/* ==========================================================================
   路径: assets/css/style.css
   项目: ColinN · 个人作品集（纯静态 / 零框架 / 零外链字体）
   设计系统: Minimalism & Swiss Style + 深色科技区块
     主色      #0F172A  深海军蓝（深色区块、页脚、按钮）
     强调色    #2563EB  单一强调蓝（CTA、链接、高亮）
     中性      #F8FAFC / #E2E8F0 / #475569
   断点: 375（基线）/ 768 / 1024 / 1440，移动端优先
   动效: 仅滚动淡入 + hover 微交互，尊重 prefers-reduced-motion
   ========================================================================== */

/* --------------------------------------------------------------------------
   1. 设计令牌
   -------------------------------------------------------------------------- */
:root {
  /* 颜色 */
  --c-ink: #0F172A;            /* 主色：深海军蓝 */
  --c-ink-2: #1B2336;          /* 深色卡片 */
  --c-ink-3: #334155;          /* 深色区块内次级文字 */
  --c-accent: #2563EB;         /* 单一强调色 */
  --c-accent-deep: #1D4ED8;
  --c-accent-soft: #60A5FA;    /* 深色底上的强调色 */
  --c-paper: #FFFFFF;
  --c-bg: #F8FAFC;
  --c-muted: #475569;
  --c-line: #E2E8F0;
  --c-line-strong: #CBD5E1;
  --c-on-dark: #F8FAFC;
  --c-on-dark-muted: #94A3B8;

  /* 字号层级（5 级） */
  --fs-1: clamp(2.125rem, 1.5rem + 2.8vw, 3.5rem);
  --fs-2: clamp(1.375rem, 1.15rem + 1.2vw, 2rem);
  --fs-3: clamp(1.0625rem, 1rem + .35vw, 1.25rem);
  --fs-4: 1rem;
  --fs-5: .875rem;

  /* 版式与间距 */
  --container: 1200px;
  --gutter: 20px;
  --section-y: clamp(56px, 6vw, 104px);
  --header-h: 64px;
  --radius: 8px;
  --radius-lg: 14px;

  /* 字体栈：免费可商用中文字体优先，系统兜底（不加载任何外链字体） */
  --font-sans: "Source Han Sans SC", "Noto Sans SC", "Source Han Sans CN",
               "Alibaba PuHuiTi 3.0", "PingFang SC", "HarmonyOS Sans SC",
               "Microsoft YaHei", -apple-system, BlinkMacSystemFont, "Segoe UI",
               Roboto, Arial, sans-serif;
  --font-mono: "JetBrains Mono", "IBM Plex Mono", "Cascadia Mono", ui-monospace,
               SFMono-Regular, Consolas, "Liberation Mono", monospace;

  /* 动效 */
  --dur: .22s;
  --dur-slow: .4s;
  --ease: cubic-bezier(.4, 0, .2, 1);
}

/* --------------------------------------------------------------------------
   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) + 16px);
}

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: var(--fs-4);
  line-height: 1.75;
  color: var(--c-ink);
  background: var(--c-paper);
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4, p, ul, ol, dl, dd, figure { margin: 0; }
ul, ol { padding: 0; list-style: none; }
button { font: inherit; color: inherit; cursor: pointer; }
a { color: var(--c-accent); text-decoration: none; }
a:hover { text-decoration: underline; text-underline-offset: 3px; }

h1 { font-size: var(--fs-1); line-height: 1.15; font-weight: 700; letter-spacing: -.02em; }
h2 { font-size: var(--fs-2); line-height: 1.3; font-weight: 700; letter-spacing: -.01em; }
h3 { font-size: var(--fs-3); line-height: 1.45; font-weight: 700; }

:where(a, button, input, textarea, summary):focus-visible {
  outline: 3px solid var(--c-accent);
  outline-offset: 3px;
  border-radius: 4px;
}

.skip-link {
  position: absolute; left: -9999px; top: 0; z-index: 200;
  background: var(--c-ink); color: #fff;
  padding: 10px 16px; border-radius: 0 0 var(--radius) 0;
}
.skip-link:focus { left: 0; }

/* --------------------------------------------------------------------------
   3. 布局与通用组件
   -------------------------------------------------------------------------- */
.container {
  width: 100%; max-width: var(--container);
  margin: 0 auto; padding: 0 var(--gutter);
}

.section { padding: var(--section-y) 0; }
.section--bg { background: var(--c-bg); }
.section--dark {
  background: var(--c-ink);
  color: var(--c-on-dark);
  position: relative;
  overflow: hidden;
}
/* 科技感：深色区块的网格底纹 */
.section--dark::before {
  content: "";
  position: absolute; inset: 0;
  background-image:
    repeating-linear-gradient(to right, rgba(255,255,255,.05) 0 1px, transparent 1px 48px),
    repeating-linear-gradient(to bottom, rgba(255,255,255,.05) 0 1px, transparent 1px 48px);
  pointer-events: none;
}
.section--dark > .container { position: relative; }

.section-head { max-width: 720px; margin-bottom: clamp(28px, 3vw, 48px); }
.section-head .eyebrow { margin-bottom: 12px; }
.section-title { margin-bottom: 12px; }
.section--dark .section-title { color: #fff; }
.section-lead { color: var(--c-muted); }
.section--dark .section-lead { color: var(--c-on-dark-muted); }

/* 等宽小标签：科技感来源 */
.eyebrow {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: var(--fs-5);
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--c-accent);
}
.section--dark .eyebrow { color: var(--c-accent-soft); }

.grid { display: grid; gap: 20px; }
.grid--2 { grid-template-columns: 1fr; }
.grid--3 { grid-template-columns: 1fr; }
.grid--4 { grid-template-columns: 1fr; }

.card {
  background: var(--c-paper);
  border: 1px solid var(--c-line);
  border-radius: var(--radius-lg);
  padding: 24px;
  transition: border-color var(--dur) var(--ease), transform var(--dur) var(--ease);
}
.card:hover { border-color: var(--c-line-strong); }
.card--lift:hover { transform: translateY(-3px); border-color: var(--c-accent); }

.tag {
  display: inline-flex; align-items: center;
  font-family: var(--font-mono);
  font-size: .8125rem;
  padding: 3px 10px;
  border-radius: 999px;
  border: 1px solid var(--c-line);
  color: var(--c-muted);
  background: var(--c-bg);
  white-space: nowrap;
}
.tag--accent { border-color: #BFDBFE; background: #EFF6FF; color: var(--c-accent-deep); }
.section--dark .tag { border-color: rgba(255,255,255,.18); background: rgba(255,255,255,.06); color: var(--c-on-dark); }

.tag-row { display: flex; flex-wrap: wrap; gap: 8px; }

.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  min-height: 44px;
  padding: 11px 22px;
  border: 1px solid transparent;
  border-radius: var(--radius);
  font-weight: 700; font-size: var(--fs-4);
  text-decoration: none;
  transition: background var(--dur) var(--ease), border-color var(--dur) var(--ease), color var(--dur) var(--ease);
}
.btn:hover { text-decoration: none; }
.btn--primary { background: var(--c-accent); color: #fff; }
.btn--primary:hover { background: var(--c-accent-deep); }
.btn--ghost { background: transparent; color: var(--c-ink); border-color: var(--c-line-strong); }
.btn--ghost:hover { border-color: var(--c-ink); }
.btn--inverse { background: #fff; color: var(--c-ink); }
.btn--inverse:hover { background: #E2E8F0; }
.btn--outline-dark { background: transparent; color: #fff; border-color: rgba(255,255,255,.32); }
.btn--outline-dark:hover { border-color: #fff; }
.btn--sm { min-height: 40px; padding: 8px 14px; font-size: var(--fs-5); }
.btn-row { display: flex; flex-wrap: wrap; gap: 12px; }

/* 图稿占位：纯 CSS 绘制，禁止外链图床 */
.ph {
  width: 100%;
  border: 1px dashed var(--c-line-strong);
  border-radius: var(--radius);
  background:
    linear-gradient(135deg, rgba(37,99,235,.06), rgba(15,23,42,.05)),
    repeating-linear-gradient(45deg, #EEF2F7 0 10px, #F5F8FB 10px 20px);
  display: grid; place-items: center; padding: 16px; text-align: center;
}
.ph span { font-size: var(--fs-5); color: var(--c-muted); line-height: 1.6; }
.ph--16x9 { aspect-ratio: 16 / 9; }
.ph--4x3 { aspect-ratio: 4 / 3; }
.ph--1x1 { aspect-ratio: 1 / 1; max-width: 200px; margin: 0 auto; }

/* --------------------------------------------------------------------------
   4. 页眉
   -------------------------------------------------------------------------- */
.site-header {
  position: sticky; top: 0; z-index: 100;
  height: var(--header-h);
  /* 用不透明底色，不用 backdrop-filter：sticky + 半透明毛玻璃在滚动时
     容易产生重绘闪烁/条纹（Chromium 已知问题），页眉也不在深色区块上
     叠加，实色没有任何视觉损失。 */
  background: var(--c-paper);
  border-bottom: 1px solid transparent;
  transition: border-color var(--dur) var(--ease), box-shadow var(--dur) var(--ease);
}
.site-header.is-stuck { border-bottom-color: var(--c-line); box-shadow: 0 1px 2px rgba(15,23,42,.06); }
.header-inner { height: var(--header-h); display: flex; align-items: center; gap: 16px; }

.brand { display: flex; align-items: center; gap: 10px; color: var(--c-ink); }
.brand:hover { text-decoration: none; }
.brand-mark {
  width: 32px; height: 32px; border-radius: 6px;
  background: var(--c-ink); color: #fff;
  display: grid; place-items: center;
  font-family: var(--font-mono); font-weight: 700; font-size: 13px; letter-spacing: .02em;
}
.brand-text { display: flex; flex-direction: column; line-height: 1.15; }
.brand-text strong { font-size: 15px; letter-spacing: .04em; }
.brand-text em {
  font-style: normal; font-family: var(--font-mono);
  font-size: 10px; letter-spacing: .16em; color: var(--c-muted);
}

.nav { margin-left: auto; }
.nav ul { display: flex; gap: 2px; }
.nav a {
  position: relative;
  display: block; padding: 8px 12px; border-radius: 6px;
  white-space: nowrap;
  color: var(--c-muted); font-size: var(--fs-4);
  /* 字重固定：滚动高亮切换时不再改变文字宽度，避免导航整体抖动 */
  font-weight: 500;
  transition: color var(--dur) var(--ease), background var(--dur) var(--ease);
}
.nav a:hover { background: var(--c-bg); color: var(--c-ink); text-decoration: none; }
.nav a.is-active { color: var(--c-accent); }
/* 高亮用下划线指示条代替加粗，宽度恒定，不产生重排 */
@media (min-width: 768px) {
  .nav a.is-active::after {
    content: ""; position: absolute; left: 12px; right: 12px; bottom: 2px;
    height: 2px; border-radius: 2px; background: var(--c-accent);
  }
}

.header-actions { display: flex; align-items: center; gap: 8px; }

.nav-toggle {
  display: inline-flex; flex-direction: column; justify-content: center; gap: 5px;
  width: 44px; height: 44px; padding: 0 11px;
  background: transparent; border: 1px solid var(--c-line); border-radius: var(--radius);
}
.nav-toggle span { display: block; height: 2px; background: var(--c-ink); border-radius: 2px; transition: transform var(--dur) var(--ease), opacity var(--dur) var(--ease); }
.nav-toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }
body.nav-open { overflow: hidden; }

/* --------------------------------------------------------------------------
   5. 首屏
   -------------------------------------------------------------------------- */
.hero {
  background: var(--c-ink);
  color: var(--c-on-dark);
  position: relative;
  overflow: hidden;
  padding: clamp(56px, 9vw, 120px) 0 clamp(48px, 6vw, 88px);
}
.hero::before {
  content: ""; position: absolute; inset: 0;
  background-image:
    repeating-linear-gradient(to right, rgba(255,255,255,.055) 0 1px, transparent 1px 56px),
    repeating-linear-gradient(to bottom, rgba(255,255,255,.055) 0 1px, transparent 1px 56px);
  pointer-events: none;
}
.hero::after {
  content: ""; position: absolute; right: -10%; top: -30%;
  width: 620px; height: 620px; border-radius: 50%;
  background: radial-gradient(circle, rgba(37,99,235,.28), transparent 68%);
  pointer-events: none;
}
.hero > .container { position: relative; }
.hero-title { color: #fff; margin-bottom: 14px; }
.hero-en {
  display: block; margin-top: 10px;
  font-family: var(--font-mono); font-weight: 500;
  font-size: clamp(.8125rem, .75rem + .5vw, 1.125rem);
  letter-spacing: .22em; color: var(--c-accent-soft);
}
.hero-role {
  font-size: clamp(1rem, .96rem + .3vw, 1.125rem);
  color: var(--c-on-dark); margin-bottom: 18px;
}
.hero-lead { color: var(--c-on-dark-muted); max-width: 60ch; margin-bottom: 28px; }
.hero .btn-row { margin-bottom: 28px; }
.hero-facts { display: flex; flex-wrap: wrap; gap: 8px; }
.hero .tag { backdrop-filter: none; }

/* --------------------------------------------------------------------------
   6. 关键事实条
   -------------------------------------------------------------------------- */
.facts { border-bottom: 1px solid var(--c-line); background: var(--c-paper); }
.facts-inner { display: grid; gap: 16px; padding: 26px 0; }
.fact { display: grid; gap: 4px; }
.fact dt {
  font-family: var(--font-mono); font-size: .8125rem;
  letter-spacing: .1em; text-transform: uppercase; color: var(--c-muted);
}
.fact dd { margin: 0; font-size: var(--fs-4); font-weight: 700; }

/* --------------------------------------------------------------------------
   7. 能力栈
   -------------------------------------------------------------------------- */
.skill-card h3 { margin-bottom: 4px; }
.skill-card .skill-note { font-size: var(--fs-5); color: var(--c-muted); margin-bottom: 14px; }

/* --------------------------------------------------------------------------
   8. 作品卡
   -------------------------------------------------------------------------- */
.work-card { display: flex; flex-direction: column; }
.work-card .ph { margin-bottom: 16px; }
.work-head { display: flex; align-items: baseline; justify-content: space-between; gap: 10px; margin-bottom: 8px; }
.work-card h3 { font-size: var(--fs-3); }
.work-status {
  font-family: var(--font-mono); font-size: .75rem;
  padding: 2px 8px; border-radius: 4px;
  border: 1px solid var(--c-line); color: var(--c-muted); white-space: nowrap;
}
.work-status--done { border-color: #BFDBFE; background: #EFF6FF; color: var(--c-accent-deep); }
.work-desc { font-size: var(--fs-5); color: var(--c-muted); margin-bottom: 14px; }
.work-meta { margin-top: auto; padding-top: 14px; border-top: 1px dashed var(--c-line); }
.work-note { font-size: var(--fs-5); color: var(--c-muted); margin-top: 16px; }

/* --------------------------------------------------------------------------
   9. 联系（原时间线区块已移除，编号保持不变）
   -------------------------------------------------------------------------- */
.contact-grid { display: grid; gap: 16px; grid-template-columns: 1fr; }
.contact-item {
  display: flex; align-items: flex-start; gap: 14px;
  padding: 18px; border: 1px solid rgba(255,255,255,.16);
  border-radius: var(--radius); background: rgba(255,255,255,.04);
}
.contact-item svg { width: 20px; height: 20px; flex: 0 0 20px; margin-top: 4px; color: var(--c-accent-soft); }
.contact-item .k {
  font-family: var(--font-mono); font-size: .8125rem;
  letter-spacing: .1em; text-transform: uppercase;
  color: var(--c-on-dark-muted); margin-bottom: 4px;
}
.contact-item .v { color: #fff; word-break: break-all; }
.contact-item .v small { display: block; color: var(--c-on-dark-muted); font-size: var(--fs-5); word-break: normal; }
.contact-item a { color: #fff; text-decoration: underline; text-underline-offset: 3px; }
.contact-item a:hover { color: var(--c-accent-soft); }
.copy-btn {
  margin-top: 8px;
  background: transparent; border: 1px solid rgba(255,255,255,.28);
  color: #fff; border-radius: 6px; padding: 6px 12px;
  font-family: var(--font-mono); font-size: .75rem;
  min-height: 36px;
}
.copy-btn:hover { border-color: #fff; }

/* --------------------------------------------------------------------------
   10. 项目详情弹层（原生 <dialog>，自带焦点陷阱与 Esc 关闭）
   -------------------------------------------------------------------------- */
.work-card { cursor: pointer; }
.work-meta { display: flex; align-items: center; justify-content: space-between; gap: 10px; flex-wrap: wrap; }
.work-open {
  display: inline-flex; align-items: center; gap: 6px;
  min-height: 36px; padding: 6px 12px;
  background: transparent; border: 1px solid var(--c-line-strong);
  border-radius: 6px; color: var(--c-ink);
  font-size: var(--fs-5); font-weight: 700;
  transition: border-color var(--dur) var(--ease), background var(--dur) var(--ease), color var(--dur) var(--ease);
}
.work-open::after { content: " →"; font-family: var(--font-mono); }
.work-open:hover { border-color: var(--c-accent); background: var(--c-bg); color: var(--c-accent); }
.work-card:hover { border-color: var(--c-line-strong); }

.pd {
  width: min(860px, calc(100vw - 32px));
  max-height: min(86vh, 860px);
  margin: auto;
  padding: 0; border: 0;
  border-radius: var(--radius-lg);
  background: var(--c-paper); color: var(--c-ink);
  box-shadow: 0 24px 60px rgba(15,23,42,.26);
  overflow: hidden;
}
.pd[open] { display: flex; flex-direction: column; animation: pd-in var(--dur) var(--ease); }
.pd::backdrop { background: rgba(15,23,42,.55); }
@keyframes pd-in { from { opacity: 0; transform: translateY(10px) scale(.985); } }

.pd-shell { display: flex; flex-direction: column; min-height: 0; }
.pd-head {
  display: flex; align-items: flex-start; justify-content: space-between; gap: 16px;
  padding: 22px 24px 18px;
  border-bottom: 1px solid var(--c-line);
}
.pd-eyebrow {
  font-family: var(--font-mono); font-size: .8125rem;
  letter-spacing: .12em; text-transform: uppercase;
  color: var(--c-accent); margin-bottom: 6px;
}
.pd-head h3 { font-size: var(--fs-2); line-height: 1.25; margin-bottom: 8px; }
.pd-close {
  flex: 0 0 44px; width: 44px; height: 44px;
  display: grid; place-items: center;
  background: transparent; border: 1px solid var(--c-line); border-radius: var(--radius);
  color: var(--c-muted);
  transition: border-color var(--dur) var(--ease), color var(--dur) var(--ease), background var(--dur) var(--ease);
}
.pd-close svg { width: 18px; height: 18px; }
.pd-close:hover { border-color: var(--c-line-strong); background: var(--c-bg); color: var(--c-ink); }

.pd-body { padding: 22px 24px 28px; overflow-y: auto; overscroll-behavior: contain; }
.pd-lead { font-size: 1.0625rem; color: var(--c-ink); line-height: 1.8; margin-bottom: 20px; }
.pd-todo {
  display: inline-block; margin-left: 6px;
  font-family: var(--font-mono); font-size: .75rem;
  padding: 1px 8px; border-radius: 4px;
  border: 1px dashed var(--c-line-strong); color: var(--c-muted);
  vertical-align: 2px;
}
.pd-facts {
  display: grid; gap: 14px; grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  padding: 16px; margin-bottom: 22px;
  background: var(--c-bg); border: 1px solid var(--c-line); border-radius: var(--radius);
}
.pd-facts dt {
  font-family: var(--font-mono); font-size: .75rem;
  letter-spacing: .1em; text-transform: uppercase;
  color: var(--c-muted); margin-bottom: 2px;
}
.pd-facts dd { margin: 0; font-weight: 700; }
.pd-body h4 {
  font-size: .8125rem; font-family: var(--font-mono);
  letter-spacing: .12em; text-transform: uppercase;
  color: var(--c-accent);
  margin: 22px 0 8px;
}
.pd-body h4:first-of-type { margin-top: 0; }
.pd-body p { color: var(--c-muted); }
.pd-body ul { display: grid; gap: 6px; margin: 0; }
.pd-body li {
  position: relative; padding-left: 18px; color: var(--c-muted);
}
.pd-body li::before {
  content: ""; position: absolute; left: 2px; top: .7em;
  width: 6px; height: 6px; border-radius: 2px;
  background: var(--c-accent);
}
body.pd-open { overflow: hidden; }

@media (max-width: 767.98px) {
  .pd {
    width: 100vw; max-width: 100vw;
    max-height: 92vh; margin: auto auto 0;
    border-radius: var(--radius-lg) var(--radius-lg) 0 0;
  }
  .pd-head { padding: 18px 18px 14px; }
  .pd-body { padding: 18px 18px 26px; }
}

/* --------------------------------------------------------------------------
   11. 页脚
   -------------------------------------------------------------------------- */
.site-footer {
  background: var(--c-ink); color: var(--c-on-dark-muted);
  padding: clamp(36px, 4vw, 56px) 0 24px; font-size: var(--fs-5);
  border-top: 1px solid rgba(255,255,255,.12);
}
.footer-grid { display: grid; gap: 28px; grid-template-columns: 1fr; }
.footer-brand p { margin-top: 12px; max-width: 40ch; line-height: 1.8; }
.footer-nav ul { display: flex; flex-wrap: wrap; gap: 8px 18px; align-items: baseline; }
.footer-nav ul li + li { margin-top: 0; }
.footer-col h3 { font-size: var(--fs-4); color: #fff; margin-bottom: 12px; }
.footer-col ul li + li { margin-top: 8px; }
.footer-col a { color: var(--c-on-dark-muted); }
.footer-col a:hover { color: #fff; }
.footer-bottom {
  margin-top: 26px; padding-top: 20px;
  border-top: 1px solid rgba(255,255,255,.12);
  display: grid; gap: 10px;
}
.footer-note { line-height: 1.8; }
.beian a { color: var(--c-on-dark-muted); text-decoration: underline; text-underline-offset: 3px; }
.beian a:hover { color: #fff; }

/* --------------------------------------------------------------------------
   12. 滚动淡入
   -------------------------------------------------------------------------- */
.reveal { opacity: 0; transform: translateY(12px); transition: opacity var(--dur-slow) var(--ease), transform var(--dur-slow) var(--ease); }
.reveal.is-in { opacity: 1; transform: none; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation-duration: .001ms !important; transition-duration: .001ms !important; }
  .reveal { opacity: 1; transform: none; }
}

/* --------------------------------------------------------------------------
   13. 断点：375（基线）/ 768 / 1024 / 1440
   -------------------------------------------------------------------------- */
@media (min-width: 768px) {
  :root { --gutter: 32px; --header-h: 72px; }
  .grid--2 { grid-template-columns: repeat(2, 1fr); }
  .grid--3 { grid-template-columns: repeat(2, 1fr); }
  .grid--4 { grid-template-columns: repeat(2, 1fr); }
  /* 事实条数量会随内容增减，用 auto-fit 自适应，不写死列数 */
  .facts-inner { grid-template-columns: repeat(auto-fit, minmax(180px, 1fr)); padding: 30px 0; }
  .contact-grid { grid-template-columns: repeat(2, 1fr); }
  .footer-grid { grid-template-columns: 1.4fr 1fr; }
  .footer-bottom { grid-template-columns: 1fr auto; align-items: center; }
  .card { padding: 28px; }
}

@media (min-width: 1024px) {
  .grid--3 { grid-template-columns: repeat(3, 1fr); }
  .grid--4 { grid-template-columns: repeat(4, 1fr); }
  .hero-split { display: grid; grid-template-columns: 1.25fr .75fr; gap: 48px; align-items: end; }
}

@media (min-width: 1440px) {
  :root { --container: 1280px; }
}

/* 移动端导航折叠 */
@media (max-width: 767.98px) {
  /* .nav 变成 fixed 后脱离文档流，右上角的菜单按钮会顶到品牌名旁边，
     所以这里由 .header-actions 承担 margin-left:auto 把它推到最右 */
  .header-actions { margin-left: auto; }
  .nav {
    position: fixed; inset: var(--header-h) 0 auto 0;
    max-height: calc(100dvh - var(--header-h)); overflow-y: auto;
    background: var(--c-paper); border-bottom: 1px solid var(--c-line);
    padding: 10px var(--gutter) 20px; margin: 0;
    transform: translateY(-8px); opacity: 0; visibility: hidden; pointer-events: none;
    transition: opacity var(--dur) var(--ease), transform var(--dur) var(--ease), visibility var(--dur);
    box-shadow: 0 10px 30px rgba(15,23,42,.1);
  }
  .nav.is-open { opacity: 1; visibility: visible; pointer-events: auto; transform: none; }
  .nav ul { flex-direction: column; gap: 2px; }
  .nav a { padding: 14px 8px; border-bottom: 1px solid var(--c-line); font-size: 1.0625rem; min-height: 44px; display: flex; align-items: center; }
  .nav a.is-active { background: var(--c-bg); }
  .site-header .btn--sm { padding: 8px 12px; }
  .brand-text em { display: none; }
}

@media (min-width: 768px) {
  .nav-toggle { display: none; }
}