/* ========================================
   Responsive Design
   ======================================== */
@media (max-width: 768px) {
    .sidebar-container {
        position: fixed;
        top: 0;
        left: 0;
        height: 100vh;
        z-index: 100;
        box-shadow: var(--shadow-lg);
    }
    
    .sidebar-container.collapsed {
        margin-left: calc(-1 * var(--sidebar-width));
    }
    
    .feature-grid {
        grid-template-columns: 1fr;
    }
    
    .welcome-message h1 {
        font-size: 1.5rem;
    }
    
    .message.user .message-content {
        max-width: 85%;
    }
    
    .chat-header {
        padding: 0 12px;
    }
    
    .model-selector {
        padding: 4px 8px;
    }
    
    .input-container {
        padding: 12px;
    }
}

@media (max-width: 480px) {
    .message.user .message-content {
        max-width: 90%;
    }
    
    .avatar {
        width: 28px;
        height: 28px;
    }
}