:root {
    --bg-color: #0f172a; --card-bg: #1e293b; --text-color: #f8fafc;
    --primary-color: #8b5cf6; --primary-hover: #7c3aed;
    --secondary-color: #334155; --accent-color: #ec4899;
    --accent-hover: #db2777; --success-color: #10b981; --warning-color: #f59e0b;
    --danger-color: #ef4444; --danger-hover: #dc2626;
    --chat-bg: #1e293b; --message-sent: #8b5cf6; --message-received: #334155;
    --border-radius-sm: 8px; --border-radius: 12px; --border-radius-lg: 16px;
    --shadow-sm: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-lg: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    --transition-fast: 0.2s ease; --transition: 0.3s ease; --transition-slow: 0.5s ease;
    --spacing-xs: 4px; --spacing-sm: 8px; --spacing: 16px; --spacing-md: 24px; --spacing-lg: 32px; --spacing-xl: 48px;
}
* { margin: 0; padding: 0; box-sizing: border-box; font-family: 'Inter', sans-serif; }
body { background-color: var(--bg-color); color: var(--text-color); height: 100vh; height: 100dvh; display: flex; flex-direction: column; overflow: hidden; }

.app-container { display: flex; flex-direction: column; width: 100%; max-width: 1600px; margin: 0 auto; padding: var(--spacing); height: 100%; }

.app-header { display: flex; flex-direction: column; align-items: center; justify-content: center; margin-bottom: var(--spacing); }
.app-logo { font-size: 2rem; font-weight: 700; background: linear-gradient(135deg, var(--primary-color), var(--accent-color)); -webkit-background-clip: text; background-clip: text; color: transparent; letter-spacing: -0.5px; margin-bottom: var(--spacing-sm); }

.mode-tabs { display: flex; background: var(--card-bg); padding: 4px; border-radius: 30px; box-shadow: var(--shadow-sm); gap: 4px; width: 100%; max-width: 500px; }
.mode-tab { flex: 1; background: transparent; border: none; color: var(--text-color); padding: 8px 16px; border-radius: 26px; cursor: pointer; font-weight: 500; font-size: 0.9rem; transition: var(--transition); display: flex; align-items: center; justify-content: center; gap: 8px; opacity: 0.7; white-space: nowrap; }
.mode-tab:hover { opacity: 1; background: rgba(255,255,255,0.05); }
.mode-tab.active { background: var(--primary-color); opacity: 1; box-shadow: var(--shadow-sm); }

.main-content { display: flex; flex: 1; gap: var(--spacing); min-height: 0; position: relative; }

.media-area { flex: 2; display: flex; flex-direction: column; background-color: var(--card-bg); border-radius: var(--border-radius); overflow: hidden; box-shadow: var(--shadow); position: relative; min-width: 0; }

.media-view { flex: 1; position: relative; background-color: #0f172a; display: flex; align-items: center; justify-content: center; overflow: hidden; }

.chat-toggle { position: absolute; right: 15px; bottom: 130px; width: 50px; height: 50px; border-radius: 50%; background-color: var(--primary-color); color: white; border: none; cursor: grab; display: flex; align-items: center; justify-content: center; z-index: 101; font-size: 1.3rem; box-shadow: 0 4px 12px rgba(0,0,0,0.4); transition: transform 0.2s, background-color 0.2s; }
.chat-toggle:active { cursor: grabbing; }
.chat-toggle:hover { background-color: var(--primary-hover); transform: scale(1.05); }

.unread-badge { position: absolute; top: -5px; right: -5px; background-color: var(--danger-color); color: white; font-size: 0.75rem; font-weight: 700; padding: 3px 7px; border-radius: 12px; display: none; box-shadow: 0 2px 4px rgba(0,0,0,0.3); pointer-events: none; border: 2px solid var(--primary-color); }
.unread-badge.show { display: block; animation: popIn 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275); }
@keyframes popIn { from { transform: scale(0); } to { transform: scale(1); } }

.video-wrapper { width: 100%; height: 100%; position: absolute; }
.video-element { width: 100%; height: 100%; object-fit: cover; }
.local-video-wrapper { position: absolute; width: 75px; height: 75px; bottom: var(--spacing); right: var(--spacing); border-radius: var(--border-radius-sm); overflow: hidden; border: 2px solid var(--primary-color); z-index: 10; box-shadow: var(--shadow); transition: all var(--transition); background: #000; pointer-events: none; }

.username-badge { position: absolute; bottom: var(--spacing); left: var(--spacing); background-color: rgba(15, 23, 42, 0.7); color: white; padding: 6px 12px; border-radius: 20px; font-size: 0.85rem; font-weight: 500; backdrop-filter: blur(5px); display: flex; align-items: center; gap: 6px; z-index: 10; }
.username-badge i { color: var(--success-color); }

.audio-wrapper { width: 100%; height: 100%; position: absolute; display: flex; flex-direction: column; align-items: center; justify-content: center; background-image: radial-gradient(circle at 25px 25px, rgba(255, 255, 255, 0.03) 2%, transparent 0%), radial-gradient(circle at 75px 75px, rgba(255, 255, 255, 0.03) 2%, transparent 0%); background-size: 100px 100px; gap: 40px; }
.audio-participants { display: flex; align-items: center; justify-content: center; gap: 40px; width: 100%; flex-wrap: wrap; }
.audio-vis { width: 150px; height: 150px; border-radius: 50%; display: flex; align-items: center; justify-content: center; position: relative; transition: all var(--transition); box-shadow: 0 10px 30px rgba(0,0,0,0.3); }
.audio-vis.remote { background: linear-gradient(135deg, var(--primary-color), #a78bfa); }
.audio-vis.local { background: linear-gradient(135deg, var(--success-color), #34d399); width: 100px; height: 100px; }
.audio-vis.active { transform: scale(1.05); box-shadow: 0 0 25px rgba(255,255,255,0.4); }
.audio-vis .avatar { font-size: 50px; color: white; }
.audio-vis.local .avatar { font-size: 35px; }
.audio-label { position: absolute; bottom: -30px; font-size: 0.85rem; font-weight: 500; background: rgba(0,0,0,0.5); padding: 4px 10px; border-radius: 12px; white-space: nowrap; }

.chat-placeholder { display: flex; flex-direction: column; align-items: center; justify-content: center; position: absolute; width: 100%; height: 100%; background: var(--bg-color); z-index: 5; }

.unified-controls { display: flex; align-items: center; justify-content: center; flex-wrap: wrap; gap: 12px; padding: 12px 20px; background-color: var(--secondary-color); border-top: 1px solid rgba(255,255,255,0.05); z-index: 20; }

.info-pill { display: flex; align-items: center; gap: 8px; font-size: 0.85rem; font-weight: 500; background: rgba(0,0,0,0.2); padding: 6px 12px; border-radius: 20px; }
.pulse-dot { width: 8px; height: 8px; background-color: var(--success-color); border-radius: 50%; animation: pulse 1.5s infinite; }

.switch-container { display: flex; align-items: center; gap: 8px; font-size: 0.85rem; font-weight: 500; }
.switch { position: relative; display: inline-block; width: 44px; height: 22px; }
.switch input { opacity: 0; width: 0; height: 0; }
.slider { position: absolute; cursor: pointer; top: 0; left: 0; right: 0; bottom: 0; background-color: #475569; transition: .4s; border-radius: 22px; }
.slider:before { position: absolute; content: ""; height: 16px; width: 16px; left: 3px; bottom: 3px; background-color: white; transition: .4s; border-radius: 50%; }
input:checked + .slider { background-color: var(--primary-color); }
input:checked + .slider:before { transform: translateX(22px); }

.action-btn { padding: 10px 24px; border-radius: 24px; border: none; font-weight: 600; font-size: 0.95rem; cursor: pointer; color: white; display: flex; align-items: center; gap: 8px; transition: all 0.3s; box-shadow: var(--shadow-sm); }
.action-btn.start { background-color: var(--primary-color); }
.action-btn.start:hover { background-color: var(--primary-hover); transform: translateY(-2px); }
.action-btn.searching { background-color: var(--warning-color); animation: pulse 1.5s infinite; }
.action-btn.end { background-color: var(--danger-color); }
.action-btn.end:hover { background-color: var(--danger-hover); transform: translateY(-2px); }
@keyframes pulse { 0% { opacity: 0.8; } 50% { opacity: 1; } 100% { opacity: 0.8; } }

.media-toggles { display: flex; gap: 8px; margin-left: auto; }
.control-btn { width: 42px; height: 42px; border-radius: 50%; border: none; background-color: rgba(255,255,255,0.1); color: white; cursor: pointer; display: flex; align-items: center; justify-content: center; font-size: 1rem; transition: all var(--transition); }
.control-btn:hover { background-color: rgba(255,255,255,0.2); }
.control-btn.mute { background-color: var(--danger-color); }

.chat-box { flex: 1; min-width: 300px; max-width: 400px; background-color: var(--chat-bg); border-radius: var(--border-radius); box-shadow: var(--shadow); display: flex; flex-direction: column; position: relative; z-index: 100; }
.chat-header { padding: 12px 16px; background-color: rgba(0,0,0,0.2); display: flex; align-items: center; justify-content: space-between; border-bottom: 1px solid rgba(255,255,255,0.05); border-radius: var(--border-radius) var(--border-radius) 0 0; }
.chat-header h3 { font-size: 1rem; font-weight: 600; display: flex; align-items: center; gap: 8px; margin: 0; }
.close-chat-btn { background: transparent; border: none; color: var(--text-color); cursor: pointer; font-size: 1.2rem; opacity: 0.7; }
.close-chat-btn:hover { opacity: 1; }

.chat-messages { flex: 1; overflow-y: auto; padding: var(--spacing); display: flex; flex-direction: column; gap: var(--spacing-sm); }
.chat-messages::-webkit-scrollbar { width: 4px; }
.chat-messages::-webkit-scrollbar-track { background: transparent; }
.chat-messages::-webkit-scrollbar-thumb { background: rgba(255, 255, 255, 0.1); border-radius: 10px; }

.message { padding: 10px 14px; border-radius: 16px; max-width: 85%; word-break: break-word; font-size: 0.9rem; animation: fadeIn 0.3s ease-out; }
@keyframes fadeIn { from { opacity: 0; transform: translateY(5px); } to { opacity: 1; transform: translateY(0); } }
.message.received { background-color: var(--message-received); align-self: flex-start; border-bottom-left-radius: 4px; }
.message.sent { background-color: var(--message-sent); color: white; align-self: flex-end; border-bottom-right-radius: 4px; }
.message img { max-width: 100%; border-radius: 8px; margin-top: 4px; }

.message-input { display: flex; padding: 10px 12px; background-color: rgba(0,0,0,0.2); align-items: center; gap: 8px; border-radius: 0 0 var(--border-radius) var(--border-radius); position: relative; }
.message-input input[type="text"] { flex: 1; min-width: 0; padding: 10px 14px; border: none; border-radius: 20px; outline: none; background-color: rgba(255, 255, 255, 0.05); color: var(--text-color); font-size: 0.9rem; transition: background 0.3s; }
.message-input input[type="text"]:focus { background-color: rgba(255, 255, 255, 0.1); }
.message-input button { flex-shrink: 0; padding: 0; width: 34px; height: 34px; border: none; border-radius: 50%; background-color: transparent; color: var(--text-color); cursor: pointer; display: flex; align-items: center; justify-content: center; font-size: 1.1rem; opacity: 0.7; transition: all 0.2s; }
.message-input button:hover { opacity: 1; background-color: rgba(255, 255, 255, 0.1); }
.message-input button#send-message { background-color: var(--primary-color); opacity: 1; }
.message-input button#send-message:hover { background-color: var(--primary-hover); transform: scale(1.05); }

.emoji-picker { position: absolute; bottom: 65px; right: 10px; display: none; z-index: 9999; box-shadow: var(--shadow-lg); border-radius: var(--border-radius); overflow: hidden; }
.emoji-picker.active { display: block; }
.hidden { display: none !important; }

@media (min-width: 1024px) {
    .chat-toggle { display: none !important; }
    #flip-camera { display: none !important; }
}

/* CHAT ONLY MODE GIAO DIỆN (TRÀN MÀN HÌNH CHUYÊN NGHIỆP) */
body.chat-only-mode .main-content { flex-direction: column; align-items: center; }
body.chat-only-mode .media-view { display: none !important; }
body.chat-only-mode .media-area { flex: none; width: 100%; max-width: 800px; order: 2; background: transparent; box-shadow: none; border-radius: 0; }
body.chat-only-mode .unified-controls { border-radius: var(--border-radius); box-shadow: var(--shadow); }

body.chat-only-mode .chat-box { 
    position: relative; display: flex !important; flex: 1; order: 1; 
    width: 100%; max-width: 800px; margin-bottom: var(--spacing); 
    z-index: 10; height: auto; min-height: 0; 
    border-radius: var(--border-radius); box-shadow: var(--shadow); 
}
body.chat-only-mode .chat-toggle, body.chat-only-mode .close-chat-btn { display: none !important; }

@media (max-width: 767px) {
    .app-container { padding: 10px; }
    .app-logo { font-size: 1.5rem; margin-bottom: 5px; }
    
    .mode-tabs { padding: 4px; gap: 4px; }
    .mode-tab { padding: 8px 6px; font-size: 0.75rem; gap: 4px; }
    .mode-tab i { font-size: 0.85rem; }
    
    .main-content { flex-direction: column; }
    
    .unified-controls { padding: 10px 8px; gap: 8px; justify-content: center; }
    .info-pill { font-size: 0.75rem; padding: 4px 8px; }
    .switch-container { font-size: 0.75rem; }
    .action-btn { padding: 8px 12px; font-size: 0.85rem; }
    .media-toggles { margin-left: 0; }
    .control-btn { width: 36px; height: 36px; font-size: 0.9rem; }
    
    .local-video-wrapper { width: 70px; height: 90px; bottom: 15px; right: 15px; }
    .audio-vis { width: 120px; height: 120px; }
    .audio-vis.local { width: 80px; height: 80px; }
    
    .chat-box { position: absolute; top: 0; left: 0; width: 100%; height: 100%; z-index: 150; max-width: none; display: none; border-radius: 0; }
    .chat-box.active { display: flex; }
    
    body.chat-only-mode .chat-box { max-width: 100%; margin-bottom: 10px; }
}

@media (min-width: 768px) and (max-width: 1023px) {
    .chat-box { position: absolute; top: 0; right: 0; width: 350px; height: 100%; z-index: 150; display: none; }
    .chat-box.active { display: flex; }
}