/* 学生学习工作台（2026-11）：与教师端同一视觉体系，配色更明快 */
.sd-shell {
  --sd-blue: #1f63e8; --sd-blue-d: #0f3fa8; --sd-blue-l: #eaf1ff; --sd-teal: #0e9c8c; --sd-teal-l: #e4f7f4;
  --sd-violet: #6a4fe0; --sd-violet-l: #efebff; --sd-amber: #d97a06; --sd-amber-l: #fff3df; --sd-green: #12a58f;
  --sd-ink: #0e1b33; --sd-ink-2: #34425e; --sd-muted: #6b7895; --sd-faint: #98a3ba; --sd-line: #e3e9f3;
  --sd-shadow: 0 1px 2px rgba(16, 35, 72, .04), 0 8px 24px rgba(16, 35, 72, .06);
  --sd-num: "DIN Alternate", Inter, "HarmonyOS Sans SC", sans-serif;
  min-height: 100vh; color: var(--sd-ink); font-family: "HarmonyOS Sans SC", "MiSans", "PingFang SC", "Noto Sans SC", "Microsoft YaHei", sans-serif;
}
body.student-mode { background: #f2f5fa !important; }
.sd-shell a { color: inherit; text-decoration: none; }
.sd-shell svg { display: block; }

/* 主视觉 */
.sd-hero { position: relative; overflow: hidden; color: #fff;
  background: radial-gradient(900px 340px at 88% -10%, rgba(96, 165, 255, .5), transparent 60%), radial-gradient(700px 300px at 8% 120%, rgba(56, 214, 196, .28), transparent 60%), linear-gradient(120deg, #0b318a 0%, #1452c8 46%, #2f7bff 100%); }
.sd-hero::before { content: ""; position: absolute; inset: 0; opacity: .5; pointer-events: none; background-image: radial-gradient(rgba(255, 255, 255, .22) 1px, transparent 1.2px); background-size: 22px 22px;
  mask-image: linear-gradient(100deg, transparent 30%, #000 75%); -webkit-mask-image: linear-gradient(100deg, transparent 30%, #000 75%); }
.sd-hero::after { content: ""; position: absolute; right: -120px; top: -160px; width: 520px; height: 520px; border-radius: 50%; pointer-events: none; border: 1px solid rgba(255, 255, 255, .14); box-shadow: 0 0 0 70px rgba(255, 255, 255, .03), 0 0 0 140px rgba(255, 255, 255, .025); }
.sd-hero-inner { position: relative; z-index: 1; width: min(1360px, calc(100% - 48px)); margin: 0 auto; padding: 36px 0 92px; display: flex; align-items: flex-end; justify-content: space-between; gap: 28px; }
.sd-date { font-size: 13px; color: rgba(255, 255, 255, .74); }
.sd-hero h1 { margin: 8px 0 0; font-size: clamp(28px, 2.6vw, 38px); font-weight: 800; line-height: 1.2; }
.sd-meta { margin-top: 12px; display: flex; flex-wrap: wrap; gap: 8px; }
.sd-meta span { padding: 4px 11px; border-radius: 999px; font-size: 12.5px; color: rgba(255, 255, 255, .92); background: rgba(255, 255, 255, .12); border: 1px solid rgba(255, 255, 255, .16); }
.sd-insight { margin-top: 16px; max-width: 640px; display: flex; align-items: center; gap: 10px; font-size: 14px; line-height: 1.6; color: rgba(255, 255, 255, .9); }
.sd-pulse { flex: none; width: 8px; height: 8px; border-radius: 50%; background: #5eead4; box-shadow: 0 0 0 4px rgba(94, 234, 212, .2); }
.sd-hero-actions { display: flex; flex-wrap: wrap; gap: 12px; }
.sd-hero-btn { min-height: 44px; padding: 0 18px; display: inline-flex; align-items: center; gap: 9px; border-radius: 12px; font-size: 14px; font-weight: 650; color: #fff !important; white-space: nowrap; background: rgba(255, 255, 255, .1); border: 1px solid rgba(255, 255, 255, .26); transition: background .18s, transform .18s; }
.sd-hero-btn span { width: 18px; height: 18px; display: inline-flex; }
.sd-hero-btn span svg { width: 100%; height: 100%; }
.sd-hero-btn:hover { background: rgba(255, 255, 255, .18); transform: translateY(-1px); }
.sd-hero-btn.primary { color: var(--sd-blue-d) !important; background: #fff; border-color: #fff; box-shadow: 0 10px 26px rgba(4, 22, 70, .28); }

.sd-main { position: relative; z-index: 2; width: min(1360px, calc(100% - 48px)); margin: -60px auto 0; padding-bottom: 56px; }

/* 指标 */
.sd-kpis { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 16px; }
.sd-kpi { min-height: 112px; padding: 20px; display: flex; align-items: flex-start; gap: 14px; border-radius: 16px; background: #fff; border: 1px solid var(--sd-line); box-shadow: var(--sd-shadow); transition: transform .18s, box-shadow .18s; }
a.sd-kpi:hover { transform: translateY(-2px); box-shadow: 0 14px 30px rgba(16, 35, 72, .1); }
.sd-kpi > div { min-width: 0; }
.sd-kpi-ico { flex: none; width: 42px; height: 42px; border-radius: 12px; display: grid; place-items: center; }
.sd-kpi-ico svg { width: 21px; height: 21px; }
.sd-kpi.blue .sd-kpi-ico { color: var(--sd-blue); background: var(--sd-blue-l); }
.sd-kpi.teal .sd-kpi-ico { color: var(--sd-teal); background: var(--sd-teal-l); }
.sd-kpi.violet .sd-kpi-ico { color: var(--sd-violet); background: var(--sd-violet-l); }
.sd-kpi.amber .sd-kpi-ico { color: var(--sd-amber); background: var(--sd-amber-l); }
.sd-kpi span { display: block; font-size: 13px; color: var(--sd-muted); }
.sd-kpi b { display: flex; align-items: baseline; gap: 4px; margin-top: 6px; font: 700 30px/1 var(--sd-num); }
.sd-kpi b em { font: 400 13px var(--sd-num); font-style: normal; color: var(--sd-muted); }
.sd-kpi small { display: block; margin-top: 8px; font-size: 12px; color: var(--sd-faint); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }

/* 布局与卡片 */
.sd-grid { margin-top: 20px; display: grid; grid-template-columns: minmax(0, 1fr) 380px; gap: 20px; align-items: start; }
.sd-col { display: grid; gap: 20px; min-width: 0; }
.sd-card { background: #fff; border: 1px solid var(--sd-line); border-radius: 16px; box-shadow: var(--sd-shadow); overflow: hidden; }
.sd-card-head { min-height: 58px; padding: 0 22px; display: flex; align-items: center; justify-content: space-between; gap: 12px; border-bottom: 1px solid var(--sd-line); }
.sd-card-head h2 { display: flex; align-items: center; gap: 8px; margin: 0; font-size: 16px; font-weight: 750; }
.sd-card-head h2::before { content: ""; width: 4px; height: 16px; border-radius: 4px; background: var(--sd-blue); }
.sd-card-head h2 small { padding: 1px 8px; border-radius: 999px; font: 650 12px/18px var(--sd-num); color: var(--sd-blue); background: var(--sd-blue-l); }
.sd-card-head a { font-size: 13px; color: var(--sd-muted); }
.sd-card-head a:hover { color: var(--sd-blue); }
.sd-card-pad { padding: 18px 22px 20px; }

/* 封面 */
.sd-cover { position: absolute; inset: 0; background-size: cover !important; background-position: center !important; }
.sd-cover.gen { display: flex; flex-direction: column; justify-content: flex-end; padding: 14px 16px; color: #fff; overflow: hidden;
  background: radial-gradient(160px 120px at 92% 8%, rgba(255, 255, 255, .28), transparent 70%), linear-gradient(135deg, var(--c1), var(--c2)) !important; }
.sd-cover.gen::before { content: ""; position: absolute; right: -30px; bottom: -40px; width: 150px; height: 150px; border-radius: 34px; transform: rotate(24deg); border: 1px solid rgba(255, 255, 255, .25); background: rgba(255, 255, 255, .06); }
.sd-cover.gen i { position: absolute; right: 14px; top: 14px; width: 36px; height: 36px; border-radius: 11px; display: grid; place-items: center; background: rgba(255, 255, 255, .18); border: 1px solid rgba(255, 255, 255, .28); }
.sd-cover.gen i svg { width: 19px; height: 19px; }
.sd-cover.gen b { position: relative; font-size: 16px; font-weight: 750; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.sd-cover.gen small { position: relative; margin-top: 3px; font-size: 12px; opacity: .84; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; min-height: 15px; }

/* 继续学习 */
.sd-continue { padding: 22px; display: grid; grid-template-columns: minmax(260px, 42%) minmax(0, 1fr); gap: 24px; align-items: center; }
.sd-continue-media { position: relative; display: block; aspect-ratio: 16 / 9; border-radius: 14px; overflow: hidden; box-shadow: 0 12px 28px rgba(16, 35, 72, .14); }
.sd-play { position: absolute; left: 50%; top: 50%; width: 56px; height: 56px; margin: -28px 0 0 -28px; border-radius: 50%; display: grid; place-items: center; color: var(--sd-blue); background: rgba(255, 255, 255, .94); box-shadow: 0 10px 24px rgba(4, 22, 70, .25); transition: transform .18s; }
.sd-play svg { width: 24px; height: 24px; }
.sd-continue-media:hover .sd-play { transform: scale(1.08); }
.sd-label { font-size: 12.5px; font-weight: 650; color: var(--sd-blue); }
.sd-continue-body h3 { margin: 6px 0 0; font-size: 20px; font-weight: 800; line-height: 1.4; }
.sd-continue-body h3 a:hover { color: var(--sd-blue); }
.sd-chapter { margin-top: 6px; font-size: 13.5px; color: var(--sd-muted); }
.sd-progress { margin-top: 18px; }
.sd-progress-top { display: flex; justify-content: space-between; align-items: baseline; font-size: 13px; color: var(--sd-ink-2); }
.sd-progress-top b { font: 700 20px var(--sd-num); color: var(--sd-blue); }
.sd-bar { display: block; height: 8px; margin-top: 8px; border-radius: 8px; background: #edf1f8; overflow: hidden; }
.sd-bar i { display: block; width: 0; height: 100%; border-radius: inherit; background: linear-gradient(90deg, #3f86ff, var(--sd-blue)); transition: width .8s cubic-bezier(.2, .8, .2, 1); }
.sd-bar.sm { height: 5px; margin-top: 10px; }
.sd-progress small { display: block; margin-top: 8px; font-size: 12px; color: var(--sd-faint); }
.sd-continue-actions { margin-top: 20px; display: flex; gap: 10px; flex-wrap: wrap; }
.sd-btn { height: 40px; padding: 0 18px; display: inline-flex; align-items: center; justify-content: center; border-radius: 10px; border: 1px solid #cfd8e8; font-size: 14px; font-weight: 650; color: var(--sd-ink-2) !important; background: #fff; transition: all .15s; }
.sd-btn:hover { border-color: var(--sd-blue); color: var(--sd-blue) !important; }
.sd-btn.primary { color: #fff !important; border-color: var(--sd-blue); background: var(--sd-blue); box-shadow: 0 8px 20px rgba(31, 99, 232, .22); }
.sd-btn.primary:hover { background: var(--sd-blue-d); }
.sd-btn.ghost { border-color: transparent; color: var(--sd-muted) !important; }

/* 我的课程 */
.sd-courses { padding: 20px 22px 22px; display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 16px; }
.sd-course { display: flex; flex-direction: column; min-width: 0; border: 1px solid var(--sd-line); border-radius: 14px; overflow: hidden; background: #fff; transition: transform .18s, box-shadow .18s, border-color .18s; }
.sd-course:hover { transform: translateY(-3px); border-color: #cddaf4; box-shadow: 0 16px 32px rgba(16, 35, 72, .1); }
.sd-course-media { position: relative; display: block; aspect-ratio: 16 / 9; }
.sd-badge { position: absolute; left: 10px; top: 10px; padding: 3px 9px; border-radius: 7px; font-size: 11.5px; font-weight: 650; line-height: 18px; color: #fff; background: rgba(31, 99, 232, .9); }
.sd-badge.done { background: rgba(18, 165, 143, .92); }
.sd-course-body { display: flex; flex-direction: column; padding: 12px 14px 14px; }
.sd-course-body b { font-size: 14.5px; line-height: 1.45; min-height: 42px; display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; }
.sd-course-body small { margin-top: 4px; font-size: 12px; color: var(--sd-faint); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.sd-course-foot { margin-top: 8px; display: flex; justify-content: space-between; font-size: 12.5px; color: var(--sd-blue); }
.sd-course-foot em { font: 700 14px var(--sd-num); font-style: normal; color: var(--sd-ink); }
.sd-course-new { align-items: center; justify-content: center; text-align: center; gap: 6px; padding: 20px; border: 1.5px dashed #c5d3ee; background: linear-gradient(180deg, #f8faff, #f2f6ff); color: var(--sd-blue); }
.sd-course-new:hover { border-color: var(--sd-blue); background: #eef4ff; }
.sd-plus { width: 46px; height: 46px; border-radius: 14px; display: grid; place-items: center; font-size: 26px; font-weight: 300; color: #fff; background: var(--sd-blue); box-shadow: 0 10px 22px rgba(31, 99, 232, .28); }
.sd-course-new b { margin-top: 6px; font-size: 14.5px; }
.sd-course-new small { font-size: 12px; color: var(--sd-muted); }

/* 今日任务 */
.sd-tasks { padding: 12px; display: grid; gap: 8px; }
.sd-task { width: 100%; display: grid; grid-template-columns: 28px minmax(0, 1fr) auto; gap: 12px; align-items: center; padding: 12px; border: 1px solid var(--sd-line); border-radius: 12px; background: #fff; font: inherit; text-align: left; cursor: pointer; transition: all .15s; }
.sd-task:hover { border-color: #c6d4ef; background: #fafcff; }
.sd-check { width: 26px; height: 26px; border-radius: 50%; display: grid; place-items: center; color: transparent; border: 2px solid #cfd8e8; }
.sd-check svg { width: 14px; height: 14px; }
.sd-task.done .sd-check { color: #fff; border-color: var(--sd-green); background: var(--sd-green); }
.sd-task.done .sd-task-text b { color: var(--sd-faint); text-decoration: line-through; }
.sd-task-text b { display: block; font-size: 14px; color: var(--sd-ink); }
.sd-task-text small { display: block; margin-top: 2px; font-size: 12px; color: var(--sd-faint); }
.sd-task em { font-size: 12px; font-style: normal; color: var(--sd-amber); }
.sd-task.done em { color: var(--sd-green); }
.sd-task.skipped em { color: var(--sd-faint); }

/* 学习趋势 */
.sd-trend-sum { display: flex; align-items: baseline; gap: 8px; }
.sd-trend-sum b { font: 700 28px/1 var(--sd-num); }
.sd-trend-sum span { font-size: 13px; color: var(--sd-muted); }
.sd-trend { margin-top: 16px; height: 150px; display: grid; grid-template-columns: repeat(7, 1fr); gap: 8px; align-items: end; }
.sd-day { height: 100%; display: flex; flex-direction: column; align-items: center; gap: 6px; }
.sd-colbar { flex: 1; width: 100%; max-width: 30px; display: flex; align-items: flex-end; border-radius: 8px; background: #f1f4f9; overflow: hidden; }
.sd-colbar i { display: block; width: 100%; height: 0; border-radius: 8px; background: linear-gradient(180deg, #7aa8ff, var(--sd-blue)); transition: height .8s cubic-bezier(.2, .8, .2, 1); }
.sd-day.today .sd-colbar i { background: linear-gradient(180deg, #34cbb8, var(--sd-teal)); }
.sd-day b { min-height: 14px; font: 600 11px var(--sd-num); color: var(--sd-ink-2); }
.sd-day small { font-size: 11.5px; color: var(--sd-faint); }
.sd-day.today small { color: var(--sd-teal); font-weight: 700; }

/* 空状态 */
.sd-empty { padding: 36px 22px; display: flex; flex-direction: column; align-items: center; gap: 8px; text-align: center; color: var(--sd-muted); font-size: 13px; }
.sd-empty.sm { padding: 26px 18px; }
.sd-empty b { font-size: 15px; color: var(--sd-ink); }
.sd-empty .sd-btn { margin-top: 6px; }
.sd-empty-ico { width: 52px; height: 52px; border-radius: 16px; display: grid; place-items: center; color: var(--sd-blue); background: var(--sd-blue-l); margin-bottom: 4px; }
.sd-empty-ico svg { width: 24px; height: 24px; }

/* 学习工具 */
.sd-tools-wrap { margin-top: 28px; }
.sd-section-head { display: flex; align-items: baseline; gap: 12px; margin-bottom: 14px; }
.sd-section-head h2 { margin: 0; font-size: 18px; font-weight: 750; }
.sd-section-head span { font-size: 13px; color: var(--sd-faint); }
.sd-tools { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 16px; }
.sd-tool { display: grid; grid-template-columns: 46px minmax(0, 1fr); grid-template-rows: auto auto; column-gap: 14px; align-items: center; padding: 18px; border-radius: 16px; background: #fff; border: 1px solid var(--sd-line); box-shadow: var(--sd-shadow); transition: transform .18s, box-shadow .18s; }
.sd-tool:hover { transform: translateY(-2px); box-shadow: 0 14px 30px rgba(16, 35, 72, .1); }
.sd-tool-ico { grid-row: 1 / 3; width: 46px; height: 46px; border-radius: 13px; display: grid; place-items: center; color: #fff; }
.sd-tool-ico svg { width: 22px; height: 22px; }
.sd-tool-ico.blue { background: linear-gradient(135deg, #3f86ff, #1f63e8); }
.sd-tool-ico.teal { background: linear-gradient(135deg, #2cc5b2, #0e9c8c); }
.sd-tool-ico.violet { background: linear-gradient(135deg, #8b74ff, #6a4fe0); }
.sd-tool-ico.amber { background: linear-gradient(135deg, #f8b13c, #d97a06); }
.sd-tool b { font-size: 14.5px; }
.sd-tool small { font-size: 12px; color: var(--sd-faint); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }

@media (max-width: 1280px) { .sd-courses { grid-template-columns: repeat(2, minmax(0, 1fr)); } .sd-grid { grid-template-columns: minmax(0, 1fr) 330px; } }
@media (max-width: 1024px) {
  .sd-grid { grid-template-columns: 1fr; }
  .sd-kpis { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .sd-tools { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .sd-hero-inner { flex-direction: column; align-items: flex-start; }
}
@media (max-width: 680px) {
  .sd-hero-inner, .sd-main { width: calc(100% - 32px); }
  .sd-hero-inner { padding: 26px 0 84px; }
  .sd-hero-actions { width: 100%; }
  .sd-hero-btn { flex: 1 1 auto; justify-content: center; }
  .sd-kpis { gap: 12px; }
  .sd-kpi { min-height: 0; padding: 14px; flex-direction: column; gap: 10px; }
  .sd-kpi b { font-size: 24px; }
  .sd-continue { grid-template-columns: 1fr; padding: 16px; gap: 16px; }
  .sd-continue-actions .sd-btn { flex: 1; }
  .sd-courses { grid-template-columns: 1fr; padding: 16px; }
  .sd-card-head { padding: 0 16px; }
  .sd-tools { grid-template-columns: 1fr; }
}
@media (prefers-reduced-motion: reduce) { .sd-shell * { transition: none !important; } }