:root{--green: #06c755;--green-dark: #05a846;--green-light: #e8f9ef;--chat-bg: #f1f3f5;--panel: #ffffff;--line: #e5e8eb;--text: #22262b;--text-soft: #7a8087;--own-bubble: #06c755;--danger: #ec4444;font-family:system-ui,-apple-system,Segoe UI,PingFang TC,Microsoft JhengHei,Noto Sans TC,sans-serif;color:var(--text);font-synthesis:none;text-rendering:optimizeLegibility;-webkit-font-smoothing:antialiased}*{box-sizing:border-box}html,body,#root{height:100%;margin:0}button{font:inherit;border:none;background:none;cursor:pointer;color:inherit;padding:0}ul{list-style:none;margin:0;padding:0}.app{height:100vh;display:flex;overflow:hidden}.avatar{display:inline-flex;align-items:center;justify-content:center;flex-shrink:0;color:#fff;font-weight:700;border-radius:50%;-webkit-user-select:none;user-select:none}.icon-btn{display:inline-flex;align-items:center;justify-content:center;width:36px;height:36px;border-radius:50%;font-size:18px;color:var(--text-soft);transition:background .15s}.icon-btn:hover{background:#eef0f2}.login-screen{height:100vh;display:flex;align-items:center;justify-content:center;background:linear-gradient(160deg,#06c755,#0aab4c 55%,#067f3a)}.login-card{width:380px;background:var(--panel);border-radius:18px;padding:36px 32px;box-shadow:0 24px 60px #00000040;display:flex;flex-direction:column;gap:10px}.login-card h1{margin:4px 0 0;font-size:24px;text-align:center}.login-logo{display:flex;justify-content:center}.login-hint{margin:0 0 12px;text-align:center;color:var(--text-soft);font-size:13px}.login-label{font-size:12px;font-weight:600;color:var(--text-soft);margin-top:6px}.login-input{font:inherit;border:1.5px solid var(--line);border-radius:10px;padding:11px 14px;outline:none;transition:border-color .15s,box-shadow .15s}.login-input:focus{border-color:var(--green);box-shadow:0 0 0 3px #06c75526}.login-colors{display:flex;gap:10px;flex-wrap:wrap}.color-swatch{width:30px;height:30px;border-radius:50%;border:3px solid transparent;transition:transform .12s,border-color .12s}.color-swatch:hover{transform:scale(1.12)}.color-swatch.active{border-color:#fff;outline:2px solid var(--text);transform:scale(1.05)}.login-submit{margin-top:16px;background:var(--green);color:#fff;font-weight:700;font-size:15px;padding:13px;border-radius:10px;transition:background .15s}.login-submit:hover:not(:disabled){background:var(--green-dark)}.login-submit:disabled{opacity:.45;cursor:not-allowed}.sidebar{width:330px;flex-shrink:0;background:var(--panel);border-right:1px solid var(--line);display:flex;flex-direction:column;overflow:hidden}.sidebar-user{display:flex;align-items:center;gap:12px;padding:14px 16px;border-bottom:1px solid var(--line)}.sidebar-user-info{flex:1;display:flex;flex-direction:column;gap:2px;min-width:0}.sidebar-user-name{font-weight:700;font-size:15px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.sidebar-status{display:inline-flex;align-items:center;gap:5px;font-size:11px;color:var(--text-soft)}.status-dot{width:8px;height:8px;border-radius:50%;background:#c3c8cd}.status-dot.status-ready,.status-dot.status-login{background:var(--green)}.status-dot.status-connecting{background:#eab308}.status-dot.status-disconnected{background:var(--danger)}.sidebar-section{padding:16px 18px 8px;font-size:12px;font-weight:700;color:var(--text-soft);letter-spacing:.04em;overflow-y:auto}.room-list{flex:1;overflow-y:auto}.room-item{width:100%;display:flex;align-items:flex-start;gap:12px;padding:12px 16px;text-align:left;transition:background .12s}.room-item:hover{background:#f5f6f7}.room-item.active{background:var(--green-light)}.room-item-main{flex:1;min-width:0;display:flex;flex-direction:column;gap:4px}.room-item-top,.room-item-bottom{display:flex;align-items:center;justify-content:space-between;gap:8px}.room-item-name{font-weight:700;font-size:14px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.room-item-time{font-size:11px;color:var(--text-soft);flex-shrink:0}.room-item-preview{font-size:13px;color:var(--text-soft);overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.room-item-members{font-size:11px;color:#a3a9af}.unread-badge{background:var(--green);color:#fff;font-size:11px;font-weight:700;border-radius:999px;padding:2px 7px;flex-shrink:0}.chat-window{flex:1;display:flex;flex-direction:column;min-width:0;background:var(--chat-bg)}.chat-window.empty{align-items:center;justify-content:center;color:var(--text-soft)}.chat-header{height:62px;background:var(--panel);border-bottom:1px solid var(--line);display:flex;align-items:center;gap:14px;padding:0 18px;flex-shrink:0}.chat-header-info{display:flex;align-items:baseline;gap:8px;min-width:0}.chat-header-info h2{margin:0;font-size:17px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}.chat-header-sub{font-size:12px;color:var(--text-soft);flex-shrink:0}.chat-header-members{display:flex;align-items:center;margin-left:auto}.member-chip{margin-left:-6px;border:2px solid var(--panel);border-radius:50%;line-height:0}.member-chip:first-child{margin-left:0}.member-more{font-size:12px;color:var(--text-soft);margin-left:6px}.bot-toggle{font-size:12px;font-weight:600;color:var(--text-soft);border:1px solid var(--line);border-radius:999px;padding:5px 12px;margin-left:10px;flex-shrink:0;transition:background .15s,color .15s,border-color .15s}.bot-toggle:hover{background:var(--green-light);border-color:var(--green);color:var(--green-dark)}.bot-toggle.on{background:var(--green);border-color:var(--green);color:#fff}.bot-tag{font-size:10px;font-weight:700;color:#8b5cf6;background:#f3efff;border-radius:999px;padding:2px 8px;margin-left:6px;vertical-align:1px}.bot-tag.en{color:#2563eb;background:#eaf1fe}.speak-btn{font-size:14px;margin-bottom:2px;flex-shrink:0;opacity:.55;transition:opacity .15s,transform .1s}.speak-btn:hover{opacity:1;transform:scale(1.15)}.tutor-banner{background:var(--green-light);color:var(--green-dark);font-size:12.5px;font-weight:600;text-align:center;padding:5px 16px;flex-shrink:0}.bot-toggle.tutor-mode.on:not(:hover){background:#2563eb;border-color:#2563eb;color:#fff}.leave-btn{color:var(--danger)}.leave-btn:hover{background:#fdeaea}.chat-scroll{flex:1;overflow-y:auto;padding:18px 24px 10px}.day-separator{text-align:center;margin:14px 0 10px}.day-separator span{display:inline-block;background:#d7dce0;color:#fff;font-size:11px;padding:3px 14px;border-radius:999px}.system-message{text-align:center;font-size:12px;color:var(--text-soft);margin:10px 0 6px}.msg-row{display:flex;align-items:flex-end;gap:8px;margin-bottom:10px}.msg-row.other{margin-top:16px}.msg-row.own{justify-content:flex-end}.msg-other-main{display:flex;flex-direction:column;gap:4px;min-width:0}.msg-sender{font-size:12px;color:var(--text-soft);margin-left:2px}.msg-with-time{display:flex;align-items:flex-end;gap:8px}.msg-time{font-size:11px;color:var(--text-soft);flex-shrink:0;margin-bottom:3px}.bubble{max-width:min(480px,72%);padding:10px 14px;border-radius:16px;font-size:14.5px;line-height:1.55;word-break:break-word;white-space:pre-wrap}.own-bubble{background:var(--own-bubble);color:#fff;border-bottom-right-radius:4px}.other-bubble{background:#fff;color:var(--text);border-bottom-left-radius:4px;box-shadow:0 1px 1.5px #0000000f}.error-banner{background:#fdd;color:var(--danger);font-size:13px;text-align:center;padding:6px;flex-shrink:0}.composer-wrap{padding:10px 20px 14px;position:relative;flex-shrink:0}.typing-hint{height:16px;font-size:12px;color:var(--text-soft);padding:0 8px}.composer{display:flex;align-items:flex-end;gap:8px;background:var(--panel);border:1px solid var(--line);border-radius:14px;padding:8px 10px;box-shadow:0 1px 3px #0000000d}.composer-input{font:inherit;flex:1;border:none;outline:none;resize:none;max-height:120px;padding:6px 4px;background:transparent;line-height:1.5}.emoji-toggle.active{background:var(--green-light);color:var(--green-dark)}.emoji-panel{position:absolute;bottom:64px;left:20px;width:320px;background:var(--panel);border:1px solid var(--line);border-radius:14px;box-shadow:0 10px 34px #00000029;padding:10px;display:grid;grid-template-columns:repeat(10,1fr);gap:2px;z-index:5}.emoji-btn{font-size:19px;padding:5px 0;border-radius:8px;transition:background .1s}.emoji-btn:hover{background:var(--green-light)}.send-btn{width:38px;height:38px;border-radius:50%;background:var(--green);color:#fff;display:inline-flex;align-items:center;justify-content:center;flex-shrink:0;transition:background .15s,transform .1s}.send-btn:hover:not(:disabled){background:var(--green-dark);transform:scale(1.05)}.send-btn:disabled{background:#d8dde1;cursor:not-allowed}.char-count{position:absolute;right:26px;top:50px;font-size:11px;color:#a3a9af;pointer-events:none}.modal-overlay{position:fixed;inset:0;background:#14181c73;display:flex;align-items:center;justify-content:center;z-index:20}.modal{width:360px;background:var(--panel);border-radius:16px;padding:24px;display:flex;flex-direction:column;gap:12px;box-shadow:0 20px 50px #0003}.modal h2{margin:0;font-size:18px}.modal-hint{margin:0;font-size:13px;color:var(--text-soft)}.modal-actions{display:flex;justify-content:flex-end;gap:10px;margin-top:6px}.btn-ghost{padding:9px 16px;border-radius:10px;color:var(--text-soft);font-size:14px;transition:background .12s}.btn-ghost:hover{background:#eef0f2}.btn-primary{padding:9px 20px;border-radius:10px;background:var(--green);color:#fff;font-weight:700;font-size:14px;transition:background .15s}.btn-primary:hover:not(:disabled){background:var(--green-dark)}.btn-primary:disabled{opacity:.45;cursor:not-allowed}::-webkit-scrollbar{width:8px;height:8px}::-webkit-scrollbar-thumb{background:#ccd1d6;border-radius:999px}::-webkit-scrollbar-thumb:hover{background:#b4bac0}