:root{
  --coffee:#6f4e37;
  --coffee-dark:#4a3325;
  --coffee-light:#a9826b;
  --cream:#f7f1e8;
  --green:#3b6d11;
  --gray:#888780;
  --line:#e3dcd0;
  --bg:#faf6f0;
}
*{box-sizing:border-box;-webkit-tap-highlight-color:transparent;}
html,body{margin:0;padding:0;background:var(--bg);color:var(--coffee-dark);font-family:-apple-system,BlinkMacSystemFont,"PingFang SC","Microsoft YaHei",sans-serif;font-size:15px;line-height:1.6;}
#app{max-width:560px;margin:0 auto;min-height:100vh;background:var(--bg);}
.topbar{position:sticky;top:0;background:var(--coffee);color:#fff;padding:14px 16px;display:flex;align-items:center;justify-content:space-between;z-index:10;}
.topbar h1{font-size:16px;margin:0;font-weight:600;letter-spacing:1px;}
.topbar .who{font-size:12px;opacity:.85;}
.topbar button{background:rgba(255,255,255,.18);border:none;color:#fff;padding:6px 10px;border-radius:8px;font-size:12px;}
.page{padding:16px;}
.section-title{font-size:13px;color:var(--gray);margin:4px 2px 12px;}
.card{background:#fff;border:1px solid var(--line);border-radius:14px;padding:16px;margin-bottom:14px;box-shadow:0 1px 2px rgba(0,0,0,.03);}
.course-title{font-size:16px;font-weight:600;color:var(--coffee-dark);}
.course-desc{font-size:13px;color:var(--gray);margin:6px 0 12px;}
.bar{height:8px;background:var(--cream);border-radius:6px;overflow:hidden;}
.bar>i{display:block;height:100%;background:linear-gradient(90deg,var(--coffee-light),var(--coffee));}
.bar.done>i{background:var(--green);}
.bar-label{font-size:12px;color:var(--gray);margin-top:6px;display:flex;justify-content:space-between;}
.btn{display:inline-block;background:var(--coffee);color:#fff;border:none;padding:10px 18px;border-radius:10px;font-size:14px;font-weight:500;cursor:pointer;text-align:center;}
.btn.ghost{background:#fff;color:var(--coffee);border:1px solid var(--coffee);}
.btn.full{width:100%;}
.btn:disabled{opacity:.5;}
.login{max-width:560px;margin:0 auto;padding:48px 24px;}
.login h2{text-align:center;color:var(--coffee);font-weight:600;letter-spacing:2px;}
.login .sub{text-align:center;color:var(--gray);font-size:13px;margin-bottom:28px;}
.field{margin-bottom:16px;}
.field label{display:block;font-size:13px;color:var(--coffee-dark);margin-bottom:6px;}
.field input{width:100%;padding:12px 14px;border:1px solid var(--line);border-radius:10px;font-size:15px;background:#fff;}
.field input:focus{outline:none;border-color:var(--coffee-light);}
.err{color:#a32d2d;font-size:13px;text-align:center;min-height:20px;margin-top:8px;}
.lesson{border:1px solid var(--line);border-radius:12px;padding:12px 14px;margin-bottom:10px;display:flex;align-items:center;justify-content:space-between;background:#fff;}
.lesson .lt{font-size:14px;}
.lesson .lt small{display:block;color:var(--gray);font-size:12px;}
.lesson .st{font-size:12px;padding:4px 10px;border-radius:20px;}
.st.todo{background:var(--cream);color:var(--coffee);}
.st.done{background:#eaf3de;color:var(--green);}
video{width:100%;border-radius:12px;background:#000;margin-bottom:14px;}
.back{background:none;border:none;color:#fff;font-size:14px;cursor:pointer;padding:0;margin-right:8px;}
.learn-head{display:flex;align-items:center;padding:14px 16px;background:var(--coffee);color:#fff;position:sticky;top:0;z-index:10;}
.learn-head .t{font-size:15px;font-weight:600;}
.empty{text-align:center;color:var(--gray);padding:40px 0;font-size:14px;}
.tag{display:inline-block;background:var(--cream);color:var(--coffee);font-size:11px;padding:2px 8px;border-radius:6px;margin-left:8px;}
.admin-row{display:flex;align-items:center;justify-content:space-between;gap:10px;}
.admin-row .course-title small{color:var(--gray);font-size:11px;font-weight:400;margin-left:6px;}
.row-btns{display:flex;gap:6px;flex-shrink:0;}
.btn.sm{padding:6px 12px;font-size:12px;border-radius:8px;}
.btn.sm.danger{background:#a94442;color:#fff;}
.btn.danger{background:#a94442;color:#fff;}
.field.row{display:flex;align-items:center;gap:10px;}
.field.row label{min-width:48px;margin-bottom:0;}
.section-title.sm{margin-top:0;margin-bottom:10px;font-weight:600;color:var(--coffee-dark);}