/* CSS Custom Properties for theming */
:root {
    --primary-color: #667eea;
    --secondary-color: #764ba2;
    --accent-color: #f093fb;
    --text-primary: #2d3748;
    --text-secondary: #4a5568;
    --text-muted: #718096;
    --bg-primary: #ffffff;
    --bg-secondary: #f7fafc;
    --bg-sidebar: #ffffff;
    --border-color: #e2e8f0;
    --shadow-light: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-medium: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-heavy: 0 10px 25px rgba(0, 0, 0, 0.15);
    --transition-fast: 0.2s ease;
    --transition-medium: 0.3s ease;
    --sidebar-width: 250px;
}

/* Dark theme variables */
[data-theme="dark"] {
    --text-primary: #f7fafc;
    --text-secondary: #e2e8f0;
    --text-muted: #a0aec0;
    --bg-primary: #1a202c;
    --bg-secondary: #2d3748;
    --bg-sidebar: #2d3748;
    --border-color: #4a5568;
    --shadow-light: 0 1px 3px rgba(0, 0, 0, 0.3);
    --shadow-medium: 0 4px 6px rgba(0, 0, 0, 0.3);
    --shadow-heavy: 0 10px 25px rgba(0, 0, 0, 0.4);
}

/* Reset and base styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

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

/* Mobile menu toggle button */
.mobile-menu-toggle {
    display: none;
    position: fixed;
    top: 1rem;
    left: 1rem;
    z-index: 1001;
    background: var(--bg-sidebar);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    width: 44px;
    height: 44px;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    gap: 4px;
    cursor: pointer;
    box-shadow: var(--shadow-medium);
    transition: all var(--transition-fast);
}

.mobile-menu-toggle:hover {
    background: var(--bg-secondary);
    transform: translateY(-1px);
}

.mobile-menu-toggle span {
    width: 20px;
    height: 2px;
    background: var(--text-primary);
    border-radius: 1px;
    transition: all var(--transition-fast);
}

.mobile-menu-toggle.active span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
}

.mobile-menu-toggle.active span:nth-child(2) {
    opacity: 0;
}

.mobile-menu-toggle.active span:nth-child(3) {
    transform: rotate(-45deg) translate(7px, -6px);
}

/* Sidebar navigation */
.sidebar {
    position: fixed;
    top: 0;
    left: 0;
    width: var(--sidebar-width);
    height: 100vh;
    background: var(--bg-sidebar);
    border-right: 1px solid var(--border-color);
    box-shadow: var(--shadow-medium);
    z-index: 1000;
    transition: transform var(--transition-medium);
    overflow-y: auto;
}

.sidebar-header {
    padding: 2rem 1.5rem 1.5rem;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.theme-toggle {
    background: none;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.theme-toggle:hover {
    background: var(--bg-secondary);
    transform: scale(1.05);
}

.theme-icon {
    font-size: 1.2rem;
    transition: transform var(--transition-fast);
}

.theme-toggle:hover .theme-icon {
    transform: rotate(20deg);
}

.nav-menu {
    list-style: none;
    padding: 1rem 0;
}

.nav-menu li {
    margin: 0.25rem 0;
}

.nav-link {
    display: block;
    padding: 0.75rem 1.5rem;
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    transition: all var(--transition-fast);
    position: relative;
    border-radius: 0 25px 25px 0;
    margin-right: 1rem;
}

.nav-link:hover {
    color: var(--primary-color);
    background: linear-gradient(90deg, transparent, var(--bg-secondary));
    transform: translateX(5px);
}

.nav-link.active {
    color: var(--primary-color);
    background: linear-gradient(90deg, var(--primary-color), transparent);
    background-size: 4px 100%;
    background-repeat: no-repeat;
    background-position: left center;
    font-weight: 600;
}

.nav-link.active::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 4px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    border-radius: 0 2px 2px 0;
}

/* Main content area */
.main-content {
    margin-left: var(--sidebar-width);
    min-height: 100vh;
    transition: margin-left var(--transition-medium);
}

.content-section {
    min-height: 100vh;
    padding: 4rem 3rem;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    animation: fadeInUp 0.8s ease forwards;
}

.content-section:nth-child(even) {
    background: var(--bg-secondary);
}

.section-content {
    max-width: 800px;
    width: 100%;
    text-align: center;
}

.section-title {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    line-height: 1.2;
}

.section-text {
    font-size: 1.125rem;
    color: var(--text-secondary);
    margin-bottom: 2.5rem;
    line-height: 1.7;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.image-placeholder {
    margin-top: 2rem;
    border-radius: 12px;
    overflow: hidden;
    box-shadow: var(--shadow-heavy);
    transition: transform var(--transition-medium);
}

.image-placeholder:hover {
    transform: translateY(-5px) scale(1.02);
}

.section-image {
    width: 100%;
    height: auto;
    display: block;
    transition: transform var(--transition-medium);
}

/* Overlay for mobile menu */
.overlay {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    z-index: 999;
    opacity: 0;
    transition: opacity var(--transition-medium);
}

.overlay.active {
    opacity: 1;
}

/* Animations */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Responsive design */
@media (max-width: 768px) {
    .mobile-menu-toggle {
        display: flex;
    }

    .sidebar {
        transform: translateX(-100%);
    }

    .sidebar.active {
        transform: translateX(0);
    }

    .main-content {
        margin-left: 0;
    }

    .content-section {
        padding: 3rem 1.5rem;
        min-height: calc(100vh - 80px);
    }

    .section-title {
        font-size: 2.25rem;
    }

    .section-text {
        font-size: 1rem;
    }

    .overlay {
        display: block;
    }
}

@media (max-width: 480px) {
    .content-section {
        padding: 2rem 1rem;
    }

    .section-title {
        font-size: 1.875rem;
    }

    .sidebar-header {
        padding: 1.5rem 1rem 1rem;
    }

    .nav-link {
        padding: 0.625rem 1rem;
        margin-right: 0.5rem;
    }
}

/* Smooth scrolling enhancement */
@media (prefers-reduced-motion: reduce) {
    html {
        scroll-behavior: auto;
    }
    
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* Focus styles for accessibility */
.nav-link:focus,
.mobile-menu-toggle:focus,
.theme-toggle:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

/* High contrast mode support */
@media (prefers-contrast: high) {
    :root {
        --shadow-light: 0 1px 3px rgba(0, 0, 0, 0.3);
        --shadow-medium: 0 4px 6px rgba(0, 0, 0, 0.3);
        --shadow-heavy: 0 10px 25px rgba(0, 0, 0, 0.4);
    }
}