:root {
            --bg-color: #1a1a1a;
            --card-color: #2d2d2d;
            --text-color: #e0e0e0;
            --primary-color: #4a6fa5;
            --secondary-color: #3a3a3a;
            --border-color: #444;
            --hover-color: #3d5a80;
            --disabled-color: #555;
        }
        
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
        }
        
        body {
            background-color: var(--bg-color);
            color: var(--text-color);
            height: 100vh;
            display: flex;
            flex-direction: column;
        }
        
        header {
            padding: 1rem;
            border-bottom: 1px solid var(--border-color);
            display: flex;
            justify-content: space-between;
            align-items: center;
        }
        
        .logo {
            font-weight: bold;
            font-size: 1.2rem;
            display: flex;
            align-items: center;
            gap: 0.5rem;
        }
        
        .logo svg {
            width: 24px;
            height: 24px;
        }
        
        nav {
            display: flex;
            gap: 1rem;
        }
        
        nav button {
            background: none;
            border: none;
            color: var(--text-color);
            cursor: pointer;
            padding: 0.5rem;
            border-radius: 4px;
        }
        
        nav button:hover {
            background-color: var(--secondary-color);
        }
        
        main {
            flex: 1;
            display: flex;
            overflow: hidden;
        }
        
        .sidebar {
            width: 260px;
            border-right: 1px solid var(--border-color);
            padding: 1rem;
            display: flex;
            flex-direction: column;
            gap: 1rem;
        }
        
        .new-chat-btn {
            background-color: var(--primary-color);
            color: white;
            border: none;
            padding: 0.75rem;
            border-radius: 6px;
            cursor: pointer;
            display: flex;
            align-items: center;
            justify-content: center;
            gap: 0.5rem;
            font-weight: 500;
        }
        
        .new-chat-btn:hover {
            background-color: var(--hover-color);
        }
        
        .chat-history {
            flex: 1;
            overflow-y: auto;
        }
        
        .chat-item {
            padding: 0.75rem;
            border-radius: 6px;
            cursor: pointer;
            white-space: nowrap;
            overflow: hidden;
            text-overflow: ellipsis;
        }
        
        .chat-item:hover {
            background-color: var(--secondary-color);
        }
        
        .chat-container {
            flex: 1;
            display: flex;
            flex-direction: column;
            position: relative;
        }
        
        .chat-messages {
            flex: 1;
            overflow-y: auto;
            padding: 1.5rem;
            display: flex;
            flex-direction: column;
            gap: 1.5rem;
        }
        
        .message {
            max-width: 800px;
            margin: 0 auto;
            width: 100%;
        }
        
        .user-message {
            margin-left: auto;
        }
        
        .ai-message {
            margin-right: auto;
            display: flex;
            gap: 1rem;
        }
        
        .avatar {
            width: 36px;
            height: 36px;
            border-radius: 50%;
            background-color: var(--primary-color);
            display: flex;
            align-items: center;
            justify-content: center;
            flex-shrink: 0;
        }
        
        .message-content {
            background-color: var(--card-color);
            padding: 1rem;
            border-radius: 8px;
            line-height: 1.6;
        }
        
        .user-message .message-content {
            background-color: var(--secondary-color);
        }
        
        .input-container {
            padding: 1rem;
            display: flex;
            justify-content: center;
            position: relative;
        }
        
        .input-wrapper {
            max-width: 800px;
            width: 100%;
            position: relative;
        }
        
        .chat-input {
            width: 100%;
            background-color: var(--card-color);
            border: 1px solid var(--border-color);
            border-radius: 8px;
            padding: 1rem 3.5rem 1rem 1rem;
            color: var(--text-color);
            resize: none;
            min-height: 60px;
            max-height: 200px;
            outline: none;
        }
        
        .chat-input:focus {
            border-color: var(--primary-color);
        }
        
        .send-btn {
            position: absolute;
            right: 1rem;
            bottom: 1rem;
            background-color: var(--primary-color);
            color: white;
            border: none;
            width: 32px;
            height: 32px;
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            cursor: pointer;
        }
        
        .send-btn:hover {
            background-color: var(--hover-color);
        }
        
        .send-btn:disabled {
            background-color: var(--disabled-color);
            cursor: not-allowed;
        }
        
        .model-selector {
            position: absolute;
            top: -2.5rem;
            left: 0;
            background-color: var(--card-color);
            border-radius: 6px;
            padding: 0.5rem;
            display: flex;
            gap: 0.5rem;
        }
        
        .model-btn {
            background-color: var(--secondary-color);
            border: none;
            color: var(--text-color);
            padding: 0.5rem 1rem;
            border-radius: 4px;
            cursor: pointer;
            font-size: 0.85rem;
        }
        
        .model-btn.active {
            background-color: var(--primary-color);
        }
        
        .typing-indicator {
            display: none;
            padding: 1rem;
            text-align: center;
            color: #aaa;
        }
        
        @media (max-width: 768px) {
            .sidebar {
                display: none;
            }
            
            .model-selector {
                top: -3.5rem;
            }
        }