/* ============================================================
   《密语》密码学小书 —— 亮色「机密档案」设计系统
   自包含,无外部字体/CDN。全书统一亮色。
   ============================================================ */

:root {
  /* 纸张与墨色 */
  --paper:      #f6f1e7;   /* 主纸底 */
  --paper-2:    #efe8d8;   /* 次级纸底(卡片/侧栏) */
  --paper-3:    #e7dec9;   /* 更深的纸底(表头/分隔) */
  --ink:        #24201a;   /* 正文墨色 */
  --ink-soft:   #574f42;   /* 次级文字 */
  --ink-faint:  #8a8069;   /* 弱化文字/说明 */
  --line:       #d8ccb0;   /* 分隔线 */
  --line-soft:  #e6dcc6;

  /* 印章红 & 强调色 */
  --stamp:      #b3261e;   /* 绝密印章红 */
  --stamp-soft: #c85a52;
  --accent:     #1f6f5c;   /* 解密绿(次强调) */
  --accent-2:   #9a6b12;   /* 档案金(链接/标记) */
  --blue:       #2d5c8a;   /* 冷色信息 */

  /* 提示框 */
  --note-bg:    #eef3ee;   --note-line: #1f6f5c;
  --warn-bg:    #fbeeea;   --warn-line: #b3261e;
  --lore-bg:    #f3eede;   --lore-line: #9a6b12;
  --def-bg:     #ecf0f5;   --def-line: #2d5c8a;

  /* 代码(亮色) */
  --code-bg:    #f2ecdd;
  --code-ink:   #2a2620;
  --code-line:  #ddd2b8;
  --tok-key:    #a52a1f;   /* 关键字 */
  --tok-str:    #1f6f5c;   /* 字符串 */
  --tok-num:    #2d5c8a;   /* 数字 */
  --tok-com:    #9a9074;   /* 注释 */
  --tok-fn:     #8a5a12;   /* 函数名 */

  --serif: "Songti SC", "STSong", "Noto Serif SC", "Source Han Serif SC", Georgia, "Times New Roman", serif;
  --sans:  "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", system-ui, -apple-system, sans-serif;
  --mono:  "SF Mono", "JetBrains Mono", "Fira Code", Menlo, Consolas, "Courier New", monospace;

  --radius: 4px;
  --maxw: 860px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background-color: var(--paper);
  /* 纸张纹理:极淡的斜向噪点 + 网格,纯 CSS 生成 */
  background-image:
    radial-gradient(circle at 20% 30%, rgba(0,0,0,0.012) 0, transparent 40%),
    radial-gradient(circle at 80% 70%, rgba(0,0,0,0.012) 0, transparent 40%),
    repeating-linear-gradient(90deg, rgba(120,100,60,0.03) 0 1px, transparent 1px 42px);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

/* ===================== 布局 ===================== */
.wrap {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 22px 120px;
}

.page { position: relative; }

/* 顶部档案栏 */
.topbar {
  position: sticky; top: 0; z-index: 50;
  background: rgba(246,241,231,0.9);
  backdrop-filter: blur(6px);
  border-bottom: 1px solid var(--line);
}
.topbar-inner {
  max-width: var(--maxw); margin: 0 auto;
  padding: 10px 22px;
  display: flex; align-items: center; gap: 14px;
  font-size: 13px; letter-spacing: .04em;
}
.topbar a { color: var(--ink-soft); text-decoration: none; }
.topbar a:hover { color: var(--stamp); }
.topbar .brand {
  font-family: var(--mono); font-weight: 700; color: var(--stamp);
  letter-spacing: .12em;
}
.topbar .sep { color: var(--line); }
.topbar .spacer { flex: 1; }
.topbar .filecode { font-family: var(--mono); color: var(--ink-faint); }

/* 阅读进度条 */
.progress {
  position: fixed; top: 0; left: 0; height: 3px; width: 0%;
  background: linear-gradient(90deg, var(--stamp), var(--accent-2));
  z-index: 60; transition: width .1s linear;
}

/* ===================== 章节页头 ===================== */
.chapter-head {
  margin: 40px 0 30px;
  padding-bottom: 24px;
  border-bottom: 2px solid var(--ink);
  position: relative;
}
.chapter-kicker {
  font-family: var(--mono);
  font-size: 12.5px; letter-spacing: .2em; text-transform: uppercase;
  color: var(--stamp);
  display: flex; align-items: center; gap: 10px;
}
.chapter-kicker::before {
  content: ""; width: 26px; height: 1px; background: var(--stamp);
}
.chapter-title {
  font-family: var(--serif);
  font-size: clamp(28px, 5vw, 42px);
  line-height: 1.2; margin: 14px 0 10px; font-weight: 800;
  letter-spacing: .01em;
}
.chapter-sub {
  color: var(--ink-soft); font-size: 17px; margin: 0; max-width: 62ch;
}
.chapter-meta {
  margin-top: 16px; display: flex; gap: 16px; flex-wrap: wrap;
  font-family: var(--mono); font-size: 12px; color: var(--ink-faint);
  letter-spacing: .05em;
}
.chapter-meta b { color: var(--ink-soft); font-weight: 600; }

/* 「绝密」印章 */
.stamp {
  position: absolute; top: -8px; right: 0;
  font-family: var(--mono); font-weight: 800;
  color: var(--stamp);
  border: 2.5px solid var(--stamp);
  border-radius: 6px;
  padding: 5px 12px; font-size: 15px; letter-spacing: .18em;
  transform: rotate(8deg);
  opacity: .82;
  box-shadow: inset 0 0 0 1px rgba(179,38,30,.25);
  user-select: none;
}
@media (max-width: 640px) { .stamp { display: none; } }

/* ===================== 正文排版 ===================== */
.prose { }
.prose h2 {
  font-family: var(--serif);
  font-size: 26px; margin: 46px 0 14px; font-weight: 700;
  padding-left: 14px; border-left: 4px solid var(--stamp);
  line-height: 1.3;
}
.prose h3 {
  font-family: var(--serif);
  font-size: 20.5px; margin: 32px 0 10px; font-weight: 700; color: var(--ink);
}
.prose h4 {
  font-size: 16px; margin: 22px 0 8px; font-weight: 700;
  color: var(--ink-soft); letter-spacing: .02em;
}
.prose p { margin: 14px 0; }
.prose ul, .prose ol { margin: 14px 0; padding-left: 26px; }
.prose li { margin: 7px 0; }
.prose li::marker { color: var(--stamp); }
.prose a {
  color: var(--accent-2); text-decoration: none;
  border-bottom: 1px solid var(--line);
}
.prose a:hover { border-bottom-color: var(--accent-2); }
.prose strong { color: #16120c; font-weight: 700; }
.prose em { color: var(--stamp); font-style: normal; font-weight: 600; }

.prose blockquote {
  margin: 20px 0; padding: 4px 20px;
  border-left: 3px solid var(--line);
  color: var(--ink-soft); font-style: italic;
  font-family: var(--serif); font-size: 18px;
}

.lead {
  font-family: var(--serif); font-size: 19.5px; line-height: 1.7;
  color: var(--ink-soft); margin: 0 0 26px;
}

/* 行内代码 */
.prose code {
  font-family: var(--mono); font-size: .88em;
  background: var(--code-bg); color: var(--tok-key);
  padding: 1.5px 6px; border-radius: 3px;
  border: 1px solid var(--code-line);
}

/* 代码块 */
.code {
  position: relative;
  background: var(--code-bg);
  border: 1px solid var(--code-line);
  border-radius: var(--radius);
  margin: 20px 0;
  overflow: hidden;
}
.code-head {
  display: flex; align-items: center; gap: 8px;
  padding: 7px 14px; font-family: var(--mono); font-size: 11.5px;
  color: var(--ink-faint); letter-spacing: .08em;
  background: var(--paper-3); border-bottom: 1px solid var(--code-line);
  text-transform: uppercase;
}
.code-head .dot { width: 9px; height: 9px; border-radius: 50%; background: var(--stamp-soft); }
.code pre {
  margin: 0; padding: 16px 18px; overflow-x: auto;
  font-family: var(--mono); font-size: 13.5px; line-height: 1.65;
  color: var(--code-ink);
}
.code pre code { background: none; border: none; padding: 0; color: inherit; font-size: inherit; }
/* 极简语法高亮 token */
.tok-key { color: var(--tok-key); font-weight: 600; }
.tok-str { color: var(--tok-str); }
.tok-num { color: var(--tok-num); }
.tok-com { color: var(--tok-com); font-style: italic; }
.tok-fn  { color: var(--tok-fn); }

/* ===================== 提示框 ===================== */
.callout {
  margin: 22px 0; padding: 14px 18px 14px 44px;
  border-radius: var(--radius); position: relative;
  border-left: 4px solid var(--note-line); background: var(--note-bg);
  font-size: 15.5px; line-height: 1.65;
}
.callout::before {
  position: absolute; left: 14px; top: 13px;
  font-family: var(--mono); font-weight: 700; font-size: 15px;
}
.callout p { margin: 6px 0; }
.callout p:first-child { margin-top: 0; }
.callout p:last-child { margin-bottom: 0; }
.callout .callout-title {
  font-weight: 700; letter-spacing: .02em; margin-bottom: 4px; display: block;
  font-family: var(--sans);
}
.callout.note  { border-color: var(--note-line); background: var(--note-bg); }
.callout.note::before  { content: "✎"; color: var(--note-line); }
.callout.warn  { border-color: var(--warn-line); background: var(--warn-bg); }
.callout.warn::before  { content: "!"; color: var(--warn-line); }
.callout.warn .callout-title { color: var(--stamp); }
.callout.lore  { border-color: var(--lore-line); background: var(--lore-bg); }
.callout.lore::before  { content: "§"; color: var(--lore-line); }
.callout.lore .callout-title { color: var(--accent-2); }
.callout.def   { border-color: var(--def-line); background: var(--def-bg); }
.callout.def::before   { content: "≡"; color: var(--def-line); }
.callout.def .callout-title { color: var(--blue); }

/* ===================== 表格 ===================== */
.tbl-wrap { overflow-x: auto; margin: 20px 0; }
table.data {
  border-collapse: collapse; width: 100%; font-size: 14.5px;
  font-family: var(--sans);
}
table.data th, table.data td {
  border: 1px solid var(--line); padding: 8px 12px; text-align: left;
  vertical-align: top;
}
table.data th {
  background: var(--paper-3); font-weight: 700; color: var(--ink);
  letter-spacing: .02em;
}
table.data tr:nth-child(even) td { background: rgba(255,255,255,.35); }
table.data code { font-size: .85em; }

/* 公式(纯文本居中框) */
.math {
  margin: 20px 0; padding: 14px 18px; text-align: center;
  background: var(--paper-2); border: 1px dashed var(--line);
  border-radius: var(--radius);
  font-family: var(--mono); font-size: 15px; color: var(--ink);
  overflow-x: auto;
}
.math .var { color: var(--stamp); font-style: italic; }

/* ===================== 交互 Demo 容器 ===================== */
.demo {
  margin: 28px 0; border: 1px solid var(--line);
  border-radius: 6px; overflow: hidden;
  background: var(--paper-2);
  box-shadow: 0 1px 0 rgba(0,0,0,.03), 0 8px 24px -18px rgba(60,45,20,.4);
}
.demo-head {
  display: flex; align-items: center; gap: 10px;
  padding: 10px 16px; background: var(--paper-3);
  border-bottom: 1px solid var(--line);
  font-family: var(--mono); font-size: 12px; letter-spacing: .08em;
  color: var(--ink-soft); text-transform: uppercase;
}
.demo-head .tag {
  background: var(--stamp); color: #fff; padding: 1px 8px; border-radius: 3px;
  font-size: 10.5px; letter-spacing: .1em; font-weight: 700;
}
.demo-head .title { font-weight: 700; color: var(--ink); text-transform: none; letter-spacing: .02em; font-family: var(--sans); }
.demo-body { padding: 18px 16px; }
.demo-note {
  font-size: 13px; color: var(--ink-faint); padding: 0 16px 14px;
  font-style: italic;
}

/* Demo 通用控件 */
.ctl-row { display: flex; flex-wrap: wrap; gap: 12px 18px; align-items: center; margin: 12px 0; }
.ctl { display: flex; flex-direction: column; gap: 5px; }
.ctl label {
  font-size: 12px; color: var(--ink-faint); font-family: var(--mono);
  letter-spacing: .06em; text-transform: uppercase;
}
.demo input[type="text"], .demo input[type="number"], .demo textarea, .demo select {
  font-family: var(--mono); font-size: 14px;
  background: #fffdf7; color: var(--ink);
  border: 1px solid var(--code-line); border-radius: 4px;
  padding: 8px 10px;
}
.demo textarea { width: 100%; resize: vertical; min-height: 66px; line-height: 1.55; }
.demo input:focus, .demo textarea:focus, .demo select:focus {
  outline: none; border-color: var(--stamp); box-shadow: 0 0 0 3px rgba(179,38,30,.12);
}
.demo input[type="range"] { accent-color: var(--stamp); }

.btn {
  font-family: var(--sans); font-size: 14px; font-weight: 600;
  background: var(--ink); color: var(--paper);
  border: none; border-radius: 4px; padding: 8px 16px; cursor: pointer;
  letter-spacing: .02em; transition: background .15s, transform .05s;
}
.btn:hover { background: var(--stamp); }
.btn:active { transform: translateY(1px); }
.btn.ghost {
  background: transparent; color: var(--ink-soft);
  border: 1px solid var(--line);
}
.btn.ghost:hover { background: var(--paper-3); color: var(--stamp); border-color: var(--stamp); }
.btn.sm { padding: 5px 11px; font-size: 12.5px; }

.mono-out {
  font-family: var(--mono); font-size: 13.5px; line-height: 1.6;
  background: #fffdf7; border: 1px solid var(--code-line);
  border-radius: 4px; padding: 12px 14px; margin: 12px 0;
  overflow-x: auto; white-space: pre-wrap; word-break: break-all;
  color: var(--code-ink);
}
.mono-out .hl { background: #ffe3a0; color: #6b4a00; border-radius: 2px; padding: 0 1px; }
.mono-out .bad { background: #ffd4cf; color: var(--stamp); border-radius: 2px; padding: 0 1px; }
.mono-out .good { color: var(--accent); font-weight: 700; }
.mono-out .dim { color: var(--ink-faint); }

.pill {
  display: inline-block; font-family: var(--mono); font-size: 11px;
  padding: 2px 8px; border-radius: 20px; letter-spacing: .05em;
  background: var(--paper-3); color: var(--ink-soft); border: 1px solid var(--line);
}
.pill.ok  { background: #e3f0e6; color: var(--accent); border-color: #b9d8c0; }
.pill.no  { background: #fbe3df; color: var(--stamp); border-color: #e6bab3; }

canvas.demo-canvas {
  display: block; max-width: 100%; border: 1px solid var(--code-line);
  border-radius: 4px; background: #fffdf7;
}

/* 键盘/字母块 */
.glyph-row { display: flex; flex-wrap: wrap; gap: 4px; margin: 10px 0; font-family: var(--mono); }
.glyph {
  width: 26px; height: 30px; display: grid; place-items: center;
  background: #fffdf7; border: 1px solid var(--code-line); border-radius: 3px;
  font-size: 14px; transition: all .1s;
}
.glyph.active { background: var(--stamp); color: #fff; border-color: var(--stamp); }
.glyph.dim { color: var(--ink-faint); }

/* ===================== 上/下章导航 ===================== */
.chapter-nav {
  margin-top: 60px; padding-top: 26px; border-top: 2px solid var(--ink);
  display: flex; gap: 14px; justify-content: space-between; flex-wrap: wrap;
}
.chapter-nav a {
  flex: 1 1 240px; text-decoration: none; color: var(--ink);
  border: 1px solid var(--line); border-radius: 6px; padding: 14px 18px;
  background: var(--paper-2); transition: border-color .15s, transform .1s;
  display: block;
}
.chapter-nav a:hover { border-color: var(--stamp); transform: translateY(-2px); }
.chapter-nav .dir {
  font-family: var(--mono); font-size: 11px; letter-spacing: .12em;
  color: var(--ink-faint); text-transform: uppercase;
}
.chapter-nav .nav-title { font-family: var(--serif); font-weight: 700; font-size: 17px; margin-top: 4px; }
.chapter-nav a.next { text-align: right; }
.chapter-nav a.disabled { opacity: .4; pointer-events: none; }

/* 章内目录 (TOC) 浮块 */
.toc-inline {
  background: var(--paper-2); border: 1px solid var(--line);
  border-radius: 6px; padding: 16px 20px; margin: 24px 0;
}
.toc-inline .toc-h {
  font-family: var(--mono); font-size: 11.5px; letter-spacing: .12em;
  text-transform: uppercase; color: var(--stamp); margin-bottom: 8px;
}
.toc-inline ol { margin: 0; padding-left: 20px; }
.toc-inline a { color: var(--ink-soft); text-decoration: none; border-bottom: 1px dotted var(--line); }
.toc-inline a:hover { color: var(--stamp); }

/* 关键要点小结 */
.recap {
  margin: 40px 0 10px; padding: 20px 24px;
  background: var(--paper-2); border: 1px solid var(--line);
  border-top: 3px solid var(--stamp); border-radius: 4px;
}
.recap h4 {
  font-family: var(--mono); font-size: 12px; letter-spacing: .12em;
  text-transform: uppercase; color: var(--stamp); margin: 0 0 10px;
}
.recap ul { margin: 0; padding-left: 22px; }
.recap li { margin: 6px 0; }

/* footnote / 免责 */
.disclaimer {
  font-size: 12.5px; color: var(--ink-faint); font-style: italic;
  margin-top: 8px;
}

/* ===================== index 首页专用 ===================== */
.hero {
  padding: 70px 0 40px; text-align: center; position: relative;
}
.hero .book-label {
  font-family: var(--mono); font-size: 13px; letter-spacing: .3em;
  text-transform: uppercase; color: var(--stamp);
}
.hero h1 {
  font-family: var(--serif); font-weight: 800;
  font-size: clamp(40px, 8vw, 76px); line-height: 1.05;
  margin: 16px 0 8px; letter-spacing: .02em;
}
.hero .cipher {
  font-family: var(--mono); font-size: clamp(15px, 3vw, 20px);
  color: var(--ink-soft); letter-spacing: .15em; margin: 0 0 18px;
  min-height: 1.4em;
}
.hero .tagline {
  font-family: var(--serif); font-size: 19px; color: var(--ink-soft);
  max-width: 54ch; margin: 0 auto 26px;
}
.hero .stamp-big {
  display: inline-block; margin-top: 8px;
  font-family: var(--mono); font-weight: 800; color: var(--stamp);
  border: 3px solid var(--stamp); border-radius: 8px;
  padding: 8px 20px; letter-spacing: .2em; font-size: 15px;
  transform: rotate(-4deg); opacity: .85;
}
.hero-meta {
  display: flex; gap: 26px; justify-content: center; flex-wrap: wrap;
  margin-top: 32px; font-family: var(--mono); font-size: 13px; color: var(--ink-faint);
}
.hero-meta b { color: var(--stamp); font-size: 22px; display: block; font-weight: 800; }

/* 路线图 */
.roadmap {
  display: flex; flex-wrap: wrap; gap: 8px; justify-content: center;
  margin: 30px 0 10px;
}
.roadmap .stage {
  font-family: var(--mono); font-size: 12.5px; padding: 6px 12px;
  border: 1px solid var(--line); border-radius: 20px; background: var(--paper-2);
  color: var(--ink-soft); position: relative;
}
.roadmap .arrow { color: var(--line); align-self: center; }

/* Phase 分组 */
.phase { margin: 46px 0; }
.phase-head {
  display: flex; align-items: baseline; gap: 14px; margin-bottom: 4px;
  border-bottom: 1px solid var(--line); padding-bottom: 8px;
}
.phase-num {
  font-family: var(--mono); font-size: 13px; color: #fff; background: var(--stamp);
  padding: 2px 10px; border-radius: 4px; letter-spacing: .1em; font-weight: 700;
}
.phase-head h2 { font-family: var(--serif); font-size: 24px; margin: 0; font-weight: 700; }
.phase-head .phase-desc { color: var(--ink-faint); font-size: 14px; margin-left: auto; }

.ch-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(250px, 1fr)); gap: 14px; margin-top: 18px; }
.ch-card {
  text-decoration: none; color: var(--ink);
  border: 1px solid var(--line); border-radius: 6px; padding: 16px 18px;
  background: var(--paper-2); transition: all .15s; position: relative;
  display: flex; flex-direction: column; gap: 6px;
}
.ch-card:hover { border-color: var(--stamp); transform: translateY(-3px); box-shadow: 0 10px 30px -20px rgba(80,50,20,.6); }
.ch-card .ch-num {
  font-family: var(--mono); font-size: 12px; color: var(--stamp); letter-spacing: .1em; font-weight: 700;
}
.ch-card .ch-title { font-family: var(--serif); font-size: 18px; font-weight: 700; line-height: 1.3; }
.ch-card .ch-desc { font-size: 13.5px; color: var(--ink-soft); line-height: 1.5; }
.ch-card .ch-demo {
  margin-top: auto; font-family: var(--mono); font-size: 10.5px; letter-spacing: .08em;
  color: var(--accent); text-transform: uppercase;
  display: inline-flex; align-items: center; gap: 5px;
}
.ch-card .ch-demo::before { content: "▸"; }

.readme {
  margin: 60px 0 0; padding: 28px 30px; background: var(--paper-2);
  border: 1px solid var(--line); border-radius: 8px;
}
.readme h3 { font-family: var(--serif); margin: 0 0 12px; font-size: 21px; }
.readme .cols { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; }
@media (max-width: 640px) { .readme .cols { grid-template-columns: 1fr; } }
.readme h4 { margin: 0 0 6px; color: var(--stamp); font-size: 14px; letter-spacing: .04em; }

.site-foot {
  margin-top: 50px; padding-top: 20px; border-top: 1px solid var(--line);
  text-align: center; font-size: 12.5px; color: var(--ink-faint);
  font-family: var(--mono); letter-spacing: .05em;
}
.site-foot a { color: var(--ink-faint); }

/* 让长公式/宽内容不撑破手机 */
@media (max-width: 560px) {
  body { font-size: 16px; }
  .wrap { padding: 0 16px 90px; }
  .ctl-row { gap: 10px; }
}