:root {
    --primary-color: #007bff;
    --primary-dark: #0056b3;
    --secondary-color: #6c757d;
    --success-color: #28a745;
    --danger-color: #dc3545;
    --warning-color: #ffc107;
    --info-color: #17a2b8;
    --light-color: #f8f9fa;
    --dark-color: #343a40;
    --white: #ffffff;
    --gray-100: #f8f9fa;
    --gray-200: #e9ecef;
    --gray-300: #dee2e6;
    --gray-400: #ced4da;
    --gray-500: #adb5bd;
    --gray-600: #6c757d;
    --gray-700: #495057;
    --gray-800: #343a40;
    --gray-900: #212529;
    
    --font-family-primary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-family-mono: 'Fira Code', 'Monaco', 'Menlo', 'Ubuntu Mono', monospace;
    
    --border-radius-sm: 0.375rem;
    --border-radius: 0.5rem;
    --border-radius-lg: 0.75rem;
    --border-radius-xl: 1rem;
    
    --shadow-sm: 0 0.125rem 0.25rem rgba(0, 0, 0, 0.075);
    --shadow: 0 0.5rem 1rem rgba(0, 0, 0, 0.15);
    --shadow-lg: 0 1rem 3rem rgba(0, 0, 0, 0.175);
    
    --transition-base: all 0.2s ease-in-out;
}

/* Base styles */
body {
    font-family: var(--font-family-primary);
    line-height: 1.6;
    color: var(--gray-800);
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
}

.bg-gradient {
    background: linear-gradient(135deg, var(--gray-800) 0%, var(--gray-900) 100%) !important;
}

.gradient-text {
    background: linear-gradient(135deg, var(--primary-color), #00d4ff);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.transition-all {
    transition: var(--transition-base);
}

/* Navigation */
.navbar-brand {
    font-size: 1.5rem;
    font-weight: 700;
}

.nav-link {
    font-weight: 500;
    transition: var(--transition-base);
}

.nav-link:hover {
    background-color: rgba(255, 255, 255, 0.1);
    transform: translateY(-2px);
}

/* Modern card styling */
.modern-card {
    background: var(--white);
    border-radius: var(--border-radius-xl);
    box-shadow: var(--shadow);
    border: none;
    overflow: hidden;
    transition: var(--transition-base);
}

.modern-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

/* Chat styles */
.chat-container {
    background: var(--white);
    border-radius: var(--border-radius-xl);
    box-shadow: var(--shadow);
    overflow: hidden;
}

.chat-list {
    max-height: calc(100vh - 280px);
    overflow-y: auto;
    padding: 1.5rem;
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    scrollbar-width: thin;
    scrollbar-color: var(--gray-400) transparent;
}

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

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

.chat-list::-webkit-scrollbar-thumb {
    background: var(--gray-400);
    border-radius: var(--border-radius);
}

.chat-list::-webkit-scrollbar-thumb:hover {
    background: var(--gray-500);
}

/* Chat bubbles */
.my-chat, .ai-chat {
    position: relative;
    max-width: 75%;
    margin: 1rem 0;
    padding: 1rem 1.25rem;
    border-radius: var(--border-radius-xl);
    box-shadow: var(--shadow-sm);
    font-family: var(--font-family-primary);
    font-size: 0.95rem;
    line-height: 1.6;
    word-wrap: break-word;
    transition: var(--transition-base);
    animation: slideIn 0.3s ease-out;
}

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

.my-chat:hover, .ai-chat:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow);
}

.my-chat {
    align-self: flex-end;
    background: linear-gradient(135deg, var(--primary-color), #0d6efd);
    color: var(--white);
    margin-left: auto;
    border-bottom-right-radius: var(--border-radius-sm);
}

.my-chat::before {
    content: 'You';
    position: absolute;
    top: -1.5rem;
    right: 1rem;
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--gray-600);
    background-color: var(--white);
    padding: 0.25rem 0.75rem;
    border-radius: var(--border-radius-xl);
    box-shadow: var(--shadow-sm);
}

.ai-chat {
    align-self: flex-start;
    background: linear-gradient(135deg, var(--gray-700), var(--gray-800));
    color: var(--white);
    border-bottom-left-radius: var(--border-radius-sm);
}

.ai-chat::before {
    content: 'AI Assistant';
    position: absolute;
    top: -1.5rem;
    left: 1rem;
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--gray-600);
    background-color: var(--white);
    padding: 0.25rem 0.75rem;
    border-radius: var(--border-radius-xl);
    box-shadow: var(--shadow-sm);
}

/* AI Chat content styling */
.ai-chat table {
    border-collapse: collapse;
    width: 100%;
    margin: 1rem 0;
    background-color: var(--white);
    border-radius: var(--border-radius);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
}

.ai-chat th, .ai-chat td {
    border: none;
    padding: 0.75rem;
    text-align: left;
    font-size: 0.9rem;
}

.ai-chat th {
    background: linear-gradient(135deg, var(--gray-200), var(--gray-300));
    font-weight: 600;
    color: var(--gray-800);
}

.ai-chat td {
    background-color: var(--white);
    color: var(--gray-800);
}

.ai-chat tr:nth-child(even) td {
    background-color: var(--gray-100);
}

.ai-chat pre {
    background: linear-gradient(135deg, #282c34, #21262d);
    color: #abb2bf;
    padding: 1.25rem;
    border-radius: var(--border-radius);
    overflow-x: auto;
    font-size: 0.875rem;
    line-height: 1.5;
    margin: 1rem 0;
    font-family: var(--font-family-mono);
    box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.1);
}

.ai-chat code {
    font-family: var(--font-family-mono);
    background-color: rgba(255, 255, 255, 0.1);
    padding: 0.125rem 0.25rem;
    border-radius: var(--border-radius-sm);
    font-size: 0.875rem;
}

.ai-chat pre code {
    background-color: transparent;
    padding: 0;
}

.ai-chat ul, .ai-chat ol {
    margin: 1rem 0;
    padding-left: 1.5rem;
    color: var(--white);
}

.ai-chat ul li, .ai-chat ol li {
    margin-bottom: 0.5rem;
}

.ai-chat h1, .ai-chat h2, .ai-chat h3, .ai-chat h4, .ai-chat h5, .ai-chat h6 {
    margin: 1.5rem 0 1rem 0;
    color: var(--white);
    font-weight: 600;
}

.ai-chat h1 { font-size: 1.75rem; }
.ai-chat h2 { font-size: 1.5rem; }
.ai-chat h3 { font-size: 1.25rem; }
.ai-chat h4 { font-size: 1.125rem; }
.ai-chat h5 { font-size: 1rem; }
.ai-chat h6 { font-size: 0.875rem; }

.ai-chat blockquote {
    border-left: 4px solid var(--primary-color);
    padding-left: 1rem;
    margin: 1rem 0;
    background-color: rgba(255, 255, 255, 0.05);
    border-radius: 0 var(--border-radius-sm) var(--border-radius-sm) 0;
}

/* Input styling */
.chat-input {
    background: var(--white);
    border-radius: 0 0 var(--border-radius-xl) var(--border-radius-xl);
    padding: 1.5rem;
    border-top: 1px solid var(--gray-200);
}

#userMessage {
    resize: vertical;
    max-height: 120px;
    min-height: 60px;
    border-radius: var(--border-radius-lg);
    padding: 0.875rem 1rem;
    font-size: 1rem;
    font-family: var(--font-family-primary);
    border: 2px solid var(--gray-300);
    transition: var(--transition-base);
    background-color: var(--gray-100);
}

#userMessage:focus {
    border-color: var(--primary-color);
    outline: none;
    box-shadow: 0 0 0 3px rgba(0, 123, 255, 0.15);
    background-color: var(--white);
}

#userMessage::placeholder {
    color: var(--gray-500);
    font-style: italic;
}

/* Button styling */
.btn {
    border-radius: var(--border-radius-lg);
    padding: 0.75rem 1.5rem;
    font-weight: 600;
    font-size: 0.875rem;
    transition: var(--transition-base);
    border: none;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow);
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    box-shadow: var(--shadow-sm);
}

.btn-primary:hover {
    background: linear-gradient(135deg, var(--primary-dark), #004085);
}

.btn-outline-secondary {
    border: 2px solid var(--gray-400);
    color: var(--gray-600);
    background-color: transparent;
}

.btn-outline-secondary:hover {
    background-color: var(--gray-600);
    border-color: var(--gray-600);
    color: var(--white);
}

.btn-danger {
    background: linear-gradient(135deg, var(--danger-color), #c82333);
}

.btn-danger:hover {
    background: linear-gradient(135deg, #c82333, #a71e2a);
}

/* File upload styling */
.form-control {
    border-radius: var(--border-radius);
    border: 2px solid var(--gray-300);
    transition: var(--transition-base);
    font-family: var(--font-family-primary);
}

.form-control:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(0, 123, 255, 0.15);
}

/* Hero section */
.hero {
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.1), rgba(118, 75, 162, 0.1));
    border-radius: var(--border-radius-xl);
    padding: 3rem 2rem;
    text-align: center;
    margin: 2rem 0;
}

.hero h1 {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 1rem;
    background: linear-gradient(135deg, var(--primary-color), #764ba2);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero p {
    font-size: 1.25rem;
    color: var(--gray-600);
    margin-bottom: 2rem;
}

/* Feature cards */
.feature-card {
    background: var(--white);
    border-radius: var(--border-radius-xl);
    padding: 2rem;
    text-align: center;
    box-shadow: var(--shadow);
    transition: var(--transition-base);
    border: none;
    height: 100%;
}

.feature-card:hover {
    transform: translateY(-10px);
    box-shadow: var(--shadow-lg);
}

.feature-card .icon {
    font-size: 3rem;
    margin-bottom: 1rem;
    background: linear-gradient(135deg, var(--primary-color), #764ba2);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.feature-card h5 {
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--gray-800);
}

.feature-card p {
    color: var(--gray-600);
    line-height: 1.6;
}

/* Responsive adjustments */
@media (max-width: 768px) {
    .hero h1 {
        font-size: 2rem;
    }
    
    .hero p {
        font-size: 1rem;
    }
    
    .feature-card {
        margin-bottom: 1.5rem;
    }
    
    .my-chat, .ai-chat {
        max-width: 90%;
        padding: 0.875rem 1rem;
    }
    
    .chat-list {
        padding: 1rem;
    }
    
    .chat-input {
        padding: 1rem;
    }
}

/* Loading animation */
.loading {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid var(--gray-300);
    border-radius: 50%;
    border-top-color: var(--primary-color);
    animation: spin 1s ease-in-out infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* Utility classes */
.text-gradient {
    background: linear-gradient(135deg, var(--primary-color), #764ba2);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.bg-glass {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.2);
}

.border-gradient {
    border: 2px solid;
    border-image: linear-gradient(135deg, var(--primary-color), #764ba2) 1;
}