:root{color:#18211f;background:#eef2f0;font-family:Inter,Microsoft YaHei,PingFang SC,Noto Sans CJK SC,sans-serif;font-synthesis:none;text-rendering:optimizeLegibility;--ink: #18211f;--muted: #65716d;--line: #d7dfdc;--surface: #ffffff;--canvas: #eef2f0;--teal: #0d766a;--teal-dark: #095f56;--amber: #b46913;--danger: #b33b3b;--success: #24744f;--shadow: 0 10px 30px rgba(24, 33, 31, .07)}*{box-sizing:border-box}body{margin:0;min-width:320px;min-height:100vh}button,input,textarea{font:inherit}button{cursor:pointer}button:disabled{cursor:not-allowed;opacity:.55}.auth-shell{min-height:100vh;display:grid;place-items:center;padding:28px;background:linear-gradient(90deg,rgba(13,118,106,.07),transparent 36%),var(--canvas)}.auth-panel{width:min(430px,100%);padding:28px;border:1px solid var(--line);border-radius:8px;background:var(--surface);box-shadow:var(--shadow)}.session-loading{border:1px solid var(--line);border-radius:8px;color:var(--muted);background:var(--surface);padding:14px 18px;box-shadow:var(--shadow)}.brand-mark{display:flex;align-items:center;gap:12px;color:var(--teal-dark)}.brand-mark div{display:grid;gap:2px}.brand-mark strong{color:var(--ink);font-size:20px}.brand-mark span{color:var(--muted);font-size:12px}.brand-mark.compact{gap:9px}.brand-mark.compact strong{font-size:17px}.auth-tabs{display:grid;grid-template-columns:1fr 1fr;gap:4px;margin:26px 0 20px;padding:4px;border:1px solid var(--line);border-radius:8px;background:#f6f8f7}.auth-tabs button,.segmented button{border:0;border-radius:6px;background:transparent;color:var(--muted);padding:9px 12px;font-weight:700}.auth-tabs button.active,.segmented button.active{color:var(--ink);background:#fff;box-shadow:0 2px 8px #18211f14}.auth-form{display:grid;gap:16px}label{display:grid;gap:7px;color:#42504c;font-size:13px;font-weight:700}input,textarea{width:100%;border:1px solid var(--line);border-radius:6px;background:#fbfcfb;color:var(--ink);padding:11px 12px;outline:none;transition:border-color .16s ease,box-shadow .16s ease}input:focus,textarea:focus{border-color:var(--teal);box-shadow:0 0 0 3px #0d766a1f}textarea{resize:vertical;line-height:1.65}.primary-button,.secondary-button{display:inline-flex;align-items:center;justify-content:center;gap:7px;border:1px solid transparent;border-radius:6px;padding:10px 14px;font-weight:800}.primary-button{color:#fff;background:var(--teal)}.primary-button:hover:not(:disabled){background:var(--teal-dark)}.secondary-button{color:var(--teal-dark);border-color:#9fcac4;background:#eff8f6}.full-width{width:100%}.notice{border-radius:6px;padding:10px 12px;font-size:13px}.notice-neutral{color:#42504c;background:#edf1ef}.notice-success{color:#175b3b;background:#e8f5ed}.notice-error,.form-error{color:var(--danger);background:#fbecec}.form-error{margin:8px 0 0;border-radius:5px;padding:8px 10px;font-size:12px}.app-shell{min-height:100vh}.topbar{height:62px;display:flex;align-items:center;justify-content:space-between;padding:0 22px;border-bottom:1px solid var(--line);background:#fffffff0;-webkit-backdrop-filter:blur(12px);backdrop-filter:blur(12px);position:sticky;top:0;z-index:10}.teacher-chip{display:flex;align-items:center;gap:8px;color:#45524e;font-size:13px;font-weight:700}.teacher-chip button{display:grid;place-items:center;width:32px;height:32px;border:0;border-radius:6px;color:var(--muted);background:transparent}.teacher-chip button:hover{color:var(--danger);background:#f8eeee}.workspace{display:grid;grid-template-columns:320px minmax(0,1fr);min-height:calc(100vh - 62px)}.class-sidebar{border-right:1px solid var(--line);padding:22px;background:#f8faf9}.sidebar-title,.section-heading,.composer-heading,.composer-actions,.history-meta,.history-status{display:flex;align-items:center;justify-content:space-between;gap:12px}.eyebrow{display:block;color:var(--muted);font-size:11px;font-weight:800;letter-spacing:.08em;text-transform:uppercase}h1,h2,p{margin:0}.sidebar-title h1,.composer h2{margin-top:3px;font-size:21px}.count{display:inline-grid;min-width:27px;height:27px;place-items:center;border-radius:999px;color:#43504c;background:#e9eeec;font-size:12px;font-weight:800}.add-class{margin-top:22px;padding:15px;border:1px solid var(--line);border-radius:8px;background:#fff}.inline-form{display:grid;grid-template-columns:minmax(0,1fr) auto;gap:8px;margin-top:14px}.inline-form input{letter-spacing:.18em;font-variant-numeric:tabular-nums}.class-list{display:grid;gap:7px;margin-top:20px}.class-list>button{display:grid;grid-template-columns:8px minmax(0,1fr) auto;align-items:center;gap:11px;width:100%;padding:11px;border:1px solid transparent;border-radius:7px;color:var(--ink);background:transparent;text-align:left}.class-list>button:hover,.class-list>button.selected{border-color:#c8d8d4;background:#fff}.presence-dot{width:8px;height:8px;border-radius:50%;background:#aeb8b5}.presence-dot.online{background:#2a9d68;box-shadow:0 0 0 4px #2a9d681f}.class-copy{display:grid;gap:3px;min-width:0}.class-copy strong,.class-copy small{overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.class-copy strong{font-size:14px}.class-copy small,.history-meta,.history-status{color:var(--muted);font-size:12px}.message-count{color:var(--muted);font-size:12px;font-variant-numeric:tabular-nums}.main-panel{display:grid;align-content:start;gap:18px;padding:24px}.composer,.history-panel{border:1px solid var(--line);border-radius:8px;background:var(--surface);box-shadow:0 5px 20px #18211f09}.composer{display:grid;gap:16px;padding:22px}.composer-heading .online,.composer-heading .offline{display:inline-flex;align-items:center;gap:6px;border-radius:999px;padding:6px 10px;font-size:12px;font-weight:800}.composer-heading .online{color:var(--success);background:#eaf6ee}.composer-heading .offline{color:#7b5a22;background:#faf1df}.display-options{display:flex;align-items:end;justify-content:space-between;gap:18px}.segmented{display:grid;grid-template-columns:1fr 1fr;gap:4px;width:min(360px,100%);padding:4px;border:1px solid var(--line);border-radius:8px;background:#f6f8f7}.seconds-input{width:130px}.composer-actions{padding-top:2px}.composer-actions>span{color:var(--muted);font-size:12px;font-variant-numeric:tabular-nums}.history-panel{padding:20px 22px 8px}.message-history{margin-top:16px}.history-item{padding:16px 0;border-top:1px solid #e8edeb}.history-item p{margin:10px 0 12px;color:#2d3835;white-space:pre-wrap;line-height:1.65}.status-badge{display:inline-flex;align-items:center;gap:5px;border-radius:999px;padding:4px 8px;font-size:11px;font-weight:800}.status-queued{color:#76581f;background:#faf1dd}.status-delivered{color:#1f5f7a;background:#e8f4f8}.status-acknowledged{color:var(--success);background:#e8f5ed}.status-timed_out,.status-missed{color:var(--danger);background:#fbecec}.empty-state,.main-empty{display:grid;place-items:center;gap:10px;color:var(--muted);text-align:center}.empty-state{padding:26px 12px}.main-empty{min-height:54vh;border:1px dashed #c8d2cf;border-radius:8px}.main-empty h2{color:var(--ink)}@media(max-width:860px){.workspace{grid-template-columns:1fr}.class-sidebar{border-right:0;border-bottom:1px solid var(--line)}.main-panel{padding:16px}.display-options{align-items:stretch;flex-direction:column}.segmented,.seconds-input{width:100%}}