/* R09 · 技术手册 / 骨架反解自 makingsoftware.com
   基因：旧纸黄 · 等宽 FIG 编号 · 图与文交替（图占三分之一）· 章节按字数列的目录 · 零卡片 */

:root{
  --paper:#f6f1e3;
  --paper-2:#efe8d6;
  --ink:#15130e;
  --muted:#6b6455;
  --line:#c9c0a8;
  --red:#a8342a;
  --pad:clamp(20px,4.4vw,64px);
  --mono:ui-monospace,"SFMono-Regular",Menlo,Consolas,"Courier New",monospace;
  --serif:"Songti SC","Source Han Serif SC",Georgia,"Times New Roman",serif;
}

*{margin:0;padding:0;box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{
  background:var(--paper);color:var(--ink);
  font-family:"Helvetica Neue","PingFang SC","Hiragino Sans GB","Microsoft YaHei",Arial,sans-serif;
  font-size:16px;line-height:1.7;
  -webkit-font-smoothing:antialiased;
}
a{color:inherit;text-decoration:none}
button{font:inherit;color:inherit;background:none;border:0;cursor:pointer}
::selection{background:var(--ink);color:var(--paper)}
:focus-visible{outline:2px solid var(--red);outline-offset:4px}

/* 纸纹：横线 + 极淡斑点 */
body::before{
  content:"";position:fixed;inset:0;z-index:0;pointer-events:none;
  background-image:
    radial-gradient(rgba(21,19,14,.045) .5px,transparent .5px),
    repeating-linear-gradient(0deg,rgba(21,19,14,.014) 0 1px,transparent 1px 3px);
  background-size:5px 5px,auto;
  opacity:.9;
}
body > *{position:relative;z-index:1}

.mono{font-family:var(--mono);font-size:11.5px;letter-spacing:.04em}
.fig-tag{font-family:var(--mono);font-size:11px;letter-spacing:.14em;color:var(--red);text-transform:uppercase}

/* 顶栏 */
.top{border-bottom:1px solid var(--ink);position:sticky;top:0;z-index:40;background:rgba(246,241,227,.94);backdrop-filter:blur(8px)}
.top-in{max-width:1200px;margin:0 auto;padding:0 var(--pad);height:62px;display:flex;align-items:center;justify-content:space-between;gap:18px}
.brand{font-size:13px;font-weight:700;letter-spacing:.02em}
.brand span{font-family:var(--mono);font-size:10px;font-weight:400;letter-spacing:.12em;color:var(--muted);margin-left:8px}
.nav{display:flex;gap:clamp(12px,2vw,26px);align-items:center}
.nav a{font-size:12.5px;color:var(--muted);transition:color .2s}
.nav a:hover,.nav a[aria-current]{color:var(--ink)}
.nav .buy{border:1px solid var(--ink);padding:7px 14px;border-radius:2px;color:var(--ink);font-size:12px;transition:background .22s,color .22s}
.nav .buy:hover{background:var(--ink);color:var(--paper)}

/* 首屏 */
.hero{max-width:1200px;margin:0 auto;padding:clamp(36px,5.4vw,80px) var(--pad) clamp(24px,3vw,40px)}
.hero .kicker{display:flex;align-items:center;gap:12px;margin-bottom:clamp(18px,2.4vw,28px)}
.hero .kicker::before{content:"";width:34px;height:1px;background:var(--ink)}
.hero h1{
  font-size:clamp(1.9rem,4.8vw,3.9rem);line-height:1.06;letter-spacing:-.035em;font-weight:600;max-width:26ch;
}
.hero .lede{margin-top:20px;max-width:56ch;color:var(--muted);font-size:16px;line-height:1.85}
.hero .byline{margin-top:18px;font-family:var(--mono);font-size:11.5px;color:var(--muted);letter-spacing:.06em}

/* 图版 */
.fig{
  border:1px solid var(--line);background:var(--paper-2);
  padding:clamp(14px,2vw,22px);margin:clamp(18px,2.6vw,28px) 0;
  position:relative;
}
.fig .stage{
  position:relative;aspect-ratio:16/9;background:
    repeating-linear-gradient(0deg,rgba(21,19,14,.055) 0 1px,transparent 1px 22px),
    repeating-linear-gradient(90deg,rgba(21,19,14,.055) 0 1px,transparent 1px 22px),
    #f3ecdb;
  overflow:hidden;
}
.fig .cap{display:flex;justify-content:space-between;gap:14px;margin-top:11px;font-family:var(--mono);font-size:10.5px;letter-spacing:.06em;color:var(--muted)}
.fig .cap b{color:var(--ink);font-weight:500}

/* 图形一：软盘 */
.g-floppy{position:absolute;left:50%;top:50%;width:38%;aspect-ratio:1;transform:translate(-50%,-50%);
  background:#dcd4bf;border:1.5px solid #6b6455;border-radius:3px}
.g-floppy::before{content:"";position:absolute;left:24%;top:7%;width:52%;height:32%;background:#9a927d;border:1px solid #6b6455}
.g-floppy::after{content:"";position:absolute;left:14%;bottom:10%;width:72%;height:30%;background:#f6f1e3;border:1px solid #6b6455}

/* 图形二：电极网格 */
.g-grid{position:absolute;inset:0;
  background-image:
    radial-gradient(circle at 1px 1px,rgba(168,52,42,.9) 1.6px,transparent 1.6px);
  background-size:28px 28px;
  -webkit-mask:radial-gradient(60% 60% at 50% 50%,#000 30%,transparent 100%);
  mask:radial-gradient(60% 60% at 50% 50%,#000 30%,transparent 100%);
}
.g-grid::after{
  content:"";position:absolute;left:50%;top:50%;width:64px;height:64px;border-radius:50%;
  border:1.5px dashed rgba(168,52,42,.75);transform:translate(-50%,-50%);
}

/* 图形三：高斯核 */
.g-gauss{position:absolute;left:50%;top:50%;width:56%;aspect-ratio:1;transform:translate(-50%,-50%);
  background:radial-gradient(circle at 50% 50%,#15130e 0%,rgba(21,19,14,.7) 22%,rgba(21,19,14,.28) 46%,rgba(21,19,14,0) 72%);
  filter:blur(.4px);
}

/* 图形四：贝塞尔 */
.g-bezier{position:absolute;inset:0}
.g-bezier .curve{position:absolute;left:12%;right:12%;top:26%;height:48%;border-bottom:2px solid var(--ink);border-radius:0 0 60% 60%/0 0 100% 100%}
.g-bezier .p{position:absolute;width:9px;height:9px;border-radius:50%;background:var(--red);box-shadow:0 0 0 3px rgba(168,52,42,.18)}
.g-bezier .p.a{left:calc(12% - 4px);top:calc(74% - 4px)}
.g-bezier .p.b{left:calc(88% - 4px);top:calc(74% - 4px)}
.g-bezier .p.c{left:calc(50% - 4px);top:calc(74% - 4px)}
.g-bezier .h{position:absolute;top:4%;width:1px;height:70%;background:rgba(21,19,14,.35);border-left:1px dashed rgba(21,19,14,.35);background:none}
.g-bezier .h.l{left:14%}
.g-bezier .h.r{left:86%}
.g-bezier .h.l::after,.g-bezier .h.r::after{content:"";position:absolute;width:8px;height:8px;border:1.5px solid var(--ink);top:-4px;left:-4px;border-radius:50%;background:var(--paper-2)}

/* 图形五：像素栅格 */
.g-pix{position:absolute;inset:8%;display:grid;grid-template-columns:repeat(10,1fr);grid-template-rows:repeat(6,1fr);gap:2px}
.g-pix i{background:rgba(21,19,14,.08)}
.g-pix i:nth-child(3n){background:rgba(168,52,42,.5)}
.g-pix i:nth-child(7n){background:rgba(21,19,14,.6)}

/* 图形六：CRT */
.g-crt{position:absolute;left:50%;top:50%;transform:translate(-50%,-50%);width:62%;aspect-ratio:4/3;
  border-radius:8% / 11%;background:#d8d0ba;border:1.5px solid #6b6455;box-shadow:inset 0 0 26px rgba(21,19,14,.25)}
.g-crt::before{content:"";position:absolute;inset:9%;border-radius:6% / 9%;background:linear-gradient(160deg,#3c3a33,#1b1a15);box-shadow:inset 0 0 22px rgba(0,0,0,.6)}
.g-crt::after{content:"";position:absolute;left:38%;bottom:-11%;width:24%;height:11%;background:#c9c1a9;border:1px solid #6b6455;border-top:0}

/* 图文交替 */
.duo{max-width:1200px;margin:0 auto;padding:0 var(--pad);display:grid;grid-template-columns:1fr;gap:0}
.duo .block{border-top:1px solid var(--line);padding:clamp(24px,3.4vw,44px) 0}
.duo .block h2{font-size:clamp(1.05rem,1.7vw,1.3rem);letter-spacing:-.02em;line-height:1.3;font-weight:600;max-width:40ch}
.duo .block p{margin-top:12px;font-size:15.5px;line-height:1.85;color:#332f26;max-width:62ch}
.duo .block p + p{margin-top:1em}
.duo .block .note{font-family:var(--mono);font-size:11px;color:var(--muted);letter-spacing:.04em;margin-top:14px;display:block}

/* 章节清单 */
.toc{max-width:1200px;margin:0 auto;padding:clamp(30px,4vw,56px) var(--pad)}
.toc-head{display:flex;justify-content:space-between;align-items:baseline;gap:16px;border-bottom:1px solid var(--ink);padding-bottom:12px}
.toc-head h2{font-size:clamp(1.2rem,2vw,1.5rem);letter-spacing:-.02em;font-weight:600}
.toc-grid{columns:4;column-gap:clamp(16px,2.4vw,36px);margin-top:18px}
@media (max-width:900px){.toc-grid{columns:2}}
@media (max-width:560px){.toc-grid{columns:1}}
.toc-grid a{
  display:flex;justify-content:space-between;gap:10px;padding:7px 0;border-bottom:1px dotted var(--line);
  break-inside:avoid;font-size:13.5px;line-height:1.4;
}
.toc-grid a:hover{color:var(--red)}
.toc-grid a span{font-family:var(--mono);font-size:10.5px;color:var(--muted);white-space:nowrap}

/* 购买条 */
.buybar{
  max-width:1200px;margin:0 auto clamp(40px,6vw,80px);padding:clamp(24px,3.6vw,44px) var(--pad);
  border-top:2px solid var(--ink);border-bottom:1px solid var(--line);
  display:flex;justify-content:space-between;align-items:center;gap:24px;flex-wrap:wrap;
}
.buybar h2{font-size:clamp(1.15rem,2.2vw,1.6rem);letter-spacing:-.025em;line-height:1.3;font-weight:600;max-width:26ch}
.buybar .price{font-family:var(--mono);font-size:13px;color:var(--muted);margin-top:8px}
.buybar .price b{color:var(--ink);font-size:18px}

.btn{
  display:inline-flex;align-items:center;gap:8px;background:var(--ink);color:var(--paper);
  padding:12px 22px;font-size:13.5px;border-radius:2px;transition:opacity .2s;
}
.btn:hover{opacity:.85}
.btn.line{background:transparent;color:var(--ink);border:1px solid var(--ink)}
.btn.line:hover{background:var(--ink);color:var(--paper);opacity:1}

/* 阅读页 */
.article{max-width:720px;margin:0 auto;padding:clamp(28px,4vw,52px) var(--pad) clamp(40px,6vw,80px)}
.article .meta{display:flex;gap:16px;flex-wrap:wrap;font-family:var(--mono);font-size:11px;color:var(--muted);letter-spacing:.06em;padding-bottom:14px;border-bottom:1px solid var(--line)}
.article h1{font-size:clamp(1.7rem,3.6vw,2.6rem);line-height:1.16;letter-spacing:-.03em;margin:22px 0 18px;font-weight:600}
.article h2{font-size:1.15rem;margin:36px 0 12px;letter-spacing:-.02em;font-weight:600}
.article p{font-family:var(--serif);font-size:17.5px;line-height:1.95;color:#2b2720}
.article p + p{margin-top:1.05em}
.article p:first-of-type::first-letter{
  float:left;font-size:3.1em;line-height:.82;padding:4px 10px 0 0;font-weight:600;
}
.article .fig{margin:30px 0}
.article blockquote{
  margin:30px 0;padding:16px 0 16px 22px;border-left:2px solid var(--red);
  font-family:var(--serif);font-size:16.5px;line-height:1.85;color:#3a352c;
}
.article .pager{display:flex;justify-content:space-between;gap:16px;margin-top:clamp(30px,4vw,50px);padding-top:18px;border-top:1px solid var(--line);font-size:13px}

/* 页脚 */
.foot{border-top:1px solid var(--ink);margin-top:clamp(30px,4vw,60px)}
.foot-in{max-width:1200px;margin:0 auto;padding:clamp(26px,3.6vw,44px) var(--pad) 26px;
  display:flex;justify-content:space-between;gap:22px;flex-wrap:wrap;align-items:flex-start}
.foot p{font-size:12.5px;color:var(--muted);line-height:1.75;max-width:42ch}
.foot nav{display:flex;gap:16px;flex-wrap:wrap}
.foot nav a{font-size:12.5px;color:var(--muted)}
.foot nav a:hover{color:var(--ink)}
.foot-btm{max-width:1200px;margin:0 auto;padding:14px var(--pad) 28px;border-top:1px solid var(--line);
  font-family:var(--mono);font-size:10.5px;color:var(--muted);display:flex;justify-content:space-between;gap:12px;flex-wrap:wrap}

@media (max-width:600px){
  .top-in{height:56px}
  .brand span{display:none}
  .nav a{font-size:12px}
  .nav a:not(.buy){display:none}
  .article p{font-size:16.5px}
}
@media (prefers-reduced-motion:reduce){
  *{transition:none!important;animation:none!important}
}