:root{
  --rice-50:#FBF6EC;
  --rice-100:#F1E3D0;
  --sauce-950:#2B0B0D;
  --sauce-800:#4E1014;
  --sauce-600:#7D1D22;
  --pepper-500:#F26A21;
  --pepper-300:#FFB27B;
  --celadon-600:#3F6F5E;
  --celadon-200:#CFE0D5;
  --ink-500:#5B4A43;
  --line-300:#D9C6B2;
  --white:#FFFFFF;

  --font-display:"Alibaba PuHuiTi","Alibaba PuHuiTi 3.0","Source Han Sans SC","Noto Sans SC","PingFang SC","Microsoft YaHei",system-ui,sans-serif;
  --font-body:"Source Han Serif SC","Noto Serif SC","Songti SC","STSong","SimSun",Georgia,serif;
  --font-mono:"JetBrains Mono",ui-monospace,SFMono-Regular,Menlo,Consolas,"Courier New",monospace;

  --shell:1240px;
  --edge:clamp(20px,4vw,48px);
  --gap:24px;
  --ease:cubic-bezier(.22,.61,.36,1);
}

*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth}
body,h1,h2,h3,h4,h5,h6,p,figure,blockquote,dl,dd,ul,ol{margin:0}
ul,ol{padding:0;list-style:none}
img,svg,video{display:block;max-width:100%;height:auto}
button,input,select,textarea{font:inherit;color:inherit}
a{color:inherit;text-decoration:none}
table{border-collapse:collapse;width:100%}

body{
  background:var(--rice-50);
  color:var(--sauce-950);
  font-family:var(--font-body);
  font-size:clamp(16px,.2vw + 13.5px,17.5px);
  line-height:1.85;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
  overflow-x:hidden;
}

h1,h2,h3,h4,h5,h6{
  font-family:var(--font-display);
  font-weight:900;
  line-height:1.1;
  letter-spacing:-.01em;
}

:where(a,button,summary,[tabindex]):focus-visible{
  outline:2px solid var(--pepper-500);
  outline-offset:3px;
}

::selection{background:var(--pepper-300);color:var(--sauce-950)}

/* ---------- 骨架与栅格 ---------- */
.yb-shell{
  width:100%;
  max-width:var(--shell);
  margin:0 auto;
  padding-left:var(--edge);
  padding-right:var(--edge);
}
.yb-main{display:block;min-height:52vh}
.yb-section{padding:clamp(48px,7vw,96px) 0}
.yb-section--tight{padding:clamp(28px,4vw,52px) 0}
.yb-rule{height:0;border:0;border-top:1px solid var(--line-300);margin:0}

.yb-grid{
  display:grid;
  grid-template-columns:repeat(12,minmax(0,1fr));
  gap:var(--gap);
}
.yb-col-3{grid-column:span 3}
.yb-col-4{grid-column:span 4}
.yb-col-5{grid-column:span 5}
.yb-col-6{grid-column:span 6}
.yb-col-7{grid-column:span 7}
.yb-col-8{grid-column:span 8}
.yb-col-9{grid-column:span 9}
.yb-col-12{grid-column:span 12}

/* ---------- 文本与标签 ---------- */
.yb-eyebrow{
  display:inline-flex;
  align-items:center;
  gap:8px;
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.2em;
  text-transform:uppercase;
  color:var(--ink-500);
}
.yb-eyebrow::before{
  content:"";
  width:8px;height:8px;
  background:var(--pepper-500);
  flex:0 0 auto;
}
.yb-vertical{
  writing-mode:vertical-rl;
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.34em;
  text-transform:uppercase;
  color:var(--ink-500);
}
.yb-prose{max-width:68ch}
.yb-prose p + p{margin-top:1.05em}
.yb-prose h2,.yb-prose h3{margin-top:1.6em;margin-bottom:.6em}
.yb-prose ul,.yb-prose ol{margin:1em 0;padding-left:1.1em;list-style:square}
.yb-prose li{margin:.35em 0}
.yb-prose a{
  color:var(--sauce-600);
  border-bottom:1px solid var(--pepper-300);
  padding-bottom:1px;
}
.yb-prose a:hover{border-bottom-color:var(--sauce-600)}
.yb-prose strong{font-weight:700;color:var(--sauce-800)}

/* ---------- 按钮 ---------- */
.yb-btn{
  display:inline-flex;
  align-items:center;
  gap:10px;
  padding:13px 22px;
  border:1px solid var(--sauce-600);
  background:transparent;
  color:var(--sauce-800);
  font-family:var(--font-mono);
  font-size:12px;
  letter-spacing:.16em;
  text-transform:uppercase;
  cursor:pointer;
  transition:background .2s var(--ease),color .2s var(--ease),border-color .2s var(--ease);
}
.yb-btn:hover{background:var(--sauce-800);color:var(--rice-50);border-color:var(--sauce-800)}
.yb-btn--solid{
  background:var(--pepper-500);
  border-color:var(--pepper-500);
  color:var(--sauce-950);
  font-family:var(--font-display);
  font-weight:800;
  letter-spacing:.1em;
  text-transform:none;
  font-size:14px;
}
.yb-btn--solid:hover{background:var(--sauce-950);border-color:var(--sauce-950);color:var(--rice-50)}
.yb-btn--ghost{
  border-color:var(--line-300);
  color:var(--sauce-950);
  font-family:var(--font-display);
  font-weight:700;
  letter-spacing:.08em;
  text-transform:none;
  font-size:14px;
}
.yb-btn--ghost:hover{background:var(--sauce-600);border-color:var(--sauce-600);color:var(--rice-50)}

/* ---------- 卡片与标签 ---------- */
.yb-card{
  background:var(--rice-100);
  border:1px solid var(--line-300);
  padding:clamp(18px,2.4vw,30px);
}
.yb-card--dark{
  background:var(--sauce-800);
  border-color:var(--sauce-800);
  color:var(--rice-50);
}
.yb-card--dark :where(h2,h3,h4){color:var(--rice-50)}
.yb-tag{
  display:inline-flex;
  align-items:center;
  gap:6px;
  padding:4px 8px;
  border:1px solid var(--line-300);
  background:transparent;
  color:var(--ink-500);
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.14em;
  text-transform:uppercase;
  white-space:nowrap;
}
.yb-tag--pepper{background:var(--pepper-300);border-color:var(--pepper-300);color:var(--sauce-950)}
.yb-tag--celadon{background:var(--celadon-200);border-color:var(--celadon-200);color:var(--celadon-600)}

/* ---------- 面包屑 ---------- */
.yb-crumbs{
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  gap:8px;
  padding:16px 0;
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.14em;
  text-transform:uppercase;
  color:var(--ink-500);
}
.yb-crumbs-link{color:var(--ink-500);border-bottom:1px solid transparent}
.yb-crumbs-link:hover{color:var(--sauce-800);border-bottom-color:var(--pepper-500)}
.yb-crumbs-sep{color:var(--line-300)}

/* ---------- 图片容器 ---------- */
.yb-figure{
  position:relative;
  display:block;
  overflow:hidden;
  background:var(--rice-100);
  border:1px solid var(--line-300);
  aspect-ratio:4 / 3;
}
.yb-figure-img{width:100%;height:100%;object-fit:cover}
.yb-figure--wide{aspect-ratio:16 / 9}
.yb-figure--tall{aspect-ratio:3 / 4}
.yb-figure--plate{aspect-ratio:1 / 1}
.yb-figure--bleed{border:0;background:var(--sauce-800)}
.yb-figure-caption{
  display:flex;
  flex-wrap:wrap;
  gap:8px 12px;
  padding:8px 10px;
  border-top:1px solid var(--line-300);
  background:var(--rice-50);
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.1em;
  color:var(--ink-500);
}
.yb-figure-tag{
  font-family:var(--font-mono);
  font-size:10px;
  letter-spacing:.16em;
  text-transform:uppercase;
  color:var(--celadon-600);
}

/* ---------- 章节索引 ---------- */
.yb-index{
  display:flex;
  flex-direction:column;
  gap:2px;
  border-left:1px solid var(--line-300);
}
.yb-index-link{
  display:block;
  padding:6px 0 6px 14px;
  margin-left:-1px;
  border-left:2px solid transparent;
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.14em;
  text-transform:uppercase;
  color:var(--ink-500);
  transition:color .2s var(--ease),border-color .2s var(--ease);
}
.yb-index-link:hover{color:var(--sauce-800)}
.yb-index-link[aria-current="true"]{
  color:var(--sauce-800);
  border-left-color:var(--pepper-500);
  font-weight:700;
}

/* ---------- 通用状态点 ---------- */
.yb-dot{
  display:inline-block;
  width:6px;height:6px;
  background:var(--celadon-600);
  flex:0 0 auto;
}
.yb-dot--pepper{background:var(--pepper-500)}

/* ---------- 显现动效 ---------- */
[data-reveal]{
  opacity:0;
  transform:translateY(14px);
  transition:opacity .6s var(--ease),transform .6s var(--ease);
  will-change:opacity,transform;
}
[data-reveal].is-in{opacity:1;transform:none}

/* ================= 头部 ================= */
.yb-header{
  --hd-bg:rgba(43,11,13,.94);
  --hd-fg:var(--rice-50);
  --hd-dim:rgba(251,246,236,.62);
  --hd-line:rgba(251,246,236,.16);
  --hd-active:var(--pepper-300);
  --hd-cta-bg:var(--pepper-500);
  --hd-cta-fg:var(--sauce-950);
  position:sticky;
  top:0;
  z-index:90;
  background:var(--hd-bg);
  color:var(--hd-fg);
  border-bottom:1px solid var(--hd-line);
  -webkit-backdrop-filter:blur(10px);
  backdrop-filter:blur(10px);
  transition:background .3s var(--ease),color .3s var(--ease),border-color .3s var(--ease);
}
.yb-header[data-scrolled="true"]{
  --hd-bg:rgba(251,246,236,.96);
  --hd-fg:var(--sauce-950);
  --hd-dim:var(--ink-500);
  --hd-line:var(--line-300);
  --hd-active:var(--sauce-600);
  --hd-cta-bg:var(--sauce-800);
  --hd-cta-fg:var(--rice-50);
}

.yb-skip{
  position:absolute;
  top:8px;
  left:12px;
  z-index:120;
  padding:10px 16px;
  background:var(--pepper-500);
  color:var(--sauce-950);
  font-family:var(--font-mono);
  font-size:12px;
  letter-spacing:.12em;
  transform:translateY(-180%);
  transition:transform .2s var(--ease);
}
.yb-skip:focus,
.yb-skip:focus-visible{transform:none}

.yb-rail{border-bottom:1px solid var(--hd-line);transition:border-color .3s var(--ease)}
.yb-rail-inner{
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap:16px;
  min-height:32px;
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.16em;
}
.yb-rail-note{
  display:flex;
  align-items:center;
  gap:8px;
  color:var(--hd-dim);
  text-transform:uppercase;
}
.yb-utility{display:flex;align-items:center;gap:18px}
.yb-utility-link{
  padding:6px 0;
  color:var(--hd-dim);
  border-bottom:1px solid transparent;
  transition:color .2s var(--ease),border-color .2s var(--ease);
}
.yb-utility-link:hover{color:var(--hd-fg);border-bottom-color:var(--pepper-500)}

.yb-bar{
  display:flex;
  align-items:center;
  gap:clamp(12px,2vw,28px);
  min-height:70px;
  padding-top:10px;
  padding-bottom:10px;
}
.yb-brand{display:flex;align-items:baseline;gap:10px;flex:0 0 auto;color:inherit}
.yb-brand-mark{
  font-family:var(--font-display);
  font-weight:900;
  font-size:clamp(20px,2vw,24px);
  letter-spacing:.04em;
  line-height:1;
  transition:color .2s var(--ease);
}
.yb-brand-sub{
  font-family:var(--font-mono);
  font-size:10px;
  letter-spacing:.24em;
  color:var(--hd-dim);
}
.yb-brand:hover .yb-brand-mark{color:var(--pepper-500)}

.yb-nav-toggle{
  display:none;
  margin-left:auto;
  align-items:center;
  gap:10px;
  padding:9px 12px;
  background:transparent;
  border:1px solid var(--hd-line);
  color:inherit;
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.16em;
  cursor:pointer;
}
.yb-nav-toggle-bars{
  position:relative;
  display:block;
  width:16px;
  height:11px;
}
.yb-nav-toggle-bars::before,
.yb-nav-toggle-bars::after{
  content:"";
  position:absolute;
  left:0;right:0;
  height:1.5px;
  background:currentColor;
  transition:transform .25s var(--ease),top .25s var(--ease);
}
.yb-nav-toggle-bars::before{top:1px}
.yb-nav-toggle-bars::after{top:8px}
.yb-header[data-open="true"] .yb-nav-toggle-bars::before{top:4.5px;transform:rotate(45deg)}
.yb-header[data-open="true"] .yb-nav-toggle-bars::after{top:4.5px;transform:rotate(-45deg)}

.yb-nav{margin-left:auto}
.yb-nav-list{display:flex;align-items:center;gap:clamp(4px,1.3vw,18px)}
.yb-nav-item{display:block}
.yb-nav-link{
  display:inline-flex;
  align-items:baseline;
  gap:6px;
  padding:10px 2px 8px;
  border-bottom:2px solid transparent;
  color:var(--hd-fg);
  font-family:var(--font-display);
  font-weight:700;
  font-size:14px;
  letter-spacing:.06em;
  transition:color .2s var(--ease),border-color .2s var(--ease);
}
.yb-nav-idx{
  font-family:var(--font-mono);
  font-size:9px;
  letter-spacing:.1em;
  color:var(--hd-dim);
}
.yb-nav-link:hover{border-bottom-color:var(--pepper-300);color:var(--hd-active)}
.yb-nav-link[aria-current="page"]{
  color:var(--hd-active);
  border-bottom-color:var(--pepper-500);
}
.yb-nav-foot{display:none}

.yb-actions{display:flex;align-items:center;gap:14px;flex:0 0 auto}
.yb-actions-link{
  padding:8px 0;
  border-bottom:1px solid transparent;
  color:var(--hd-dim);
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.14em;
  transition:color .2s var(--ease),border-color .2s var(--ease);
}
.yb-actions-link:hover{color:var(--hd-fg);border-bottom-color:var(--pepper-500)}
.yb-cta{
  display:inline-flex;
  align-items:center;
  gap:8px;
  padding:11px 18px;
  background:var(--hd-cta-bg);
  color:var(--hd-cta-fg);
  border:1px solid transparent;
  font-family:var(--font-display);
  font-weight:800;
  font-size:13px;
  letter-spacing:.1em;
  white-space:nowrap;
  transition:background .2s var(--ease),color .2s var(--ease);
}
.yb-cta::after{
  content:"→";
  font-family:var(--font-mono);
  font-size:12px;
  transition:transform .2s var(--ease);
}
.yb-cta:hover{background:var(--pepper-500);color:var(--sauce-950)}
.yb-cta:hover::after{transform:translateX(3px)}

.yb-progress{
  position:absolute;
  left:0;right:0;bottom:-1px;
  height:2px;
  background:transparent;
  pointer-events:none;
}
.yb-progress-bar{
  display:block;
  width:0;
  height:100%;
  background:var(--pepper-500);
  transition:width .12s linear;
}

/* ================= 页脚 ================= */
.yb-footer{
  margin-top:clamp(56px,8vw,110px);
  background:var(--sauce-950);
  color:var(--rice-50);
  border-top:3px solid var(--pepper-500);
}
.yb-footer-top{
  padding:clamp(40px,6vw,76px) 0 clamp(28px,4vw,48px);
  border-bottom:1px solid rgba(251,246,236,.14);
}
.yb-footer-brand{display:flex;flex-direction:column;gap:18px}
.yb-footer-kicker{
  display:flex;
  align-items:center;
  gap:8px;
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.2em;
  text-transform:uppercase;
  color:rgba(251,246,236,.62);
}
.yb-footer-head{
  font-family:var(--font-display);
  font-weight:900;
  font-size:clamp(22px,2.9vw,38px);
  line-height:1.3;
  letter-spacing:.01em;
  max-width:24ch;
}

.yb-footer-contact{
  display:flex;
  flex-direction:column;
  gap:10px;
  padding-left:clamp(0px,2vw,28px);
  border-left:1px solid rgba(251,246,236,.14);
}
.yb-contact-label{
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.2em;
  text-transform:uppercase;
  color:var(--pepper-300);
}
.yb-contact-line{
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  gap:10px;
  font-size:15px;
  line-height:1.7;
}
.yb-contact-key{
  min-width:34px;
  font-family:var(--font-mono);
  font-size:10px;
  letter-spacing:.16em;
  text-transform:uppercase;
  color:rgba(251,246,236,.5);
}
.yb-contact-value{color:var(--rice-50);word-break:break-word}
.yb-copy{
  padding:4px 8px;
  background:transparent;
  border:1px solid rgba(251,246,236,.32);
  color:rgba(251,246,236,.82);
  font-family:var(--font-mono);
  font-size:10px;
  letter-spacing:.14em;
  cursor:pointer;
  transition:background .2s var(--ease),color .2s var(--ease),border-color .2s var(--ease);
}
.yb-copy:hover{background:var(--pepper-500);border-color:var(--pepper-500);color:var(--sauce-950)}
.yb-copy[data-copied="true"]{background:var(--celadon-600);border-color:var(--celadon-600);color:var(--white)}
.yb-contact-note{
  max-width:44ch;
  font-size:13px;
  line-height:1.8;
  color:rgba(251,246,236,.55);
}
.yb-copy-status{
  min-height:1.2em;
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.12em;
  color:var(--celadon-200);
}

.yb-footer-grid{
  display:grid;
  grid-template-columns:repeat(3,minmax(0,1fr));
  gap:clamp(20px,4vw,48px);
  padding:clamp(28px,4vw,44px) 0;
  border-bottom:1px solid rgba(251,246,236,.14);
}
.yb-footer-col{display:flex;flex-direction:column;gap:12px}
.yb-footer-title{
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.2em;
  text-transform:uppercase;
  color:var(--pepper-300);
}
.yb-footer-list{display:flex;flex-direction:column;gap:8px}
.yb-footer-link{
  display:inline-block;
  padding-bottom:2px;
  border-bottom:1px solid transparent;
  color:rgba(251,246,236,.78);
  font-family:var(--font-display);
  font-weight:600;
  font-size:15px;
  letter-spacing:.04em;
  transition:color .2s var(--ease),border-color .2s var(--ease);
}
.yb-footer-link:hover{color:var(--rice-50);border-bottom-color:var(--pepper-500)}

.yb-footer-bottom{
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  gap:12px 22px;
  padding:clamp(20px,3vw,30px) 0 clamp(28px,4vw,40px);
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.1em;
  color:rgba(251,246,236,.5);
}
.yb-footer-icp{color:rgba(251,246,236,.5)}
.yb-footer-copyline{color:rgba(251,246,236,.5)}
.yb-footer-legal{display:flex;flex-wrap:wrap;gap:8px 16px;margin-left:auto}
.yb-footer-legal .yb-footer-link{
  font-family:var(--font-mono);
  font-weight:400;
  font-size:11px;
  letter-spacing:.1em;
  color:rgba(251,246,236,.6);
}
.yb-footer-legal .yb-footer-link:hover{color:var(--rice-50)}

/* ================= 响应式 ================= */
@media (max-width:1080px){
  .yb-rail{display:none}
  .yb-nav-toggle{display:inline-flex}
  .yb-actions-link{display:none}
  .yb-nav{
    position:absolute;
    top:100%;
    left:0;
    right:0;
    display:none;
    flex-direction:column;
    align-items:stretch;
    margin-left:0;
    padding:6px 0 26px;
    background:var(--sauce-950);
    color:var(--rice-50);
    border-top:1px solid rgba(251,246,236,.16);
    border-bottom:1px solid rgba(251,246,236,.16);
    max-height:calc(100dvh - 72px);
    overflow-y:auto;
    box-shadow:0 24px 44px rgba(43,11,13,.32);
  }
  .yb-header[data-open="true"] .yb-nav{display:flex}
  .yb-nav-list{
    flex-direction:column;
    align-items:stretch;
    gap:0;
  }
  .yb-nav-item{border-bottom:1px solid rgba(251,246,236,.12)}
  .yb-nav-item:last-child{border-bottom:0}
  .yb-nav-link{
    display:flex;
    align-items:baseline;
    gap:12px;
    padding:16px var(--edge);
    border-bottom:0;
    color:var(--rice-50);
    font-size:19px;
  }
  .yb-nav-link:hover{color:var(--pepper-300)}
  .yb-nav-link[aria-current="page"]{
    color:var(--pepper-300);
    border-bottom:0;
    box-shadow:inset 3px 0 0 var(--pepper-500);
  }
  .yb-nav-idx{font-size:10px;color:rgba(251,246,236,.45)}
  .yb-nav-foot{
    display:flex;
    flex-wrap:wrap;
    gap:10px 18px;
    padding:22px var(--edge) 0;
    font-family:var(--font-mono);
    font-size:11px;
    letter-spacing:.14em;
  }
  .yb-nav-foot-link{
    padding-bottom:2px;
    color:rgba(251,246,236,.7);
    border-bottom:1px solid rgba(251,246,236,.3);
    transition:color .2s var(--ease),border-color .2s var(--ease);
  }
  .yb-nav-foot-link:hover{color:var(--rice-50);border-bottom-color:var(--pepper-500)}
  .yb-nav-foot-link--cta{
    padding:8px 14px;
    background:var(--pepper-500);
    color:var(--sauce-950);
    border:0;
  }
}

@media (max-width:880px){
  .yb-col-3,.yb-col-4,.yb-col-5,.yb-col-6,
  .yb-col-7,.yb-col-8,.yb-col-9{grid-column:span 12}
  .yb-footer-contact{
    padding-left:0;
    padding-top:22px;
    border-left:0;
    border-top:1px solid rgba(251,246,236,.14);
  }
  .yb-footer-grid{grid-template-columns:1fr 1fr}
  .yb-footer-legal{margin-left:0;width:100%}
}

@media (max-width:600px){
  .yb-bar{min-height:62px;padding-top:8px;padding-bottom:8px}
  .yb-brand-sub{display:none}
  .yb-cta{padding:10px 14px;font-size:12px}
  .yb-footer-grid{grid-template-columns:1fr}
  .yb-footer-head{max-width:none}
  .yb-footer-bottom{flex-direction:column;align-items:flex-start;gap:10px}
  .yb-figure-caption{font-size:10px}
}

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