/* ==========================================================================
   YY易游 · CN — 共享站点样式 /assets/site.css
   编辑部匝道 × 仪表盘：纸色大面积、墨绿压舱、青蓝轨道、暖橙信号
   ========================================================================== */

:root{
  --paper:      #F6EFE3;
  --sand:       #EADCC7;
  --ink:        #12211D;
  --ink-2:      #1E3B33;
  --teal:       #0B7F8A;
  --teal-soft:  #77CDD3;
  --orange:     #F26A3B;
  --amber:      #E7A33A;
  --white:      #FFFDF7;
  --alert:      #B8422E;

  --rail-w:     100px;
  --shell-max:  1180px;
  --pad:        clamp(20px, 5vw, 48px);

  --font-display: "Noto Sans SC", "Source Han Sans SC", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  --font-body:    "Noto Sans SC", "Source Han Sans SC", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  --font-mono:    "JetBrains Mono", "IBM Plex Mono", ui-monospace, SFMono-Regular, Menlo, Consolas, "Courier New", monospace;

  --bd-hair: 1px solid rgba(18,33,29,.14);
  --bd-hair-light: 1px solid rgba(246,239,227,.16);
  --ease: cubic-bezier(.4,0,.2,1);
}

/* ---------- reset ---------- */
*,*::before,*::after{ box-sizing:border-box; }
html{ -webkit-text-size-adjust:100%; }
body,h1,h2,h3,h4,h5,p,ul,ol,figure,blockquote,dl,dd{ margin:0; }
ul,ol{ padding:0; list-style:none; }
img,svg,picture,video{ max-width:100%; }
button{ font:inherit; color:inherit; }
a{ color:var(--teal); }
::selection{ background:var(--teal-soft); color:var(--ink); }

@media (prefers-reduced-motion: no-preference){
  html{ scroll-behavior:smooth; }
}

/* ---------- 基础排版 ---------- */
body{
  background:var(--paper);
  color:var(--ink);
  font-family:var(--font-body);
  font-size:17px;
  line-height:1.75;
  font-weight:400;
  -webkit-font-smoothing:antialiased;
  -moz-osx-font-smoothing:grayscale;
  overflow-x:hidden;
}

h1,h2,h3,h4{
  font-family:var(--font-display);
  font-weight:900;
  letter-spacing:-.02em;
  line-height:1.12;
  color:var(--ink);
  text-wrap:balance;
}
h1{ font-size:clamp(2.8rem, 7vw, 6.2rem); }
h2{ font-size:clamp(2rem, 4vw, 3.4rem); }
h3{ font-size:clamp(1.25rem, 2vw, 1.65rem); letter-spacing:-.01em; }
h4{ font-size:1.05rem; letter-spacing:0; }

p{ text-wrap:pretty; }

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

/* ---------- 无障碍跳转 ---------- */
.skip-link{
  position:fixed;
  left:14px;
  top:-140px;
  z-index:200;
  display:inline-block;
  padding:12px 20px;
  border-radius:8px;
  background:var(--ink);
  color:var(--paper);
  font-family:var(--font-display);
  font-weight:700;
  font-size:14px;
  text-decoration:none;
  box-shadow:0 8px 24px -12px rgba(18,33,29,.6);
  transition:top .2s var(--ease);
}
.skip-link:focus{ top:14px; }

/* ---------- 页头外壳 ---------- */
.site-header{
  position:sticky;
  top:0;
  z-index:90;
  background:var(--paper);
  color:var(--ink);
  border-bottom:var(--bd-hair);
}

.scroll-progress{
  position:fixed;
  top:0;
  left:0;
  right:0;
  height:3px;
  background:transparent;
  pointer-events:none;
  z-index:100;
}
.scroll-progress__bar{
  height:100%;
  width:0;
  background:linear-gradient(90deg, var(--teal), var(--teal-soft) 55%, var(--orange));
  transition:width .12s linear;
}

/* ---------- 品牌条 ---------- */
.header-bar{
  display:flex;
  align-items:center;
  gap:12px;
  padding:10px clamp(14px, 4vw, 24px);
}

.brand{
  display:flex;
  align-items:center;
  gap:10px;
  flex:none;
  text-decoration:none;
  color:inherit;
}
.brand__mark{
  position:relative;
  flex:none;
  width:42px;
  height:42px;
  display:grid;
  place-items:center;
  border-radius:7px;
  background:var(--ink);
  color:var(--paper);
  font-family:var(--font-mono);
  font-size:13px;
  font-weight:700;
  letter-spacing:.06em;
}
.brand__mark::after{
  content:"";
  position:absolute;
  right:-3px;
  bottom:-3px;
  width:11px;
  height:11px;
  border-radius:2px;
  background:var(--orange);
}
.brand__words{ display:flex; flex-direction:column; line-height:1.35; }
.brand__line{
  font-family:var(--font-mono);
  font-size:12px;
  font-weight:700;
  letter-spacing:.06em;
  color:var(--ink-2);
}
.brand__tag{
  font-size:11px;
  letter-spacing:.04em;
  color:rgba(18,33,29,.58);
}

/* ---------- 通用按钮 ---------- */
.cta{
  display:inline-flex;
  align-items:center;
  justify-content:center;
  gap:8px;
  padding:10px 18px;
  border-radius:999px;
  border:1px solid transparent;
  font-family:var(--font-display);
  font-weight:700;
  font-size:15px;
  line-height:1.3;
  text-decoration:none;
  cursor:pointer;
  transition:background-color .18s var(--ease), color .18s var(--ease), transform .18s var(--ease), box-shadow .18s var(--ease);
}
.cta--signal{
  background:var(--orange);
  color:var(--ink);
  box-shadow:0 2px 0 0 rgba(18,33,29,.2);
}
.cta--signal:hover{
  background:#ff7d4f;
  transform:translateY(-1px);
  box-shadow:0 4px 0 0 rgba(18,33,29,.2);
}
.cta--ghost{
  background:transparent;
  color:var(--ink);
  border-color:rgba(18,33,29,.3);
}
.cta--ghost:hover{ background:var(--sand); border-color:rgba(18,33,29,.45); }
.header-bar__cta{ margin-left:auto; }

/* ---------- 移动菜单按钮 ---------- */
.nav-toggle{
  display:inline-flex;
  align-items:center;
  gap:8px;
  padding:9px 12px;
  border-radius:10px;
  border:1px solid rgba(18,33,29,.24);
  background:transparent;
  color:var(--ink);
  font-family:var(--font-display);
  font-weight:700;
  font-size:13px;
  cursor:pointer;
  transition:background-color .18s var(--ease), border-color .18s var(--ease);
}
.nav-toggle:hover{ background:var(--sand); border-color:rgba(18,33,29,.4); }
.nav-toggle__bars{
  display:flex;
  flex-direction:column;
  justify-content:center;
  gap:4px;
  width:16px;
}
.nav-toggle__bars span{
  display:block;
  height:2px;
  border-radius:2px;
  background:currentColor;
  transition:transform .2s var(--ease), opacity .16s var(--ease);
}
.nav-toggle[aria-expanded="true"] .nav-toggle__bars span:nth-child(1){ transform:translateY(6px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars span:nth-child(2){ opacity:0; }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars span:nth-child(3){ transform:translateY(-6px) rotate(-45deg); }
.nav-toggle__word{ letter-spacing:.04em; }

/* ---------- 导航（移动端抽屉为默认态） ---------- */
.site-nav{
  position:absolute;
  top:100%;
  left:0;
  width:min(312px, 86vw);
  max-height:calc(100vh - 72px);
  overflow-y:auto;
  z-index:95;
  display:flex;
  flex-direction:column;
  gap:16px;
  padding:20px 16px 28px;
  background:var(--ink);
  color:var(--paper);
  border-right:1px solid rgba(246,239,227,.1);
  border-bottom:1px solid rgba(246,239,227,.1);
  box-shadow:10px 16px 32px -12px rgba(18,33,29,.35);
  transform:translateX(-104%);
  transition:transform .28s var(--ease);
}
.site-nav[data-open]{ transform:translateX(0); }

.site-nav__list{ display:flex; flex-direction:column; gap:2px; }
.site-nav__item{ display:block; }
.site-nav__link{
  position:relative;
  display:flex;
  align-items:center;
  gap:12px;
  padding:12px 10px;
  border-radius:8px;
  border-bottom:1px solid rgba(246,239,227,.08);
  color:var(--paper);
  font-family:var(--font-display);
  font-weight:700;
  font-size:15px;
  line-height:1.4;
  text-decoration:none;
  transition:background-color .16s var(--ease), color .16s var(--ease);
}
.site-nav__link:hover{ background:rgba(119,205,211,.12); }
.site-nav__num{
  font-family:var(--font-mono);
  font-size:10px;
  font-weight:700;
  letter-spacing:.12em;
  color:var(--teal-soft);
}
.site-nav__link[aria-current="page"]{
  background:rgba(119,205,211,.16);
  color:var(--white);
}
.site-nav__link[aria-current="page"]::before{
  content:"";
  position:absolute;
  left:0;
  top:10px;
  bottom:10px;
  width:3px;
  border-radius:2px;
  background:var(--amber);
}
.site-nav__note{
  margin-top:auto;
  padding-top:14px;
  border-top:1px solid rgba(246,239,227,.14);
  font-family:var(--font-mono);
  font-size:10px;
  letter-spacing:.18em;
  color:rgba(246,239,227,.45);
}

/* ---------- 页脚 ---------- */
.site-footer{
  position:relative;
  margin-top:clamp(56px, 9vw, 120px);
  padding:clamp(40px, 6vw, 72px) 0 26px;
  background:var(--ink-2);
  color:var(--paper);
  overflow:hidden;
}
.site-footer::before{
  content:"";
  position:absolute;
  inset:0 0 auto 0;
  height:3px;
  background:linear-gradient(90deg, var(--teal), var(--teal-soft) 38%, var(--amber) 68%, var(--orange));
}
.footer-inner{ position:relative; }
.footer-top{
  display:grid;
  gap:clamp(26px, 4vw, 48px);
}
.footer-brand__line{
  font-family:var(--font-display);
  font-weight:900;
  font-size:clamp(22px, 3vw, 30px);
  letter-spacing:-.02em;
  color:var(--white);
}
.footer-brand__summary{
  margin-top:12px;
  max-width:36ch;
  font-size:15px;
  line-height:1.75;
  color:rgba(246,239,227,.76);
}
.footer-nav{
  display:grid;
  grid-template-columns:repeat(2, minmax(0,1fr));
  gap:clamp(20px, 4vw, 40px);
}
.footer-col__title{
  margin-bottom:12px;
  font-family:var(--font-mono);
  font-size:11px;
  font-weight:700;
  letter-spacing:.2em;
  color:var(--teal-soft);
}
.footer-col__list li + li{ margin-top:8px; }
.footer-col__list a{
  display:inline-block;
  padding-bottom:1px;
  border-bottom:1px solid transparent;
  color:rgba(246,239,227,.86);
  font-size:15px;
  text-decoration:none;
  transition:color .16s var(--ease), border-color .16s var(--ease);
}
.footer-col__list a:hover{
  color:var(--white);
  border-bottom-color:var(--teal-soft);
}
.footer-meta{
  display:flex;
  flex-direction:column;
  gap:8px;
  margin-top:clamp(28px, 5vw, 44px);
  padding-top:20px;
  border-top:1px solid rgba(246,239,227,.16);
  font-size:13px;
  line-height:1.72;
  color:rgba(246,239,227,.62);
}
.footer-legal{
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.05em;
  color:rgba(246,239,227,.46);
}

/* ---------- 回到顶部 ---------- */
.backtop{
  position:fixed;
  right:16px;
  bottom:16px;
  z-index:70;
  display:inline-flex;
  align-items:center;
  gap:7px;
  padding:10px 14px;
  border-radius:999px;
  border:1px solid rgba(246,239,227,.3);
  background:var(--ink);
  color:var(--paper);
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.08em;
  cursor:pointer;
  opacity:0;
  visibility:hidden;
  transform:translateY(10px);
  transition:opacity .22s var(--ease), transform .22s var(--ease), visibility .22s var(--ease), background-color .18s var(--ease);
}
.backtop:hover{ background:var(--teal); }
.backtop[data-visible]{
  opacity:1;
  visibility:visible;
  transform:translateY(0);
}
.backtop__icon{ font-size:13px; line-height:1; }

/* ---------- 通内容容器 ---------- */
.wrap{
  width:100%;
  max-width:var(--shell-max);
  margin-inline:auto;
  padding-inline:var(--pad);
}

/* ---------- 小标签与导语 ---------- */
.eyebrow{
  display:inline-flex;
  align-items:center;
  gap:8px;
  font-family:var(--font-mono);
  font-size:11px;
  font-weight:700;
  letter-spacing:.2em;
  text-transform:uppercase;
  color:var(--teal);
}
.eyebrow::before{
  content:"";
  width:20px;
  height:2px;
  background:currentColor;
}
.lede{
  max-width:60ch;
  font-size:clamp(17px, 1.4vw, 19px);
  line-height:1.8;
  color:rgba(18,33,29,.78);
}
.rule{
  height:0;
  border:0;
  border-top:var(--bd-hair);
}

/* ---------- 编号章节 ---------- */
.chapter{
  display:grid;
  gap:14px 36px;
}
.chapter__num{
  font-family:var(--font-mono);
  font-size:clamp(48px, 8vw, 96px);
  font-weight:700;
  line-height:.85;
  letter-spacing:-.05em;
  color:var(--teal);
}
.chapter__body{ min-width:0; }
.chapter__text{
  max-width:68ch;
  color:rgba(18,33,29,.82);
}
.chapter__text + .chapter__text{ margin-top:14px; }

/* ---------- 面板 ---------- */
.panel{
  padding:clamp(18px, 3vw, 28px);
  border:var(--bd-hair);
  border-radius:12px;
  background:var(--white);
  box-shadow:0 1px 0 rgba(18,33,29,.04), 0 14px 28px -22px rgba(18,33,29,.55);
}
.panel--dark{
  background:var(--ink-2);
  color:var(--paper);
  border-color:rgba(246,239,227,.14);
  box-shadow:0 16px 32px -22px rgba(18,33,29,.8);
}
.panel__title{
  font-family:var(--font-display);
  font-weight:900;
  font-size:1.1rem;
  letter-spacing:-.01em;
  color:var(--ink);
  margin-bottom:10px;
}
.panel--dark .panel__title{ color:var(--white); }

/* ---------- 标签 ---------- */
.tag{
  display:inline-flex;
  align-items:center;
  gap:6px;
  padding:6px 9px;
  border-radius:4px;
  border:1px solid rgba(18,33,29,.12);
  background:var(--sand);
  color:var(--ink-2);
  font-family:var(--font-mono);
  font-size:11px;
  font-weight:700;
  letter-spacing:.1em;
  line-height:1;
  white-space:nowrap;
}
.tag--amber{ background:var(--amber); color:var(--ink); border-color:rgba(18,33,29,.18); }
.tag--teal{ background:var(--teal); color:var(--white); border-color:transparent; }
.tag--alert{ background:var(--alert); color:var(--white); border-color:transparent; }
.tag--ghost{ background:transparent; color:var(--ink-2); border-color:rgba(18,33,29,.24); }

/* ---------- 图片容器基座 ---------- */
.media{
  position:relative;
  display:block;
  overflow:hidden;
  border-radius:12px;
  border:var(--bd-hair);
  aspect-ratio:16 / 10;
  background:
    repeating-linear-gradient(135deg, rgba(11,127,138,.14) 0 12px, rgba(234,220,199,.55) 12px 24px),
    linear-gradient(150deg, rgba(11,127,138,.16), rgba(242,106,59,.14));
}
.media > img,
.media > picture,
.media > picture > img,
.media > svg{
  display:block;
  width:100%;
  height:100%;
  object-fit:cover;
}
.media--wide{ aspect-ratio:21 / 9; }
.media--square{ aspect-ratio:1 / 1; }
.media--tall{ aspect-ratio:3 / 4; }
.media__caption{
  position:absolute;
  inset:auto 0 0 0;
  padding:16px 18px;
  background:linear-gradient(0deg, rgba(18,33,29,.82), rgba(18,33,29,0));
  color:var(--paper);
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.08em;
  line-height:1.6;
}

/* ---------- 面包屑 ---------- */
.breadcrumb{
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  gap:8px;
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.08em;
  color:rgba(18,33,29,.55);
}
.breadcrumb a{
  color:inherit;
  text-decoration:none;
  border-bottom:1px solid transparent;
  transition:color .16s var(--ease), border-color .16s var(--ease);
}
.breadcrumb a:hover{
  color:var(--teal);
  border-bottom-color:var(--teal);
}
.breadcrumb__sep{ color:rgba(18,33,29,.3); }

/* ---------- 显现动画 ---------- */
[data-reveal]{ transition:opacity .55s var(--ease), transform .55s var(--ease); }
[data-reveal].is-hidden{
  opacity:0;
  transform:translateY(16px);
}
[data-reveal].is-visible{
  opacity:1;
  transform:none;
}

/* ==========================================================================
   平板及以上
   ========================================================================== */
@media (min-width: 640px){
  .footer-top{ grid-template-columns:1.05fr 1.25fr; }
  .footer-nav{ grid-template-columns:repeat(2, minmax(0,1fr)); }
}

@media (min-width: 768px){
  .chapter{ grid-template-columns:96px minmax(0, 1fr); }
  .chapter__num{ grid-row:1 / span 3; }
  .footer-meta{ flex-direction:row; flex-wrap:wrap; justify-content:space-between; align-items:baseline; gap:10px 24px; }
  .backtop{ right:24px; bottom:24px; }
}

/* ==========================================================================
   桌面端：左侧固定轨道导航
   ========================================================================== */
@media (min-width: 900px){
  body{ padding-left:var(--rail-w); }

  .site-header{
    position:fixed;
    inset:0 auto 0 0;
    width:var(--rail-w);
    display:flex;
    flex-direction:column;
    border-bottom:0;
    border-right:var(--bd-hair);
    background:var(--paper);
    overflow:hidden;
  }
  .site-header::before{
    content:"";
    position:absolute;
    left:0;
    top:0;
    bottom:0;
    width:4px;
    background:linear-gradient(180deg, var(--teal), var(--teal-soft) 52%, var(--orange));
  }

  .scroll-progress{ left:var(--rail-w); right:0; }

  .header-bar{
    flex-direction:column;
    align-items:center;
    gap:14px;
    padding:22px 8px 8px;
  }
  .header-bar__cta{
    position:absolute;
    left:10px;
    right:10px;
    bottom:22px;
    margin:0;
    padding:10px 4px;
    font-size:12px;
    letter-spacing:.02em;
    text-align:center;
  }
  .nav-toggle{ display:none; }

  .brand{ flex-direction:column; gap:8px; }
  .brand__words{ align-items:center; text-align:center; }
  .brand__tag{ display:none; }
  .brand__line{ font-size:10px; letter-spacing:.08em; max-width:78px; }

  .site-nav{
    position:static;
    top:auto;
    left:auto;
    width:auto;
    max-height:none;
    transform:none;
    overflow-y:auto;
    flex:1 1 auto;
    gap:0;
    margin-top:14px;
    padding:14px 6px 104px;
    background:transparent;
    color:var(--ink);
    border-top:var(--bd-hair);
    border-right:0;
    border-bottom:0;
    box-shadow:none;
    scrollbar-width:thin;
  }
  .site-nav[data-open]{ transform:none; }

  .site-nav__list{
    flex-direction:column;
    align-items:stretch;
    gap:2px;
  }
  .site-nav__link{
    flex-direction:column;
    justify-content:center;
    gap:5px;
    padding:9px 4px;
    border-bottom:0;
    border-radius:8px;
    color:var(--ink);
    font-size:13px;
  }
  .site-nav__link:hover{ background:rgba(11,127,138,.1); }
  .site-nav__num{ font-size:9px; color:var(--teal); }
  .site-nav__text{
    writing-mode:vertical-rl;
    line-height:1.15;
    letter-spacing:.16em;
    font-size:12.5px;
  }
  .site-nav__link[aria-current="page"]{
    background:var(--sand);
    color:var(--ink);
  }
  .site-nav__link[aria-current="page"]::before{
    top:8px;
    bottom:8px;
    left:0;
    background:var(--teal);
  }
  .site-nav__link[aria-current="page"] .site-nav__num{ color:var(--teal); }
  .site-nav__note{ display:none; }

  .footer-top{ gap:48px; }
  .backtop{ right:32px; bottom:32px; }
}

/* ==========================================================================
   窄屏微调
   ========================================================================== */
@media (max-width: 639px){
  .header-bar__cta{ display:none; }
  .nav-toggle{ margin-left:auto; }
  .backtop__word{ display:none; }
  .backtop{ padding:11px 13px; }
}

@media (max-width: 420px){
  .brand__tag{ display:none; }
  .brand__mark{ width:38px; height:38px; font-size:12px; }
}

/* ==========================================================================
   减弱动效
   ========================================================================== */
@media (prefers-reduced-motion: reduce){
  *,
  *::before,
  *::after{
    animation-duration:.001ms !important;
    animation-iteration-count:1 !important;
    transition-duration:.001ms !important;
    scroll-behavior:auto !important;
  }
  [data-reveal],
  [data-reveal].is-hidden{
    opacity:1 !important;
    transform:none !important;
  }
  .site-nav{ transition:none; }
  .backtop{ transition:none; }
}