 12.5px;
}

.curve-demo__controls input[type="range"] {
  flex: 1;
  accent-color: var(--red);
}

.curve-demo__value {
  min-width: 74px;
  color: var(--red);
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 700;
  text-align: right;
}

.curve-demo__note {
  margin: 12px 0 0;
  color: var(--ink-4);
  font-size: 12px;
  line-height: 1.7;
}

/* ══════════════════════════════════════════
   10. 页脚
   ══════════════════════════════════════════ */
.site-footer {
  background: #171313;
  color: rgba(255, 255, 255, .72);
  font-size: 13px;
}

.site-footer__top {
  display: grid;
  grid-template-columns: 1.6fr 1fr 1fr 1fr;
  gap: 40px;
  padding: 54px 0 42px;
}

.footer-brand {
  max-width: 340px;
}

.footer-brand .brand {
  margin-bottom: 14px;
  color: #fff;
}

.footer-brand .brand__name {
  color: #fff;
}

.footer-brand .brand__en {
  color: rgba(255, 255, 255, .45);
}

.footer-brand p {
  margin: 0 0 16px;
  color: rgba(255, 255, 255, .58);
  font-size: 12.5px;
  line-height: 1.8;
}

.footer-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.footer-tags li {
  margin: 0;
  padding: 4px 9px;
  border: 1px solid rgba(255, 255, 255, .14);
  border-radius: var(--radius-pill);
  color: rgba(255, 255, 255, .58);
  font-size: 10.5px;
  line-height: 1.5;
}

.footer-col h3 {
  margin: 3px 0 14px;
  color: #fff;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: .08em;
  text-transform: uppercase;
}

.footer-col ul {
  margin: 0;
  padding: 0;
  list-style: none;
}

.footer-col li {
  margin: 0;
}

.footer-col a {
  display: inline-block;
  padding: 4px 0;
  color: rgba(255, 255, 255, .62);
  font-size: 12.5px;
  line-height: 1.6;
}

.footer-col a:hover {
  color: #fff;
  text-decoration: none;
}

.site-footer__bottom {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 18px 0 26px;
  border-top: 1px solid rgba(255, 255, 255, .1);
  color: rgba(255, 255, 255, .62);
  font-size: 11.5px;
  line-height: 1.6;
}

.site-footer__bottom p {
  margin: 0;
}

.site-footer__bottom a {
  color: rgba(255, 255, 255, .76);
  text-decoration: underline;
  text-underline-offset: 2px;
}

.site-footer__bottom a:hover {
  color: #fff;
}

.footer-dot {
  display: inline-block;
  width: 5px;
  height: 5px;
  margin: 0 7px;
  border-radius: 50%;
  background: var(--red);
  vertical-align: middle;
}

/* ══════════════════════════════════════════
   11. 404
   ══════════════════════════════════════════ */
.error-page {
  display: grid;
  place-items: center;
  min-height: 62vh;
  padding: 70px 0;
  text-align: center;
}

.error-code {
  margin: 0;
  color: var(--red);
  font-family: var(--font-serif);
  font-size: clamp(6rem, 4rem + 9vw, 12rem);
  font-weight: 700;
  letter-spacing: -.04em;
  line-height: .9;
}

.error-page h1 {
  margin-top: 18px;
}

.error-page p {
  max-width: 560px;
  margin-inline: auto;
  color: var(--ink-3);
}

.error-actions {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 12px;
  margin-top: 24px;
}

/* ══════════════════════════════════════════
   12. 响应式
   ══════════════════════════════════════════ */
@media (max-width: 1080px) {
  .nav__link {
    padding: 9px 10px;
    font-size: 14px;
  }

  .header__cta {
    display: none;
  }

  .page-layout {
    grid-template-columns: 220px minmax(0, 1fr);
    gap: 36px;
  }

  .site-footer__top {
    grid-template-columns: 1.4fr 1fr 1fr;
  }

  .footer-brand {
    grid-column: 1 / -1;
    max-width: 560px;
  }
}

@media (max-width: 900px) {
  :root {
    --header-h: 68px;
  }

  .nav {
    display: none;
  }

  .nav-toggle {
    display: block;
  }

  .hero {
    padding: 44px 0 54px;
  }

  .hero__title {
    font-size: clamp(2.2rem, 1.6rem + 3vw, 3.4rem);
  }

  .tool-card__body {
    padding: 18px;
  }

  .dropzone {
    min-height: 260px;
  }

  .grid--3,
  .grid--4,
  .steps {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .split {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .trust-strip__inner {
    grid-template-columns: 1fr;
  }

  .trust-item {
    padding: 18px 20px;
  }

  .trust-item + .trust-item {
    border-top: 1px solid var(--line);
    border-left: 0;
  }

  .page-layout {
    display: block;
    padding: 40px 0 60px;
  }

  .toc {
    position: static;
    margin-bottom: 30px;
  }

  .toc ol {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 0 20px;
  }

  .cta-band__inner {
    display: block;
  }

  .cta-band__actions {
    margin-top: 22px;
  }

  .article-card {
    grid-template-columns: 86px minmax(0, 1fr) auto;
    gap: 16px;
  }

  .section {
    padding: 60px 0;
  }
}

@media (max-width: 720px) {
  .wrap,
  .wrap--narrow {
    width: min(100% - 32px, var(--wrap));
  }

  .notice-bar {
    font-size: 11px;
  }

  .notice-bar__inner {
    gap: 7px;
    padding: 7px 0;
  }

  .brand__mark {
    width: 34px;
    height: 34px;
  }

  .brand__name {
    font-size: 16px;
  }

  .brand__en {
    font-size: 9px;
  }

  .hero {
    padding: 36px 0 46px;
  }

  .hero__lead {
    margin-bottom: 24px;
    font-size: 15.5px;
  }

  .hero__meta {
    margin-bottom: 22px;
  }

  .hero__meta li {
    font-size: 11.5px;
  }

  .tool-card {
    border-radius: var(--radius-md);
  }

  .tool-card__top {
    padding: 14px 16px;
  }

  .tool-card__status {
    font-size: 12.5px;
  }

  .tool-card__body {
    padding: 14px;
  }

  .dropzone {
    min-height: 230px;
    padding: 18px 14px;
  }

  .dropzone__icon {
    width: 58px;
    height: 58px;
    margin-bottom: 14px;
  }

  .dropzone__icon svg {
    width: 26px;
    height: 26px;
  }

  .dropzone__title {
    font-size: 17px;
  }

  .preview {
    min-height: 210px;
  }

  .preview img {
    max-height: 360px;
  }

  .tool-actions {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 8px;
  }

  .tool-actions .btn {
    width: 100%;
    min-height: 44px;
    padding: 9px 12px;
    font-size: 13.5px;
  }

  .tool-notes {
    grid-template-columns: 1fr;
    gap: 9px;
  }

  .tool-note {
    font-size: 11.5px;
  }

  .hero__chips {
    justify-content: flex-start;
  }

  .grid,
  .grid--2,
  .grid--3,
  .grid--4 {
    grid-template-columns: 1fr;
    gap: 16px;
  }

  .steps {
    grid-template-columns: 1fr;
    gap: 12px;
  }

  .step {
    padding: 22px 20px;
  }

  .stat-row {
    grid-template-columns: 1fr;
    gap: 12px;
  }

  .check-list {
    grid-template-columns: 1fr;
  }

  .compare-visual {
    grid-template-columns: 1fr;
    gap: 10px;
  }

  .compare-arrow {
    width: 36px;
    height: 36px;
    margin: 0 auto;
    transform: rotate(90deg);
  }

  .compare-panel__frame {
    aspect-ratio: 16 / 10;
  }

  .section {
    padding: 48px 0;
  }

  .section--tight {
    padding: 34px 0;
  }

  .section-head {
    margin-bottom: 24px;
  }

  .section-head p {
    font-size: 15px;
    line-height: 1.8;
  }

  .card {
    padding: 22px;
  }

  .page-hero {
    padding: 32px 0 38px;
  }

  .page-hero__lead {
    font-size: 15px;
  }

  .breadcrumb {
    margin-bottom: 16px;
    font-size: 11.5px;
  }

  .prose {
    font-size: 15.5px;
    line-height: 1.85;
  }

  .prose h2 {
    margin-top: 1.9em;
  }

  .toc ol {
    grid-template-columns: 1fr;
  }

  .mini-grid {
    grid-template-columns: 1fr;
  }

  .related-links {
    grid-template-columns: 1fr;
  }

  .article-card {
    grid-template-columns: 1fr auto;
    gap: 10px 14px;
    padding: 20px;
  }

  .article-card__date {
    grid-column: 1 / -1;
    display: flex;
    align-items: center;
    gap: 8px;
  }

  .article-card__date span {
    margin: 0;
  }

  .article-card h2,
  .article-card h3 {
    font-size: 17px;
  }

  .article-card p {
    grid-column: 1 / -1;
  }

  .article-card__arrow {
    grid-column: 2;
    grid-row: 2;
    width: 34px;
    height: 34px;
    font-size: 15px;
  }

  .curve-demo {
    padding: 16px;
  }

  .curve-demo__grid {
    grid-template-columns: 1fr;
    gap: 10px;
  }

  .curve-demo__arrow {
    margin: 0 auto;
    transform: rotate(90deg);
  }

  .curve-demo__controls {
    display: block;
  }

  .curve-demo__controls label {
    display: flex;
    margin-bottom: 10px;
  }

  .curve-demo__value {
    display: block;
    text-align: left;
  }

  .cta-band {
    padding: 42px 0;
  }

  .cta-band__actions .btn {
    flex: 1 1 100%;
  }

  .site-footer__top {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 28px 24px;
    padding: 40px 0 30px;
  }

  .footer-brand {
    grid-column: 1 / -1;
  }

  .site-footer__bottom {
    display: block;
    padding: 16px 0 22px;
  }

  .site-footer__bottom p + p {
    margin-top: 5px;
  }

  .error-page {
    min-height: 55vh;
    padding: 50px 0;
  }
}

@media (max-width: 420px) {
  .tool-actions {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .tool-actions #downloadBtn {
    grid-column: 1 / -1;
  }

  .tool-card__top .badge {
    display: none;
  }

  .hero__meta {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 6px;
  }

  .hero__meta li {
    justify-content: center;
  }

  .site-footer__top {
    grid-template-columns: 1fr;
  }

  .footer-brand {
    grid-column: auto;
  }
}

/* ══════════════════════════════════════════
   13. 动效与打印
   ══════════════════════════════════════════ */
@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    animation-duration: .01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .01ms !important;
  }
}

@media print {
  .notice-bar,
  .site-header,
  .site-footer,
  .tool-card,
  .nav-drawer,
  .cta-band,
  .skip-link {
    display: none !important;
  }

  body {
    color: #000;
    background: #fff;
  }

  .page-hero,
  .section {
    padding: 16px 0;
    background: none;
  }

  .wrap,
  .wrap--narrow {
    width: 100%;
  }

  a {
    color: #000;
    text-decoration: underline;
  }
}