/* ===== 基础与变量 ===== */
:root {
  --primary: #c0392b;
  --primary-dark: #962d22;
  --accent: #e67e22;
  --bg: #f4f6f8;
  --card: #ffffff;
  --text: #1f2d3d;
  --muted: #7a8a99;
  --border: #e3e8ee;
  --ok: #27ae60;
  --bad: #e74c3c;
  --radius: 12px;
  --shadow: 0 2px 12px rgba(31,45,61,.06);
}
* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }

/* 题目配图 */
.q-img {
  display: block;
  max-width: 100%;
  width: auto;
  height: auto;
  max-height: 320px;
  margin: 14px auto 4px;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: #fff;
  padding: 6px;
}
.img-preview { margin: 8px 0; }
.img-preview img { max-width: 220px; max-height: 160px; border: 1px solid var(--border); border-radius: 8px; display: block; }
.rm-img { font-weight: 400; font-size: 14px; color: var(--bad); margin-left: 10px; }
table .q-thumb { max-width: 80px; max-height: 56px; border-radius: 6px; border: 1px solid var(--border); }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  font-size: 16px;
}
a { color: var(--primary); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ===== 顶栏 ===== */
.topbar { background: var(--primary); color: #fff; position: sticky; top: 0; z-index: 50; box-shadow: var(--shadow); }
.topbar-inner { max-width: 1080px; margin: 0 auto; padding: 0 16px; display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; }
.brand { color: #fff; font-weight: 700; font-size: 17px; padding: 12px 0; white-space: nowrap; }
.nav { display: flex; flex-wrap: wrap; gap: 4px; }
.nav a { color: #fff; padding: 12px 10px; font-size: 15px; }
.nav a:hover { background: rgba(255,255,255,.12); text-decoration: none; }
.nav a.admin-link { background: var(--accent); border-radius: 6px; margin: 6px 0; }

/* ===== 布局 ===== */
.container { max-width: 1080px; margin: 0 auto; padding: 20px 16px 60px; }
.card { background: var(--card); border: 1px solid var(--border); border-radius: var(--radius); padding: 18px; box-shadow: var(--shadow); margin-bottom: 18px; }
.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 16px; }
.muted { color: var(--muted); font-size: 14px; }

/* ===== 标题 ===== */
h1 { font-size: 24px; margin: 4px 0 14px; }
h2 { font-size: 19px; margin: 6px 0 12px; }
h3 { font-size: 16px; margin: 10px 0; }

/* ===== 按钮 ===== */
.btn { display: inline-block; background: var(--primary); color: #fff; border: none; border-radius: 8px; padding: 11px 20px; font-size: 15px; cursor: pointer; text-align: center; }
.btn:hover { background: var(--primary-dark); text-decoration: none; }
.btn-block { display: block; width: 100%; }
.btn-ghost { background: #fff; color: var(--primary); border: 1px solid var(--primary); }
.btn-ghost:hover { background: #fdecea; }
.btn-sm { padding: 6px 12px; font-size: 13px; }
.btn-danger { background: var(--bad); }
.btn-danger:hover { background: #c0392b; }

/* ===== 表单 ===== */
.form-wrap { max-width: 420px; margin: 20px auto; }
label { display: block; font-weight: 600; margin: 12px 0 6px; font-size: 14px; }
input[type=text], input[type=password], input[type=email], input[type=number], textarea, select {
  width: 100%; padding: 10px 12px; border: 1px solid var(--border); border-radius: 8px; font-size: 15px; background: #fff; color: var(--text);
}
textarea { min-height: 80px; resize: vertical; }
.alert { padding: 12px 14px; border-radius: 8px; margin-bottom: 14px; font-size: 14px; }
.alert-ok { background: #e8f7ee; color: #1e7e45; border: 1px solid #b7e3c8; }
.alert-err { background: #fdecea; color: #b03a2e; border: 1px solid #f5c6c0; }

/* ===== 章节 / 小节列表 ===== */
.chapter { display: block; background: var(--card); border: 1px solid var(--border); border-radius: var(--radius); padding: 16px; box-shadow: var(--shadow); }
.chapter .seq { display: inline-block; background: var(--primary); color: #fff; width: 26px; height: 26px; line-height: 26px; text-align: center; border-radius: 50%; font-size: 13px; margin-right: 8px; }
.section-list { list-style: none; padding: 0; margin: 10px 0 0; }
.section-list li { padding: 8px 0; border-top: 1px dashed var(--border); }
.section-list li:first-child { border-top: none; }
.section-list a { font-size: 15px; }
.tag { display: inline-block; font-size: 12px; padding: 2px 8px; border-radius: 20px; background: #eef2f6; color: var(--muted); margin-left: 6px; }

/* 数据表格 */
.tbl { width: 100%; border-collapse: collapse; font-size: 14px; }
.tbl th, .tbl td { padding: 10px 12px; text-align: left; border-bottom: 1px solid var(--border); }
.tbl th { background: #f7f9fb; color: var(--muted); font-weight: 600; }
.tbl tbody tr:hover { background: #fafbfc; }

/* 验证码 */
.captcha-row { display: flex; align-items: center; gap: 10px; margin-bottom: 6px; }
.captcha-img { height: 40px; border: 1px solid var(--border); border-radius: 6px; cursor: pointer; }
.cap-refresh { font-size: 13px; color: var(--primary); }

/* 续学提示条 */
.resume-bar { background: linear-gradient(90deg,#e8f3ff,#f3f8ff); border: 1px solid #cfe3ff; border-radius: var(--radius); padding: 14px 16px; margin-bottom: 16px; display:flex; justify-content:space-between; align-items:center; flex-wrap:wrap; gap:10px; }
.resume-bar .rb-text { font-size: 14px; }
.sec-done { color:#27ae60; font-weight:600; }


/* ===== 题目卡 ===== */
.q-card { background: var(--card); border: 1px solid var(--border); border-radius: var(--radius); padding: 18px; box-shadow: var(--shadow); margin-bottom: 16px; }
.q-meta { font-size: 13px; color: var(--muted); margin-bottom: 8px; }
.q-content { font-size: 17px; font-weight: 600; margin-bottom: 12px; }
.options { list-style: none; padding: 0; margin: 0; }
.options li { margin-bottom: 10px; }
.opt { display: flex; align-items: flex-start; gap: 10px; border: 1px solid var(--border); border-radius: 8px; padding: 11px 13px; cursor: pointer; transition: .15s; }
.opt:hover { border-color: var(--primary); background: #fff8f7; }
.opt input { margin-top: 4px; }
.opt.correct { border-color: var(--ok); background: #eafaf0; }
.opt.wrong { border-color: var(--bad); background: #fdecea; }
.analysis { margin-top: 12px; padding: 12px; background: #f7fafc; border-left: 3px solid var(--accent); border-radius: 0 8px 8px 0; font-size: 14px; }

/* ===== 进度 / 计时 ===== */
.exam-bar { position: sticky; top: 56px; z-index: 40; background: #fff; border: 1px solid var(--border); border-radius: var(--radius); padding: 10px 14px; display: flex; justify-content: space-between; align-items: center; flex-wrap: wrap; gap: 8px; margin-bottom: 16px; box-shadow: var(--shadow); }
.timer { font-weight: 700; color: var(--primary); font-variant-numeric: tabular-nums; }
.progress-dots { display: flex; flex-wrap: wrap; gap: 4px; max-width: 100%; }
.dot { width: 14px; height: 14px; border-radius: 3px; background: #dfe6ec; font-size: 0; }
.dot.done { background: var(--ok); }
.dot.wrong { background: var(--bad); }
.dot.current { outline: 2px solid var(--primary); }

/* ===== 结果 ===== */
.score-big { font-size: 52px; font-weight: 800; color: var(--primary); text-align: center; }
.score-ring { text-align: center; padding: 20px; }

/* ===== 表格 ===== */
table { width: 100%; border-collapse: collapse; font-size: 14px; }
th, td { text-align: left; padding: 9px 10px; border-bottom: 1px solid var(--border); }
th { background: #f7fafc; font-weight: 600; }
tr:hover td { background: #fafcfe; }

/* ===== 后台布局 ===== */
.admin-layout { display: flex; gap: 18px; align-items: flex-start; }
.admin-side { width: 180px; flex: 0 0 180px; }
.admin-side a { display: block; padding: 10px 12px; border-radius: 8px; margin-bottom: 4px; color: var(--text); }
.admin-side a:hover, .admin-side a.active { background: var(--primary); color: #fff; text-decoration: none; }
.admin-main { flex: 1; min-width: 0; }

/* ===== 响应式：手机 ===== */
@media (max-width: 640px) {
  body { font-size: 15px; }
  .topbar-inner { padding: 0 10px; }
  .brand { font-size: 15px; }
  .nav a { padding: 10px 7px; font-size: 13px; }
  .container { padding: 14px 12px 50px; }
  .grid { grid-template-columns: 1fr; }
  .q-content { font-size: 16px; }
  .admin-layout { flex-direction: column; }
  .admin-side { width: 100%; flex: none; display: flex; flex-wrap: wrap; gap: 6px; }
  .admin-side a { margin-bottom: 0; }
  .exam-bar { top: 52px; }
  .score-big { font-size: 40px; }
}