:root{
  --primary:#2563eb;
  --primary-d:#1d4ed8;
  --bg:#f4f6fb;
  --card:#ffffff;
  --text:#1f2937;
  --muted:#6b7280;
  --line:#e5e7eb;
  --green:#16a34a;
  --orange:#f59e0b;
  --radius:12px;
}
*{box-sizing:border-box;}
html,body{margin:0;padding:0;}
body{
  font-family:-apple-system,BlinkMacSystemFont,"PingFang SC","Microsoft YaHei",Segoe UI,Roboto,sans-serif;
  background:var(--bg); color:var(--text); font-size:14px; line-height:1.5;
}
a{color:inherit;text-decoration:none;}
.hidden{display:none !important;}

/* topbar */
#topbar{
  display:flex;align-items:center;gap:24px;
  height:60px;padding:0 24px;background:#fff;border-bottom:1px solid var(--line);
  position:sticky;top:0;z-index:20;
}
#topbar .brand{display:flex;align-items:center;gap:10px;font-weight:700;cursor:pointer;font-size:16px;}
#topbar .logo{
  width:30px;height:30px;border-radius:8px;background:linear-gradient(135deg,#3b82f6,#2563eb);
  color:#fff;display:flex;align-items:center;justify-content:center;font-weight:700;
}
#topbar nav{display:flex;gap:6px;flex:1;}
#topbar nav a{padding:8px 14px;border-radius:8px;color:var(--muted);font-weight:500;}
#topbar nav a.active,#topbar nav a:hover{background:#eff6ff;color:var(--primary);}
#topbar .user{display:flex;align-items:center;gap:12px;color:var(--muted);}

main{padding:24px;max-width:1180px;margin:0 auto;}
.view{padding-bottom:40px;}
.page-head{display:flex;align-items:center;gap:14px;margin-bottom:18px;}
.page-head h2{margin:0;font-size:20px;}
.pill{background:#eff6ff;color:var(--primary);border-radius:999px;padding:4px 12px;font-size:13px;font-weight:600;}

/* buttons */
.btn{
  border:1px solid var(--line);background:#fff;color:var(--text);border-radius:9px;
  padding:8px 16px;font-size:14px;cursor:pointer;transition:.15s;font-weight:500;
}
.btn:hover{border-color:#cbd5e1;background:#f8fafc;}
.btn.primary{background:var(--primary);border-color:var(--primary);color:#fff;}
.btn.primary:hover{background:var(--primary-d);}
.btn.ghost{background:transparent;}
.btn.small{padding:5px 10px;font-size:13px;}
.btn.block{width:100%;display:block;margin-top:16px;padding:11px;font-size:15px;}
.btn:disabled{opacity:.6;cursor:not-allowed;}

/* login */
.login-wrap{display:flex;justify-content:center;padding-top:40px;}
.login-card{width:420px;max-width:100%;background:#fff;border-radius:16px;padding:30px;box-shadow:0 12px 40px rgba(15,23,42,.08);}
.login-card h1{margin:0 0 18px;font-size:22px;}
.tabs{display:flex;gap:8px;border-bottom:1px solid var(--line);margin-bottom:18px;}
.tab{padding:10px 4px;margin-right:18px;cursor:pointer;color:var(--muted);border-bottom:2px solid transparent;font-weight:600;}
.tab.active{color:var(--primary);border-bottom-color:var(--primary);}
.tab-pane label{display:block;margin:12px 0 6px;color:var(--muted);font-size:13px;}
.tab-pane input{
  width:100%;padding:11px 12px;border:1px solid var(--line);border-radius:9px;font-size:14px;outline:none;
}
.tab-pane input:focus{border-color:var(--primary);box-shadow:0 0 0 3px rgba(37,99,235,.12);}
.captcha-row{display:flex;gap:10px;align-items:center;}
.captcha-row input{flex:1;}
.captcha{height:42px;border:1px solid var(--line);border-radius:9px;cursor:pointer;background:#f8fafc;}
.hint{color:var(--muted);font-size:13px;margin-top:12px;}
.wechat-tip{display:flex;gap:12px;margin-top:22px;padding-top:18px;border-top:1px dashed var(--line);color:var(--muted);font-size:12px;align-items:center;}
.wechat-tip img{width:64px;height:64px;border-radius:8px;object-fit:cover;}
.qr-box{text-align:center;padding:10px 0;}
.qr-canvas{display:inline-block;padding:12px;background:#fff;border:1px solid var(--line);border-radius:12px;min-height:180px;min-width:180px;}
.qr-canvas img{display:block;}
.qr-status{color:var(--muted);margin-top:12px;font-size:13px;}

/* course grid */
.course-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(330px,1fr));gap:16px;}
.course-card{background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:18px;display:flex;flex-direction:column;gap:10px;transition:.15s;}
.course-card:hover{box-shadow:0 8px 24px rgba(15,23,42,.07);transform:translateY(-1px);}
.course-card .no{color:var(--primary);font-weight:600;font-size:13px;}
.course-card .name{font-weight:600;font-size:15px;line-height:1.45;}
.course-card .tags{display:flex;flex-wrap:wrap;gap:6px;}
.tag{background:#f1f5f9;color:#475569;border-radius:6px;padding:2px 8px;font-size:12px;}
.course-card .row{display:flex;justify-content:space-between;align-items:center;color:var(--muted);font-size:13px;}
.course-card .actions{display:flex;gap:10px;margin-top:4px;}
.progress{height:7px;background:#eef2f7;border-radius:999px;overflow:hidden;}
.progress > i{display:block;height:100%;background:linear-gradient(90deg,#3b82f6,#22c55e);}
.badge{font-size:12px;padding:2px 8px;border-radius:999px;font-weight:600;}
.badge.done{background:#dcfce7;color:#15803d;}
.badge.ing{background:#dbeafe;color:#1d4ed8;}
.badge.none{background:#f1f5f9;color:#64748b;}

/* chapters */
.meta{color:var(--muted);margin-bottom:18px;font-size:13px;}
.chapters{display:flex;flex-direction:column;gap:12px;}
.chapter{background:#fff;border:1px solid var(--line);border-radius:var(--radius);overflow:hidden;}
.chapter-head{padding:14px 18px;display:flex;justify-content:space-between;align-items:center;cursor:pointer;font-weight:600;}
.chapter-head:hover{background:#f8fafc;}
.sections{border-top:1px solid var(--line);}
.section{padding:12px 18px;display:flex;justify-content:space-between;align-items:center;border-bottom:1px solid #f1f5f9;}
.section:last-child{border-bottom:none;}
.section .sname{color:#334155;}
.videos{display:flex;flex-direction:column;gap:6px;padding:6px 18px 12px 30px;background:#fafbfc;}
.video-item{display:flex;justify-content:space-between;align-items:center;padding:8px 12px;background:#fff;border:1px solid var(--line);border-radius:8px;}
.video-item .vname{font-size:13px;}
.video-item .vmeta{color:var(--muted);font-size:12px;}

/* player */
.player-wrap{background:#0b1220;border-radius:var(--radius);padding:14px;}
#player{width:100%;max-height:70vh;background:#000;border-radius:8px;display:block;}
.player-bar{display:flex;justify-content:space-between;align-items:center;color:#cbd5e1;margin-top:12px;font-size:13px;}
.player-bar .pill{background:rgba(59,130,246,.2);color:#93c5fd;}

/* toast */
.toast{
  position:fixed;left:50%;top:24px;transform:translateX(-50%);
  background:#111827;color:#fff;padding:10px 18px;border-radius:10px;z-index:100;
  box-shadow:0 10px 30px rgba(0,0,0,.2);font-size:14px;
}
.toast.ok{background:#15803d;}
.toast.err{background:#b91c1c;}
.loading{color:var(--muted);padding:30px;text-align:center;}
.account-box{background:#f8fafc;border:1px solid var(--line);border-radius:10px;padding:12px;margin-bottom:14px;font-size:13px;}

/* subtabs */
.subtabs{display:flex;gap:8px;margin-bottom:18px;flex-wrap:wrap;}
.subtab{padding:8px 16px;border:1px solid var(--line);border-radius:999px;cursor:pointer;color:var(--muted);background:#fff;font-weight:500;}
.subtab.active{background:var(--primary);border-color:var(--primary);color:#fff;}
/* player tools */
.player-tools{display:flex;align-items:center;gap:14px;flex-wrap:wrap;color:#cbd5e1;margin-top:12px;font-size:13px;}
.player-tools select{padding:6px 10px;border-radius:8px;border:1px solid #334155;background:#1e293b;color:#e2e8f0;}
.player-tools .btn.primary{background:var(--primary);}
label.inline{display:flex;align-items:center;gap:6px;color:var(--muted);font-size:13px;margin-top:8px;}
/* exam */
.exam-head{display:flex;align-items:center;gap:16px;flex-wrap:wrap;background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:16px 18px;margin-bottom:16px;}
.exam-head-title{line-height:1.5;}
.exam-head .exam-records{color:var(--muted);font-size:13px;align-self:center;}
.exam-paper{background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:20px;}
.exam-paper h3{margin:20px 0 10px;font-size:16px;}
.exam-q{padding:12px 0;border-bottom:1px dashed var(--line);}
.exam-q .q-title{font-weight:500;margin-bottom:8px;}
.exam-q label{display:block;padding:4px 0;color:#334155;cursor:pointer;}
.exam-actions{margin-top:20px;display:flex;align-items:center;gap:14px;}
/* tasks */
.task-list{display:grid;grid-template-columns:repeat(auto-fill,minmax(340px,1fr));gap:16px;}
.task-card{background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:18px;display:flex;flex-direction:column;gap:10px;}
.task-card .row{display:flex;justify-content:space-between;align-items:center;}
.task-card .actions{display:flex;gap:10px;}

/* modal */
.modal{position:fixed;inset:0;background:rgba(15,23,42,.45);display:flex;align-items:center;justify-content:center;z-index:200;}
.modal-box{background:#fff;border-radius:14px;padding:24px;width:340px;max-width:92%;box-shadow:0 20px 50px rgba(0,0,0,.25);}
.modal-box h3{margin:0 0 14px;font-size:18px;}
.modal-box label{display:block;margin:10px 0 6px;color:var(--muted);font-size:13px;}
.modal-box input{width:100%;padding:10px 12px;border:1px solid var(--line);border-radius:9px;outline:none;}
.modal-actions{display:flex;justify-content:flex-end;gap:10px;margin-top:18px;}
/* catalog search */
.catalog-tools{display:flex;gap:10px;align-items:center;margin-bottom:14px;}
.catalog-tools input{flex:1;max-width:420px;padding:9px 12px;border:1px solid var(--line);border-radius:9px;outline:none;}

/* admin login form (inputs are direct children of .login-card) */
.login-card label{display:block;margin:12px 0 6px;color:var(--muted);font-size:13px;}
.login-card input{width:100%;box-sizing:border-box;padding:11px 12px;border:1px solid var(--line);border-radius:9px;font-size:14px;outline:none;background:#fff;}
.login-card input:focus{border-color:var(--primary);box-shadow:0 0 0 3px rgba(37,99,235,.12);}

/* 任务卡标题过长时省略，避免徽标被挤压成竖排 */
.task-card .row{align-items:center;gap:10px;}
.task-card .row b{flex:1;min-width:0;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;}
.task-card .badge{flex-shrink:0;white-space:nowrap;}

/* 邀请码（登录页） */
.invite-box{margin-top:20px;padding-top:16px;border-top:1px dashed var(--line);}
.invite-box label{display:block;margin-bottom:6px;color:var(--muted);font-size:13px;}
.invite-box input{width:100%;box-sizing:border-box;padding:11px 12px;border:1px solid var(--line);border-radius:9px;font-size:14px;outline:none;}
.invite-box input:focus{border-color:var(--primary);box-shadow:0 0 0 3px rgba(37,99,235,.12);}
/* 邀请码（管理后台） */
.invite-gen{display:flex;align-items:center;gap:10px;flex-wrap:wrap;margin-bottom:16px;}
.invite-gen label{color:var(--muted);font-size:13px;}
.invite-gen input{padding:9px 12px;border:1px solid var(--line);border-radius:9px;outline:none;}
.invite-gen input[type=number]{width:80px;}
.invite-list{display:grid;grid-template-columns:repeat(auto-fill,minmax(300px,1fr));gap:14px;}
.invite-card{background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:16px;display:flex;flex-direction:column;gap:8px;}
.invite-card .row{display:flex;justify-content:space-between;align-items:center;gap:10px;}
.invite-card .code{font-family:ui-monospace,Menlo,monospace;font-size:17px;letter-spacing:1px;color:var(--primary);}
.invite-gen input.wide{min-width:300px;flex:1;max-width:460px;}
.invite-card .actions{display:flex;gap:8px;flex-shrink:0;}
.speed-select{padding:7px 10px;border:1px solid var(--line);border-radius:9px;background:#fff;outline:none;font-size:13px;cursor:pointer;}
/* “去学习”按钮：绿色，避免与“选课”（蓝色）混淆 */
.btn.success{background:var(--green);border-color:var(--green);color:#fff;}
.btn.success:hover{background:#15803d;border-color:#15803d;}

/* 小节详情：学习视频 / 学习资源 / 学习活动 */
.section-clickable{cursor:pointer;}
.section-clickable:hover{background:#f8fafc;}
.sec-body{padding:8px 18px 14px 30px;background:#fafbfc;border-bottom:1px solid #f1f5f9;}
.sec-group{margin:8px 0;}
.sec-group-title{font-weight:600;color:#334155;font-size:13px;margin-bottom:6px;}
.sec-item{display:flex;align-items:center;gap:10px;justify-content:space-between;background:#fff;border:1px solid var(--line);border-radius:8px;padding:7px 12px;margin-bottom:6px;}
.sec-item .sec-name{flex:1;min-width:0;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;font-size:13px;}
.sec-meta{color:var(--muted);font-size:12px;white-space:nowrap;}
.sec-empty{color:var(--muted);font-size:13px;padding:2px 0;}
.sec-acts{display:flex;flex-wrap:wrap;gap:8px;}

/* 学习活动 */
.act-list{display:grid;grid-template-columns:repeat(auto-fill,minmax(340px,1fr));gap:14px;}
.act-card{background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:16px;display:flex;flex-direction:column;gap:8px;}
.act-card .act-title{font-weight:600;}
.act-card .act-meta{color:var(--muted);font-size:13px;}
.act-content{background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:16px 18px;margin:12px 0;line-height:1.7;word-break:break-word;}
.act-form{background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:16px 18px;margin-top:12px;}
.act-form label{display:block;margin:10px 0 6px;color:var(--muted);font-size:13px;}
.act-form textarea{width:100%;box-sizing:border-box;min-height:90px;padding:10px 12px;border:1px solid var(--line);border-radius:9px;font-size:14px;outline:none;resize:vertical;font-family:inherit;}
.act-form textarea:focus{border-color:var(--primary);box-shadow:0 0 0 3px rgba(37,99,235,.12);}
.act-opt{display:flex;align-items:center;gap:8px;padding:5px 0;color:#334155;cursor:pointer;}
.act-q{padding:10px 0;border-bottom:1px dashed var(--line);}
.act-actions{margin-top:16px;display:flex;gap:12px;}

/* 置灰的不可进入活动（源站 total=0） */
.tag.muted{background:#f8fafc;color:#cbd5e1;border:1px dashed #e2e8f0;cursor:not-allowed;}

/* 讨论回帖卡片 */
.reply-card{background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:12px 14px;margin:10px 0;}
.reply-card.sub{background:#fbfcfe;border-color:#eef2f7;}
.reply-card-head{display:flex;align-items:center;justify-content:space-between;gap:10px;}
.reply-card-meta{display:flex;gap:10px;align-items:baseline;flex-wrap:wrap;}
.reply-card .reply-author{font-weight:600;color:#334155;font-size:13px;}
.reply-body{margin-top:6px;line-height:1.7;word-break:break-word;}
.reply-body p{margin:4px 0;}
.reply-subs{margin-top:8px;padding-left:12px;border-left:2px solid #eef2f7;}
.reply-form{margin-top:10px;padding-top:8px;border-top:1px dashed var(--line);}
.reply-form label{display:block;margin:0 0 6px;color:var(--muted);font-size:13px;font-weight:600;}
.reply-form textarea{width:100%;box-sizing:border-box;min-height:70px;padding:8px 10px;border:1px solid var(--line);border-radius:9px;font-size:14px;outline:none;resize:vertical;font-family:inherit;}
.reply-form textarea:focus{border-color:var(--primary);box-shadow:0 0 0 3px rgba(37,99,235,.12);}

/* 回帖分页 */
.pager{display:flex;justify-content:center;align-items:center;gap:10px;margin:14px 0 6px;flex-wrap:wrap;}
.pager .pager-select{padding:4px 8px;border:1px solid var(--line);border-radius:8px;background:#fff;font-size:13px;color:#334155;outline:none;cursor:pointer;}
.pager .pager-total{color:var(--muted);font-size:13px;}

/* 讨论要求与完成情况 */
.discuss-req{background:#f8fafc;border:1px solid var(--line);border-radius:var(--radius);padding:12px 16px;margin:10px 0;font-size:14px;line-height:1.7;display:flex;flex-wrap:wrap;gap:4px 8px;align-items:baseline;}
.discuss-req .req-title{font-weight:600;color:#334155;}
.discuss-req .req-done{font-weight:600;}

/* 倍速选择框前的说明文字 */
.speed-label{color:var(--muted);font-size:13px;margin-right:-6px;white-space:nowrap;}