/* ==========================================================================
   selandia.top — 设计系统
   单文件样式表，无外部依赖、无网络字体。
   层叠顺序：reset → tokens → base → layout → components → motion → utils
   ========================================================================== */

@layer reset, tokens, base, layout, components, motion, utils;

/* ==========================================================================
   1. Reset
   ========================================================================== */
@layer reset {

  *,
  *::before,
  *::after {
    box-sizing: border-box;
  }

  * {
    margin: 0;
  }

  html {
    -webkit-text-size-adjust: 100%;
    scroll-behavior: smooth;
    scrollbar-gutter: stable;
  }

  body {
    min-height: 100dvh;
    -webkit-font-smoothing: antialiased;
    text-rendering: optimizeLegibility;
  }

  img,
  picture,
  svg,
  video {
    display: block;
    max-width: 100%;
  }

  input,
  button,
  textarea,
  select {
    font: inherit;
    color: inherit;
  }

  button {
    background: none;
    border: 0;
    cursor: pointer;
  }

  a {
    color: inherit;
    text-decoration: none;
  }

  ul,
  ol {
    padding: 0;
    list-style: none;
  }

  :focus-visible {
    outline: 2px solid var(--focus);
    outline-offset: 3px;
    border-radius: 4px;
  }

  ::selection {
    background: color-mix(in oklab, var(--a2) 45%, transparent);
    color: var(--text);
  }
}

/* ==========================================================================
   2. Design tokens
   ========================================================================== */
@layer tokens {
  :root {
    /* 排版 */
    --font-sans: "Inter", "Segoe UI Variable Text", "Segoe UI", system-ui,
      "PingFang SC", "HarmonyOS Sans SC", "Source Han Sans SC",
      "Microsoft YaHei", sans-serif;
    --font-mono: ui-monospace, "Cascadia Code", "JetBrains Mono", "SF Mono",
      Consolas, "Liberation Mono", monospace;

    /* 尺寸节奏 */
    --wrap: 1120px;
    --wrap-narrow: 760px;
    --gutter: clamp(1.15rem, 4vw, 2.5rem);
    --section-y: clamp(4.5rem, 10vw, 8.5rem);

    --r-xs: 8px;
    --r-sm: 12px;
    --r-md: 18px;
    --r-lg: 26px;
    --r-full: 999px;

    /* 动效令牌 */
    --t-1: 120ms;
    --t-2: 220ms;
    --t-3: 380ms;
    --t-4: 640ms;
    --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
    --ease-in-out: cubic-bezier(0.65, 0, 0.35, 1);
    --ease-spring: cubic-bezier(0.34, 1.4, 0.64, 1);

    /* 品牌强调色（三色渐变，源自樱粉 / 紫罗兰） */
    --a1: #8b7cf6;
    --a2: #f472b6;
    --a3: #38bdf8;
    --grad: linear-gradient(115deg, var(--a1) 0%, var(--a2) 52%, var(--a3) 100%);
    --focus: #8b7cf6;
  }

  /* ---- 深色（默认） ---- */
  :root,
  [data-theme="dark"] {
    color-scheme: dark;

    --bg: #0a0c11;
    --bg-elev: #10131a;
    --surface: rgba(255, 255, 255, 0.038);
    --surface-hi: rgba(255, 255, 255, 0.072);
    --line: rgba(255, 255, 255, 0.085);
    --line-hi: rgba(255, 255, 255, 0.16);

    --text: #eceff6;
    --text-dim: #a3abbc;
    --text-mute: #737d8f;

    --shadow-1: 0 1px 2px rgba(0, 0, 0, 0.5);
    --shadow-2: 0 18px 40px -22px rgba(0, 0, 0, 0.85);
    --shadow-glow: 0 24px 60px -28px rgba(139, 124, 246, 0.55);

    --header-bg: rgba(10, 12, 17, 0.72);
    --code-bg: #0d1017;
    --hero-veil: rgba(10, 12, 17, 0.55);

    /* 背景氛围光强度 */
    --blob-a: 26%;
    --blob-b: 20%;
    --blob-c: 15%;
    --halo: 30%;
  }

  /* ---- 浅色 ---- */
  [data-theme="light"] {
    color-scheme: light;

    --bg: #f4f5f9;
    --bg-elev: #ffffff;
    --surface: #ffffff;
    --surface-hi: #ffffff;
    --line: rgba(18, 22, 34, 0.11);
    --line-hi: rgba(18, 22, 34, 0.22);

    --text: #10141c;
    --text-dim: #4a5261;
    --text-mute: #737b8a;

    --shadow-1: 0 1px 2px rgba(18, 22, 34, 0.05);
    --shadow-2: 0 16px 36px -22px rgba(18, 22, 34, 0.3);
    --shadow-glow: 0 22px 48px -26px rgba(109, 92, 231, 0.45);

    --a1: #6a56e0;
    --a2: #d93f7f;
    --a3: #0b8fd4;
    --focus: #6a56e0;

    --header-bg: rgba(248, 249, 252, 0.78);
    --code-bg: #171b26;
    --hero-veil: rgba(244, 245, 249, 0.35);

    --blob-a: 12%;
    --blob-b: 9%;
    --blob-c: 7%;
    --halo: 16%;
  }
}

/* ==========================================================================
   3. Base
   ========================================================================== */
@layer base {

  body {
    font-family: var(--font-sans);
    font-size: clamp(0.975rem, 0.94rem + 0.18vw, 1.0625rem);
    line-height: 1.78;
    color: var(--text);
    background-color: var(--bg);
    overflow-x: clip;
    text-underline-offset: 0.22em;
  }

  /* 背景氛围层：三团柔光 + 极淡网格，纯 CSS，无滤镜开销 */
  body::before {
    content: "";
    position: fixed;
    inset: 0;
    z-index: -2;
    pointer-events: none;
    background:
      radial-gradient(46rem 34rem at 12% -8%, color-mix(in oklab, var(--a1) var(--blob-a), transparent), transparent 62%),
      radial-gradient(40rem 30rem at 92% 4%, color-mix(in oklab, var(--a2) var(--blob-b), transparent), transparent 60%),
      radial-gradient(48rem 32rem at 50% 108%, color-mix(in oklab, var(--a3) var(--blob-c), transparent), transparent 64%);
  }

  body::after {
    content: "";
    position: fixed;
    inset: 0;
    z-index: -1;
    pointer-events: none;
    opacity: 0.5;
    background-image:
      linear-gradient(to right, var(--line) 1px, transparent 1px),
      linear-gradient(to bottom, var(--line) 1px, transparent 1px);
    background-size: 68px 68px;
    mask-image: radial-gradient(72% 58% at 50% 0%, #000 0%, transparent 78%);
    -webkit-mask-image: radial-gradient(72% 58% at 50% 0%, #000 0%, transparent 78%);
  }

  h1,
  h2,
  h3,
  h4 {
    line-height: 1.18;
    letter-spacing: -0.021em;
    font-weight: 750;
    text-wrap: balance;
  }

  h1 {
    font-size: clamp(2.25rem, 1.35rem + 3.9vw, 4rem);
    letter-spacing: -0.035em;
  }

  h2 {
    font-size: clamp(1.65rem, 1.15rem + 1.7vw, 2.5rem);
    letter-spacing: -0.028em;
  }

  h3 {
    font-size: clamp(1.12rem, 1.03rem + 0.4vw, 1.35rem);
  }

  h4 {
    font-size: 1rem;
  }

  p {
    text-wrap: pretty;
  }

  strong {
    font-weight: 700;
    color: var(--text);
  }

  code,
  kbd,
  pre,
  samp {
    font-family: var(--font-mono);
    font-size: 0.875em;
    font-feature-settings: "liga" 0;
  }

  kbd {
    display: inline-block;
    padding: 0.15em 0.5em;
    border: 1px solid var(--line-hi);
    border-bottom-width: 2px;
    border-radius: 6px;
    background: var(--surface-hi);
    font-size: 0.78em;
    line-height: 1.6;
    color: var(--text);
    white-space: nowrap;
  }

  /* 正文内的行内代码 */
  :not(pre) > code {
    padding: 0.16em 0.42em;
    border: 1px solid var(--line);
    border-radius: 6px;
    background: var(--surface);
    color: color-mix(in oklab, var(--a2) 72%, var(--text));
    white-space: nowrap;
  }

  ::-webkit-scrollbar {
    width: 10px;
    height: 10px;
  }

  ::-webkit-scrollbar-track {
    background: transparent;
  }

  ::-webkit-scrollbar-thumb {
    background: var(--line-hi);
    border: 3px solid transparent;
    border-radius: 99px;
    background-clip: content-box;
  }

  ::-webkit-scrollbar-thumb:hover {
    background: color-mix(in oklab, var(--a1) 60%, var(--line-hi));
    background-clip: content-box;
  }
}

/* ==========================================================================
   4. Layout
   ========================================================================== */
@layer layout {

  .wrap {
    width: min(100% - var(--gutter) * 2, var(--wrap));
    margin-inline: auto;
  }

  .wrap--narrow {
    width: min(100% - var(--gutter) * 2, var(--wrap-narrow));
    margin-inline: auto;
  }

  .section {
    padding-block: var(--section-y);
  }

  .section--tight {
    padding-block: clamp(2.5rem, 6vw, 4.5rem);
  }

  main {
    display: block;
  }

  .stack > * + * {
    margin-top: var(--gap, 1rem);
  }

  .skip-link {
    position: fixed;
    top: -100px;
    left: 1rem;
    z-index: 999;
    padding: 0.6rem 1rem;
    border-radius: var(--r-sm);
    background: var(--bg-elev);
    border: 1px solid var(--line-hi);
    transition: top var(--t-2) var(--ease-out);
  }

  .skip-link:focus {
    top: 1rem;
  }
}

/* ==========================================================================
   5. Components
   ========================================================================== */
@layer components {

  /* ---------- 滚动进度条 ---------- */
  .progress {
    position: fixed;
    inset-block-start: 0;
    inset-inline: 0;
    z-index: 60;
    height: 2px;
    transform-origin: 0 50%;
    background: var(--grad);
    scale: 0 1;
  }

  @supports (animation-timeline: scroll()) {
    .progress {
      animation: progress-grow linear both;
      animation-timeline: scroll(root block);
    }

    @keyframes progress-grow {
      to {
        scale: 1 1;
      }
    }
  }

  /* ---------- 顶栏 ---------- */
  .site-header {
    position: sticky;
    inset-block-start: 0;
    z-index: 50;
    background: transparent;
    transition: background var(--t-3) var(--ease-out),
      border-color var(--t-3) var(--ease-out),
      box-shadow var(--t-3) var(--ease-out);
    border-block-end: 1px solid transparent;
  }

  .site-header.is-scrolled {
    background: var(--header-bg);
    -webkit-backdrop-filter: blur(16px) saturate(160%);
    backdrop-filter: blur(16px) saturate(160%);
    border-block-end-color: var(--line);
    box-shadow: var(--shadow-1);
  }

  .site-header__inner {
    display: flex;
    align-items: center;
    gap: 1rem;
    min-height: 66px;
  }

  .brand {
    display: inline-flex;
    align-items: center;
    gap: 0.6rem;
    font-weight: 700;
    letter-spacing: -0.01em;
    margin-inline-end: auto;
  }

  .brand__mark {
    display: grid;
    place-items: center;
    width: 30px;
    height: 30px;
    border-radius: 9px;
    background: var(--grad);
    color: #fff;
    font-size: 0.82rem;
    font-weight: 800;
    letter-spacing: 0;
    box-shadow: var(--shadow-glow);
    transition: transform var(--t-3) var(--ease-spring);
  }

  .brand:hover .brand__mark {
    transform: rotate(-8deg) scale(1.08);
  }

  .brand__name {
    font-size: 0.98rem;
  }

  .brand__sub {
    color: var(--text-mute);
    font-weight: 500;
  }

  .nav {
    display: flex;
    align-items: center;
    gap: 0.35rem;
  }

  .nav a {
    position: relative;
    padding: 0.45rem 0.7rem;
    border-radius: var(--r-full);
    font-size: 0.92rem;
    color: var(--text-dim);
    transition: color var(--t-2) var(--ease-out),
      background var(--t-2) var(--ease-out);
  }

  .nav a:hover {
    color: var(--text);
    background: var(--surface-hi);
  }

  .nav a[aria-current="page"] {
    color: var(--text);
  }

  .nav a[aria-current="page"]::after {
    content: "";
    position: absolute;
    inset-inline: 0.7rem;
    inset-block-end: 0.18rem;
    height: 2px;
    border-radius: 2px;
    background: var(--grad);
  }

  .icon-btn {
    display: grid;
    place-items: center;
    width: 38px;
    height: 38px;
    border-radius: var(--r-full);
    border: 1px solid var(--line);
    background: var(--surface);
    color: var(--text-dim);
    transition: color var(--t-2) var(--ease-out),
      border-color var(--t-2) var(--ease-out),
      background var(--t-2) var(--ease-out),
      transform var(--t-2) var(--ease-spring);
  }

  .icon-btn:hover {
    color: var(--text);
    border-color: var(--line-hi);
    background: var(--surface-hi);
    transform: translateY(-1px);
  }

  .icon-btn:active {
    transform: scale(0.93);
  }

  .icon-btn svg {
    width: 18px;
    height: 18px;
  }

  [data-theme="dark"] .icon-btn .i-sun,
  [data-theme="light"] .icon-btn .i-moon {
    display: none;
  }

  .nav-toggle {
    display: none;
  }

  /* ---------- 按钮 ---------- */
  .btn {
    --btn-bg: var(--surface-hi);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.55rem;
    padding: 0.72rem 1.35rem;
    border: 1px solid var(--line-hi);
    border-radius: var(--r-full);
    background: var(--btn-bg);
    font-size: 0.94rem;
    font-weight: 650;
    letter-spacing: -0.005em;
    white-space: nowrap;
    transition: transform var(--t-2) var(--ease-spring),
      box-shadow var(--t-3) var(--ease-out),
      border-color var(--t-2) var(--ease-out),
      background var(--t-2) var(--ease-out),
      color var(--t-2) var(--ease-out);
  }

  .btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-2);
  }

  .btn:active {
    transform: translateY(0) scale(0.975);
  }

  .btn svg {
    width: 17px;
    height: 17px;
    flex: none;
  }

  .btn--primary {
    position: relative;
    border-color: transparent;
    background: var(--grad);
    color: #fff;
    box-shadow: var(--shadow-glow);
  }

  .btn--primary:hover {
    box-shadow: 0 28px 60px -24px color-mix(in oklab, var(--a1) 78%, transparent);
  }

  .btn--ghost {
    background: transparent;
    border-color: var(--line);
    color: var(--text-dim);
  }

  .btn--ghost:hover {
    color: var(--text);
    border-color: var(--line-hi);
    background: var(--surface);
  }

  .btn--sm {
    padding: 0.45rem 0.9rem;
    font-size: 0.85rem;
  }

  .btn-row {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    align-items: center;
  }

  /* ---------- 标签 / 徽章 ---------- */
  .eyebrow {
    display: inline-flex;
    align-items: center;
    gap: 0.55rem;
    padding: 0.35rem 0.85rem 0.35rem 0.4rem;
    border: 1px solid var(--line);
    border-radius: var(--r-full);
    background: var(--surface);
    font-size: 0.8rem;
    font-weight: 550;
    letter-spacing: 0.01em;
    color: var(--text-dim);
  }

  .eyebrow::before {
    content: "";
    width: 7px;
    height: 7px;
    margin-inline-start: 0.35rem;
    border-radius: 50%;
    background: var(--grad);
    box-shadow: 0 0 0 4px color-mix(in oklab, var(--a1) 22%, transparent);
  }

  .chip {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    padding: 0.3rem 0.7rem;
    border: 1px solid var(--line);
    border-radius: var(--r-full);
    background: var(--surface);
    font-size: 0.79rem;
    color: var(--text-mute);
    letter-spacing: 0.005em;
  }

  .chip strong {
    color: var(--text-dim);
    font-weight: 600;
  }

  .chip-row {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
  }

  .grad-text {
    background: var(--grad);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
  }

  /* ---------- 卡片 ---------- */
  .card {
    position: relative;
    border: 1px solid var(--line);
    border-radius: var(--r-lg);
    background: var(--surface);
    overflow: hidden;
    transition: border-color var(--t-3) var(--ease-out),
      transform var(--t-3) var(--ease-out),
      box-shadow var(--t-3) var(--ease-out);
  }

  /* 指针跟随的光晕 */
  .card--glow::before {
    content: "";
    position: absolute;
    inset: 0;
    border-radius: inherit;
    pointer-events: none;
    opacity: 0;
    background: radial-gradient(22rem 22rem at var(--mx, 50%) var(--my, 0%),
        color-mix(in oklab, var(--a1) 16%, transparent), transparent 70%);
    transition: opacity var(--t-3) var(--ease-out);
  }

  .card--glow:hover::before {
    opacity: 1;
  }

  .card--link:hover {
    transform: translateY(-4px);
    border-color: var(--line-hi);
    box-shadow: var(--shadow-2);
  }

  .card__body {
    padding: clamp(1.3rem, 3vw, 1.9rem);
  }

  /* ---------- 首页 Hero ---------- */
  .hero {
    position: relative;
    padding-block: clamp(3.5rem, 9vw, 7rem) clamp(3rem, 7vw, 5.5rem);
  }

  .hero__inner {
    display: grid;
    gap: clamp(2.5rem, 5vw, 4rem);
    grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
    align-items: center;
  }

  .hero__title {
    margin-block: 1.4rem 1.1rem;
  }

  .hero__lead {
    max-width: 46ch;
    font-size: clamp(1rem, 0.95rem + 0.3vw, 1.13rem);
    color: var(--text-dim);
  }

  .hero__actions {
    margin-block-start: 1.9rem;
  }

  .hero__stats {
    display: flex;
    flex-wrap: wrap;
    gap: 1.9rem;
    margin-block-start: 2.4rem;
    padding-block-start: 1.7rem;
    border-block-start: 1px solid var(--line);
  }

  .stat__num {
    display: block;
    font-size: 1.5rem;
    font-weight: 750;
    letter-spacing: -0.03em;
    line-height: 1.1;
  }

  .stat__label {
    font-size: 0.82rem;
    color: var(--text-mute);
  }

  /* 首屏应用预览 */
  .hero__visual {
    position: relative;
  }

  .hero__visual::before {
    content: "";
    position: absolute;
    inset: -12% -8% -18% -8%;
    z-index: -1;
    border-radius: 50%;
    background: radial-gradient(closest-side, color-mix(in oklab, var(--a1) var(--halo), transparent), transparent 72%);
    opacity: 0.85;
  }

  /* ---------- 应用窗口外框 ---------- */
  .frame {
    border: 1px solid var(--line-hi);
    border-radius: var(--r-md);
    background: var(--bg-elev);
    box-shadow: var(--shadow-2);
    overflow: hidden;
  }

  .frame__bar {
    display: flex;
    align-items: center;
    gap: 0.45rem;
    padding: 0.6rem 0.85rem;
    border-block-end: 1px solid var(--line);
    background: var(--surface);
  }

  .frame__dot {
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background: var(--line-hi);
  }

  .frame__dot:nth-child(1) {
    background: #ff5f57;
  }

  .frame__dot:nth-child(2) {
    background: #ffbd2e;
  }

  .frame__dot:nth-child(3) {
    background: #28c840;
  }

  .frame__title {
    margin-inline-start: 0.5rem;
    font-size: 0.78rem;
    color: var(--text-mute);
    font-family: var(--font-mono);
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
  }

  .frame img {
    width: 100%;
    height: auto;
  }

  /* ---------- 区块标题 ---------- */
  .section-head {
    max-width: 60ch;
    margin-block-end: clamp(2rem, 4vw, 3rem);
  }

  .section-head h2 {
    margin-block: 0.9rem 0.7rem;
  }

  .section-head p {
    color: var(--text-dim);
  }

  /* ---------- 项目网格 ---------- */
  .grid {
    display: grid;
    gap: clamp(1rem, 2.2vw, 1.5rem);
  }

  /* grid / flex 子项默认 min-width:auto，宽代码块会把轨道撑破，这里统一放开 */
  .grid > *,
  .steps > li,
  .note > *,
  .prose > * {
    min-width: 0;
  }

  .grid--2 {
    grid-template-columns: repeat(auto-fit, minmax(min(100%, 420px), 1fr));
  }

  .grid--3 {
    grid-template-columns: repeat(auto-fit, minmax(min(100%, 268px), 1fr));
  }

  /* 特色项目：大卡片 */
  .feature {
    display: grid;
    grid-template-columns: minmax(0, 1fr) minmax(0, 1.15fr);
    align-items: stretch;
    gap: 0;
  }

  .feature__media {
    position: relative;
    padding: clamp(1.1rem, 3vw, 2.2rem);
    display: grid;
    place-items: center;
    background:
      radial-gradient(120% 100% at 0% 0%, color-mix(in oklab, var(--a1) 22%, transparent), transparent 60%),
      radial-gradient(100% 100% at 100% 100%, color-mix(in oklab, var(--a2) 18%, transparent), transparent 60%);
    border-inline-end: 1px solid var(--line);
  }

  .feature__media img {
    width: 100%;
    border-radius: var(--r-sm);
    border: 1px solid var(--line-hi);
    box-shadow: var(--shadow-2);
  }

  .feature__body {
    padding: clamp(1.6rem, 3.5vw, 2.7rem);
    display: flex;
    flex-direction: column;
    gap: 1rem;
  }

  .feature__title {
    display: flex;
    align-items: center;
    gap: 0.7rem;
  }

  .feature__title img {
    width: 40px;
    height: 40px;
    border-radius: 11px;
    box-shadow: var(--shadow-1);
  }

  .feature__title h3 {
    font-size: clamp(1.35rem, 1.1rem + 0.9vw, 1.75rem);
    letter-spacing: -0.03em;
  }

  .feature__title span {
    display: block;
    font-size: 0.8rem;
    font-weight: 500;
    letter-spacing: 0.02em;
    color: var(--text-mute);
  }

  .ticks {
    display: grid;
    gap: 0.55rem;
  }

  .ticks li {
    position: relative;
    padding-inline-start: 1.6rem;
    font-size: 0.94rem;
    color: var(--text-dim);
  }

  .ticks li::before {
    content: "";
    position: absolute;
    inset-inline-start: 0;
    inset-block-start: 0.52em;
    width: 15px;
    height: 15px;
    border-radius: 50%;
    background: color-mix(in oklab, var(--a1) 24%, transparent);
    box-shadow: inset 0 0 0 1px color-mix(in oklab, var(--a1) 45%, transparent);
  }

  .ticks li::after {
    content: "";
    position: absolute;
    inset-inline-start: 4.6px;
    inset-block-start: 0.72em;
    width: 6px;
    height: 3px;
    border-inline-start: 1.6px solid var(--a1);
    border-block-end: 1.6px solid var(--a1);
    rotate: -45deg;
  }

  /* 小项目卡 */
  .project {
    display: flex;
    flex-direction: column;
    gap: 0.7rem;
    padding: clamp(1.3rem, 3vw, 1.7rem);
    height: 100%;
  }

  .project__icon {
    display: grid;
    place-items: center;
    width: 42px;
    height: 42px;
    border-radius: 12px;
    border: 1px solid var(--line);
    background: var(--surface-hi);
    font-size: 1.15rem;
  }

  .project h3 {
    display: flex;
    align-items: center;
    gap: 0.5rem;
  }

  .project h3 svg {
    width: 15px;
    height: 15px;
    color: var(--text-mute);
    transition: transform var(--t-2) var(--ease-out), color var(--t-2) var(--ease-out);
  }

  .card--link:hover h3 svg {
    color: var(--a1);
    transform: translate(3px, -3px);
  }

  .project p {
    font-size: 0.92rem;
    color: var(--text-dim);
    flex: 1;
  }

  .project__tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.4rem;
    margin-block-start: 0.3rem;
  }

  /* ---------- 图片展示 ---------- */
  .shot {
    position: relative;
    border: 1px solid var(--line);
    border-radius: var(--r-md);
    background: var(--bg-elev);
    overflow: hidden;
    cursor: zoom-in;
  }

  .shot img {
    width: 100%;
    height: auto;
    transition: transform var(--t-4) var(--ease-out);
  }

  .shot:hover img {
    transform: scale(1.018);
  }

  .shot figcaption {
    padding: 0.85rem 1.1rem;
    border-block-start: 1px solid var(--line);
    font-size: 0.86rem;
    color: var(--text-mute);
    background: var(--surface);
  }

  .shot-grid {
    display: grid;
    gap: clamp(1rem, 2.5vw, 1.6rem);
  }

  .shot-grid--split {
    grid-template-columns: minmax(0, 1.35fr) minmax(0, 1fr);
    align-items: start;
  }

  /* ---------- 灯箱 ---------- */
  .lightbox {
    position: fixed;
    inset: 0;
    z-index: 90;
    display: none;
    place-items: center;
    padding: clamp(1rem, 5vw, 3rem);
    border: 0;
    max-width: none;
    max-height: none;
    width: 100%;
    height: 100%;
    background: color-mix(in oklab, var(--bg) 82%, transparent);
    -webkit-backdrop-filter: blur(14px);
    backdrop-filter: blur(14px);
    opacity: 0;
    transition: opacity var(--t-3) var(--ease-out), overlay var(--t-3) allow-discrete,
      display var(--t-3) allow-discrete;
  }

  .lightbox[open] {
    display: grid;
    opacity: 1;
  }

  @starting-style {
    .lightbox[open] {
      opacity: 0;
    }
  }

  .lightbox img {
    max-width: 100%;
    max-height: 100%;
    border-radius: var(--r-md);
    border: 1px solid var(--line-hi);
    box-shadow: var(--shadow-2);
    scale: 0.97;
    transition: scale var(--t-3) var(--ease-out);
  }

  .lightbox[open] img {
    scale: 1;
  }

  .lightbox::backdrop {
    background: transparent;
  }

  .lightbox__close {
    position: absolute;
    inset-block-start: clamp(0.8rem, 3vw, 1.5rem);
    inset-inline-end: clamp(0.8rem, 3vw, 1.5rem);
  }

  /* ---------- 功能网格 ---------- */
  .feat {
    display: flex;
    flex-direction: column;
    gap: 0.65rem;
    padding: 1.4rem;
    height: 100%;
  }

  .feat h3 {
    font-size: 1rem;
  }

  .feat p {
    font-size: 0.89rem;
    color: var(--text-dim);
    line-height: 1.7;
  }

  .feat__icon {
    display: grid;
    place-items: center;
    width: 36px;
    height: 36px;
    border-radius: 10px;
    background: color-mix(in oklab, var(--a1) 16%, transparent);
    color: var(--a1);
    font-size: 1rem;
  }

  /* ---------- 代码块 ---------- */
  /* 裸 <pre> 先有完整样式（无 JS 也好看），再由 JS 升级为带工具条的 .code */
  pre {
    margin-block: 1rem;
    padding: 0.95rem 1.05rem 1.1rem;
    border: 1px solid var(--line);
    border-radius: var(--r-sm);
    background: var(--code-bg);
    color: #c7cddb;
    line-height: 1.68;
    overflow-x: auto;
    tab-size: 2;
  }

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

  .code {
    position: relative;
    margin-block: 1rem;
    max-width: 100%;
    border: 1px solid var(--line);
    border-radius: var(--r-sm);
    background: var(--code-bg);
    overflow: hidden;
  }

  .code pre {
    margin: 0;
    padding: 0.95rem 1.05rem 1.1rem;
    border: 0;
    border-radius: 0;
    background: transparent;
    overflow-x: auto;
    color: #c7cddb;
  }

  .code pre code {
    color: inherit;
    background: none;
    border: 0;
    padding: 0;
    white-space: pre;
  }

  .code__bar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
    padding: 0.4rem 0.5rem 0.4rem 0.95rem;
    border-block-end: 1px solid rgba(255, 255, 255, 0.07);
  }

  .code__lang {
    font-family: var(--font-mono);
    font-size: 0.72rem;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: #7f8797;
  }

  .code__copy {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    padding: 0.3rem 0.6rem;
    border-radius: 7px;
    font-size: 0.76rem;
    color: #9aa3b3;
    transition: color var(--t-2) var(--ease-out), background var(--t-2) var(--ease-out);
  }

  .code__copy:hover {
    color: #e6e9f0;
    background: rgba(255, 255, 255, 0.07);
  }

  .code__copy.is-done {
    color: #4ade80;
  }

  .code__copy svg {
    width: 13px;
    height: 13px;
  }

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

  table {
    width: 100%;
    min-width: 30rem;
    border-collapse: collapse;
    font-size: 0.92rem;
  }

  th,
  td {
    padding: 0.8rem 1.1rem;
    text-align: start;
    border-block-end: 1px solid var(--line);
    vertical-align: top;
  }

  thead th {
    position: sticky;
    inset-block-start: 0;
    background: var(--bg-elev);
    font-size: 0.78rem;
    font-weight: 650;
    letter-spacing: 0.05em;
    text-transform: uppercase;
    color: var(--text-mute);
  }

  tbody tr {
    transition: background var(--t-2) var(--ease-out);
  }

  tbody tr:hover {
    background: var(--surface-hi);
  }

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

  td:first-child {
    white-space: nowrap;
    width: 1%;
  }

  /* ---------- 提示条 ---------- */
  .note {
    display: flex;
    gap: 0.85rem;
    padding: 1.05rem 1.2rem;
    border: 1px solid color-mix(in oklab, var(--a3) 32%, var(--line));
    border-radius: var(--r-md);
    background: color-mix(in oklab, var(--a3) 9%, transparent);
    font-size: 0.92rem;
  }

  .note__icon {
    flex: none;
    font-size: 1.05rem;
    line-height: 1.5;
  }

  .note p + p {
    margin-block-start: 0.5rem;
  }

  .note .code {
    margin-block: 0.7rem 0;
  }

  /* ---------- 引用 ---------- */
  .quote {
    padding-inline-start: 1.2rem;
    border-inline-start: 2px solid transparent;
    border-image: var(--grad) 1;
    color: var(--text-dim);
    font-size: 0.94rem;
  }

  /* ---------- 步骤列表 ---------- */
  .steps {
    counter-reset: step;
    display: grid;
    gap: 1.6rem;
  }

  .steps,
  .prose ol.steps {
    list-style: none;
  }

  .steps > li {
    counter-increment: step;
    position: relative;
    padding-inline-start: 2.9rem;
  }

  .steps > li::before {
    content: counter(step);
    position: absolute;
    inset-inline-start: 0;
    inset-block-start: 0.1rem;
    display: grid;
    place-items: center;
    width: 30px;
    height: 30px;
    border-radius: 50%;
    border: 1px solid var(--line-hi);
    background: var(--surface-hi);
    font-size: 0.82rem;
    font-weight: 700;
    color: var(--text-dim);
  }

  .steps h3 {
    margin-block-end: 0.5rem;
  }

  /* ---------- 文章排版 ---------- */
  .prose {
    font-size: 1.01rem;
  }

  .prose > * + * {
    margin-block-start: 1.15rem;
  }

  .prose h2 {
    margin-block-start: clamp(2.5rem, 5vw, 3.5rem);
    padding-block-end: 0.6rem;
    border-block-end: 1px solid var(--line);
  }

  .prose h3 {
    margin-block-start: 2rem;
  }

  .prose ul,
  .prose ol {
    display: grid;
    gap: 0.5rem;
    padding-inline-start: 1.3rem;
  }

  .prose ul li {
    position: relative;
  }

  .prose ul li::before {
    content: "";
    position: absolute;
    inset-inline-start: -1.05rem;
    inset-block-start: 0.7em;
    width: 5px;
    height: 5px;
    border-radius: 50%;
    background: var(--a1);
  }

  .prose ol {
    list-style: decimal;
  }

  .prose ol li::marker {
    color: var(--text-mute);
    font-variant-numeric: tabular-nums;
  }

  .prose a:not(.btn) {
    color: var(--a3);
    text-decoration: underline;
    text-decoration-color: color-mix(in oklab, var(--a3) 35%, transparent);
    text-decoration-thickness: 1.5px;
    transition: text-decoration-color var(--t-2) var(--ease-out), color var(--t-2) var(--ease-out);
  }

  .prose a:not(.btn):hover {
    color: var(--a2);
    text-decoration-color: currentColor;
  }

  /* 正文之外的行内链接同样要看得出来是可点的 */
  .lead a,
  .section-head a,
  .note a,
  .feat a,
  .cta a:not(.btn) {
    color: var(--a3);
    text-decoration: underline;
    text-decoration-color: color-mix(in oklab, var(--a3) 40%, transparent);
    text-decoration-thickness: 1.5px;
    text-underline-offset: 0.2em;
    transition: color var(--t-2) var(--ease-out),
      text-decoration-color var(--t-2) var(--ease-out);
  }

  .lead a:hover,
  .section-head a:hover,
  .note a:hover,
  .feat a:hover,
  .cta a:not(.btn):hover {
    color: var(--a2);
    text-decoration-color: currentColor;
  }

  /* ---------- 页面头（子页面） ---------- */
  .page-head {
    padding-block: clamp(2.5rem, 6vw, 4.5rem) clamp(2rem, 4vw, 3rem);
  }

  .breadcrumb {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 0.5rem;
    margin-block-end: 1.6rem;
    font-size: 0.85rem;
    color: var(--text-mute);
  }

  .breadcrumb a {
    transition: color var(--t-2) var(--ease-out);
  }

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

  .breadcrumb span {
    opacity: 0.45;
  }

  .page-head h1 {
    margin-block: 0.9rem 1rem;
  }

  .page-head .lead {
    max-width: 62ch;
    font-size: clamp(1rem, 0.96rem + 0.28vw, 1.1rem);
    color: var(--text-dim);
  }

  /* ---------- CTA 面板 ---------- */
  .cta {
    position: relative;
    padding: clamp(2rem, 5vw, 3.4rem);
    border-radius: var(--r-lg);
    border: 1px solid var(--line);
    overflow: hidden;
    text-align: center;
    background:
      radial-gradient(90% 130% at 50% -20%, color-mix(in oklab, var(--a1) 26%, transparent), transparent 65%),
      radial-gradient(70% 120% at 100% 120%, color-mix(in oklab, var(--a2) 20%, transparent), transparent 62%),
      var(--surface);
  }

  .cta h2 {
    margin-block-end: 0.8rem;
  }

  .cta p {
    max-width: 54ch;
    margin-inline: auto;
    color: var(--text-dim);
  }

  .cta .btn-row {
    justify-content: center;
    margin-block-start: 1.8rem;
  }

  /* ---------- 页脚 ---------- */
  .site-footer {
    margin-block-start: clamp(2.5rem, 5vw, 4rem);
    padding-block: clamp(2.25rem, 4vw, 3rem);
    border-block-start: 1px solid var(--line);
    font-size: 0.87rem;
    color: var(--text-mute);
  }

  .site-footer__grid {
    display: flex;
    flex-wrap: wrap;
    gap: 1.25rem 2.5rem;
    justify-content: space-between;
    align-items: flex-start;
  }

  .site-footer__links {
    display: flex;
    flex-wrap: wrap;
    gap: 0.4rem 1.4rem;
  }

  .site-footer a {
    transition: color var(--t-2) var(--ease-out);
  }

  .site-footer a:hover {
    color: var(--text);
  }

  .site-footer__meta {
    flex: 1 1 22rem;
    min-width: 0;
    line-height: 1.75;
  }

  /* ---------- 封面插画 ---------- */
  .cover {
    position: relative;
    border-radius: var(--r-lg);
    border: 1px solid var(--line);
    overflow: hidden;
    background-color: var(--bg-elev);
    background-size: cover;
    background-position: center 22%;
  }

  .cover img {
    position: relative;
    width: 100%;
    height: auto;
    opacity: 0;
    transition: opacity var(--t-4) var(--ease-out);
  }

  .cover img.is-loaded {
    opacity: 1;
  }

  .cover__credit {
    position: absolute;
    inset-block-end: 0;
    inset-inline: 0;
    display: flex;
    justify-content: space-between;
    gap: 1rem;
    padding: 2.5rem 1.2rem 1rem;
    font-size: 0.8rem;
    color: rgba(255, 255, 255, 0.92);
    background: linear-gradient(to top, rgba(0, 0, 0, 0.68), transparent);
  }

  .cover__credit a {
    text-decoration: underline;
    text-decoration-color: rgba(255, 255, 255, 0.4);
  }

  .cover__credit a:hover {
    text-decoration-color: currentColor;
  }

  /* ---------- 目录卡 ---------- */
  .toc {
    display: grid;
    gap: 0.5rem;
    counter-reset: toc;
  }

  .toc a {
    display: flex;
    align-items: baseline;
    gap: 0.8rem;
    padding: 0.7rem 0.9rem;
    border-radius: var(--r-sm);
    color: var(--text-dim);
    transition: background var(--t-2) var(--ease-out), color var(--t-2) var(--ease-out);
  }

  .toc a::before {
    counter-increment: toc;
    content: counter(toc, decimal-leading-zero);
    font-family: var(--font-mono);
    font-size: 0.76rem;
    color: var(--text-mute);
  }

  .toc a:hover {
    background: var(--surface-hi);
    color: var(--text);
  }

  /* ---------- 404 ---------- */
  .notfound {
    display: grid;
    place-items: center;
    min-height: min(70vh, 34rem);
    text-align: center;
  }

  .notfound__code {
    font-size: clamp(4.5rem, 16vw, 9rem);
    font-weight: 800;
    letter-spacing: -0.06em;
    line-height: 0.9;
  }
}

/* ==========================================================================
   6. Motion
   ========================================================================== */
@layer motion {

  /* 跨文档页面过渡（支持 View Transitions 的浏览器） */
  @view-transition {
    navigation: auto;
  }

  ::view-transition-old(root) {
    animation: vt-out var(--t-2) var(--ease-out) both;
  }

  ::view-transition-new(root) {
    animation: vt-in var(--t-3) var(--ease-out) both;
  }

  @keyframes vt-out {
    to {
      opacity: 0;
      transform: translateY(-6px);
    }
  }

  @keyframes vt-in {
    from {
      opacity: 0;
      transform: translateY(10px);
    }
  }

  /* 首屏入场 */
  .rise {
    animation: rise var(--t-4) var(--ease-out) both;
    animation-delay: calc(var(--i, 0) * 75ms + 40ms);
  }

  @keyframes rise {
    from {
      opacity: 0;
      transform: translateY(18px);
    }
  }

  /* 滚动进场：仅在 JS 可用时隐藏初始状态 */
  .js .reveal {
    opacity: 0;
    transform: translateY(20px);
    transition: opacity var(--t-4) var(--ease-out), transform var(--t-4) var(--ease-out);
    transition-delay: calc(var(--i, 0) * 65ms);
  }

  .js .reveal.is-in {
    opacity: 1;
    transform: none;
  }

  /* 目录树 / 列表错峰淡入 */
  .js .stagger > * {
    animation: rise var(--t-3) var(--ease-out) both;
    animation-delay: calc(var(--i, 0) * 45ms);
  }

  /* 滚动浮现（表格、卡片列表） */
  @supports (animation-timeline: view()) {
    .js .reveal:not(.is-in) {
      transition-delay: 0ms;
    }
  }

  @media (prefers-reduced-motion: reduce) {

    html {
      scroll-behavior: auto;
    }

    *,
    *::before,
    *::after {
      animation-duration: 0.001ms !important;
      animation-iteration-count: 1 !important;
      transition-duration: 0.001ms !important;
      scroll-behavior: auto !important;
    }

    .js .reveal {
      opacity: 1;
      transform: none;
    }

    .progress {
      display: none;
    }

    ::view-transition-old(root),
    ::view-transition-new(root) {
      animation: none;
    }
  }
}

/* ==========================================================================
   7. Utilities & 响应式
   ========================================================================== */
@layer utils {

  .sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    overflow: hidden;
    clip-path: inset(50%);
    white-space: nowrap;
  }

  .text-dim {
    color: var(--text-dim);
  }

  .text-mute {
    color: var(--text-mute);
  }

  .mt-0 {
    margin-block-start: 0;
  }

  .mt-2 {
    margin-block-start: 1rem;
  }

  .mt-3 {
    margin-block-start: 1.6rem;
  }

  .mt-4 {
    margin-block-start: 2.4rem;
  }

  .mb-3 {
    margin-block-end: 1.6rem;
  }

  .nowrap {
    white-space: nowrap;
  }

  .divider {
    height: 1px;
    border: 0;
    background: linear-gradient(to right, transparent, var(--line-hi) 18%, var(--line-hi) 82%, transparent);
    margin-block: clamp(2.5rem, 6vw, 4rem);
  }

  /* ---- 平板 ---- */
  @media (max-width: 1000px) {
    .hero__inner {
      grid-template-columns: 1fr;
    }

    .hero__visual {
      order: -1;
    }

    .hero__lead {
      max-width: 60ch;
    }

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

    .feature__media {
      border-inline-end: 0;
      border-block-end: 1px solid var(--line);
    }

    .shot-grid--split {
      grid-template-columns: 1fr;
    }
  }

  /* ---- 手机 ---- */
  @media (max-width: 720px) {

    .nav-toggle {
      display: grid;
    }

    .nav {
      position: fixed;
      inset-block-start: 66px;
      inset-inline: var(--gutter);
      z-index: 55;
      flex-direction: column;
      align-items: stretch;
      padding: 0.6rem;
      border: 1px solid var(--line);
      border-radius: var(--r-md);
      background: var(--bg-elev);
      box-shadow: var(--shadow-2);
      opacity: 0;
      transform: translateY(-10px) scale(0.98);
      transform-origin: top center;
      pointer-events: none;
      transition: opacity var(--t-2) var(--ease-out), transform var(--t-2) var(--ease-out);
    }

    .nav.is-open {
      opacity: 1;
      transform: none;
      pointer-events: auto;
    }

    .nav a {
      padding: 0.7rem 0.9rem;
      border-radius: var(--r-sm);
    }

    .nav a[aria-current="page"]::after {
      display: none;
    }

    .nav a[aria-current="page"] {
      background: var(--surface-hi);
    }

    .hero__stats {
      gap: 1.4rem 2rem;
    }

    .brand__sub {
      display: none;
    }
  }

  @media (max-width: 420px) {
    .btn {
      width: 100%;
    }

    .btn-row {
      gap: 0.6rem;
    }
  }

  /* ---- 高对比偏好 ---- */
  @media (prefers-contrast: more) {
    :root {
      --line: rgba(255, 255, 255, 0.22);
      --text-dim: #cdd3de;
    }

    [data-theme="light"] {
      --line: rgba(18, 22, 34, 0.28);
      --text-dim: #333b4a;
    }
  }
}