:root {
  --primary: #185FA5;
  --primary-light: #E6F1FB;
  --ok: #3B6D11;
  --ok-light: #EAF3DE;
  --bad: #A32D2D;
  --bad-light: #FCEBEB;
  --text: #222;
  --muted: #666;
  --border: #ddd;
  --bg: #f5f7fa;
  --card: #fff;
  --radius: 12px;
}
* { box-sizing: border-box; margin: 0; padding: 0; }
body {
  font-family: -apple-system, "Segoe UI", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
}
.container { max-width: 760px; margin: 0 auto; padding: 16px; }

/* 顶部栏 */
.topbar {
  display: flex; align-items: center; justify-content: space-between;
  background: var(--primary); color: #fff;
  padding: 10px 16px; position: sticky; top: 0; z-index: 10;
}
.topbar .brand { font-size: 16px; font-weight: 600; }
.topbar .user { font-size: 13px; opacity: .95; }
.topbar button {
  background: transparent; border: 1px solid rgba(255,255,255,.6);
  color: #fff; border-radius: 6px; padding: 4px 12px; cursor: pointer;
  font-size: 13px;
}
.topbar .right { display: flex; gap: 8px; align-items: center; }

/* 面板 */
.card {
  background: var(--card); border-radius: var(--radius);
  border: 1px solid var(--border); padding: 20px; margin: 16px 0;
  box-shadow: 0 1px 3px rgba(0,0,0,.05);
}
.card h2 { font-size: 16px; margin-bottom: 12px; }

/* 按钮 */
.btn {
  display: inline-block; background: var(--primary); color: #fff;
  border: none; border-radius: 8px; padding: 10px 20px;
  font-size: 15px; cursor: pointer;
}
.btn:disabled { background: #aaa; cursor: not-allowed; }
.btn.ghost { background: #fff; color: var(--primary); border: 1px solid var(--primary); }
.btn.danger { background: var(--bad); }
.btn.small { padding: 4px 10px; font-size: 13px; border-radius: 6px; }

/* 输入框 */
input, select {
  width: 100%; padding: 10px 12px; border: 1px solid var(--border);
  border-radius: 8px; font-size: 14px; outline: none;
}
input:focus, select:focus { border-color: var(--primary); }
.field { margin-bottom: 12px; }
.field label { display: block; font-size: 13px; color: var(--muted); margin-bottom: 4px; }

/* 登录页 */
.login-wrap {
  min-height: 100vh; display: flex; align-items: center; justify-content: center;
  padding: 20px;
}
.login-card {
  width: 100%; max-width: 380px; background: var(--card);
  border-radius: 16px; border: 1px solid var(--border);
  padding: 32px 28px; box-shadow: 0 4px 20px rgba(0,0,0,.08);
}
.login-card h1 { font-size: 20px; text-align: center; margin-bottom: 4px; }
.login-card .sub { text-align: center; color: var(--muted); font-size: 13px; margin-bottom: 22px; }
.err { color: var(--bad); font-size: 13px; min-height: 20px; margin-bottom: 8px; }
.tip { text-align: center; font-size: 12px; color: var(--muted); margin-top: 14px; }

/* 题目 */
.q-meta { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 10px; }
.badge {
  font-size: 12px; padding: 2px 10px; border-radius: 999px;
  background: var(--primary-light); color: var(--primary);
}
.badge.multi { background: #FAEEDA; color: #854F0B; }
.badge.diff { background: #F1EFE8; color: #5F5E5A; }
.q-text { font-size: 15px; margin-bottom: 14px; }
.q-text img { max-width: 100%; vertical-align: middle; }
.q-text p { margin: 4px 0; }

/* 选项 */
.opt {
  display: flex; align-items: flex-start; gap: 10px;
  border: 1.5px solid var(--border); border-radius: 10px;
  padding: 10px 14px; margin-bottom: 10px; cursor: pointer;
  transition: all .15s; background: #fff; font-size: 14px;
}
.opt:hover { border-color: var(--primary); background: var(--primary-light); }
.opt .letter {
  flex-shrink: 0; width: 26px; height: 26px; border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  border: 1.5px solid var(--border); font-size: 13px; font-weight: 600;
}
.opt img { max-width: 100%; vertical-align: middle; }
.opt .content { flex: 1; min-width: 0; }
.opt .content p { margin: 2px 0; }
.opt.selected { border-color: var(--primary); background: var(--primary-light); }
.opt.selected .letter { background: var(--primary); color: #fff; border-color: var(--primary); }
.opt.correct { border-color: var(--ok); background: var(--ok-light); }
.opt.correct .letter { background: var(--ok); color: #fff; border-color: var(--ok); }
.opt.wrong { border-color: var(--bad); background: var(--bad-light); }
.opt.wrong .letter { background: var(--bad); color: #fff; border-color: var(--bad); }
.opt.dim { opacity: .55; }

/* 解析 */
.answer-box {
  margin-top: 12px; border-radius: 10px; padding: 14px;
  background: #F7FAF2; border: 1px solid #C0DD97; display: none;
}
.answer-box.show { display: block; }
.answer-box .ans-tag { font-weight: 600; color: var(--ok); margin-bottom: 6px; }
.answer-box .explain { font-size: 14px; }
.answer-box .explain img { max-width: 100%; vertical-align: middle; }
.answer-box .explain p { margin: 4px 0; }

/* 答题操作区 */
.actions { display: flex; gap: 10px; margin-top: 14px; flex-wrap: wrap; }
.actions .btn { flex: 1; min-width: 110px; }

/* 进度条 */
.progress { display: flex; gap: 6px; align-items: center; margin-bottom: 14px; font-size: 13px; color: var(--muted); }
.progress .bar {
  flex: 1; height: 8px; border-radius: 4px; background: #e5e5e5; overflow: hidden;
}
.progress .bar i {
  display: block; height: 100%; background: var(--primary); border-radius: 4px;
  transition: width .2s;
}

/* 模式切换 */
.modes { display: flex; gap: 8px; margin-bottom: 14px; flex-wrap: wrap; }
.mode {
  font-size: 13px; padding: 6px 14px; border-radius: 999px;
  border: 1.5px solid var(--border); background: #fff; cursor: pointer; color: var(--muted);
}
.mode.active { border-color: var(--primary); color: var(--primary); background: var(--primary-light); font-weight: 600; }

/* 统计卡 */
.stats { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; }
.stat {
  background: #fff; border: 1px solid var(--border); border-radius: 10px;
  padding: 12px; text-align: center;
}
.stat .num { font-size: 22px; font-weight: 700; color: var(--primary); }
.stat .lab { font-size: 12px; color: var(--muted); }

/* 表格 */
table { width: 100%; border-collapse: collapse; font-size: 14px; }
th, td { text-align: left; padding: 8px 10px; border-bottom: 1px solid var(--border); }
th { color: var(--muted); font-weight: 500; font-size: 13px; }
.row-actions { display: flex; gap: 6px; flex-wrap: wrap; }

/* 提示条 */
.notice {
  padding: 10px 14px; border-radius: 8px; font-size: 13px; margin: 8px 0; display: none;
}
.notice.ok { background: var(--ok-light); color: var(--ok); border: 1px solid #C0DD97; display: block; }
.notice.bad { background: var(--bad-light); color: var(--bad); border: 1px solid #F7C1C1; display: block; }

/* 空状态 */
.empty { text-align: center; color: var(--muted); padding: 40px 0; font-size: 14px; }

.muted { color: var(--muted); font-size: 13px; }
.hidden { display: none !important; }
a.link { color: var(--primary); text-decoration: none; font-size: 13px; cursor: pointer; }
h3.section { font-size: 15px; margin: 18px 0 10px; }