:root {
  --bg: #f5f7fa;
  --card: #ffffff;
  --primary: #2f6fed;
  --primary-dark: #1f54c4;
  --text: #1f2733;
  --muted: #6b7785;
  --border: #e3e8ef;
  --green: #18a058;
  --red: #e03e3e;
  --shadow: 0 2px 10px rgba(20, 30, 50, 0.08);
}
* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: -apple-system, "Segoe UI", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
}
.topbar {
  display: flex; align-items: center; justify-content: space-between;
  background: var(--card); border-bottom: 1px solid var(--border);
  padding: 12px 24px; position: sticky; top: 0; z-index: 50;
}
.brand { font-weight: 700; font-size: 18px; }
.nav a {
  margin-left: 18px; text-decoration: none; color: var(--muted);
  font-size: 14px; padding: 6px 10px; border-radius: 6px;
}
.nav a:hover { background: var(--bg); color: var(--primary); }
.container { max-width: 1100px; margin: 24px auto; padding: 0 20px; }
.card {
  background: var(--card); border: 1px solid var(--border);
  border-radius: 12px; padding: 20px; box-shadow: var(--shadow); margin-bottom: 20px;
}
h1, h2, h3 { margin-top: 0; }
button, .btn {
  background: var(--primary); color: #fff; border: none; cursor: pointer;
  padding: 8px 14px; border-radius: 8px; font-size: 14px; text-decoration: none;
  display: inline-block;
}
button:hover, .btn:hover { background: var(--primary-dark); }
button.secondary { background: #eceff5; color: var(--text); }
button.danger { background: var(--red); }
input, select, textarea {
  width: 100%; padding: 8px 10px; border: 1px solid var(--border);
  border-radius: 8px; font-size: 14px; font-family: inherit; margin-top: 4px;
}
label { font-size: 13px; color: var(--muted); display: block; margin-top: 10px; }
.muted { color: var(--muted); font-size: 13px; }
.row { display: flex; gap: 12px; flex-wrap: wrap; }
.row > * { flex: 1; min-width: 160px; }
.tag {
  display: inline-block; background: #eef3ff; color: var(--primary);
  border-radius: 6px; padding: 2px 8px; font-size: 12px; margin: 2px;
}
.table { width: 100%; border-collapse: collapse; }
.table th, .table td {
  text-align: left; padding: 10px; border-bottom: 1px solid var(--border); font-size: 14px;
}
.table th { color: var(--muted); font-weight: 600; }
.empty { color: var(--muted); padding: 12px 0; }

/* 播放页 */
.player-wrap { position: relative; background: #000; border-radius: 12px; overflow: hidden; }
.player-wrap video { width: 100%; display: block; background: #000; }
.qr-overlay {
  position: absolute; right: 20px; top: 20px; width: 220px;
  background: rgba(255,255,255,0.96); border-radius: 12px; padding: 14px;
  box-shadow: var(--shadow); text-align: center; display: none; z-index: 20;
}
.qr-overlay img { width: 180px; height: 180px; }
.qr-overlay .close {
  position: absolute; right: 8px; top: 6px; background: transparent; color: #333;
  font-size: 18px; padding: 0 6px;
}
.node-pill {
  position: absolute; bottom: 16px; left: 50%; transform: translateX(-50%);
  background: rgba(0,0,0,0.7); color: #fff; padding: 6px 14px; border-radius: 20px;
  font-size: 13px; display: none;
}
.timeline { margin-top: 12px; }
.timeline input[type=range] { width: 100%; }

/* 分析后台 */
.stat-grid { display: flex; gap: 18px; flex-wrap: wrap; margin-top: 10px; }
.stat-box {
  flex: 1; min-width: 200px; border: 1px solid var(--border); border-radius: 10px;
  padding: 14px; background: var(--card);
}
.bar-track { background: #eef0f4; border-radius: 8px; height: 14px; overflow: hidden; margin-top: 8px; }
.bar-fill { height: 100%; background: var(--primary); border-radius: 8px; transition: width .4s; }
.stat-box-wide { flex: 0 0 100% !important; max-width: 100% !important; }
.stat-sub { margin-top: 6px; }
.stat-sub .bar-track { margin-top: 4px; height: 10px; }

/* ALL 分析：正确答案绿色 + 可点击项 */
.stat-sub.clickable { cursor: pointer; border-radius: 6px; padding: 4px 6px; transition: background .15s; }
.stat-sub.clickable:hover { background: #f0f4ff; }
.stat-sub.opt-correct-row { background: #e9f8ef; border-radius: 6px; }
.bar-fill-green { background: var(--green) !important; }

/* 作答人弹窗 */
.respondent-modal { width: 420px; max-height: 70vh; }
.respondent-title { font-weight: 700; font-size: 16px; margin-bottom: 12px; }
.respondent-body { max-height: 50vh; overflow-y: auto; }
.respondent-item { padding: 6px 0; border-bottom: 1px solid var(--border); font-size: 14px; }
.live-dot {
  display: inline-block; width: 9px; height: 9px; border-radius: 50%;
  background: var(--green); margin-right: 6px; animation: blink 1.2s infinite;
}
@keyframes blink { 50% { opacity: .3; } }

/* 答题页 */
.answer-card { max-width: 560px; margin: 20px auto; }
.option-btn {
  display: block; width: 100%; text-align: left; background: #fff; color: var(--text);
  border: 1px solid var(--border); padding: 14px; border-radius: 10px; margin-top: 10px;
}
.option-btn.selected { border-color: var(--primary); background: #eef3ff; }
.option-btn.opt-correct { border-color: var(--green); background: #e9f8ef; }
.option-btn.opt-wrong { opacity: 0.55; }
.success { color: var(--green); font-weight: 600; }
.answer-reveal {
  margin-top: 10px; padding: 10px 12px; border-radius: 10px;
  background: #e9f8ef; color: var(--green); font-weight: 600; font-size: 14px;
}

/* 题库后台 - 查看态 / 编辑态 */
.badge {
  display: inline-block; background: #eef3ff; color: var(--primary);
  border-radius: 6px; padding: 1px 8px; font-size: 12px; font-weight: 600; margin-left: 6px;
}
.qcontent { margin: 10px 0; font-size: 15px; line-height: 1.5; }
.opts { margin: 6px 0 0; padding-left: 22px; }
.opts li { margin: 4px 0; }
.opt-correct { color: var(--green); font-weight: 600; }
.ok-tag { color: var(--green); font-size: 12px; margin-left: 4px; }
.saved-tag {
  color: var(--green); font-size: 12px; font-weight: 600; margin-left: 8px;
  background: #e9f8ef; border-radius: 6px; padding: 1px 8px;
}

/* 题库后台 - 填空题 / 输入框 */
.fill-input {
  width: 100%; padding: 12px 14px; border: 1px solid var(--border);
  border-radius: 10px; font-size: 15px; margin-top: 8px;
}
.qmeta { margin: 8px 0; font-size: 13px; }
.chk-row { display: flex; align-items: center; gap: 8px; font-size: 14px; color: var(--text); }
.chk-row input { width: auto; margin: 0; }
.logout-link { color: var(--red) !important; }

/* 删除确认弹窗 */
.modal-mask {
  position: fixed; inset: 0; background: rgba(15, 23, 42, 0.45);
  display: flex; align-items: center; justify-content: center; z-index: 100;
}
.modal {
  background: #fff; border-radius: 12px; padding: 24px; width: 360px; max-width: 90vw;
  box-shadow: var(--shadow);
}
.modal-actions { display: flex; gap: 10px; justify-content: flex-end; margin-top: 18px; }

/* 登录页 */
.login-wrap { display: flex; align-items: center; justify-content: center; min-height: 100vh; }
.login-card { width: 340px; max-width: 90vw; }
.login-error {
  background: #fdecec; color: var(--red); border: 1px solid #f5c2c2;
  border-radius: 8px; padding: 8px 12px; margin: 10px 0; font-size: 14px;
}