/* ============================================================
   软考信息安全工程师 · 共享课程样式
   Tufte 风格：纸张底色、衬线标题、克制用色、打印友好
   ============================================================ */

:root {
  --paper: #faf8f2;
  --paper-2: #f3efe4;
  --ink: #2b2926;
  --ink-soft: #6b665c;
  --line: #ddd6c6;
  --accent: #a1392b;      /* 砖红：重点 */
  --accent-2: #2f5d50;    /* 深绿：正确/成功 */
  --accent-3: #3a5a8c;    /* 深蓝：链接/提示 */
  --quiz-bg: #f2eee2;
  --code-bg: #efece0;
}

* { box-sizing: border-box; }

html { font-size: 17px; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: -apple-system, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans CJK SC", sans-serif;
  line-height: 1.75;
}

/* ============ 页面布局：左侧目录 + 正文 ============ */
.page-shell {
  display: flex;
  align-items: flex-start;
  min-height: 100vh;
}

.course-sidebar {
  position: sticky;
  top: 0;
  flex: 0 0 15rem;
  width: 15rem;
  height: 100vh;
  overflow-y: auto;
  padding: 1.25rem 0.9rem 2rem;
  border-right: 1px solid var(--line);
  background: var(--paper-2);
}

.sidebar-head {
  padding: 0 0.35rem 1rem;
  margin-bottom: 0.5rem;
  border-bottom: 1px solid var(--line);
}

.sidebar-brand {
  display: block;
  font-family: "Songti SC", "Noto Serif SC", Georgia, serif;
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--ink);
  text-decoration: none;
}

.sidebar-brand:hover {
  color: var(--accent-3);
  text-decoration: none;
}

.sidebar-sub {
  margin-top: 0.25rem;
  font-size: 0.78rem;
  color: var(--ink-soft);
}

.nav-section { margin-bottom: 1.1rem; }

.nav-section-title {
  padding: 0 0.45rem;
  margin-bottom: 0.35rem;
  font-size: 0.72rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--ink-soft);
}

.nav-list {
  display: flex;
  flex-direction: column;
  gap: 0.15rem;
}

.nav-link {
  display: block;
  padding: 0.45rem 0.55rem;
  border-radius: 4px;
  color: var(--ink);
  text-decoration: none;
  border-left: 3px solid transparent;
  transition: background 0.15s ease, border-color 0.15s ease;
}

.nav-link:hover {
  background: var(--paper);
  text-decoration: none;
}

.nav-link.active {
  background: #dce9e0;
  border-left-color: var(--accent-2);
  color: var(--ink);
}

.nav-label {
  display: block;
  font-size: 0.82rem;
  font-weight: 600;
}

.nav-title {
  display: block;
  margin-top: 0.1rem;
  font-size: 0.76rem;
  line-height: 1.35;
  color: var(--ink-soft);
}

.nav-link.active .nav-title { color: var(--ink); }

.nav-toggle {
  display: none;
  position: fixed;
  top: 0.75rem;
  left: 0.75rem;
  z-index: 120;
  padding: 0.45rem 0.75rem;
  border: 1px solid var(--line);
  border-radius: 4px;
  background: var(--paper);
  color: var(--ink);
  font-size: 0.9rem;
  cursor: pointer;
}

.nav-overlay {
  display: none;
}

/* 内容容器 */
.page-shell > main {
  flex: 1;
  min-width: 0;
  max-width: 46rem;
  margin: 0 auto;
  padding: 2.5rem 1.5rem 6rem;
}

main {
  max-width: 46rem;
  margin: 0 auto;
  padding: 2.5rem 1.5rem 6rem;
}

/* 版头 */
header.lesson-head {
  border-bottom: 3px double var(--line);
  padding-bottom: 1.2rem;
  margin-bottom: 2rem;
}

.lesson-no {
  font-size: 0.85rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--ink-soft);
}

h1 {
  font-family: "Songti SC", "Noto Serif SC", Georgia, serif;
  font-size: 1.9rem;
  line-height: 1.3;
  margin: 0.35rem 0 0.6rem;
}

.meta {
  font-size: 0.9rem;
  color: var(--ink-soft);
}

/* 小节标题 */
h2 {
  font-family: "Songti SC", "Noto Serif SC", Georgia, serif;
  font-size: 1.35rem;
  margin: 2.8rem 0 0.9rem;
  padding-bottom: 0.3rem;
  border-bottom: 1px solid var(--line);
}

h3 { font-size: 1.08rem; margin: 1.8rem 0 0.6rem; }

/* 正文 */
p { margin: 0.7rem 0; }

strong { color: var(--accent); }

a { color: var(--accent-3); text-decoration-thickness: 1px; text-underline-offset: 2px; }
a:hover { text-decoration-thickness: 2px; }

/* 列表 */
ul, ol { padding-left: 1.4rem; }
li { margin: 0.35rem 0; }

/* 表格 */
table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.95rem;
  margin: 1.2rem 0;
}
th, td {
  border: 1px solid var(--line);
  padding: 0.55rem 0.75rem;
  text-align: left;
  vertical-align: top;
}
th {
  background: var(--paper-2);
  font-weight: 600;
}

/* 引用块 / 提示框 */
blockquote, .callout {
  margin: 1.2rem 0;
  padding: 0.8rem 1.1rem;
  border-left: 4px solid var(--accent);
  background: var(--quiz-bg);
  font-size: 0.95rem;
}
.callout.warn { border-left-color: var(--accent); }
.callout.ok   { border-left-color: var(--accent-2); }
.callout.info { border-left-color: var(--accent-3); }

/* 代码 / 术语 */
code {
  background: var(--code-bg);
  padding: 0.1rem 0.35rem;
  border-radius: 3px;
  font-size: 0.9em;
}
.term { font-weight: 600; }

/* ============ 测验组件 ============ */
.quiz {
  background: var(--quiz-bg);
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 1.1rem 1.3rem;
  margin: 1.4rem 0;
}
.quiz .q {
  font-weight: 600;
  margin-bottom: 0.6rem;
}
.quiz .opts { margin: 0.6rem 0; }
.quiz .opt {
  display: block;
  margin: 0.35rem 0;
  padding: 0.4rem 0.7rem;
  border: 1px solid var(--line);
  border-radius: 4px;
  background: var(--paper);
  cursor: pointer;
  user-select: none;
  transition: background 0.15s ease;
}
.quiz .opt:hover { background: var(--paper-2); }

/* 回答后状态 */
.quiz .opt.correct { background: #dce9e0; border-color: var(--accent-2); }
.quiz .opt.wrong   { background: #ecdcd8; border-color: var(--accent); }
.quiz .opt:disabled { cursor: default; }

/* 解释 */
.explain {
  display: none;
  margin-top: 0.8rem;
  padding: 0.7rem 0.9rem;
  border-top: 1px dashed var(--line);
  font-size: 0.92rem;
  color: var(--ink-soft);
}
.explain.show { display: block; animation: fadein 0.25s ease; }
@keyframes fadein { from { opacity: 0; } to { opacity: 1; } }

/* 简答题（点开看答案） */
.details {
  margin: 0.7rem 0;
}
.details summary {
  cursor: pointer;
  color: var(--accent-3);
  font-weight: 600;
}
.details .ans {
  margin-top: 0.5rem;
  padding: 0.7rem 0.9rem;
  border-left: 3px solid var(--accent-2);
  background: var(--paper);
  font-size: 0.95rem;
}

/* 冲刺练习：进度条与目录 */
.practice-progress {
  position: sticky;
  top: 0;
  z-index: 20;
  margin: 0 0 1.2rem;
  padding: 0.55rem 0.85rem;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--paper-2);
  font-size: 0.88rem;
  color: var(--ink-soft);
}
.practice-toc {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin: 0.8rem 0 1.2rem;
}
.practice-toc a {
  display: inline-block;
  padding: 0.3rem 0.65rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--paper-2);
  font-size: 0.8rem;
  text-decoration: none;
}
.practice-toc a:hover { background: var(--paper); }
.case-prompt {
  background: var(--quiz-bg);
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 1.1rem 1.3rem;
  margin: 1.4rem 0;
}
.case-prompt h3 { margin-top: 0; }
.case-prompt ol { margin-bottom: 0.4rem; }
.quiz, .case-prompt { scroll-margin-top: 3.6rem; }

/* 作业清单 */
.task-list {
  counter-reset: task;
  list-style: none;
  padding-left: 0;
}
.task-list li {
  counter-increment: task;
  padding: 0.6rem 0 0.6rem 2.6rem;
  position: relative;
  border-bottom: 1px dashed var(--line);
}
.task-list li::before {
  content: counter(task);
  position: absolute;
  left: 0;
  top: 0.55rem;
  width: 1.7rem;
  height: 1.7rem;
  border-radius: 50%;
  background: var(--accent-3);
  color: #fff;
  font-size: 0.85rem;
  text-align: center;
  line-height: 1.7rem;
}

/* 页脚 */
footer {
  margin-top: 4rem;
  padding-top: 1.2rem;
  border-top: 1px solid var(--line);
  font-size: 0.85rem;
  color: var(--ink-soft);
}

/* ============ 窄屏：目录折叠 ============ */
@media (max-width: 768px) {
  .practice-progress { top: 3.2rem; }
  .quiz, .case-prompt { scroll-margin-top: 6.4rem; }

  .nav-toggle { display: block; }

  .page-shell > main {
    padding-top: 3.5rem;
  }

  .course-sidebar {
    position: fixed;
    top: 0;
    left: 0;
    z-index: 110;
    transform: translateX(-100%);
    transition: transform 0.2s ease;
    box-shadow: 0 0 0 rgba(0, 0, 0, 0);
  }

  body.nav-open .course-sidebar {
    transform: translateX(0);
    box-shadow: 4px 0 24px rgba(0, 0, 0, 0.12);
  }

  /* 仅打开目录时显示遮罩；勿写 .nav-overlay { display:block }，会覆盖 [hidden] 导致整页常暗 */
  body.nav-open .nav-overlay {
    display: block;
    position: fixed;
    inset: 0;
    z-index: 100;
    background: rgba(43, 41, 38, 0.35);
  }
}

/* 拓扑示意（下午卷填设备名） */
pre, .topo-ascii {
  background: var(--code-bg);
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: 0.85rem 1rem;
  overflow-x: auto;
  font-size: 0.82rem;
  line-height: 1.45;
  white-space: pre;
}

.topo-flow {
  display: flex;
  flex-wrap: wrap;
  align-items: stretch;
  justify-content: center;
  gap: 0.35rem 0.4rem;
  margin: 1rem 0;
  padding: 0.85rem 0.7rem;
  background: var(--code-bg);
  border: 1px solid var(--line);
  border-radius: 4px;
}

.topo-box {
  flex: 1 1 6.2rem;
  max-width: 9.5rem;
  padding: 0.45rem 0.5rem;
  border: 1px solid var(--line);
  border-radius: 4px;
  background: var(--paper);
  text-align: center;
  font-size: 0.86rem;
  line-height: 1.4;
}

.topo-box strong { display: block; }
.topo-box.dmz { border-color: var(--accent); background: #f7ebe8; }
.topo-box.lan { border-color: var(--accent-2); background: #e8f0ec; }
.topo-arrow {
  display: flex;
  align-items: center;
  color: var(--ink-soft);
  font-size: 1.1rem;
}

@media (max-width: 720px) {
  .topo-arrow { width: 100%; justify-content: center; }
  .topo-box { max-width: none; }
}

/* ============ 打印 ============ */
@media print {
  html { font-size: 12pt; }
  body { background: #fff; }
  .course-sidebar,
  .nav-toggle,
  .nav-overlay { display: none !important; }
  .practice-progress { position: static; }
  .page-shell { display: block; }
  .page-shell > main,
  main { max-width: none; padding: 1rem; }
  a { color: var(--ink); text-decoration: none; }
  .quiz .opt { cursor: default; }
}