:root {
    --bg-primary: #0f0f0f;
    --bg-secondary: #1a1a1a;
    --bg-tertiary: #252525;
    --bg-hover: #2a2a2a;
    --text-primary: #ffffff;
    --text-secondary: #a0a0a0;
    --text-muted: #666666;
    --accent-primary: #3b82f6;
    --accent-secondary: #60a5fa;
    --accent-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --border-color: #333333;
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --error-color: #ef4444;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.5);
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 16px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    height: 100vh;
    overflow: hidden;
    line-height: 1.5;
}

.app-container {
    display: flex;
    height: 100vh;
    width: 100vw;
}

/* Sidebar Styles */
.sidebar {
    width: 300px;
    background: var(--bg-secondary);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    transition: var(--transition);
    z-index: 100;
}

.sidebar-header {
    padding: 20px;
    border-bottom: 1px solid var(--border-color);
}

.logo {
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 16px;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.logo svg {
    stroke: url(#gradient);
}

.new-chat-btn {
    width: 100%;
    padding: 12px;
    background: var(--accent-primary);
    color: white;
    border: none;
    border-radius: var(--radius-md);
    font-size: 0.95rem;
    font-weight: 500;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    transition: var(--transition);
}

.new-chat-btn:hover {
    background: var(--accent-secondary);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.model-selector {
    padding: 20px;
    border-bottom: 1px solid var(--border-color);
}

.model-selector label {
    display: block;
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--text-secondary);
    margin-bottom: 8px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.model-select {
    width: 100%;
    padding: 10px 12px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    color: var(--text-primary);
    font-size: 0.9rem;
    cursor: pointer;
    transition: var(--transition);
}

.model-select:hover, .model-select:focus {
    border-color: var(--accent-primary);
    outline: none;
}

.chat-history {
    flex: 1;
    overflow-y: auto;
    padding: 12px;
}

.history-item {
    padding: 12px;
    margin-bottom: 4px;
    border-radius: var(--radius-sm);
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 10px;
    transition: var(--transition);
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.history-item:hover {
    background: var(--bg-hover);
    color: var(--text-primary);
}

.history-item.active {
    background: var(--bg-tertiary);
    color: var(--text-primary);
}

.history-item svg {
    flex-shrink: 0;
    opacity: 0.6;
}

.sidebar-footer {
    padding: 16px 20px;
    border-top: 1px solid var(--border-color);
}

.stats {
    font-size: 0.8rem;
    color: var(--text-muted);
    text-align: center;
}

/* Main Chat Area */
.chat-container {
    flex: 1;
    display: flex;
    flex-direction: column;
    background: var(--bg-primary);
    position: relative;
}

.chat-header {
    height: 60px;
    padding: 0 20px;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: space-between;
    background: var(--bg-secondary);
}

.mobile-menu-btn {
    display: none;
    background: none;
    border: none;
    color: var(--text-primary);
    cursor: pointer;
    padding: 8px;
}

.current-model {
    font-weight: 500;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    gap: 8px;
}

.current-model::before {
    content: '';
    width: 8px;
    height: 8px;
    background: var(--success-color);
    border-radius: 50%;
    animation: pulse 2s infinite;
}

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.5; }
}

.header-actions {
    display: flex;
    gap: 8px;
}

.icon-btn {
    background: none;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    padding: 8px;
    border-radius: var(--radius-sm);
    transition: var(--transition);
}

.icon-btn:hover {
    background: var(--bg-hover);
    color: var(--text-primary);
}

/* Messages Container */
.messages-container {
    flex: 1;
    overflow-y: auto;
    padding: 20px;
    scroll-behavior: smooth;
}

.welcome-screen {
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
}

.welcome-content h1 {
    font-size: 2.5rem;
    margin-bottom: 12px;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.welcome-content > p {
    font-size: 1.1rem;
    color: var(--text-secondary);
    margin-bottom: 40px;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 16px;
    max-width: 800px;
    margin: 0 auto 40px;
}

.feature-card {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 20px;
    transition: var(--transition);
    cursor: pointer;
}

.feature-card:hover {
    transform: translateY(-4px);
    border-color: var(--accent-primary);
    box-shadow: var(--shadow-md);
}

.feature-icon {
    font-size: 2rem;
    margin-bottom: 12px;
    display: block;
}

.feature-card h3 {
    font-size: 0.95rem;
    margin-bottom: 6px;
    color: var(--text-primary);
}

.feature-card p {
    font-size: 0.8rem;
    color: var(--text-muted);
}

.start-prompt {
    color: var(--text-muted);
    font-size: 0.9rem;
}

.sub-text {
    font-size: 0.8rem;
    margin-top: 8px;
    opacity: 0.7;
}

/* Chat Messages */
.message {
    max-width: 85%;
    margin-bottom: 24px;
    animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

.message.user {
    margin-left: auto;
}

.message-header {
    display: flex;
    align-items: center;
    gap: 8px;
    margin-bottom: 8px;
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.message-avatar {
    width: 28px;
    height: 28px;
    border-radius: 50%;
    background: var(--accent-gradient);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.9rem;
}

.message.user .message-avatar {
    background: var(--bg-tertiary);
}

.message-content {
    padding: 16px 20px;
    border-radius: var(--radius-lg);
    line-height: 1.6;
    font-size: 0.95rem;
}

.message.ai .message-content {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
}

.message.user .message-content {
    background: var(--accent-primary);
    color: white;
}

.message-content pre {
    background: #1e1e1e;
    border-radius: var(--radius-sm);
    padding: 16px;
    overflow-x: auto;
    margin: 12px 0;
}

.message-content code {
    font-family: 'Fira Code', 'Consolas', monospace;
    font-size: 0.9em;
}

.message-content p {
    margin-bottom: 12px;
}

.message-content p:last-child {
    margin-bottom: 0;
}

.message-content ul, .message-content ol {
    margin-left: 20px;
    margin-bottom: 12px;
}

.message-content li {
    margin-bottom: 4px;
}

.typing-indicator {
    display: flex;
    gap: 4px;
    padding: 20px;
    align-items: center;
}

.typing-indicator span {
    width: 8px;
    height: 8px;
    background: var(--accent-primary);
    border-radius: 50%;
    animation: bounce 1.4s infinite ease-in-out both;
}

.typing-indicator span:nth-child(1) { animation-delay: -0.32s; }
.typing-indicator span:nth-child(2) { animation-delay: -0.16s; }

@keyframes bounce {
    0%, 80%, 100% { transform: scale(0); }
    40% { transform: scale(1); }
}

/* Input Container */
.input-container {
    padding: 20px;
    background: var(--bg-secondary);
    border-top: 1px solid var(--border-color);
}

.input-wrapper {
    display: flex;
    gap: 12px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 4px;
    transition: var(--transition);
}

.input-wrapper:focus-within {
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

#messageInput {
    flex: 1;
    background: none;
    border: none;
    color: var(--text-primary);
    padding: 12px 16px;
    font-size: 0.95rem;
    resize: none;
    max-height: 200px;
    font-family: inherit;
}

#messageInput:focus {
    outline: none;
}

.send-btn {
    background: var(--accent-primary);
    color: white;
    border: none;
    border-radius: var(--radius-md);
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: var(--transition);
    margin: 4px;
}

.send-btn:hover:not(:disabled) {
    background: var(--accent-secondary);
    transform: scale(1.05);
}

.send-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.input-footer {
    margin-top: 8px;
    text-align: center;
}

.disclaimer {
    font-size: 0.75rem;
    color: var(--text-muted);
}

/* Responsive */
@media (max-width: 768px) {
    .sidebar {
        position: fixed;
        left: -300px;
        height: 100vh;
    }

    .sidebar.open {
        left: 0;
    }

    .mobile-menu-btn {
        display: block;
    }

    .features-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .message {
        max-width: 95%;
    }
}

@media (max-width: 480px) {
    .features-grid {
        grid-template-columns: 1fr;
    }

    .welcome-content h1 {
        font-size: 1.8rem;
    }
}

/* Scrollbar */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-primary);
}

::-webkit-scrollbar-thumb {
    background: var(--bg-tertiary);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--border-color);
}

/* Code highlighting */
.hljs {
    background: #1e1e1e !important;
    border-radius: var(--radius-sm);
}