/* Base Styles — Shared across all article/landing pages */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&display=swap');

/* CSS Variables */
:root {
    /* Neutral colors */
    --text-primary: #e2e8f0;
    --text-secondary: #cbd5e1;
    --text-muted: #94a3b8;
    --background-white: #0f172a;
    --background-gray: #1e293b;
    --background-light: #334155;
    --border-light: #e5e7eb;
    --border-medium: #d1d5db;

    /* Semantic colors */
    --success-green: #10b981;
    --warning-orange: #f59e0b;
    --error-red: #ef4444;
    --info-blue: #3b82f6;

    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);

    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 4rem;

    /* Border radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
}

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

html {
    scroll-behavior: smooth;
    overflow-x: hidden;
    max-width: 100%;
}

/* Page fade-in animation */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    line-height: 1.6;
    color: #e2e8f0;
    background-color: #020617;
    font-size: 16px;
    overflow-x: hidden;
    max-width: 100%;
    width: 100%;
    animation: fadeInUp 0.8s ease-out;
}

/* Button Styles */
.btn {
    display: inline-block;
    padding: 12px 24px;
    border-radius: var(--radius-md);
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    text-align: center;
    text-decoration: none;
    border: none;
}

.btn-primary {
    background: linear-gradient(135deg, #6366f1 0%, #8b5cf6 100%);
    color: white;
}

.btn-primary:hover {
    box-shadow: 0 5px 20px rgba(99, 102, 241, 0.6), 0 0 30px rgba(99, 102, 241, 0.3);
    color: white;
    transform: translateY(-2px);
}

.btn-secondary {
    background-color: rgba(30, 41, 59, 0.8);
    color: white;
    border: 2px solid #475569;
}

.btn-secondary:hover {
    border-color: #6366f1;
    background-color: rgba(99, 102, 241, 0.1);
    transform: translateY(-2px);
}

.btn-outline {
    background: transparent;
    border: 2px solid #6366f1;
    color: #a5b4fc;
}

.btn-outline:hover {
    background-color: #6366f1;
    color: white;
    box-shadow: 0 0 20px rgba(99, 102, 241, 0.4);
}

/* Reading Progress Bar */
#reading-progress {
    position: fixed;
    top: 0;
    left: 0;
    height: 3px;
    width: 0%;
    z-index: 9999;
    transition: width 0.1s linear;
}

/* Main Content Layout */
.main-content {
    padding: var(--spacing-xl) var(--spacing-md);
    max-width: 1200px;
    margin: 0 auto;
}

.content-container {
    display: grid;
    grid-template-columns: 300px 1fr;
    gap: var(--spacing-xl);
    align-items: start;
}

/* Table of Contents Sidebar */
.toc-sidebar {
    position: sticky;
    top: calc(64px + var(--spacing-lg));
    background: var(--background-white);
    border-radius: var(--radius-xl);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--border-light);
    animation: slideInFromLeft 0.8s ease-out 0.2s both;
}

@keyframes slideInFromLeft {
    from { opacity: 0; transform: translateX(-30px); }
    to   { opacity: 1; transform: translateX(0); }
}

.toc-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
}

.toc-title i {
    color: var(--primary-color);
}

.toc-list {
    list-style: none;
}

.toc-item {
    margin-bottom: var(--spacing-xs);
}

.toc-link {
    display: flex;
    align-items: center;
    color: var(--text-secondary);
    text-decoration: none;
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-md);
    transition: all 0.3s ease;
    font-weight: 500;
    font-size: 0.9rem;
    line-height: 1.4;
}

.toc-link:hover,
.toc-link.active {
    color: var(--primary-color);
    background: var(--background-light);
    transform: translateX(4px);
}

.toc-link::before {
    content: '';
    display: block;
    flex-shrink: 0;
    width: 5px;
    height: 5px;
    background: var(--primary-color);
    border-radius: 50%;
    margin-right: 8px;
    opacity: 0;
    transition: opacity 0.3s ease;
}

.toc-link:hover::before,
.toc-link.active::before {
    opacity: 1;
}

/* Content Sections */
.content-wrapper {
    animation: slideInFromRight 0.8s ease-out 0.4s both;
}

@keyframes slideInFromRight {
    from { opacity: 0; transform: translateX(30px); }
    to   { opacity: 1; transform: translateX(0); }
}

.content-section {
    background: var(--background-white);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    margin-bottom: var(--spacing-lg);
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-light);
    transition: all 0.3s ease;
}

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

.section-header {
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-md);
    border-bottom: 2px solid var(--background-light);
}

.section-header h2 {
    font-size: 1.75rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: var(--spacing-xs);
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.section-header h2 i {
    color: var(--primary-color);
    font-size: 1.5rem;
}

.section-header h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--primary-color);
    margin: var(--spacing-lg) 0 var(--spacing-md) 0;
}

.section-header h4 {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-primary);
    margin: var(--spacing-md) 0 var(--spacing-sm) 0;
}

.section-content p {
    margin-bottom: var(--spacing-md);
    color: var(--text-secondary);
    line-height: 1.7;
}

.section-content ul,
.section-content ol {
    margin: var(--spacing-md) 0;
    padding-left: var(--spacing-lg);
}

.section-content li {
    margin-bottom: var(--spacing-xs);
    color: var(--text-secondary);
    line-height: 1.6;
}

.section-content li::marker {
    color: var(--primary-color);
}

/* Highlight Boxes */
.highlight-box {
    background: linear-gradient(135deg, var(--light-color, rgba(255,255,255,0.05)), var(--background-light));
    border-left: 4px solid var(--primary-color);
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
    margin: var(--spacing-md) 0;
}

.highlight-box.warning {
    background: linear-gradient(135deg, rgba(245, 158, 11, 0.1), var(--background-light));
    border-left-color: var(--warning-orange);
}

.highlight-box.info {
    background: linear-gradient(135deg, rgba(59, 130, 246, 0.1), var(--background-light));
    border-left-color: var(--info-blue);
}

.highlight-box p {
    margin: 0;
    font-weight: 500;
}

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

@keyframes slideInFromTop {
    from { opacity: 0; transform: translateY(-50px); }
    to   { opacity: 1; transform: translateY(0); }
}

/* Responsive */
@media (max-width: 1024px) {
    .content-container {
        grid-template-columns: 1fr;
        gap: var(--spacing-lg);
    }

    .toc-sidebar {
        position: static;
        order: -1;
        background: var(--background-light);
        border-radius: var(--radius-md);
        padding: var(--spacing-md);
    }
}

@media (max-width: 768px) {
    .hero {
        padding: calc(64px + var(--spacing-lg)) var(--spacing-sm) var(--spacing-lg);
    }

    .hero-title {
        font-size: 2.5rem;
    }

    .main-content {
        padding: var(--spacing-lg) var(--spacing-sm);
    }

    .content-section {
        padding: var(--spacing-lg);
    }
}

@media (max-width: 480px) {
    .hero {
        padding: calc(64px + var(--spacing-lg)) var(--spacing-sm) var(--spacing-lg);
    }

    .hero-title {
        font-size: 2rem;
    }

    .main-content {
        padding: var(--spacing-lg) var(--spacing-sm);
    }

    .content-section {
        padding: var(--spacing-lg);
    }

    .section-header h2 {
        font-size: 1.5rem;
    }
}

/* Print */
@media print {
    .navbar, .toc-sidebar { display: none; }
    .content-container { grid-template-columns: 1fr; }
    .content-section { box-shadow: none; border: 1px solid var(--border-light); break-inside: avoid; }
    .hero { background: none; color: var(--text-primary); }
}

/* Bootstrap footer overrides */
footer.bg-dark ul.list-unstyled {
    padding-left: 0 !important;
    list-style: none !important;
    margin-bottom: 0;
}

footer.bg-dark ul.list-unstyled li {
    margin-bottom: 0.5rem;
    display: block !important;
}

footer.bg-dark ul.list-unstyled li a {
    color: #6c757d !important;
    text-decoration: none;
    display: inline-block;
    line-height: 1.5;
}

footer.bg-dark ul.list-unstyled li a:hover { color: #adb5bd !important; }
footer.bg-dark .text-muted  { color: #6c757d !important; }
footer.bg-dark .text-white  { color: #fff !important; }
footer.bg-dark .text-light  { color: #f8f9fa !important; }