:root{
    --ink:#16213B;
    --ink-soft:#4A5578;
    --paper:#EFF2F6;
    --paper-2:#FFFFFF;
    --line:#D7DCE6;
    --accent:#E3A93C;      /* highlighter amber */
    --accent-ink:#5B3F0A;
    --teal:#2E6F63;        /* secondary */
    --teal-soft:#E4EFEC;
    --coral:#D9552C;       /* countdown / alerts */
    --coral-soft:#FBE7DE;
    --school:#5B7FBF;
    --school-soft:#E7EDF9;
    --uni:#8B5FA6;
    --uni-soft:#F1E9F5;
    --radius:10px;
    --shadow:0 1px 2px rgba(22,33,59,.06), 0 6px 18px rgba(22,33,59,.05);
  }
  *{box-sizing:border-box;}
  html,body{height:100%;}
  body{
    margin:0;
    background:var(--paper);
    color:var(--ink);
    font-family:'Public Sans', system-ui, sans-serif;
    -webkit-font-smoothing:antialiased;
  }
  h1,h2,h3,.serif{ font-family:'Fraunces', serif; }
  h1,h2,h3{ margin:0; font-weight:600; letter-spacing:-0.01em; }
  a{ color:inherit; }
  button{ font-family:inherit; cursor:pointer; }
  ::selection{ background:var(--accent); color:var(--ink); }

  /* ---------- layout ---------- */
  #app{ display:none; min-height:100vh; }
  .shell{ display:flex; min-height:100vh; }

  .rail{
    width:230px; flex:none; background:var(--ink); color:#EDEEF3;
    display:flex; flex-direction:column; padding:22px 14px;
    position:sticky; top:0; height:100vh;
  }
  .brand{ display:flex; align-items:center; gap:10px; padding:0 8px 22px 8px; }
  .brand-mark{
    width:34px; height:34px; border-radius:8px; background:var(--accent);
    display:flex; align-items:center; justify-content:center;
    font-family:'Fraunces',serif; font-weight:700; color:var(--ink); font-size:18px;
    transform: rotate(-4deg);
  }
  .brand-name{ font-family:'Fraunces',serif; font-size:19px; font-weight:600; }
  .nav-item{
    display:flex; align-items:center; gap:10px; padding:10px 12px; border-radius:8px;
    color:#C7CBDA; font-size:14.5px; font-weight:500; margin-bottom:2px; border:none; background:none;
    width:100%; text-align:left;
  }
  .nav-item svg{ flex:none; opacity:.85; }
  .nav-item:hover{ background:rgba(255,255,255,.06); color:#fff; }
  .nav-item.active{ background:rgba(227,169,60,.16); color:#F3D089; }
  .rail-spacer{ flex:1; }
  .rail-user{
    display:flex; align-items:center; gap:9px; padding:10px 8px; border-top:1px solid rgba(255,255,255,.1); margin-top:8px;
  }
  .avatar{
    width:34px; height:34px; border-radius:50%; flex:none; display:flex; align-items:center; justify-content:center;
    font-weight:700; font-size:13px; color:#fff; font-family:'Fraunces',serif;
  }
  .rail-user .who{ font-size:13px; line-height:1.25; }
  .rail-user .who b{ display:block; font-weight:600; color:#fff; }
  .rail-user .who span{ color:#9CA3BE; font-size:11.5px; }

  .main{ flex:1; min-width:0; padding:30px 38px 60px; max-width:1180px; }
  .topline{ display:flex; align-items:baseline; justify-content:space-between; margin-bottom:22px; gap:16px; flex-wrap:wrap;}
  .topline h1{ font-size:26px; }
  .topline p{ margin:4px 0 0; color:var(--ink-soft); font-size:14px; }

  .pill{
    display:inline-flex; align-items:center; gap:6px; padding:3px 10px; border-radius:99px;
    font-size:11.5px; font-weight:600; letter-spacing:.02em;
  }
  .pill.school{ background:var(--school-soft); color:var(--school); }
  .pill.uni{ background:var(--uni-soft); color:var(--uni); }
  .pill.both{ background:#F3ECDD; color:var(--accent-ink); }

  .card{
    background:var(--paper-2); border:1px solid var(--line); border-radius:var(--radius);
    box-shadow:var(--shadow);
  }
  .btn{
    display:inline-flex; align-items:center; justify-content:center; gap:6px;
    padding:9px 16px; border-radius:8px; border:1px solid var(--line); background:var(--paper-2);
    font-size:13.5px; font-weight:600; color:var(--ink);
  }
  .btn:hover{ border-color:#B9C0D1; }
  .btn.primary{ background:var(--ink); color:#fff; border-color:var(--ink); }
  .btn.primary:hover{ background:#232F52; }
  .btn.accent{ background:var(--accent); color:var(--accent-ink); border-color:var(--accent); }
  .btn.accent:hover{ filter:brightness(1.04); }
  .btn.ghost{ background:transparent; border-color:transparent; padding:9px 10px; }
  .btn.small{ padding:6px 11px; font-size:12.5px; }
  .btn:disabled{ opacity:.5; cursor:not-allowed; }

  input,textarea,select{
    font-family:inherit; font-size:14px; padding:9px 11px; border-radius:8px; border:1px solid var(--line);
    background:#fff; color:var(--ink); width:100%;
  }
  input:focus,textarea:focus,select:focus{ outline:2px solid var(--accent); outline-offset:1px; border-color:var(--accent); }
  label{ font-size:12.5px; font-weight:600; color:var(--ink-soft); display:block; margin-bottom:5px; }
  .field{ margin-bottom:14px; }
  .row2{ display:grid; grid-template-columns:1fr 1fr; gap:12px; }

  .tag{
    display:inline-flex; align-items:center; padding:4px 10px; border-radius:99px; font-size:12px;
    font-weight:600; background:var(--teal-soft); color:var(--teal); margin:0 6px 6px 0; border:none;
  }
  .tag.selectable{ cursor:pointer; background:var(--paper); color:var(--ink-soft); border:1px solid var(--line); }
  .tag.selectable.on{ background:var(--teal-soft); color:var(--teal); border-color:var(--teal); }

  .empty{
    text-align:center; padding:50px 20px; color:var(--ink-soft); border:1.5px dashed var(--line); border-radius:var(--radius);
  }
  .empty .serif{ font-size:18px; color:var(--ink); margin-bottom:6px; }

  /* onboarding */
  .onb-wrap{
    min-height:100vh; display:flex; align-items:center; justify-content:center; padding:30px;
    background:
      radial-gradient(700px 400px at 15% -10%, #FFF6E2 0%, transparent 60%),
      radial-gradient(700px 500px at 110% 10%, var(--teal-soft) 0%, transparent 60%),
      var(--paper);
  }
  .onb-card{ width:100%; max-width:560px; background:var(--paper-2); border:1px solid var(--line); border-radius:16px; box-shadow:var(--shadow); padding:36px 40px; }
  .onb-head{ margin-bottom:22px; }
  .onb-head .brand-mark{ margin-bottom:14px; }
  .onb-head h1{ font-size:26px; margin-bottom:6px; }
  .onb-head p{ color:var(--ink-soft); font-size:14px; margin:0; }
  .choice-grid{ display:grid; grid-template-columns:1fr 1fr; gap:10px; }
  .choice{
    border:1.5px solid var(--line); border-radius:10px; padding:14px; text-align:left; background:#fff;
  }
  .choice b{ display:block; font-size:14.5px; margin-bottom:2px; }
  .choice span{ font-size:12px; color:var(--ink-soft); }
  .choice.on{ border-color:var(--ink); background:#FBFAF7; }
  .steps-dots{ display:flex; gap:6px; margin-bottom:18px; }
  .steps-dots i{ width:22px; height:4px; border-radius:2px; background:var(--line); display:block; }
  .steps-dots i.on{ background:var(--accent); }

  /* feed */
  .post{ padding:18px 20px; margin-bottom:14px; }
  .post-head{ display:flex; align-items:center; gap:10px; margin-bottom:10px; }
  .post-head .who b{ font-size:13.5px; }
  .post-head .who div{ font-size:11.5px; color:var(--ink-soft); }
  .post h3{ font-size:16.5px; margin:2px 0 6px; }
  .post p.body{ font-size:13.8px; color:#333A56; line-height:1.55; margin:0 0 10px; }
  .post-media img, .post-media video{ max-width:100%; border-radius:8px; border:1px solid var(--line); margin-bottom:10px; display:block; }
  .post-foot{ display:flex; align-items:center; gap:14px; font-size:12.5px; color:var(--ink-soft); border-top:1px solid var(--line); padding-top:10px; margin-top:4px; }
  .post-foot button{ background:none; border:none; color:var(--ink-soft); font-size:12.5px; font-weight:600; display:flex; align-items:center; gap:5px; }
  .post-foot button:hover{ color:var(--teal); }
  .solved-badge{ background:var(--teal-soft); color:var(--teal); font-weight:700; padding:2px 9px; border-radius:99px; font-size:11px; }

  .filters{ display:flex; gap:8px; flex-wrap:wrap; margin-bottom:18px; align-items:center; }
  .seg{ display:flex; background:var(--paper); border:1px solid var(--line); border-radius:8px; padding:3px; }
  .seg button{ border:none; background:none; padding:6px 12px; border-radius:6px; font-size:12.5px; font-weight:600; color:var(--ink-soft); }
  .seg button.on{ background:#fff; color:var(--ink); box-shadow:0 1px 2px rgba(0,0,0,.08); }

  /* two column */
  .two-col{ display:grid; grid-template-columns:1fr 300px; gap:24px; align-items:start; }
  @media(max-width:900px){ .two-col{ grid-template-columns:1fr; } }
  .side-card{ padding:16px 18px; margin-bottom:16px; }
  .side-card h3{ font-size:13.5px; text-transform:none; color:var(--ink-soft); margin-bottom:10px; letter-spacing:.01em; }

  /* directory / search */
  .person{ display:flex; gap:12px; padding:16px 18px; align-items:flex-start; margin-bottom:12px; }
  .person .info{ flex:1; }
  .person .info b{ font-size:14.5px; }
  .person .info .role{ font-size:12px; color:var(--ink-soft); margin:1px 0 8px; }

  /* chat */
  .chat-wrap{ display:grid; grid-template-columns:260px 1fr; gap:0; height:calc(100vh - 130px); border:1px solid var(--line); border-radius:var(--radius); overflow:hidden; background:#fff; }
  .chat-list{ border-right:1px solid var(--line); overflow-y:auto; background:var(--paper); }
  .chat-list-item{ display:flex; gap:10px; padding:12px 14px; border-bottom:1px solid var(--line); align-items:center; }
  .chat-list-item:hover{ background:#fff; }
  .chat-list-item.active{ background:#fff; box-shadow:inset 3px 0 0 var(--accent); }
  .chat-list-item .txt b{ display:block; font-size:13px; }
  .chat-list-item .txt span{ font-size:11.5px; color:var(--ink-soft); }
  .chat-main{ display:flex; flex-direction:column; }
  .chat-head{ padding:13px 18px; border-bottom:1px solid var(--line); display:flex; align-items:center; gap:10px; }
  .chat-body{ flex:1; overflow-y:auto; padding:18px; display:flex; flex-direction:column; gap:10px; }
  .msg{ max-width:70%; padding:9px 13px; border-radius:12px; font-size:13.5px; line-height:1.45; }
  .msg.me{ align-self:flex-end; background:var(--ink); color:#fff; border-bottom-right-radius:3px; }
  .msg.them{ align-self:flex-start; background:var(--paper); border:1px solid var(--line); border-bottom-left-radius:3px; }
  .msg img{ max-width:220px; border-radius:8px; display:block; margin-top:5px; }
  .chat-input{ display:flex; gap:8px; padding:12px 14px; border-top:1px solid var(--line); }
  .chat-input input{ flex:1; }

  /* focus timer */
  .timer-wrap{ display:flex; flex-direction:column; align-items:center; padding:50px 20px; }
  .ring{ width:260px; height:260px; border-radius:50%; position:relative; display:flex; align-items:center; justify-content:center; }
  .ring svg{ position:absolute; inset:0; transform:rotate(-90deg); }
  .ring .time{ font-family:'Fraunces',serif; font-size:52px; font-weight:600; }
  .ring .mode{ font-size:12.5px; color:var(--ink-soft); font-weight:600; letter-spacing:.03em; margin-top:2px; }
  .timer-controls{ display:flex; gap:10px; margin-top:26px; }
  .mode-picker{ display:flex; gap:8px; margin-top:18px; }
  .stat-row{ display:flex; gap:14px; margin-top:34px; }
  .stat-box{ text-align:center; padding:14px 22px; }
  .stat-box .n{ font-family:'Fraunces',serif; font-size:24px; }
  .stat-box .l{ font-size:11.5px; color:var(--ink-soft); }

  /* exam planner */
  .plan-day{ border-left:2px solid var(--line); padding:2px 0 22px 20px; position:relative; }
  .plan-day::before{ content:''; position:absolute; left:-6.5px; top:3px; width:11px; height:11px; border-radius:50%; background:var(--paper-2); border:2px solid var(--teal); }
  .plan-day.exam::before{ background:var(--coral); border-color:var(--coral); }
  .plan-day .d-label{ font-weight:700; font-size:13px; margin-bottom:2px; }
  .plan-day .d-date{ font-size:11.5px; color:var(--ink-soft); margin-bottom:8px; }
  .plan-topic{ display:flex; gap:8px; align-items:flex-start; font-size:13.5px; padding:7px 10px; background:var(--paper); border-radius:7px; margin-bottom:6px; }
  .plan-topic input{ width:auto; margin-top:3px; }
  .countdown{ display:flex; align-items:center; gap:16px; padding:18px 20px; margin-bottom:20px; }
  .countdown .n{ font-family:'Fraunces',serif; font-size:34px; color:var(--coral); }
  .countdown .l{ font-size:12px; color:var(--ink-soft); }

  .modal-bg{ position:fixed; inset:0; background:rgba(22,33,59,.45); display:none; align-items:center; justify-content:center; z-index:50; padding:20px; }
  .modal-bg.show{ display:flex; }
  .modal{ background:#fff; border-radius:14px; width:100%; max-width:520px; max-height:90vh; overflow-y:auto; padding:26px 28px; }
  .modal h2{ font-size:19px; margin-bottom:16px; }
  .modal-close{ position:absolute; }
  .topic-input-row{ display:flex; gap:8px; margin-bottom:8px; }
  .topic-chip{ display:flex; align-items:center; gap:8px; background:var(--paper); border-radius:8px; padding:7px 11px; margin-bottom:6px; font-size:13.5px; }
  .topic-chip button{ margin-left:auto; background:none; border:none; color:var(--coral); font-weight:700; }

  .upload-btn{ border:1.5px dashed var(--line); border-radius:8px; padding:10px 12px; font-size:12.5px; color:var(--ink-soft); display:flex; align-items:center; gap:7px; }
  .upload-btn:hover{ border-color:var(--teal); color:var(--teal); }

  /* live camera modal */
  .call-bg{ position:fixed; inset:0; background:rgba(10,14,26,.92); display:none; align-items:center; justify-content:center; z-index:60; padding:24px; }
  .call-bg.show{ display:flex; }
  .call-box{ width:100%; max-width:520px; }
  .call-video-wrap{ position:relative; width:100%; aspect-ratio:4/3; background:#1B2138; border-radius:16px; overflow:hidden; display:flex; align-items:center; justify-content:center; }
  .call-video-wrap video{ width:100%; height:100%; object-fit:cover; transform:scaleX(-1); }
  .call-label{ position:absolute; top:14px; left:14px; background:rgba(0,0,0,.45); color:#fff; font-size:12px; font-weight:600; padding:5px 11px; border-radius:99px; }
  .call-offline{ color:#8890AC; text-align:center; font-size:13.5px; padding:0 30px; }
  .call-controls{ display:flex; justify-content:center; gap:14px; margin-top:20px; }
  .call-btn{ width:52px; height:52px; border-radius:50%; border:none; background:#2A3050; color:#fff; font-size:19px; display:flex; align-items:center; justify-content:center; }
  .call-btn.off{ background:#4A5578; opacity:.6; }
  .call-btn.end{ background:var(--coral); width:auto; padding:0 22px; border-radius:26px; font-size:13.5px; font-weight:700; gap:6px; }
  .call-note{ color:#9CA3BE; font-size:12px; text-align:center; margin-top:16px; line-height:1.5; }

  ::-webkit-scrollbar{ width:9px; height:9px; }
  ::-webkit-scrollbar-thumb{ background:#C6CCDA; border-radius:99px; }
  ::-webkit-scrollbar-track{ background:transparent; }

  @media(max-width:760px){
    .rail{ display:none; }
    .main{ padding:20px 16px 50px; }
    .two-col{ grid-template-columns:1fr; }
  }