/**
 * Main Optimized CSS - Gộp tất cả styles vào 1 file
 * Gọn gàng, dễ quản lý, không rối
 */

/* ============================================
   CSS Variables - Design System
   ============================================ */
:root {
    /* Layout */
    --max-width: 1400px;
    --section-padding: 6rem 2rem;
    --section-padding-mobile: 4rem 1rem;
    --container-padding: 0 2rem;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 4rem;
    --spacing-3xl: 6rem;
    
    /* Grid Gaps */
    --gap-sm: 1.5rem;
    --gap-md: 2.5rem;
    --gap-lg: 4rem;
    --gap-xl: 5rem;
    
    /* Colors */
    --color-primary: #667eea;
    --color-primary-dark: #5568d3;
    --color-primary-light: #818cf8;
    --color-accent: #764ba2;
    --color-text: #1a1a1a;
    --color-text-secondary: #4a5568;
    --color-text-muted: #718096;
    --color-bg: #ffffff;
    --color-bg-secondary: #f8f9fa;
    --color-border: #e9ecef;
    
    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 2rem;
    --font-size-4xl: 2.5rem;
    --font-size-5xl: 3.5rem;
    --font-size-6xl: 5rem;
    
    /* Shadows */
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.08);
    --shadow-lg: 0 10px 30px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 50px rgba(0, 0, 0, 0.12);
    
    /* Border Radius */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    
    /* Transitions */
    --transition-fast: 0.15s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
}

/* Dark Mode Colors */
[data-theme="dark"] {
    --color-bg: #1a1a1a;
    --color-bg-secondary: #2d2d2d;
    --color-border: #2d2d2d;
    --color-text: #ffffff;
    --color-text-secondary: #cbd5e0;
    --color-text-muted: #a0aec0;
}

/* ============================================
   NAVBAR - Optimized
   ============================================ */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: var(--color-bg) !important;
    backdrop-filter: blur(20px) saturate(180%);
    -webkit-backdrop-filter: blur(20px) saturate(180%);
    border-bottom: 1px solid var(--color-border);
    box-shadow: var(--shadow-sm);
    padding: 0.75rem 0 !important;
    z-index: 1000;
}

.nav-container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 1.5rem;
}

.nav-logo {
    flex-shrink: 0;
}

.logo-text {
    font-size: 1.25rem !important;
    font-weight: 700 !important;
    letter-spacing: -0.01em;
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-accent) 100%) !important;
    -webkit-background-clip: text !important;
    -webkit-text-fill-color: transparent !important;
    background-clip: text !important;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 0.25rem !important;
    align-items: center;
    flex-wrap: wrap;
    margin: 0;
    padding: 0;
    flex: 1;
    justify-content: center;
}

.nav-link {
    font-size: 0.875rem !important;
    font-weight: 500 !important;
    padding: 0.5rem 0.875rem !important;
    border-radius: var(--radius-md) !important;
    color: var(--color-text-secondary) !important;
    text-decoration: none;
    transition: all var(--transition-fast) !important;
    position: relative;
    white-space: nowrap;
    display: block;
}

.nav-link::after {
    display: none !important;
}

.nav-link:hover {
    color: var(--color-primary) !important;
    background: rgba(102, 126, 234, 0.1) !important;
}

.nav-link.active {
    color: var(--color-primary) !important;
    background: rgba(102, 126, 234, 0.12) !important;
    font-weight: 600 !important;
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    flex-shrink: 0;
}

.sidebar-toggle,
.theme-toggle,
.color-scheme-toggle {
    background: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    width: 36px;
    height: 36px;
    border-radius: var(--radius-md);
    cursor: pointer;
    font-size: 1.1rem;
    transition: all var(--transition-fast);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-text-secondary);
}

.sidebar-toggle:hover,
.theme-toggle:hover,
.color-scheme-toggle:hover {
    background: var(--color-primary);
    color: white;
    border-color: var(--color-primary);
    transform: scale(1.05);
}

.lang-switch {
    display: inline-flex;
    align-items: center;
    gap: 0.25rem;
    font-size: 0.75rem;
    color: var(--color-text-muted);
    padding: 0.375rem 0.5rem;
    border-radius: 6px;
    background: var(--color-bg-secondary);
}

.lang-switch button {
    border: none;
    background: transparent;
    cursor: pointer;
    font-size: 0.75rem;
    padding: 0;
    color: var(--color-text-secondary);
    font-weight: 500;
    transition: color var(--transition-fast);
}

.lang-switch button:hover {
    color: var(--color-primary);
}

/* ============================================
   SIDEBAR - Optimized
   ============================================ */
.sidebar {
    position: fixed;
    top: 0;
    left: -300px;
    width: 280px;
    height: 100vh;
    background: var(--color-bg);
    box-shadow: 2px 0 20px rgba(0, 0, 0, 0.1);
    z-index: 2000;
    transition: left 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    overflow-y: auto;
    border-right: 1px solid var(--color-border);
}

.sidebar.active {
    left: 0;
}

.sidebar-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.25rem;
    border-bottom: 1px solid var(--color-border);
    background: var(--color-bg-secondary);
    position: sticky;
    top: 0;
    z-index: 10;
}

.sidebar-header h3 {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--color-text);
    margin: 0;
    letter-spacing: -0.01em;
}

.sidebar-close {
    background: transparent;
    border: none;
    font-size: 1.75rem;
    line-height: 1;
    cursor: pointer;
    color: var(--color-text-muted);
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 6px;
    transition: all var(--transition-fast);
}

.sidebar-close:hover {
    background: var(--color-bg-secondary);
    color: var(--color-text);
}

.sidebar-nav {
    padding: 0.75rem 0;
}

.sidebar-menu {
    list-style: none;
    margin: 0;
    padding: 0;
}

.sidebar-link {
    display: block;
    padding: 0.875rem 1.25rem;
    color: var(--color-text-secondary);
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 500;
    transition: all var(--transition-fast);
    border-left: 3px solid transparent;
}

.sidebar-link:hover {
    color: var(--color-primary);
    background: rgba(102, 126, 234, 0.08);
    border-left-color: var(--color-primary);
    padding-left: 1.5rem;
}

.sidebar-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.4);
    z-index: 1999;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s ease, visibility 0.3s ease;
    backdrop-filter: blur(2px);
}

.sidebar-overlay.active {
    opacity: 1;
    visibility: visible;
}

/* ============================================
   HOMEPAGE LAYOUT - Optimized
   ============================================ */
.hero-section {
    min-height: 90vh;
    display: flex;
    align-items: center;
    padding: var(--section-padding);
    background: linear-gradient(180deg, #ffffff 0%, #f8f9fa 50%, #ffffff 100%);
    position: relative;
    overflow: hidden;
}

.hero-section::before {
    content: '';
    position: absolute;
    top: 0;
    right: 0;
    width: 40%;
    height: 100%;
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.02) 0%, transparent 100%);
    pointer-events: none;
}

.hero-content {
    position: relative;
    z-index: 2;
    width: 100%;
}

.hero-layout {
    display: grid;
    grid-template-columns: 1.4fr 1fr;
    gap: var(--gap-xl);
    align-items: center;
    max-width: var(--max-width);
    margin: 0 auto;
}

.hero-text {
    text-align: left;
}

.hero-title {
    margin: 0;
    padding: 0;
}

.title-greeting {
    display: block;
    font-size: var(--font-size-sm);
    font-weight: 600;
    letter-spacing: 0.2em;
    text-transform: uppercase;
    color: var(--color-primary);
    margin-bottom: var(--spacing-sm);
    opacity: 0.9;
}

.title-name {
    display: block;
    font-size: var(--font-size-6xl);
    font-weight: 900;
    line-height: 1.1;
    letter-spacing: -0.04em;
    color: var(--color-text);
    margin-bottom: var(--spacing-lg);
    background: linear-gradient(135deg, #1a1a1a 0%, #667eea 50%, #764ba2 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    background-size: 200% auto;
}

.hero-subtitle {
    font-size: var(--font-size-2xl);
    font-weight: 600;
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-lg);
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.hero-subtitle::before {
    content: '';
    width: 4px;
    height: 28px;
    background: linear-gradient(180deg, var(--color-primary) 0%, var(--color-accent) 100%);
    border-radius: 2px;
}

.hero-description {
    font-size: var(--font-size-lg);
    line-height: 1.9;
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-2xl);
    max-width: 92%;
    font-weight: 400;
}

.hero-buttons {
    display: flex;
    gap: var(--spacing-md);
    flex-wrap: wrap;
}

.hero-image-wrapper {
    display: flex;
    justify-content: center;
    align-items: center;
    position: relative;
}

.hero-image-frame {
    position: relative;
    width: 380px;
    height: 380px;
    padding: 28px;
    background: #ffffff;
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-xl);
    transition: all var(--transition-normal);
}

.hero-image-frame:hover {
    transform: translateY(-10px) scale(1.02);
    box-shadow: 0 25px 60px rgba(102, 126, 234, 0.25);
}

.hero-image {
    width: 100%;
    height: 100%;
    border-radius: var(--radius-lg);
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-accent) 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    overflow: hidden;
}

.avatar-placeholder {
    font-size: 4.5rem;
    font-weight: 900;
    color: white;
    z-index: 2;
}

.frame-decoration {
    display: none;
}

/* About Preview */
.about-preview {
    padding: var(--section-padding);
    background: var(--color-bg);
    position: relative;
}

.about-content {
    display: grid;
    grid-template-columns: 1.5fr 1fr;
    gap: var(--gap-xl);
    align-items: start;
    max-width: var(--max-width);
    margin: 0 auto;
}

.about-text {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

.text-frame {
    padding: var(--spacing-xl);
    border-radius: var(--radius-lg);
    border-left: 4px solid var(--color-primary);
    background: var(--color-bg-secondary);
    transition: all var(--transition-normal);
}

.text-frame:hover {
    transform: translateX(10px);
    box-shadow: var(--shadow-lg);
    border-left-width: 6px;
    background: var(--color-bg);
}

.text-frame p {
    font-size: var(--font-size-lg);
    line-height: 1.8;
    color: var(--color-text-secondary);
    margin: 0;
}

.skills-preview {
    margin-top: var(--spacing-sm);
}

.skills-preview h3 {
    font-size: var(--font-size-2xl);
    margin-bottom: var(--spacing-md);
    color: var(--color-text);
    font-weight: 700;
}

.skills-tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
}

.skill-tag {
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--color-bg-secondary);
    color: var(--color-primary);
    border-radius: 25px;
    font-size: var(--font-size-sm);
    font-weight: 600;
    transition: all var(--transition-fast);
    border: 2px solid transparent;
}

.skill-tag:hover {
    background: var(--color-primary);
    color: white;
    transform: translateY(-3px);
    border-color: var(--color-primary);
    box-shadow: var(--shadow-md);
}

.about-stats {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
    position: sticky;
    top: 120px;
}

.stat-card {
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-accent) 100%);
    padding: var(--spacing-2xl) var(--spacing-xl);
    border-radius: var(--radius-xl);
    text-align: center;
    color: white;
    box-shadow: var(--shadow-xl);
    transition: all var(--transition-normal);
}

.stat-card:hover {
    transform: translateY(-8px) scale(1.03);
    box-shadow: 0 20px 60px rgba(102, 126, 234, 0.35);
}

.stat-number {
    font-size: var(--font-size-5xl);
    font-weight: 900;
    margin-bottom: var(--spacing-sm);
    line-height: 1;
}

.stat-label {
    font-size: var(--font-size-lg);
    opacity: 0.95;
    font-weight: 600;
}

/* Featured Projects */
.featured-projects {
    padding: var(--section-padding);
    background: linear-gradient(180deg, var(--color-bg-secondary) 0%, var(--color-bg) 100%);
    position: relative;
}

.projects-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--gap-md);
    max-width: var(--max-width);
    margin: 0 auto var(--spacing-2xl);
}

.project-card {
    background: var(--color-bg);
    border-radius: var(--radius-xl);
    overflow: hidden;
    box-shadow: var(--shadow-md);
    transition: all var(--transition-normal);
    display: flex;
    flex-direction: column;
    height: 100%;
    border: 1px solid var(--color-border);
}

.project-card:hover {
    transform: translateY(-12px);
    box-shadow: var(--shadow-xl);
    border-color: var(--color-primary);
}

.project-image {
    height: 240px;
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-accent) 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 4.5rem;
    position: relative;
    overflow: hidden;
}

.project-content {
    padding: var(--spacing-xl);
    flex-grow: 1;
    display: flex;
    flex-direction: column;
}

.project-title {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    margin-bottom: var(--spacing-md);
    color: var(--color-text);
}

.project-description {
    font-size: var(--font-size-base);
    line-height: 1.7;
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-lg);
    flex-grow: 1;
}

.project-tech {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-lg);
}

.tech-tag {
    padding: var(--spacing-xs) var(--spacing-sm);
    background: var(--color-bg-secondary);
    color: var(--color-primary);
    border-radius: var(--radius-sm);
    font-size: var(--font-size-xs);
    font-weight: 600;
    border: 1px solid var(--color-border);
}

.project-links {
    display: flex;
    gap: var(--spacing-sm);
}

.project-link {
    flex: 1;
    text-align: center;
    min-width: 120px;
}

/* Learning Journey */
.learning-preview {
    padding: var(--section-padding);
    background: linear-gradient(180deg, var(--color-bg) 0%, var(--color-bg-secondary) 100%);
}

.courses-preview-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--gap-md);
    max-width: var(--max-width);
    margin: 0 auto var(--spacing-2xl);
}

.course-preview-card {
    background: var(--color-bg);
    padding: var(--spacing-2xl);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-md);
    transition: all var(--transition-normal);
    border: 1px solid var(--color-border);
    position: relative;
    overflow: hidden;
}

.course-preview-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 5px;
    background: linear-gradient(90deg, var(--color-primary) 0%, var(--color-accent) 100%);
}

.course-preview-card:hover {
    transform: translateY(-10px);
    box-shadow: var(--shadow-xl);
    border-color: var(--color-primary);
}

.course-icon {
    font-size: 4rem;
    margin-bottom: var(--spacing-lg);
    display: block;
}

.course-preview-card h3 {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    margin-bottom: var(--spacing-md);
    color: var(--color-text);
}

.course-preview-card p {
    font-size: var(--font-size-base);
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-lg);
    line-height: 1.7;
}

.course-progress-mini {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.progress-bar-mini {
    flex: 1;
    height: 10px;
    background: var(--color-bg-secondary);
    border-radius: 10px;
    overflow: hidden;
}

.progress-fill-mini {
    height: 100%;
    background: linear-gradient(90deg, var(--color-primary) 0%, var(--color-accent) 100%);
    border-radius: 10px;
    transition: width 1s ease;
}

.course-progress-mini span {
    font-weight: 700;
    color: var(--color-primary);
    font-size: var(--font-size-base);
    min-width: 50px;
}

/* Learning Journey Title - Special Color */
.learning-journey-title {
    color: #6a1b9a !important;
    font-weight: 900 !important;
    background: none !important;
    -webkit-background-clip: unset !important;
    -webkit-text-fill-color: #6a1b9a !important;
    background-clip: unset !important;
}

.learning-journey-text {
    color: #6a1b9a !important;
    font-weight: 700 !important;
}

/* Contact Section */
.contact-preview {
    padding: var(--section-padding);
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-accent) 100%);
    color: white;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.contact-preview::before {
    content: '';
    position: absolute;
    top: -40%;
    right: -15%;
    width: 500px;
    height: 500px;
    background: radial-gradient(circle, rgba(255,255,255,0.1) 0%, transparent 70%);
    border-radius: 50%;
}

.contact-preview .section-title {
    color: white;
    font-size: var(--font-size-5xl);
    margin-bottom: var(--spacing-md);
}

.contact-preview .section-subtitle {
    color: rgba(255,255,255,0.95);
    font-size: var(--font-size-xl);
    margin-bottom: var(--spacing-2xl);
}

.contact-content {
    max-width: 750px;
    margin: 0 auto;
    position: relative;
    z-index: 2;
}

.text-frame-accent {
    background: rgba(255,255,255,0.15) !important;
    backdrop-filter: blur(12px);
    border: 2px solid rgba(255,255,255,0.25) !important;
    border-left: 5px solid white !important;
    color: white !important;
}

.text-frame-accent p {
    color: white !important;
    font-size: var(--font-size-xl);
}

/* Section Headers */
.section-header {
    text-align: center;
    margin-bottom: var(--spacing-3xl);
    max-width: 850px;
    margin-left: auto;
    margin-right: auto;
}

.section-title {
    font-size: var(--font-size-5xl);
    font-weight: 900;
    margin-bottom: var(--spacing-md);
    color: var(--color-text);
    letter-spacing: -0.03em;
    line-height: 1.2;
}

.section-subtitle {
    font-size: var(--font-size-xl);
    color: var(--color-text-secondary);
    font-weight: 400;
    line-height: 1.6;
}

.section-footer {
    text-align: center;
    margin-top: var(--spacing-2xl);
}

/* Container */
.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: var(--container-padding);
}

/* Buttons */
.btn {
    padding: var(--spacing-md) var(--spacing-xl);
    border-radius: var(--radius-md);
    font-weight: 600;
    font-size: var(--font-size-base);
    text-decoration: none;
    display: inline-block;
    transition: all var(--transition-normal);
    border: none;
    cursor: pointer;
    position: relative;
    overflow: hidden;
}

.btn-primary {
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-accent) 100%);
    color: white;
    box-shadow: var(--shadow-md);
}

.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
}

.btn-secondary {
    background: white;
    color: var(--color-primary);
    border: 2px solid var(--color-primary);
    box-shadow: var(--shadow-sm);
}

.btn-secondary:hover {
    background: var(--color-primary);
    color: white;
    transform: translateY(-3px);
    box-shadow: var(--shadow-md);
}

.btn-outline {
    background: transparent;
    border: 2px solid var(--color-primary);
    color: var(--color-primary);
}

.btn-outline:hover {
    background: var(--color-primary);
    color: white;
}

/* Color Scheme Toggle */
.color-scheme-toggle:hover {
    transform: scale(1.05) rotate(15deg);
}

/* Color Schemes */
[data-color-scheme="blue"] {
    --color-primary: #667eea;
    --color-primary-dark: #5568d3;
}

[data-color-scheme="purple"] {
    --color-primary: #764ba2;
    --color-primary-dark: #6a1b9a;
}

[data-color-scheme="green"] {
    --color-primary: #10b981;
    --color-primary-dark: #059669;
}

[data-color-scheme="red"] {
    --color-primary: #ef4444;
    --color-primary-dark: #dc2626;
}

[data-color-scheme="orange"] {
    --color-primary: #f59e0b;
    --color-primary-dark: #d97706;
}

[data-color-scheme="teal"] {
    --color-primary: #14b8a6;
    --color-primary-dark: #0d9488;
}

[data-color-scheme="pink"] {
    --color-primary: #ec4899;
    --color-primary-dark: #db2777;
}

/* ============================================
   RESPONSIVE DESIGN
   ============================================ */
@media (max-width: 1200px) {
    .hero-layout {
        gap: var(--gap-lg);
    }
    
    .about-content {
        gap: var(--gap-lg);
    }
    
    .projects-grid,
    .courses-preview-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--gap-md);
    }
}

@media (max-width: 968px) {
    :root {
        --section-padding: 5rem 1.5rem;
        --font-size-6xl: 4rem;
        --font-size-5xl: 3rem;
    }
    
    .hero-layout {
        grid-template-columns: 1fr;
        gap: var(--gap-lg);
        text-align: center;
    }
    
    .hero-text {
        text-align: center;
    }
    
    .hero-description {
        max-width: 100%;
        margin-left: auto;
        margin-right: auto;
    }
    
    .hero-buttons {
        justify-content: center;
    }
    
    .hero-image-frame {
        width: 320px;
        height: 320px;
        margin: 0 auto;
    }
    
    .about-content {
        grid-template-columns: 1fr;
        gap: var(--gap-lg);
    }
    
    .about-stats {
        position: static;
        flex-direction: row;
        flex-wrap: wrap;
    }
    
    .stat-card {
        flex: 1;
        min-width: 220px;
    }
    
    .projects-grid,
    .courses-preview-grid {
        grid-template-columns: 1fr;
        gap: var(--gap-md);
    }
    
    .section-title {
        font-size: var(--font-size-4xl);
    }
}

@media (max-width: 768px) {
    :root {
        --section-padding: 4rem 1rem;
        --font-size-6xl: 3rem;
        --font-size-5xl: 2.5rem;
        --font-size-4xl: 2rem;
    }
    
    .hero-section {
        min-height: auto;
        padding: 5rem 1rem 3rem;
    }
    
    .hero-subtitle {
        font-size: var(--font-size-xl);
    }
    
    .hero-description {
        font-size: var(--font-size-base);
    }
    
    .section-title {
        font-size: var(--font-size-3xl);
    }
    
    .section-subtitle {
        font-size: var(--font-size-lg);
    }
    
    .hero-buttons {
        flex-direction: column;
        width: 100%;
    }
    
    .btn {
        width: 100%;
        text-align: center;
    }
    
    .about-stats {
        flex-direction: column;
    }
    
    .stat-card {
        width: 100%;
    }
    
    .contact-preview .section-title {
        font-size: var(--font-size-4xl);
    }
    
    .sidebar {
        width: 260px;
        left: -260px;
    }
}

/* ============================================
   UTILITIES
   ============================================ */
html {
    scroll-behavior: smooth;
}

section {
    position: relative;
}

h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-family);
    font-weight: 700;
    line-height: 1.2;
    color: var(--color-text);
    margin: 0;
}

p {
    line-height: 1.8;
    color: var(--color-text-secondary);
    margin: 0;
}

/* Skip Link */
.skip-link {
    position: absolute;
    top: -40px;
    left: 0;
    background: var(--color-primary);
    color: white;
    padding: 8px 16px;
    text-decoration: none;
    z-index: 10000;
    font-weight: 600;
    border-radius: 0 0 4px 0;
    transition: top 0.3s;
}

.skip-link:focus {
    top: 0;
    outline: 3px solid white;
    outline-offset: 2px;
}