/* ===== CSS Variables & Reset ===== */
:root {
    /* Colors */
    --bg-primary: #0f0f14;
    --bg-secondary: #16161d;
    --bg-tertiary: #1c1c26;
    --bg-hover: #22222e;
    --bg-active: #2a2a38;
    
    --text-primary: #f0f0f5;
    --text-secondary: #a0a0b0;
    --text-muted: #606070;
    
    --accent-primary: #6366f1;
    --accent-secondary: #a855f7;
    --accent-gradient: linear-gradient(135deg, #6366f1 0%, #a855f7 100%);
    
    --border-color: #2a2a38;
    --border-light: #3a3a4a;
    
    --success: #22c55e;
    --warning: #f59e0b;
    --error: #ef4444;
    
    /* Shadows */
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.5);
    --glow: 0 0 20px rgba(99, 102, 241, 0.3);
    
    /* Spacing */
    --sidebar-width: 280px;
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 250ms ease;
    --transition-slow: 350ms ease;
    
    /* Border Radius */
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 16px;
    --radius-xl: 24px;
}

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

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    overflow: hidden;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ===== Layout ===== */
.app-container {
    display: flex;
    height: 100vh;
    width: 100vw;
    overflow: hidden;
}

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

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

.logo {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 20px;
}

.logo-icon {
    width: 40px;
    height: 40px;
    background: var(--accent-gradient);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    box-shadow: var(--glow);
}

.logo-text {
    font-size: 1.25rem;
    font-weight: 600;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.new-chat-btn {
    width: 100%;
    padding: 12px 16px;
    background: var(--accent-gradient);
    border: none;
    border-radius: var(--radius-md);
    color: white;
    font-size: 0.9rem;
    font-weight: 500;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    transition: all var(--transition-fast);
    box-shadow: var(--shadow-sm);
}

.new-chat-btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md), var(--glow);
}

.new-chat-btn:active {
    transform: translateY(0);
}

.chat-history {
    flex: 1;
    overflow-y: auto;
    padding: 16px 12px;
}

.chat-history::-webkit-scrollbar {
    width: 6px;
}

.chat-history::-webkit-scrollbar-track {
    background: transparent;
}

.chat-history::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 3px;
}

.history-section h3 {
    font-size: 0.75rem;
    font-weight: 500;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    padding: 8px 12px;
}

.history-item {
    padding: 12px 16px;
    border-radius: var(--radius-md);
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 10px;
    transition: all var(--transition-fast);
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 4px;
}

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

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

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

.history-item-text {
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.sidebar-footer {
    padding: 16px 20px;
    border-top: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: space-between;
}

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

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

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

.settings-btn {
    width: 36px;
    height: 36px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-fast);
}

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

/* ===== Main Content ===== */
.main-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    background: var(--bg-primary);
    min-width: 0;
}

.chat-header {
    padding: 16px 24px;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    gap: 16px;
    background: var(--bg-primary);
    backdrop-filter: blur(10px);
}

.menu-toggle {
    display: none;
    width: 40px;
    height: 40px;
    background: transparent;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    border-radius: var(--radius-sm);
    align-items: center;
    justify-content: center;
    transition: all var(--transition-fast);
}

.menu-toggle:hover {
    background: var(--bg-hover);
    color: var(--text-primary);
}

.chat-header h1 {
    flex: 1;
    font-size: 1.1rem;
    font-weight: 500;
    color: var(--text-primary);
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

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

.icon-btn {
    width: 36px;
    height: 36px;
    background: transparent;
    border: 1px solid transparent;
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-fast);
}

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

/* ===== Chat Container ===== */
.chat-container {
    flex: 1;
    overflow-y: auto;
    padding: 24px;
    display: flex;
    flex-direction: column;
}

.chat-container::-webkit-scrollbar {
    width: 8px;
}

.chat-container::-webkit-scrollbar-track {
    background: transparent;
}

.chat-container::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 4px;
}

.chat-container::-webkit-scrollbar-thumb:hover {
    background: var(--border-light);
}

/* ===== Welcome Screen ===== */
.welcome-screen {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 40px 20px;
    animation: fadeIn 0.5s ease;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

.welcome-icon {
    margin-bottom: 24px;
    animation: float 3s ease-in-out infinite;
}

@keyframes float {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-10px); }
}

.welcome-screen h2 {
    font-size: 2rem;
    font-weight: 600;
    margin-bottom: 8px;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.welcome-screen p {
    color: var(--text-secondary);
    margin-bottom: 40px;
}

.suggestions {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 12px;
    max-width: 600px;
    width: 100%;
}

.suggestion-card {
    padding: 16px 20px;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-secondary);
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 12px;
    text-align: left;
    transition: all var(--transition-fast);
    font-size: 0.9rem;
}

.suggestion-card:hover {
    background: var(--bg-hover);
    border-color: var(--accent-primary);
    color: var(--text-primary);
    transform: translateY(-2px);
    box-shadow: var(--shadow-sm);
}

.suggestion-icon {
    font-size: 1.2rem;
}

/* ===== Messages ===== */
.messages-container {
    display: flex;
    flex-direction: column;
    gap: 24px;
    max-width: 800px;
    width: 100%;
    margin: 0 auto;
}

.message {
    display: flex;
    gap: 16px;
    animation: messageIn 0.3s ease;
}

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

.message-avatar {
    width: 36px;
    height: 36px;
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    font-weight: 600;
    font-size: 0.85rem;
}

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

.message.assistant .message-avatar {
    background: var(--accent-gradient);
    color: white;
    box-shadow: var(--glow);
}

.message-content {
    flex: 1;
    min-width: 0;
}

.message-text {
    color: var(--text-primary);
    line-height: 1.7;
    word-wrap: break-word;
}

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

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

.message-text code {
    background: var(--bg-tertiary);
    padding: 2px 6px;
    border-radius: 4px;
    font-family: 'SF Mono', 'Fira Code', 'Monaco', monospace;
    font-size: 0.9em;
}

.message-text pre {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 16px;
    overflow-x: auto;
    margin: 12px 0;
}

.message-text pre code {
    background: transparent;
    padding: 0;
}

/* Typing Indicator */
.typing-indicator {
    display: flex;
    gap: 4px;
    padding: 8px 0;
}

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

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

@keyframes typingPulse {
    0%, 80%, 100% { transform: scale(0.6); opacity: 0.5; }
    40% { transform: scale(1); opacity: 1; }
}

/* ===== Input Area ===== */
.input-area {
    padding: 16px 24px 24px;
    background: var(--bg-primary);
}

.input-wrapper {
    max-width: 800px;
    margin: 0 auto;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    display: flex;
    align-items: flex-end;
    padding: 8px 8px 8px 16px;
    transition: all var(--transition-fast);
}

.input-wrapper:focus-within {
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.15);
}

.input-wrapper textarea {
    flex: 1;
    background: transparent;
    border: none;
    outline: none;
    color: var(--text-primary);
    font-size: 1rem;
    font-family: inherit;
    line-height: 1.5;
    resize: none;
    max-height: 200px;
    padding: 8px 0;
}

.input-wrapper textarea::placeholder {
    color: var(--text-muted);
}

.send-btn, .stop-btn {
    width: 40px;
    height: 40px;
    border-radius: var(--radius-md);
    border: none;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-fast);
    flex-shrink: 0;
}

.send-btn {
    background: var(--accent-gradient);
    color: white;
    box-shadow: var(--shadow-sm);
}

.send-btn:disabled {
    background: var(--bg-tertiary);
    color: var(--text-muted);
    cursor: not-allowed;
    box-shadow: none;
}

.send-btn:not(:disabled):hover {
    transform: scale(1.05);
    box-shadow: var(--shadow-md), var(--glow);
}

.stop-btn {
    background: var(--error);
    color: white;
}

.stop-btn:hover {
    background: #dc2626;
}

.hidden {
    display: none !important;
}

.disclaimer {
    text-align: center;
    font-size: 0.75rem;
    color: var(--text-muted);
    margin-top: 12px;
}

/* ===== Modal ===== */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.7);
    backdrop-filter: blur(4px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    padding: 20px;
    animation: fadeIn 0.2s ease;
}

.modal {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    width: 100%;
    max-width: 500px;
    max-height: 90vh;
    overflow: hidden;
    display: flex;
    flex-direction: column;
    box-shadow: var(--shadow-lg);
    animation: slideUp 0.3s ease;
}

@keyframes slideUp {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

.modal-header {
    padding: 20px 24px;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.modal-header h2 {
    font-size: 1.25rem;
    font-weight: 600;
}

.modal-close {
    width: 36px;
    height: 36px;
    background: transparent;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-fast);
}

.modal-close:hover {
    background: var(--bg-hover);
    color: var(--text-primary);
}

.modal-body {
    padding: 24px;
    overflow-y: auto;
    flex: 1;
}

.setting-group {
    margin-bottom: 24px;
}

.setting-group:last-child {
    margin-bottom: 0;
}

.setting-group label {
    display: block;
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-primary);
    margin-bottom: 8px;
}

.setting-group input[type="text"],
.setting-group input[type="number"],
.setting-group textarea {
    width: 100%;
    padding: 12px 14px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-size: 0.95rem;
    font-family: inherit;
    transition: all var(--transition-fast);
}

.setting-group input:focus,
.setting-group textarea:focus {
    outline: none;
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.15);
}

.setting-group input[type="range"] {
    width: 100%;
    height: 6px;
    background: var(--bg-tertiary);
    border-radius: 3px;
    appearance: none;
    cursor: pointer;
}

.setting-group input[type="range"]::-webkit-slider-thumb {
    appearance: none;
    width: 18px;
    height: 18px;
    background: var(--accent-primary);
    border-radius: 50%;
    cursor: pointer;
    box-shadow: var(--shadow-sm);
    transition: transform var(--transition-fast);
}

.setting-group input[type="range"]::-webkit-slider-thumb:hover {
    transform: scale(1.1);
}

.setting-hint {
    display: block;
    font-size: 0.8rem;
    color: var(--text-muted);
    margin-top: 6px;
}

.modal-footer {
    padding: 16px 24px;
    border-top: 1px solid var(--border-color);
    display: flex;
    gap: 12px;
    justify-content: flex-end;
}

.btn-primary, .btn-secondary {
    padding: 10px 20px;
    border-radius: var(--radius-md);
    font-size: 0.9rem;
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.btn-primary {
    background: var(--accent-gradient);
    border: none;
    color: white;
}

.btn-primary:hover {
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
}

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

/* ===== Responsive ===== */
@media (max-width: 768px) {
    .sidebar {
        position: fixed;
        left: 0;
        top: 0;
        height: 100vh;
        transform: translateX(-100%);
    }
    
    .sidebar.open {
        transform: translateX(0);
        box-shadow: var(--shadow-lg);
    }
    
    .menu-toggle {
        display: flex;
    }
    
    .suggestions {
        grid-template-columns: 1fr;
    }
    
    .chat-container {
        padding: 16px;
    }
    
    .input-area {
        padding: 12px 16px 16px;
    }
}

@media (max-width: 480px) {
    .welcome-screen h2 {
        font-size: 1.5rem;
    }
    
    .message {
        gap: 12px;
    }
    
    .message-avatar {
        width: 32px;
        height: 32px;
        font-size: 0.75rem;
    }
}

/* ===== Error Message ===== */
.error-message {
    background: rgba(239, 68, 68, 0.1);
    border: 1px solid rgba(239, 68, 68, 0.3);
    border-radius: var(--radius-md);
    padding: 12px 16px;
    color: #fca5a5;
    font-size: 0.9rem;
}

/* ===== Copy Button ===== */
.copy-btn {
    position: absolute;
    top: 8px;
    right: 8px;
    padding: 6px 10px;
    background: var(--bg-hover);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    font-size: 0.75rem;
    cursor: pointer;
    opacity: 0;
    transition: all var(--transition-fast);
}

.message-text pre {
    position: relative;
}

.message-text pre:hover .copy-btn {
    opacity: 1;
}

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