:root{
  --paper:#ECEAE3;
  --paper-2:#F4F2EB;
  --paper-3:#F8F6F0;
  --ink:#23201B;
  --ink-2:#46413A;
  --muted:#706A5E;
  --hair:#CBC5B6;
  --hair-soft:#DAD5C8;
  --cinnabar:#A03A2A;
  --cinnabar-deep:#823024;
  --cinnabar-soft:#B95743;
  --night:#211E1A;
  --night-2:#2A2722;
  --night-3:#332F29;
  --night-text:#DDD7C9;
  --night-muted:#9B9484;
  --night-hair:#45403A;
  --night-cinnabar:#C6674F;
  --serif:"Noto Serif SC","Noto Serif CJK SC","Source Han Serif SC","Songti SC","STSong","SimSun","NSimSun",Georgia,"Times New Roman",serif;
  --sans:"Noto Sans CJK SC","Source Han Sans SC","Noto Sans SC","PingFang SC","Microsoft YaHei","微软雅黑",-apple-system,"Segoe UI","Helvetica Neue",Arial,sans-serif;
  --w:780px;
}
*{margin:0;padding:0;box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  font-family:var(--serif);
  background:var(--paper);
  color:var(--ink);
  line-height:1.9;
  letter-spacing:.02em;
  -webkit-font-smoothing:antialiased;
  overflow-x:hidden;
}
::selection{background:var(--cinnabar);color:#F4F1E8}
a{color:inherit;text-decoration:none}
button{font-family:var(--sans);cursor:pointer;border:none;background:none;color:inherit}
.wrap{max-width:var(--w);width:100%;margin:0 auto;padding:0 26px}

/* 纸张颗粒纹理 */
.grain{position:fixed;inset:0;pointer-events:none;z-index:1;opacity:.5;
  background-image:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='160' height='160'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='2'/%3E%3CfeColorMatrix values='0 0 0 0 0.16 0 0 0 0 0.14 0 0 0 0 0.11 0 0 0 0.035 0'/%3E%3C/filter%3E%3Crect width='160' height='160' filter='url(%23n)'/%3E%3C/svg%3E");}
.view{position:relative;z-index:2}


/* ============ 顶部导航 ============ */
.nav{position:fixed;top:0;left:0;right:0;z-index:50;height:72px;
  transition:background .35s,border-color .35s,box-shadow .35s;
  border-bottom:1px solid transparent;}
.nav.scrolled{background:rgba(236,234,227,.92);backdrop-filter:blur(10px);
  border-bottom-color:var(--hair-soft);box-shadow:0 1px 0 rgba(0,0,0,.02)}
.nav-inner{max-width:1040px;margin:0 auto;padding:0 26px;height:100%;display:flex;align-items:center;justify-content:space-between;gap:16px}
.brand{display:flex;align-items:center;gap:12px;min-width:0}
.brand-seal{width:64px;height:64px;flex:none;display:grid;place-items:center;background:transparent;border-radius:3px;}
.brand-name{font-family:var(--sans);font-weight:700;letter-spacing:.22em;font-size:15px}
.brand-sub{font-size:11px;color:var(--muted);letter-spacing:.15em;font-family:var(--sans);margin-top:1px}
.brand-seal svg{width:56px;height:56px;display:block}
.nav-links{display:flex;align-items:center;gap:4px;font-family:var(--sans);font-size:14px}
.nav-links a{padding:8px 13px;color:var(--ink-2);border-radius:4px;transition:color .2s,background .2s}
.nav-links a:hover{color:var(--cinnabar);background:rgba(160,58,42,.07)}
.nav-links a.cta{background:var(--ink);color:var(--paper-3);margin-left:6px;font-size:13px;letter-spacing:.05em}
.nav-links a.cta:hover{background:var(--cinnabar);color:#fff}
.nav-burger{display:none;flex-direction:column;gap:5px;padding:8px}
.nav-burger span{width:22px;height:2px;background:var(--ink);transition:.3s}
.nav-burger.open span:nth-child(1){transform:translateY(7px) rotate(45deg)}
.nav-burger.open span:nth-child(2){opacity:0}
.nav-burger.open span:nth-child(3){transform:translateY(-7px) rotate(-45deg)}
.nav-mobile{display:none;flex-direction:column;background:var(--paper-2);border-bottom:1px solid var(--hair);padding:8px 18px 16px;font-family:var(--sans)}
.nav-mobile a{padding:13px 8px;border-bottom:1px solid var(--hair-soft);font-size:15px;color:var(--ink-2)}
.nav-mobile a.cta{border-bottom:none;margin-top:10px;background:var(--ink);color:var(--paper-3);text-align:center;border-radius:4px;padding:13px}
.nav-mobile.show{display:flex}


/* ============ 通用章节 ============ */
section.block{padding:96px 0}
.sec-no{font-family:var(--sans);font-size:12px;letter-spacing:.35em;color:var(--cinnabar);margin-bottom:16px}
.sec-title{font-size:clamp(26px,4vw,34px);font-weight:700;letter-spacing:.04em;line-height:1.5;margin-bottom:22px}
.sec-lede{font-size:17px;color:var(--ink-2);line-height:2.1;margin-bottom:18px}
.body-p{font-size:16px;color:var(--ink-2);line-height:2.1;margin-bottom:16px}
.body-p strong{color:var(--ink);font-weight:600}
.body-p .cin{color:var(--cinnabar);font-weight:600}
.divider{height:1px;background:var(--hair);border:none;margin:0}
blockquote.pull{border-left:3px solid var(--cinnabar);padding:6px 0 6px 24px;margin:36px 0;font-size:19px;line-height:2;color:var(--ink);font-weight:600}
blockquote.pull cite{display:block;font-style:normal;font-size:13px;color:var(--muted);margin-top:10px;font-family:var(--sans);font-weight:400;letter-spacing:.05em}


/* 夜色区块（必然王国 / 减法 / token CTA） */
.night{background:var(--night);color:var(--night-text);position:relative}
.night::before{content:"";position:absolute;inset:0;pointer-events:none;opacity:.5;
  background-image:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='160' height='160'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='2'/%3E%3CfeColorMatrix values='0 0 0 0 0.9 0 0 0 0 0.86 0 0 0 0 0.78 0 0 0 0.04 0'/%3E%3C/filter%3E%3Crect width='160' height='160' filter='url(%23n)'/%3E%3C/svg%3E");}
.night .wrap{position:relative;z-index:2}
.night .sec-no{color:var(--night-cinnabar)}
.night .sec-title{color:#EFE9DC}
.night .body-p{color:var(--night-muted)}
.night .body-p strong{color:var(--night-text)}
.night blockquote.pull{color:#EFE9DC;border-color:var(--night-cinnabar)}
.night cite{color:var(--night-muted)}


/* 页脚 */
footer.site{background:var(--night);color:var(--night-muted);padding:56px 0 40px;border-top:1px solid var(--night-hair)}
.foot-grid{display:flex;justify-content:space-between;flex-wrap:wrap;gap:30px;margin-bottom:36px}
.foot-brand .brand-name{color:var(--night-text);margin-bottom:8px}
.foot-brand p{font-size:13px;line-height:1.9;max-width:340px}
.foot-links{display:flex;gap:60px;font-family:var(--sans);font-size:13.5px}
.foot-links h6{color:var(--night-text);font-size:12px;letter-spacing:.2em;margin-bottom:14px;font-weight:600}
.foot-links a{display:block;padding:6px 0;color:var(--night-muted)}
.foot-links a:hover{color:var(--night-cinnabar)}
.foot-bar{border-top:1px solid var(--night-hair);padding-top:24px;font-size:12.5px;display:flex;justify-content:space-between;flex-wrap:wrap;gap:10px;font-family:var(--sans)}


/* toast */
.toast{position:fixed;left:50%;bottom:36px;transform:translateX(-50%) translateY(30px);background:var(--ink);color:var(--paper-3);
  font-family:var(--sans);font-size:14px;padding:14px 26px;border-radius:8px;opacity:0;pointer-events:none;transition:.35s;z-index:100;
  max-width:90vw;text-align:center;box-shadow:0 12px 30px rgba(0,0,0,.25)}
.toast.show{opacity:1;transform:translateX(-50%) translateY(0)}


/* 滚动揭示 */
.reveal{opacity:0;transform:translateY(26px);transition:opacity .8s ease,transform .8s ease}
.reveal.in{opacity:1;transform:none}

@media (prefers-reduced-motion:reduce){
  .reveal{opacity:1;transform:none;transition:none}
  html{scroll-behavior:auto}
}

/* 响应式 · 公共 */
@media (max-width:760px){
  .nav-links{display:none}
  .nav-burger{display:flex}
  .foot-grid{flex-direction:column}
  section.block{padding:72px 0}
}
/* （注：内容由AI生成） */