/* 群助教 · 全站样式（蓝白主色，无渐变） */
:root {
  --primary: #2563EB;
  --primary-dark: #1D4ED8;
  --primary-light: #EFF4FF;
  --text: #1E293B;
  --text-sub: #64748B;
  --bg: #F7F9FC;
  --border: #E2E8F0;
  --radius-xs: 6px;
  --radius-sm: 10px;
  --radius-lg: 14px;
  --radius-xl: 20px;
  --radius-pill: 999px;
  --container-max: 1200px;
}

* { margin: 0; padding: 0; box-sizing: border-box; }
body {
  font-family: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.7;
}
a { color: var(--primary); text-decoration: none; }
a:hover { color: var(--primary-dark); }
.container { max-width: var(--container-max); margin: 0 auto; padding: 0 20px; }

/* 顶栏 */
.site-header {
  background: rgba(255,255,255,.92);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
  position: sticky; top: 0; z-index: 10;
}
.header-inner { display: flex; align-items: center; justify-content: space-between; height: 60px; }
.logo { font-size: 22px; font-weight: 700; color: var(--text); }
.logo span { color: var(--primary); }
.site-nav a { margin-left: 24px; color: var(--text-sub); font-size: 15px; padding: 6px 2px; }
.site-nav a.active, .site-nav a:hover { color: var(--primary); }

/* Hero */
.hero { padding: 64px 0 24px; text-align: center; }
.hero h1 { font-size: 40px; letter-spacing: 1px; }
.hero h1 em { font-style: normal; color: var(--primary); }
.hero-sub { color: var(--text-sub); font-size: 17px; margin-top: 12px; }

/* 卡片 */
.card {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 28px;
  transition: transform .2s ease, border-color .2s ease, box-shadow .2s ease;
}
.card:hover { transform: translateY(-3px); border-color: var(--primary); box-shadow: 0 8px 24px rgba(37,99,235,.08); }
h2 { font-size: 22px; margin-bottom: 16px; }
h3 { font-size: 17px; margin-bottom: 8px; }

/* 表单 */
.form-card { margin-top: 8px; }
.form-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(180px, 1fr)); gap: 16px; margin: 16px 0 20px; }
.form-grid label { font-size: 14px; color: var(--text-sub); display: block; }
.form-grid select, .form-grid input {
  width: 100%; margin-top: 6px; padding: 10px 12px;
  border: 1px solid var(--border); border-radius: var(--radius-xs);
  font-size: 15px; color: var(--text); background: #fff;
}
.form-grid select:focus { outline: none; border-color: var(--primary); }
.btn {
  display: inline-block; border: none; cursor: pointer;
  border-radius: var(--radius-xs); font-size: 15px;
  padding: 10px 22px; background: #fff; color: var(--text);
}
.btn-primary { background: var(--primary); color: #fff; }
.btn-primary:hover { background: var(--primary-dark); }
.btn-lg { padding: 12px 32px; font-size: 16px; border-radius: var(--radius-pill); }
.btn-sm { padding: 3px 10px; font-size: 13px; }
.btn-plain { background: none; color: var(--primary); border: 1px solid var(--border); }
.form-hint { color: var(--text-sub); font-size: 13px; margin-top: 12px; }
.center { text-align: center; }

.alert { margin-top: 16px; padding: 12px 16px; border-radius: var(--radius-xs); font-size: 14px; }
.alert-warn { background: #FFF7E6; border: 1px solid #F5C86B; color: #8A5A00; }

/* 特性区 */
.features { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 18px; margin-top: 40px; }
.how { margin: 48px 0 64px; }
.steps { list-style: none; display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 18px; counter-reset: step; }
.steps li { background: #fff; border: 1px solid var(--border); border-radius: var(--radius-lg); padding: 22px; counter-increment: step; }
.steps li::before { content: counter(step); display: inline-flex; width: 28px; height: 28px; align-items: center; justify-content: center; background: var(--primary); color: #fff; border-radius: var(--radius-pill); margin-right: 10px; font-weight: 600; }
.steps b { margin-right: 8px; }
.steps span { color: var(--text-sub); font-size: 14px; }

/* 状态页 */
.status-box { margin-top: 48px; }
.spinner { width: 36px; height: 36px; border: 3px solid var(--border); border-top-color: var(--primary); border-radius: 50%; animation: spin .8s linear infinite; margin: 8px auto 16px; }
@keyframes spin { to { transform: rotate(360deg); } }
.paper-head { margin-top: 36px; }
.paper-head h1 { font-size: 24px; }
.paper-head .meta { color: var(--text-sub); margin: 8px 0 14px; }
.points-label { font-weight: 600; margin-right: 10px; }
.chip { display: inline-block; background: var(--primary-light); color: var(--primary); border-radius: var(--radius-pill); padding: 3px 12px; font-size: 13px; margin: 2px 6px 6px 0; }
.actions { margin-top: 18px; display: flex; align-items: center; gap: 16px; flex-wrap: wrap; }

/* 预览 */
.preview { margin: 28px 0 64px; }
.preview h2 { margin-bottom: 14px; }
.q-row { display: flex; gap: 10px; padding: 10px 0; border-bottom: 1px dashed var(--border); align-items: baseline; }
.q-row:last-child { border-bottom: none; }
.q-no { color: var(--primary); font-weight: 600; min-width: 28px; }
.q-type { flex-shrink: 0; font-size: 12px; color: var(--text-sub); border: 1px solid var(--border); border-radius: var(--radius-pill); padding: 1px 8px; }
.q-stem { flex: 1; }

/* 定价/关于 */
.pricing { padding-top: 40px; }
.price { font-size: 30px; color: var(--primary); font-weight: 700; margin: 6px 0 12px; }
.price span { font-size: 14px; color: var(--text-sub); font-weight: 400; }
.card ul { list-style: none; }
.card ul li { padding: 6px 0; color: var(--text-sub); font-size: 14px; }
.card ul li::before { content: "✓ "; color: var(--primary); font-weight: 700; }
.card.featured { border-color: var(--primary); }
.about-page { padding: 40px 0 64px; }
.about-page .card { margin-top: 16px; }
.about-page ul { padding-left: 4px; }

/* 页脚 */
.site-footer { border-top: 1px solid var(--border); margin-top: 48px; padding: 28px 0 40px; color: var(--text-sub); font-size: 13px; background: #fff; }
.site-footer p { margin: 4px 0; }

/* 后台 */
.admin-body { background: var(--bg); }
.admin-wrap { display: flex; min-height: 100vh; }
.admin-side { width: 200px; background: #fff; border-right: 1px solid var(--border); padding: 24px 16px; flex-shrink: 0; }
.admin-side h3 { font-size: 16px; margin-bottom: 20px; }
.admin-side a { display: block; padding: 9px 12px; border-radius: var(--radius-xs); color: var(--text-sub); margin-bottom: 4px; }
.admin-side a.active, .admin-side a:hover { background: var(--primary-light); color: var(--primary); }
.admin-side form { margin-top: 24px; }
.admin-main { flex: 1; padding: 28px 32px; }
.stats-row { display: grid; grid-template-columns: repeat(auto-fit, minmax(140px, 1fr)); gap: 14px; margin-bottom: 28px; }
.stat { text-align: center; padding: 18px; }
.stat b { font-size: 26px; color: var(--primary); display: block; }
.stat span { font-size: 13px; color: var(--text-sub); }
.tbl { width: 100%; border-collapse: collapse; background: #fff; border-radius: var(--radius-sm); overflow: hidden; font-size: 14px; }
.tbl th, .tbl td { text-align: left; padding: 10px 12px; border-bottom: 1px solid var(--border); }
.tbl th { background: var(--primary-light); color: var(--text); font-weight: 600; }
.err-cell { color: #C2410C; max-width: 200px; }
.filter-row a { margin-right: 14px; }
.filter-row a.active { font-weight: 700; }
.status { border-radius: var(--radius-pill); font-size: 12px; padding: 2px 10px; }
.status-ready { background: #E7F7EE; color: #15803D; }
.status-failed { background: #FEECEC; color: #B91C1C; }
.status-generating, .status-pending { background: var(--primary-light); color: var(--primary); }
.login-box { max-width: 360px; margin: 100px auto; }
.login-box label { display: block; margin-bottom: 14px; font-size: 14px; color: var(--text-sub); }
.login-box input { width: 100%; margin-top: 6px; padding: 10px 12px; border: 1px solid var(--border); border-radius: var(--radius-xs); font-size: 15px; }
.login-box .btn { width: 100%; margin-top: 6px; }

/* ===== 用户体系 / 订单 / 加练 扩展 ===== */
.nav-form { display: inline; margin-left: 16px; }
.btn-link { background: none; border: none; color: var(--primary); cursor: pointer; font-size: 13px; padding: 0; }
.btn-link:hover { color: var(--primary-dark); text-decoration: underline; }
.nav-cta { background: var(--primary); color: #fff !important; border-radius: var(--radius-pill); padding: 5px 16px !important; }
.nav-user { font-weight: 600; }
.chip-mark { background: #fff; border: 1px solid var(--border); color: var(--text); }
.chip-marked { background: var(--primary-light); border-color: var(--primary); color: var(--primary); }
.chip-mark .inline-form { display: inline; margin-left: 4px; }
.inline-form { display: inline; }
.weak-zone { margin-top: 20px; }
.account-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(320px, 1fr)); gap: 18px; margin: 18px 0 28px; }
.member-badge { color: #15803D; font-weight: 600; background: #E7F7EE; display: inline-block; padding: 4px 12px; border-radius: var(--radius-pill); }
.redeem-form { display: flex; gap: 8px; margin: 12px 0; }
.redeem-form input { flex: 1; padding: 8px 12px; border: 1px solid var(--border); border-radius: var(--radius-xs); }
.addr-label { display: block; font-size: 14px; color: var(--text-sub); margin-bottom: 16px; }
.addr-label textarea { width: 100%; margin-top: 6px; padding: 10px 12px; border: 1px solid var(--border); border-radius: var(--radius-xs); font-size: 15px; font-family: inherit; }
.reinforce-form { margin-top: 14px; }
.reason-input { width: 120px; padding: 3px 8px; border: 1px solid var(--border); border-radius: var(--radius-xs); font-size: 13px; }
.stem-cell { max-width: 320px; }
.code-list { background: var(--primary-light); padding: 14px; border-radius: var(--radius-xs); font-size: 15px; line-height: 1.9; letter-spacing: 1px; }

/* 结果页：试卷信息 + 排版效果图 */
.paper-top { display: flex; gap: 20px; align-items: flex-start; flex-wrap: wrap; }
.paper-top .paper-info { flex: 1 1 420px; }
.paper-preview { flex: 0 0 260px; padding: 12px; text-align: center; }
.paper-preview img { width: 100%; border: 1px solid var(--border); border-radius: 6px; box-shadow: 0 2px 8px rgba(30,41,59,.08); }

/* 生成进度条 */
.progress-wrap { max-width: 460px; margin: 18px auto 6px; text-align: left; }
.progress-bar { height: 14px; background: var(--border); border-radius: var(--radius-pill); overflow: hidden; }
.progress-fill { height: 100%; background: var(--primary); border-radius: var(--radius-pill); transition: width .6s ease; }
.progress-tip { margin: 10px 0 4px; font-size: 14px; color: var(--text); font-weight: 600; text-align: center; }
.progress-steps { display: flex; justify-content: center; gap: 18px; margin-top: 8px; }
.pstep { font-size: 13px; color: var(--text-sub); }
.pstep.active { color: var(--primary); font-weight: 600; }

/* 支付页 */
.pay-box { max-width: 460px; margin: 40px auto; text-align: center; }
.pay-amount { font-size: 34px; font-weight: 700; color: var(--primary); margin: 10px 0 18px; }
.qr-wrap { display: inline-block; padding: 12px; border: 1px solid var(--border); border-radius: var(--radius-sm); background: #fff; }
.pay-status { margin: 14px 0 6px; color: var(--primary); font-weight: 600; }

/* 教师工具 */
.unit-checks { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 6px; max-height: 260px; overflow-y: auto; border: 1px solid var(--border); border-radius: var(--radius-xs); padding: 10px; }
.unit-check { font-size: 14px; color: var(--text); display: flex; align-items: center; gap: 6px; }
.unit-check input { width: auto; }
.teacher-page h1 { margin-bottom: 4px; }
.doc-section { margin: 14px 0; }
.doc-section h3 { background: var(--primary-light); padding: 6px 12px; border-radius: var(--radius-xs); }
.doc-section ul { padding-left: 22px; color: var(--text); }
.doc-section li { margin: 3px 0; }