:root {
  --bg: #f5f6f8; --card: #fff; --text: #1d2129; --muted: #86909c; --line: #e5e6eb;
  --primary: #1f6feb; --primary-soft: #e8f0fe; --ok: #16a34a; --warn: #d97706; --err: #dc2626;
  --radius: 10px;
}
* { box-sizing: border-box; }
body { margin: 0; font: 15px/1.6 -apple-system, "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif; background: var(--bg); color: var(--text); }
a { color: var(--primary); text-decoration: none; }
button, input, textarea, select { font: inherit; }
.hidden { display: none !important; }

header.top { background: var(--card); border-bottom: 1px solid var(--line); position: sticky; top: 0; z-index: 10; }
header.top .in { max-width: 1200px; margin: 0 auto; padding: 0 16px; height: 56px; display: flex; align-items: center; gap: 16px; }
header.top .brand { font-weight: 600; font-size: 17px; color: var(--text); }
header.top .sp { flex: 1; }
header.top .user { color: var(--muted); font-size: 14px; }

main { max-width: 1200px; margin: 0 auto; padding: 24px 16px 64px; }
h1 { font-size: 22px; margin: 0 0 16px; }
h2 { font-size: 18px; margin: 0 0 12px; }

.btn { display: inline-flex; align-items: center; justify-content: center; gap: 6px; height: 36px; padding: 0 16px; border-radius: 8px; border: 1px solid var(--line); background: var(--card); color: var(--text); cursor: pointer; white-space: nowrap; }
.btn:hover { border-color: #c9cdd4; }
.btn.primary { background: var(--primary); border-color: var(--primary); color: #fff; }
.btn.primary:hover { filter: brightness(1.08); }
.btn.danger { color: var(--err); }
.btn.sm { height: 30px; padding: 0 10px; font-size: 13px; }
.btn:disabled { opacity: .5; cursor: not-allowed; }

input[type=text], input[type=password], textarea, select {
  width: 100%; padding: 8px 12px; border: 1px solid var(--line); border-radius: 8px; background: #fff; outline: none;
}
input:focus, textarea:focus { border-color: var(--primary); }
label.f { display: block; margin-bottom: 12px; }
label.f > span { display: block; font-size: 13px; color: var(--muted); margin-bottom: 4px; }

.card { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); padding: 20px; }
.muted { color: var(--muted); }
.err-msg { color: var(--err); font-size: 14px; min-height: 1.6em; }

/* 登录 */
.login-wrap { min-height: 100vh; display: grid; place-items: center; padding: 16px; }
.login-wrap .card { width: 100%; max-width: 380px; padding: 32px; }
.login-wrap h1 { text-align: center; margin-bottom: 24px; }

/* 课程卡片 */
.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 16px; }
.course-card { display: block; color: inherit; transition: box-shadow .15s; }
.course-card:hover { box-shadow: 0 4px 16px rgba(0,0,0,.08); }
.course-card .cover { height: 120px; border-radius: 8px; margin: -4px -4px 14px; display: grid; place-items: center; color: #fff; font-size: 22px; font-weight: 600; padding: 12px; text-align: center; }
.course-card h3 { margin: 0 0 4px; font-size: 16px; }
.course-card.expired { opacity: .85; }
.course-card.expired h3 { color: var(--muted); }
.notice { border-radius: 10px; padding: 10px 14px; margin-bottom: 14px; font-size: 14px; }
.notice.warn { background: #fef3c7; color: #92400e; }
.notice.err { background: #fee2e2; color: #991b1b; }
.dl { font-size: 12px; }
.dl.over { color: var(--err); font-weight: 600; }
.dl.soon { color: var(--warn); font-weight: 600; }
.cell-overdue { background: #fee2e2; color: var(--err); font-weight: 600; }
.bar { height: 6px; background: var(--line); border-radius: 3px; overflow: hidden; margin-top: 10px; }
.bar > i { display: block; height: 100%; background: var(--ok); }

/* 播放页 */
.player-layout { display: grid; grid-template-columns: 1fr 340px; gap: 20px; align-items: start; }
@media (max-width: 900px) { .player-layout { grid-template-columns: 1fr; } }
.player-box { position: relative; background: #000; border-radius: var(--radius); overflow: hidden; aspect-ratio: 16/9; }
.player-box video { width: 100%; height: 100%; display: block; background: #000; }
.player-box:fullscreen { border-radius: 0; aspect-ratio: auto; width: 100%; height: 100%; }
.player-box:-webkit-full-screen { border-radius: 0; aspect-ratio: auto; width: 100%; height: 100%; }
.player-box.is-fs video { object-fit: contain; }
.fs-exit { display: none; position: absolute; top: 12px; right: 12px; z-index: 4; border: 0; border-radius: 16px; padding: 6px 14px; background: rgba(0,0,0,.55); color: #fff; font-size: 14px; cursor: pointer; }
.player-box.is-fs .fs-exit { display: block; }
.watermark { position: absolute; pointer-events: none; color: rgba(255,255,255,.35); font-size: 14px; text-shadow: 0 0 2px rgba(0,0,0,.5); transition: top 1.5s, left 1.5s; white-space: nowrap; user-select: none; z-index: 2; }
.player-empty { position: absolute; inset: 0; display: grid; place-items: center; color: #aaa; }
.lesson-list { list-style: none; margin: 0; padding: 0; max-height: 70vh; overflow: auto; }
.lesson-list li { display: flex; gap: 10px; align-items: center; padding: 10px 12px; border-radius: 8px; cursor: pointer; }
.lesson-list li:hover { background: var(--bg); }
.lesson-list li.active { background: var(--primary-soft); color: var(--primary); }
.lesson-list .no { width: 24px; text-align: center; color: var(--muted); font-size: 13px; }
.lesson-list .t { flex: 1; min-width: 0; }
.lesson-list .meta { font-size: 12px; color: var(--muted); }
.tag { display: inline-block; font-size: 12px; padding: 0 8px; border-radius: 10px; line-height: 20px; }
.tag.ok { background: #dcfce7; color: var(--ok); }
.tag.warn { background: #fef3c7; color: var(--warn); }
.tag.err { background: #fee2e2; color: var(--err); }
.tag.info { background: var(--primary-soft); color: var(--primary); }

/* 后台 */
.tabs { display: flex; gap: 4px; border-bottom: 1px solid var(--line); margin-bottom: 20px; overflow-x: auto; }
.tabs button { border: 0; background: none; padding: 10px 16px; cursor: pointer; color: var(--muted); border-bottom: 2px solid transparent; margin-bottom: -1px; white-space: nowrap; }
.tabs button.on { color: var(--primary); border-color: var(--primary); font-weight: 600; }
.row { display: flex; gap: 12px; align-items: center; flex-wrap: wrap; }
.row .sp { flex: 1; }
table { width: 100%; border-collapse: collapse; background: var(--card); }
th, td { text-align: left; padding: 10px 12px; border-bottom: 1px solid var(--line); font-size: 14px; vertical-align: middle; }
th { color: var(--muted); font-weight: 500; background: #fafbfc; white-space: nowrap; }
.table-wrap { overflow-x: auto; border: 1px solid var(--line); border-radius: var(--radius); }
.table-wrap table { border: 0; }
.side-list { display: grid; grid-template-columns: 260px 1fr; gap: 20px; }
@media (max-width: 800px) { .side-list { grid-template-columns: 1fr; } }
.side-list .items button { display: block; width: 100%; text-align: left; border: 0; background: none; padding: 10px 12px; border-radius: 8px; cursor: pointer; }
.side-list .items button.on { background: var(--primary-soft); color: var(--primary); }
.upload-progress { height: 8px; background: var(--line); border-radius: 4px; overflow: hidden; }
.upload-progress > i { display: block; height: 100%; width: 0; background: var(--primary); transition: width .2s; }
.chk-list { display: flex; flex-wrap: wrap; gap: 8px 16px; }
.chk-list label { display: flex; gap: 6px; align-items: center; cursor: pointer; }
.cell-done { color: var(--ok); font-weight: 600; }
.cell-part { color: var(--warn); }
.cell-none { color: #c9cdd4; }

dialog { border: 0; border-radius: 12px; padding: 24px; width: min(520px, calc(100vw - 32px)); box-shadow: 0 10px 40px rgba(0,0,0,.2); }
dialog::backdrop { background: rgba(0,0,0,.4); }
dialog h2 { margin-bottom: 16px; }
dialog .actions { display: flex; justify-content: flex-end; gap: 8px; margin-top: 16px; }

/* 导航 */
header.top .nav { display: flex; gap: 16px; }
header.top .nav a { color: var(--muted); }
header.top .nav a:hover { color: var(--primary); }
@media (max-width: 700px) {
  header.top .in { height: auto; min-height: 52px; flex-wrap: wrap; gap: 8px 12px; padding-top: 8px; padding-bottom: 8px; }
  header.top .brand { font-size: 15px; }
  header.top .user { display: none; }
  header.top .nav { order: 10; width: 100%; gap: 20px; font-size: 14px; }
}

/* 页脚（备案号） */
.site-footer { text-align: center; color: var(--muted); font-size: 13px; padding: 24px 16px 32px; display: flex; flex-direction: column; gap: 4px; align-items: center; }
.site-footer a { color: var(--muted); }
.site-footer a:hover { color: var(--primary); }

/* 联系老师 */
.contact-qr { display: block; width: 220px; max-width: 100%; margin: 8px auto 0; border-radius: 8px; border: 1px solid var(--line); }
.contact-id { display: flex; align-items: center; justify-content: space-between; gap: 8px; margin-top: 14px; padding: 10px 12px; background: var(--bg); border-radius: 8px; }

/* 首页滚动文字 */
.marquee { display: flex; align-items: center; gap: 10px; background: #fff7e6; border: 1px solid #ffe2b3; color: #ad4e00; border-radius: 10px; padding: 8px 14px; margin-bottom: 16px; overflow: hidden; }
.marquee-icon { flex: none; }
.marquee-view { flex: 1; overflow: hidden; min-width: 0; }
.marquee-track { display: inline-flex; white-space: nowrap; animation: marquee-scroll 20s linear infinite; will-change: transform; }
.marquee:hover .marquee-track { animation-play-state: paused; }
.marquee-seg { display: inline-flex; flex: none; }
.marquee-item { padding-right: 64px; font-weight: 500; }
@keyframes marquee-scroll { from { transform: translateX(0); } to { transform: translateX(-50%); } }
@media (prefers-reduced-motion: reduce) {
  .marquee-track { animation: none; white-space: normal; }
  .marquee-seg + .marquee-seg { display: none; }
  .marquee-seg { flex-wrap: wrap; }
}

/* ===== 首页（简洁版） ===== */
.home-main { max-width: 860px; }
.home header.top .in { max-width: 860px; }
.home-head { background: #eef4ff; border-radius: 14px; padding: 28px 28px 26px; margin-bottom: 28px; }
.home-head h1 { font-size: 26px; margin: 0 0 8px; }
.home-head p { color: #4e5969; margin: 0 0 18px; white-space: pre-wrap; }
.home-head .btn { height: 40px; padding: 0 20px; }
.home-title { font-size: 18px; margin: 0 0 4px; padding-bottom: 10px; border-bottom: 1px solid var(--line); }
.news-list { display: flex; flex-direction: column; }
.news-item { display: flex; gap: 16px; align-items: center; padding: 16px 0; border-bottom: 1px solid var(--line); color: inherit; }
.news-item:hover .news-title { color: var(--primary); }
.news-text { flex: 1; min-width: 0; }
.news-title { font-size: 16px; font-weight: 600; line-height: 1.5; }
.news-sum { color: #4e5969; font-size: 14px; margin-top: 4px; overflow: hidden; display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; }
.news-meta { color: var(--muted); font-size: 12px; margin-top: 6px; }
.news-thumb { width: 120px; height: 80px; flex: none; object-fit: cover; border-radius: 8px; background: var(--bg); }
.pin-tag { display: inline-block; font-size: 12px; font-weight: 500; color: #b45309; background: #fef3c7; border-radius: 6px; padding: 0 6px; margin-right: 6px; vertical-align: 2px; }
@media (max-width: 600px) {
  .home-head { padding: 22px 18px; border-radius: 12px; }
  .home-head h1 { font-size: 22px; }
  .home-head .btn { flex: 1; }
  .news-item { gap: 12px; padding: 14px 0; }
  .news-title { font-size: 15px; }
  .news-sum { font-size: 13px; }
  .news-thumb { width: 92px; height: 66px; }
}

/* 文章正文 */
.article-page { max-width: 760px; margin: 0 auto; }
.article-page h1 { font-size: 24px; line-height: 1.4; margin-bottom: 8px; }
.article-body { font-size: 16px; line-height: 1.85; word-break: break-word; }
.article-body img { max-width: 100%; height: auto; border-radius: 6px; display: block; margin: 12px auto; }
.article-body p { margin: 0 0 12px; }
.article-body blockquote { border-left: 4px solid var(--line); margin: 12px 0; padding: 4px 14px; color: #4e5969; }
.article-body .ql-align-center { text-align: center; }
.article-body .ql-align-right { text-align: right; }
.article-body .ql-align-justify { text-align: justify; }
.article-body li[data-list="bullet"] { list-style-type: disc; }
.article-body ol:has(li[data-list="bullet"]) { padding-left: 1.5em; }
.cta-box { margin-top: 28px; padding: 18px 20px; background: var(--primary-soft); border-radius: 12px; display: flex; gap: 12px; align-items: center; flex-wrap: wrap; }

/* 视频内弹题 */
.quiz { position: absolute; inset: 0; z-index: 5; background: rgba(0,0,0,.6); display: flex; align-items: center; justify-content: center; padding: 12px; overflow: auto; }
.quiz-card { background: #fff; color: var(--text); border-radius: 12px; padding: 18px 20px; width: min(560px, 100%); max-height: 100%; overflow: auto; box-shadow: 0 10px 40px rgba(0,0,0,.3); }
.quiz-head { font-weight: 600; margin-bottom: 10px; }
.quiz-content { white-space: pre-wrap; font-size: 16px; margin-bottom: 10px; }
.quiz-img { display: block; max-width: 100%; max-height: 240px; margin: 0 auto 10px; border-radius: 6px; }
.quiz-options { display: grid; gap: 8px; margin-bottom: 8px; }
.quiz-opt { display: flex; gap: 10px; align-items: center; border: 1px solid var(--line); border-radius: 8px; padding: 10px 12px; cursor: pointer; }
.quiz-opt:hover { border-color: var(--primary); }
.quiz-opt:has(input:checked) { border-color: var(--primary); background: var(--primary-soft); }
.quiz-opt b { min-width: 18px; color: var(--primary); }
.quiz-opt.right { border-color: var(--ok); background: #dcfce7; }
.quiz-opt.wrong { border-color: var(--err); background: #fee2e2; }
.quiz-result { margin-top: 10px; padding: 10px 12px; border-radius: 8px; font-size: 15px; }
.quiz-result.ok { background: #dcfce7; color: #166534; }
.quiz-result.bad { background: #fee2e2; color: #991b1b; }
.quiz-exp { margin-top: 6px; color: var(--text); white-space: pre-wrap; }
.quiz-actions { display: flex; justify-content: flex-end; margin-top: 12px; }
@media (max-width: 600px) {
  .quiz { align-items: flex-start; padding: 6px; }
  .quiz-card { padding: 12px 14px; }
  .quiz-content { font-size: 15px; }
  .quiz-opt { padding: 8px 10px; }
}
/* 手机竖屏时视频区域太小，弹题改为占满整个屏幕 */
@media (max-width: 600px) and (orientation: portrait) {
  .quiz { position: fixed; z-index: 100; }
}

.toast { position: fixed; left: 50%; top: 20px; transform: translateX(-50%); background: #1d2129; color: #fff; padding: 10px 20px; border-radius: 8px; z-index: 1000; font-size: 14px; }