/* CSS Variables for Theme Support */
:root {
    --primary-color: #3b82f6;
    --primary-hover: #2563eb;
    --secondary-color: #6b7280;
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --error-color: #ef4444;
    
    --bg-primary: #ffffff;
    --bg-secondary: #f8fafc;
    --bg-tertiary: #f1f5f9;
    --bg-chat: #ffffff;
    --bg-message-user: #3b82f6;
    --bg-message-assistant: #f1f5f9;
    
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --text-muted: #9ca3af;
    --text-inverse: #ffffff;
    
    --border-color: #e5e7eb;
    --border-hover: #d1d5db;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
}

/* Dark Theme */
[data-theme="dark"] {
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --bg-tertiary: #334155;
    --bg-chat: #1e293b;
    --bg-message-user: #3b82f6;
    --bg-message-assistant: #334155;
    
    --text-primary: #f8fafc;
    --text-secondary: #cbd5e1;
    --text-muted: #94a3b8;
    --text-inverse: #ffffff;
    
    --border-color: #334155;
    --border-hover: #475569;
}

/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color 0.3s ease, color 0.3s ease;
}

/* App Container */
.app-container {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header */
.header {
    background-color: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 100;
    backdrop-filter: blur(10px);
}

.header-content {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.logo-icon {
    font-size: 2rem;
    filter: drop-shadow(0 2px 4px rgba(0, 0, 0, 0.1));
}

.logo h1 {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
}

.header-actions {
    display: flex;
    gap: 0.75rem;
    align-items: center;
}

/* Buttons */
.btn-primary {
    background-color: var(--primary-color);
    color: var(--text-inverse);
    border: none;
    padding: 0.75rem 1.5rem;
    border-radius: var(--radius-md);
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

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

.btn-secondary {
    background-color: transparent;
    color: var(--text-secondary);
    border: 1px solid var(--border-color);
    padding: 0.5rem 1rem;
    border-radius: var(--radius-md);
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
}

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

/* Main Content */
.main-content {
    flex: 1;
    display: flex;
    max-width: 1400px;
    margin: 0 auto;
    width: 100%;
    gap: 1.5rem;
    padding: 1.5rem;
}

/* Sidebar */
.sidebar {
    width: 300px;
    background-color: var(--bg-secondary);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    height: fit-content;
    position: sticky;
    top: 100px;
    border: 1px solid var(--border-color);
}

.sidebar h3 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px solid var(--border-color);
}

.quick-actions, .subjects {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    margin-bottom: 2rem;
}

.action-btn, .subject-btn {
    background-color: transparent;
    color: var(--text-secondary);
    border: 1px solid var(--border-color);
    padding: 0.75rem 1rem;
    border-radius: var(--radius-md);
    text-align: left;
    cursor: pointer;
    transition: all 0.2s ease;
    font-size: 0.875rem;
}

.action-btn:hover, .subject-btn:hover {
    background-color: var(--bg-tertiary);
    border-color: var(--primary-color);
    color: var(--text-primary);
    transform: translateX(2px);
}

.subject-btn.active {
    background-color: var(--primary-color);
    color: var(--text-inverse);
    border-color: var(--primary-color);
}

.study-tips {
    margin-top: 1rem;
}

.tips-container {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.tip {
    background-color: var(--bg-tertiary);
    padding: 1rem;
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    line-height: 1.5;
    border-left: 3px solid var(--primary-color);
}

/* Chat Section */
.chat-section {
    flex: 1;
    display: flex;
    flex-direction: column;
}

.chat-container {
    background-color: var(--bg-chat);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    height: calc(100vh - 200px);
    overflow: hidden;
}

.chat-messages {
    flex: 1;
    overflow-y: auto;
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.message {
    display: flex;
    gap: 0.75rem;
    max-width: 80%;
    animation: fadeInUp 0.3s ease;
}

.message.user {
    align-self: flex-end;
    flex-direction: row-reverse;
}

.message-avatar {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
    flex-shrink: 0;
    background-color: var(--bg-tertiary);
}

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

.message-content {
    flex: 1;
}

.message-text {
    background-color: var(--bg-message-assistant);
    padding: 1rem 1.25rem;
    border-radius: var(--radius-lg);
    font-size: 0.95rem;
    line-height: 1.6;
    word-wrap: break-word;
}

.message.user .message-text {
    background-color: var(--bg-message-user);
    color: var(--text-inverse);
}

.message-time {
    font-size: 0.75rem;
    color: var(--text-muted);
    margin-top: 0.5rem;
    padding-left: 1.25rem;
}

.message.user .message-time {
    text-align: right;
    padding-left: 0;
    padding-right: 1.25rem;
}

/* Chat Input */
.chat-input-container {
    border-top: 1px solid var(--border-color);
    padding: 1.5rem;
    background-color: var(--bg-secondary);
}

.chat-input-wrapper {
    display: flex;
    gap: 0.75rem;
    align-items: flex-end;
}

#messageInput {
    flex: 1;
    background-color: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 1rem 1.25rem;
    font-size: 0.95rem;
    line-height: 1.5;
    resize: none;
    min-height: 50px;
    max-height: 120px;
    font-family: inherit;
    color: var(--text-primary);
    transition: all 0.2s ease;
}

#messageInput:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

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

.send-btn {
    background-color: var(--primary-color);
    color: var(--text-inverse);
    border: none;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s ease;
    flex-shrink: 0;
}

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

.send-btn:disabled {
    background-color: var(--text-muted);
    cursor: not-allowed;
    opacity: 0.5;
}

.input-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 0.75rem;
    font-size: 0.75rem;
    color: var(--text-muted);
}

.typing-indicator {
    color: var(--primary-color);
    font-weight: 500;
    animation: pulse 1.5s ease-in-out infinite;
}

/* Loading Overlay */
.loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: rgba(0, 0, 0, 0.5);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    backdrop-filter: blur(4px);
}

.loading-spinner {
    width: 40px;
    height: 40px;
    border: 3px solid var(--border-color);
    border-top: 3px solid var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin-bottom: 1rem;
}

.loading-overlay p {
    color: var(--text-inverse);
    font-weight: 500;
}

/* Animations */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

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

/* Scrollbar Styling */
.chat-messages::-webkit-scrollbar {
    width: 6px;
}

.chat-messages::-webkit-scrollbar-track {
    background: var(--bg-secondary);
    border-radius: 3px;
}

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

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

/* Responsive Design */
@media (max-width: 1024px) {
    .main-content {
        flex-direction: column;
        gap: 1rem;
        padding: 1rem;
    }
    
    .sidebar {
        width: 100%;
        position: static;
    }
    
    .quick-actions, .subjects {
        flex-direction: row;
        flex-wrap: wrap;
        gap: 0.5rem;
    }
    
    .action-btn, .subject-btn {
        flex: 1;
        min-width: 120px;
        text-align: center;
    }
}

@media (max-width: 768px) {
    .header-content {
        padding: 0 1rem;
    }
    
    .logo h1 {
        font-size: 1.25rem;
    }
    
    .main-content {
        padding: 0.75rem;
    }
    
    .sidebar {
        padding: 1rem;
    }
    
    .chat-container {
        height: calc(100vh - 180px);
    }
    
    .message {
        max-width: 95%;
    }
    
    .chat-messages {
        padding: 1rem;
    }
    
    .chat-input-container {
        padding: 1rem;
    }
}

@media (max-width: 480px) {
    .header-content {
        flex-direction: column;
        gap: 1rem;
        text-align: center;
    }
    
    .header-actions {
        order: -1;
    }
    
    .quick-actions, .subjects {
        flex-direction: column;
    }
    
    .action-btn, .subject-btn {
        text-align: left;
    }
    
    .chat-input-wrapper {
        flex-direction: column;
        gap: 0.5rem;
    }
    
    .send-btn {
        align-self: flex-end;
    }
}

/* Print Styles */
@media print {
    .sidebar,
    .chat-input-container,
    .header-actions {
        display: none;
    }
    
    .main-content {
        flex-direction: column;
    }
    
    .chat-container {
        height: auto;
        border: none;
        box-shadow: none;
    }
}