/* ==========================================
   CHATAI - AI CHAT INTERFACE
   ========================================== */

:root {
    /* Dark Theme Colors */
    --bg-primary: #0F172A;
    --bg-secondary: #1E293B;
    --bg-tertiary: #334155;
    --bg-hover: #2D3748;
    --text-primary: #F8FAFC;
    --text-secondary: #CBD5E1;
    --text-muted: #94A3B8;
    --border-color: #334155;
    --accent-primary: #667eea;
    --accent-secondary: #764ba2;
    --success: #10b981;
    --warning: #f59e0b;

    /* User vs AI colors */
    --user-bg: #667eea;
    --ai-bg: #1E293B;

    /* Typography */
    --font-primary: 'Inter', -apple-system, sans-serif;
    --font-mono: 'JetBrains Mono', monospace;

    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 0.75rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;

    /* Shadows */
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 10px 30px rgba(0, 0, 0, 0.5);

    /* Transitions */
    --transition: 200ms cubic-bezier(0.4, 0, 0.2, 1);

    /* Sidebar */
    --sidebar-width: 280px;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-primary);
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    display: flex;
    height: 100vh;
    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: var(--transition);
}

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

.back-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.875rem;
    margin-bottom: var(--spacing-md);
    transition: var(--transition);
}

.back-link:hover {
    color: var(--text-primary);
}

.new-chat-btn {
    width: 100%;
    padding: 0.75rem 1rem;
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    font-size: 0.9375rem;
    font-weight: 500;
    border-radius: 0.5rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 0.75rem;
    transition: var(--transition);
}

.new-chat-btn:hover {
    background: var(--bg-hover);
}

.chat-history {
    flex: 1;
    overflow-y: auto;
    padding: var(--spacing-md);
}

.history-section {
    margin-bottom: var(--spacing-lg);
}

.history-section h3 {
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: var(--spacing-sm);
}

.history-item {
    padding: 0.625rem 0.75rem;
    border-radius: 0.5rem;
    color: var(--text-secondary);
    font-size: 0.875rem;
    cursor: pointer;
    transition: var(--transition);
    margin-bottom: 0.25rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

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

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

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

.user-profile {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: 0.75rem;
    border-radius: 0.5rem;
    cursor: pointer;
    transition: var(--transition);
}

.user-profile:hover {
    background: var(--bg-hover);
}

.user-avatar {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
}

.user-info {
    flex: 1;
}

.user-name {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-primary);
}

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

/* ==========================================
   MAIN CONTENT
   ========================================== */

.main-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.chat-header {
    padding: var(--spacing-md) var(--spacing-lg);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    background: var(--bg-secondary);
}

.menu-toggle {
    display: none;
    width: 40px;
    height: 40px;
    background: transparent;
    border: none;
    color: var(--text-primary);
    cursor: pointer;
    border-radius: 0.5rem;
    transition: var(--transition);
}

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

.header-title {
    flex: 1;
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.header-title h1 {
    font-size: 1.25rem;
    font-weight: 600;
}

.model-badge {
    padding: 0.375rem 0.75rem;
    background: rgba(102, 126, 234, 0.1);
    color: var(--accent-primary);
    font-size: 0.75rem;
    font-weight: 600;
    border-radius: 1rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.header-actions {
    display: flex;
    gap: var(--spacing-sm);
}

.icon-btn {
    width: 40px;
    height: 40px;
    background: transparent;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    border-radius: 0.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
}

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

/* ==========================================
   CHAT CONTAINER
   ========================================== */

.chat-container {
    flex: 1;
    overflow-y: auto;
    position: relative;
}

/* Scrollbar Styling */
.chat-container::-webkit-scrollbar,
.chat-history::-webkit-scrollbar {
    width: 8px;
}

.chat-container::-webkit-scrollbar-track,
.chat-history::-webkit-scrollbar-track {
    background: var(--bg-secondary);
}

.chat-container::-webkit-scrollbar-thumb,
.chat-history::-webkit-scrollbar-thumb {
    background: var(--bg-tertiary);
    border-radius: 4px;
}

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

/* ==========================================
   WELCOME SCREEN
   ========================================== */

.welcome-screen {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 100%;
    padding: var(--spacing-xl);
}

.welcome-content {
    max-width: 800px;
    text-align: center;
}

.ai-logo {
    width: 80px;
    height: 80px;
    margin: 0 auto var(--spacing-lg);
    animation: float 3s ease-in-out infinite;
}

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

.welcome-content h2 {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
    background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.welcome-content > p {
    color: var(--text-secondary);
    font-size: 1.125rem;
    margin-bottom: var(--spacing-xl);
}

.suggestions h3 {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: var(--spacing-md);
}

.suggestion-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-md);
}

.suggestion-card {
    padding: var(--spacing-lg);
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 0.75rem;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-sm);
    text-align: center;
}

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

.suggestion-card svg {
    color: var(--accent-primary);
}

.suggestion-card span {
    color: var(--text-secondary);
    font-size: 0.9375rem;
}

/* ==========================================
   MESSAGES
   ========================================== */

.messages-container {
    padding: var(--spacing-xl) var(--spacing-lg);
    max-width: 900px;
    margin: 0 auto;
    width: 100%;
}

.message {
    display: flex;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-xl);
    animation: fadeIn 0.3s ease;
}

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

.message-avatar {
    width: 40px;
    height: 40px;
    border-radius: 0.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.message.user .message-avatar {
    background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
}

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

.message-content {
    flex: 1;
    color: var(--text-primary);
}

.message-role {
    font-size: 0.875rem;
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
}

.message.user .message-role {
    color: var(--accent-primary);
}

.message.ai .message-role {
    color: var(--success);
}

.message-text {
    font-size: 0.9375rem;
    line-height: 1.7;
    color: var(--text-secondary);
}

.message-text p {
    margin-bottom: var(--spacing-sm);
}

.message-text code {
    padding: 0.2rem 0.4rem;
    background: var(--bg-tertiary);
    border-radius: 0.25rem;
    font-family: var(--font-mono);
    font-size: 0.875rem;
    color: var(--accent-primary);
}

.message-text pre {
    padding: var(--spacing-md);
    background: var(--bg-tertiary);
    border-radius: 0.5rem;
    overflow-x: auto;
    margin: var(--spacing-sm) 0;
}

.message-text pre code {
    padding: 0;
    background: none;
    color: var(--text-primary);
}

.typing-indicator {
    display: flex;
    gap: 0.5rem;
    padding: var(--spacing-sm) 0;
}

.typing-dot {
    width: 8px;
    height: 8px;
    background: var(--text-muted);
    border-radius: 50%;
    animation: typing 1.4s infinite;
}

.typing-dot:nth-child(2) {
    animation-delay: 0.2s;
}

.typing-dot:nth-child(3) {
    animation-delay: 0.4s;
}

@keyframes typing {
    0%, 60%, 100% {
        transform: translateY(0);
        opacity: 0.5;
    }
    30% {
        transform: translateY(-10px);
        opacity: 1;
    }
}

/* ==========================================
   INPUT AREA
   ========================================== */

.input-area {
    padding: var(--spacing-lg);
    border-top: 1px solid var(--border-color);
    background: var(--bg-secondary);
}

.input-container {
    max-width: 900px;
    margin: 0 auto;
    display: flex;
    gap: var(--spacing-sm);
    align-items: flex-end;
    padding: var(--spacing-sm);
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: 0.75rem;
    transition: var(--transition);
}

.input-container:focus-within {
    border-color: var(--accent-primary);
}

.attach-btn {
    width: 36px;
    height: 36px;
    background: transparent;
    border: none;
    color: var(--text-muted);
    cursor: pointer;
    border-radius: 0.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    transition: var(--transition);
}

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

#messageInput {
    flex: 1;
    background: transparent;
    border: none;
    color: var(--text-primary);
    font-family: var(--font-primary);
    font-size: 0.9375rem;
    resize: none;
    outline: none;
    max-height: 200px;
    line-height: 1.5;
}

#messageInput::placeholder {
    color: var(--text-muted);
}

.send-btn {
    width: 36px;
    height: 36px;
    background: var(--accent-primary);
    border: none;
    color: white;
    cursor: pointer;
    border-radius: 0.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    transition: var(--transition);
}

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

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

.input-hint {
    text-align: center;
    font-size: 0.75rem;
    color: var(--text-muted);
    margin-top: var(--spacing-sm);
    max-width: 900px;
    margin-left: auto;
    margin-right: auto;
}

/* ==========================================
   RESPONSIVE
   ========================================== */

@media (max-width: 1024px) {
    .sidebar {
        position: fixed;
        left: -var(--sidebar-width);
        top: 0;
        bottom: 0;
        z-index: 1000;
    }

    .sidebar.open {
        left: 0;
    }

    .menu-toggle {
        display: flex;
    }

    .main-content {
        width: 100%;
    }
}

@media (max-width: 768px) {
    .suggestion-grid {
        grid-template-columns: 1fr;
    }

    .messages-container {
        padding: var(--spacing-md);
    }

    .input-area {
        padding: var(--spacing-md);
    }

    .message {
        gap: var(--spacing-sm);
    }

    .message-avatar {
        width: 32px;
        height: 32px;
    }
}

@media (max-width: 480px) {
    .header-title h1 {
        font-size: 1rem;
    }

    .model-badge {
        display: none;
    }

    .welcome-content h2 {
        font-size: 1.5rem;
    }
}

/* ==========================================
   UTILITY CLASSES
   ========================================== */

.hidden {
    display: none !important;
}

/* Overlay for mobile sidebar */
.sidebar-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.5);
    z-index: 999;
    display: none;
}

.sidebar-overlay.show {
    display: block;
}