:root{color-scheme:light;--bg:#f7f7f4;--panel:#ffffff;--ink:#1f2933;--muted:#667085;--line:#d8ded8;--accent:#256f5b;--accent-strong:#174c3e}*{box-sizing:border-box}body,html{height:100%;margin:0}body{background:var(--bg);color:var(--ink);font-family:Arial,Microsoft YaHei,sans-serif}a{color:inherit;text-decoration:none}.home-shell{margin:0 auto;max-width:1040px;padding:48px 24px}.home-header{align-items:end;border-bottom:1px solid var(--line);display:flex;gap:24px;justify-content:space-between;padding-bottom:28px}.eyebrow{color:var(--accent);font-size:13px;font-weight:700;letter-spacing:0;margin:0 0 10px;text-transform:uppercase}h1{font-size:40px;line-height:1.15;margin:0}.subtitle{color:var(--muted);font-size:16px;line-height:1.7;margin:14px 0 0;max-width:680px}.primary-action{background:var(--accent);border-radius:6px;color:white;flex:0 0 auto;font-weight:700;padding:12px 18px}.primary-action:hover{background:var(--accent-strong)}.secondary-action{background:#ffffff;border:1px solid var(--line);border-radius:6px;color:var(--ink);cursor:pointer;font:inherit;font-weight:700;padding:12px 18px}.home-actions{align-items:center;display:flex;flex:0 0 auto;gap:10px}.home-actions form{margin:0}.user-strip{align-items:center;background:#ffffff;border:1px solid var(--line);border-radius:8px;display:flex;gap:10px;justify-content:space-between;margin-top:18px;padding:12px 14px}.user-strip small{color:var(--muted)}.board-list{display:grid;gap:10px;margin-top:24px}.board-row{align-items:center;background:var(--panel);border:1px solid var(--line);border-radius:8px;display:flex;justify-content:space-between;min-height:68px;padding:14px 16px}.board-row:hover{border-color:var(--accent)}.board-row span{display:grid;gap:4px}.board-row small,.board-row time{color:var(--muted);font-size:13px}.empty-state,.login-panel{background:#ffffff;border:1px solid var(--line);border-radius:8px;padding:22px}.login-shell{align-items:center;display:flex;min-height:100vh;padding:24px}.login-panel{margin:0 auto;max-width:520px}.login-panel form{margin-top:22px}.login-panel button{border:0;cursor:pointer;font:inherit}.board-shell{display:grid;grid-template-rows:56px minmax(0,1fr);height:100vh}.board-topbar{align-items:center;background:#ffffff;border-bottom:1px solid var(--line);display:grid;gap:14px;grid-template-columns:40px minmax(0,1fr) auto;padding:0 14px}.back-link{align-items:center;border:1px solid var(--line);border-radius:6px;display:inline-flex;font-size:18px;height:34px;justify-content:center;width:34px}.board-title{display:grid;min-width:0}.board-title span,.board-title strong{overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.board-title span{color:var(--muted);font-size:12px}.board-topbar code{background:#eef3ef;border-radius:6px;color:#315347;font-size:12px;padding:6px 8px}.board-loading,.whiteboard-frame{height:100%;min-height:0;width:100%}.whiteboard-frame{position:relative}.collab-panel{align-items:center;background:rgba(255,255,255,.92);border:1px solid var(--line);border-radius:8px;box-shadow:0 8px 24px rgba(31,41,51,.08);display:flex;gap:10px;padding:8px 10px;position:absolute;right:14px;top:14px;z-index:5}.collab-panel button{background:var(--accent);border:0;border-radius:6px;color:#ffffff;cursor:pointer;font:inherit;font-weight:700;padding:7px 10px}.collab-dot{border-radius:999px;display:inline-block;height:9px;width:9px}.collab-dot-connected{background:#16a34a}.collab-dot-connecting{background:#d97706}.collab-dot-disconnected{background:#dc2626}@media (max-width:720px){.collab-panel{left:12px;right:12px;top:68px}}.board-loading{align-items:center;color:var(--muted);display:flex;justify-content:center}@media (max-width:720px){.home-header{align-items:stretch;display:grid}h1{font-size:32px}.board-topbar{grid-template-columns:40px minmax(0,1fr)}.board-topbar code{display:none}}