:root{
    --paper:#FCFCFA; --panel:#FFFFFF; --line:#E4E2DC; --line-soft:#EFEEEA;
    --ink:#14171C; --ink-soft:#565C66; --ink-faint:#8A8F98;
    --navy:#0E2A4A; --navy-deep:#081B30;
    --signal:#0F7A6E; --signal-soft:#E3F3F0;
    --amber:#B5762A; --amber-soft:#FBF0E2;
    --violet:#5B4C9E; --violet-soft:#EDEAF6;
    --radius:14px;
  }
  *{box-sizing:border-box;}
  html,body{margin:0;padding:0;height:100%;}
  body{
    background:var(--paper); color:var(--ink);
    font-family:'Inter',-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;
    -webkit-font-smoothing:antialiased;
    display:flex; flex-direction:column; height:100vh; overflow:hidden;
  }
  .mono{font-family:'IBM Plex Mono','SF Mono',ui-monospace,monospace;}
  a{color:inherit; text-decoration:none;}
  a:focus-visible, button:focus-visible{outline:2px solid var(--navy); outline-offset:2px; border-radius:6px;}
  button{font-family:inherit; cursor:pointer;}

  /* ===== Top bar ===== */
  .topbar{
    display:flex; align-items:center; justify-content:space-between;
    padding:11px 22px; border-bottom:1px solid var(--line); background:var(--panel);
    flex-shrink:0;
  }
  .brand{display:flex; align-items:center; gap:10px;}
  .brand-mark{width:28px;height:28px;border-radius:8px;background:linear-gradient(155deg,var(--navy),var(--navy-deep));
    display:flex;align-items:center;justify-content:center;color:#fff;font-weight:700;font-size:12px;}
  .brand-name{font-weight:650;font-size:14.5px;letter-spacing:-.01em;}
  .brand-name span{color:var(--ink-soft);font-weight:500;}
  .crumb{color:var(--ink-faint); font-size:13px; margin-left:4px;}

  .topnav{display:flex; gap:3px;}
  .topnav a{font-size:13px; padding:7px 12px; border-radius:8px; color:var(--ink-soft); font-weight:500;}
  .topnav a:hover{background:#F1F0EC; color:var(--ink);}
  .topnav a.active{background:var(--signal-soft); color:var(--signal);}

  .top-right{display:flex; align-items:center; gap:10px;}
  .search{
    display:flex; align-items:center; gap:8px; background:#F4F3EF; border:1px solid var(--line);
    border-radius:9px; padding:7px 12px; width:280px; font-size:13px; color:var(--ink-faint);
  }
  .search input{border:none;background:none;outline:none;font-size:13px;width:100%;color:var(--ink);font-family:inherit;}
  .icon-btn{
    width:32px;height:32px;border-radius:9px;border:1px solid var(--line);background:var(--panel);
    display:flex;align-items:center;justify-content:center;font-size:14px;color:var(--ink-soft);
  }
  .icon-btn:hover{background:#F4F3EF;}
  .avatar{width:30px;height:30px;border-radius:8px;background:var(--amber-soft);color:var(--amber);
    display:flex;align-items:center;justify-content:center;font-weight:700;font-size:11.5px;border:1px solid #EEDFC7;}

  /* ===== App body: 4 panes ===== */
  .app{display:flex; flex:1; min-height:0;}

  /* --- Rail (module dock) --- */
  .rail{
    width:60px; background:var(--panel); border-right:1px solid var(--line);
    display:flex; flex-direction:column; align-items:center; padding:14px 0; gap:6px; flex-shrink:0;
  }
  .rail a{
    width:38px;height:38px;border-radius:10px;display:flex;align-items:center;justify-content:center;
    font-size:16px; color:var(--ink-faint); position:relative;
  }
  .rail a:hover{background:#F1F0EC;}
  .rail a.active{background:var(--signal-soft); color:var(--signal);}
  .rail a .badge{
    position:absolute; top:-3px; right:-3px; background:#B54B3A; color:#fff; font-size:9px;
    border-radius:100px; padding:1px 4px; font-weight:700;
  }
  .rail .spacer{flex:1;}
  .rail .compose{
    width:38px;height:38px;border-radius:10px;background:var(--navy);color:#fff;
    display:flex;align-items:center;justify-content:center;font-size:17px; border:none;
  }
  .rail .compose:hover{background:var(--navy-deep);}

  /* --- Folder sidebar --- */
  .sidebar{
    width:216px; background:var(--panel); border-right:1px solid var(--line);
    padding:16px 12px; overflow-y:auto; flex-shrink:0;
  }
  .account-switch{
    display:flex; align-items:center; justify-content:space-between; padding:8px 10px; margin-bottom:14px;
    border:1px solid var(--line); border-radius:10px; font-size:12.5px; background:#F9F9F7;
  }
  .account-switch b{font-weight:650; display:block; font-size:12.5px;}
  .account-switch span{color:var(--ink-faint); font-size:11px;}

  .nav-group{margin-bottom:16px;}
  .nav-label{font-size:10.5px; text-transform:uppercase; letter-spacing:.08em; color:var(--ink-faint); font-weight:650; padding:0 10px; margin-bottom:6px;}
  .nav-item{
    display:flex; align-items:center; gap:9px; padding:7px 10px; border-radius:8px; font-size:13.5px;
    color:var(--ink-soft); font-weight:500;
  }
  .nav-item .n{margin-left:auto; font-size:11px; color:var(--ink-faint); font-family:'IBM Plex Mono',monospace;}
  .nav-item:hover{background:#F4F3EF; color:var(--ink);}
  .nav-item.active{background:var(--navy); color:#fff;}
  .nav-item.active .n{color:#CBD6E2;}
  .dot{width:8px;height:8px;border-radius:2px;}
  .dot-work{background:var(--signal);} .dot-cust{background:var(--amber);} .dot-vip{background:var(--violet);}

  /* --- Message list --- */
  .msglist{
    width:340px; background:var(--panel); border-right:1px solid var(--line);
    display:flex; flex-direction:column; flex-shrink:0; min-width:0;
  }
  .list-head{padding:14px 16px 10px; border-bottom:1px solid var(--line-soft);}
  .list-head-top{display:flex; justify-content:space-between; align-items:center; margin-bottom:10px;}
  .list-head h2{font-size:15.5px; margin:0; letter-spacing:-.01em;}
  .list-tools{display:flex; gap:6px;}
  .list-filters{display:flex; gap:6px;}
  .filter-chip{font-size:11.5px; padding:5px 10px; border-radius:100px; border:1px solid var(--line); color:var(--ink-soft);}
  .filter-chip.active{background:var(--ink); color:#fff; border-color:var(--ink);}

  .list-scroll{flex:1; overflow-y:auto;}
  .mail-row{
    padding:12px 16px; border-bottom:1px solid var(--line-soft); cursor:pointer; position:relative;
  }
  .mail-row:hover{background:#FAFAF8;}
  .mail-row.selected{background:var(--signal-soft);}
  .mail-row.selected::before{content:'';position:absolute;left:0;top:0;bottom:0;width:3px;background:var(--signal);}
  .mail-row.unread .mail-subject{font-weight:650;}
  .mail-top{display:flex; justify-content:space-between; gap:8px; margin-bottom:3px;}
  .mail-from{font-size:13px; font-weight:600;}
  .mail-time{font-size:11px; color:var(--ink-faint); white-space:nowrap;}
  .mail-subject{font-size:13px; margin-bottom:3px;}
  .mail-preview{font-size:12px; color:var(--ink-faint); white-space:nowrap; overflow:hidden; text-overflow:ellipsis;}
  .mail-tags{display:flex; gap:5px; margin-top:6px;}
  .tag{font-size:10px; padding:2px 7px; border-radius:100px; font-weight:650;}
  .tag-cust{background:var(--amber-soft); color:var(--amber);}
  .tag-urgent{background:#FBEAE6; color:#B54B3A;}
  .tag-ai{background:var(--violet-soft); color:var(--violet);}
  .unread-dot{width:7px;height:7px;border-radius:50%; background:var(--signal); position:absolute; left:5px; top:17px;}

  /* --- Reading pane --- */
  .reading{flex:1; display:flex; flex-direction:column; min-width:0; background:var(--paper);}
  .read-head{padding:18px 26px 14px; border-bottom:1px solid var(--line); background:var(--panel);}
  .read-subject{font-size:19px; font-weight:650; letter-spacing:-.01em; margin:0 0 10px;}
  .read-meta{display:flex; align-items:center; gap:12px;}
  .read-avatar{width:36px;height:36px;border-radius:10px;background:var(--violet-soft);color:var(--violet);
    display:flex;align-items:center;justify-content:center;font-weight:700;font-size:13px;}
  .read-who b{font-size:13.5px; display:block;}
  .read-who span{font-size:12px; color:var(--ink-faint);}
  .read-actions{margin-left:auto; display:flex; gap:6px;}
  .btn{font-size:12.5px; padding:7px 13px; border-radius:8px; border:1px solid var(--line); background:var(--panel); color:var(--ink-soft); font-weight:600;}
  .btn:hover{background:#F4F3EF; color:var(--ink);}
  .btn-primary{background:var(--navy); color:#fff; border-color:var(--navy);}
  .btn-primary:hover{background:var(--navy-deep);}

  .read-body{flex:1; overflow-y:auto; padding:24px 26px 40px; font-size:14px; line-height:1.7; color:var(--ink);}
  .read-body p{margin:0 0 14px;}
  .quoted{border-left:2px solid var(--line); padding-left:14px; color:var(--ink-soft); margin-top:20px;}

  .attach{display:flex; gap:10px; margin-top:20px;}
  .attach-chip{display:flex; align-items:center; gap:8px; padding:8px 12px; border:1px solid var(--line); border-radius:9px; font-size:12.5px; background:var(--panel);}
  .attach-chip .fi{width:26px;height:26px;border-radius:6px;background:var(--signal-soft);color:var(--signal);display:flex;align-items:center;justify-content:center;font-size:11px;font-weight:700;}

  .reply-bar{padding:14px 26px; border-top:1px solid var(--line); background:var(--panel); display:flex; gap:8px;}

  /* --- AI panel --- */
  .aipane{
    width:300px; background:var(--panel); border-left:1px solid var(--line);
    display:flex; flex-direction:column; flex-shrink:0;
  }
  .ai-head{padding:16px 18px 12px; border-bottom:1px solid var(--line-soft); display:flex; align-items:center; justify-content:space-between;}
  .ai-head h3{font-size:13.5px; margin:0; display:flex; align-items:center; gap:7px;}
  .ai-dot{width:7px;height:7px;border-radius:50%;background:var(--violet);}
  .ai-scroll{flex:1; overflow-y:auto; padding:16px 18px;}
  .ai-card{border:1px solid var(--line); border-radius:11px; padding:13px 14px; margin-bottom:12px; background:#FBFAFC;}
  .ai-card-title{font-size:11px; text-transform:uppercase; letter-spacing:.06em; color:var(--violet); font-weight:650; margin-bottom:8px;}
  .ai-card p{font-size:12.5px; line-height:1.6; color:var(--ink-soft); margin:0 0 6px;}
  .ai-bullets{margin:8px 0 0; padding-left:16px; font-size:12.5px; color:var(--ink-soft); line-height:1.6;}
  .ai-actions{display:flex; gap:6px; margin-top:10px;}
  .ai-btn{font-size:11.5px; padding:6px 10px; border-radius:7px; border:1px solid var(--line); background:var(--panel); color:var(--ink-soft); font-weight:600;}
  .ai-btn:hover{background:#F4F3EF;}
  .ai-btn.primary{background:var(--violet); color:#fff; border-color:var(--violet);}

  .ai-task{display:flex; align-items:flex-start; gap:8px; font-size:12.5px; padding:8px 0; border-bottom:1px solid var(--line-soft);}
  .ai-task:last-child{border-bottom:none;}
  .ai-usage{padding:12px 18px; border-top:1px solid var(--line-soft); font-size:11px; color:var(--ink-faint);}
  .usage-bar{height:5px; border-radius:100px; background:var(--line-soft); margin-top:6px; overflow:hidden;}
  .usage-fill{height:100%; width:0; background:var(--violet);}

  ::-webkit-scrollbar{width:8px;height:8px;}
  ::-webkit-scrollbar-thumb{background:#DDD9D1;border-radius:100px;}
  ::-webkit-scrollbar-track{background:transparent;}