/* ===========================
   Modern CSS Design System
   =========================== */

:root {
    /* Color Palette - Light Mode */
    --primary: #2563eb;
    --primary-dark: #1e40af;
    --primary-light: #3b82f6;
    --secondary: #7c3aed;
    --accent: #f59e0b;
    --success: #10b981;
    --warning: #f97316;
    --error: #ef4444;
    
    /* Neutrals - Light Mode */
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --text-tertiary: #9ca3af;
    --bg-primary: #ffffff;
    --bg-secondary: #f9fafb;
    --bg-tertiary: #f3f4f6;
    --border: #e5e7eb;
    --border-dark: #d1d5db;
}

/* Dark Mode Color Scheme */
@media (prefers-color-scheme: dark) {
    :root {
        /* Color Palette - Dark Mode */
        --primary: #3b82f6;
        --primary-dark: #60a5fa;
        --primary-light: #93c5fd;
        --secondary: #a78bfa;
        --accent: #fbbf24;
        --success: #34d399;
        --warning: #fb923c;
        --error: #f87171;
        
        /* Neutrals - Dark Mode */
        --text-primary: #f3f4f6;
        --text-secondary: #d1d5db;
        --text-tertiary: #9ca3af;
        --bg-primary: #111827;
        --bg-secondary: #1f2937;
        --bg-tertiary: #374151;
        --border: #4b5563;
        --border-dark: #374151;
    }
}

/* Explicit Dark Mode Class (when user toggles) */
html.dark-mode {
    /* Color Palette - Dark Mode */
    --primary: #3b82f6;
    --primary-dark: #60a5fa;
    --primary-light: #93c5fd;
    --secondary: #a78bfa;
    --accent: #fbbf24;
    --success: #34d399;
    --warning: #fb923c;
    --error: #f87171;
    
    /* Neutrals - Dark Mode */
    --text-primary: #f3f4f6;
    --text-secondary: #d1d5db;
    --text-tertiary: #9ca3af;
    --bg-primary: #111827;
    --bg-secondary: #1f2937;
    --bg-tertiary: #374151;
    --border: #4b5563;
    --border-dark: #374151;
}

/* Light Mode Class (when user explicitly toggles) */
html.light-mode {
    /* Color Palette - Light Mode */
    --primary: #2563eb;
    --primary-dark: #1e40af;
    --primary-light: #3b82f6;
    --secondary: #7c3aed;
    --accent: #f59e0b;
    --success: #10b981;
    --warning: #f97316;
    --error: #ef4444;
    
    /* Neutrals - Light Mode */
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --text-tertiary: #9ca3af;
    --bg-primary: #ffffff;
    --bg-secondary: #f9fafb;
    --bg-tertiary: #f3f4f6;
    --border: #e5e7eb;
    --border-dark: #d1d5db;
}

:root {
    /* This section will be overridden by prefers-color-scheme or dark-mode class */
    /* Color Palette - Light Mode (Default) */
    --primary: #2563eb;
    --primary-dark: #1e40af;
    --primary-light: #3b82f6;
    --secondary: #7c3aed;
    --accent: #f59e0b;
    --success: #10b981;
    --warning: #f97316;
    --error: #ef4444;
    
    /* Neutrals - Light Mode (Default) */
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --text-tertiary: #9ca3af;
    --bg-primary: #ffffff;
    --bg-secondary: #f9fafb;
    --bg-tertiary: #f3f4f6;
    --border: #e5e7eb;
    --border-dark: #d1d5db;
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    --spacing-3xl: 4rem;
    --spacing-4xl: 6rem;
    
    /* Typography */
    --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-mono: 'Monaco', 'Menlo', 'Ubuntu Mono', monospace;
    --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: 1.875rem;
    --font-size-4xl: 2.25rem;
    --font-size-5xl: 3rem;
    
    /* Line Heights */
    --line-height-tight: 1.25;
    --line-height-snug: 1.375;
    --line-height-normal: 1.5;
    --line-height-relaxed: 1.625;
    --line-height-loose: 2;
    
    /* Border Radius */
    --radius-sm: 0.25rem;
    --radius-md: 0.375rem;
    --radius-lg: 0.5rem;
    --radius-xl: 0.75rem;
    --radius-2xl: 1rem;
    --radius-full: 9999px;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
    --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);
    
    /* Transitions */
    --transition-fast: 150ms ease-in-out;
    --transition-normal: 250ms ease-in-out;
    --transition-slow: 350ms ease-in-out;
}

/* ===========================
   Global Styles
   =========================== */

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    font-size: var(--font-size-base);
    line-height: var(--line-height-normal);
    color: var(--text-primary);
    background-color: var(--bg-primary);
    overflow-x: hidden;
    transition: background-color var(--transition-normal), color var(--transition-normal);
}

/* ===========================
   Typography
   =========================== */

h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: var(--line-height-snug);
    margin-bottom: var(--spacing-lg);
}

h1 {
    font-size: var(--font-size-5xl);
}

h2 {
    font-size: var(--font-size-4xl);
}

h3 {
    font-size: var(--font-size-2xl);
}

h4 {
    font-size: var(--font-size-xl);
}

h5, h6 {
    font-size: var(--font-size-lg);
}

p {
    margin-bottom: var(--spacing-md);
    color: var(--text-secondary);
}

a {
    color: var(--primary);
    text-decoration: none;
    transition: color var(--transition-fast);
}

a:hover {
    color: var(--primary-dark);
}

mark {
    background-color: rgba(245, 158, 11, 0.2);
    padding: 0.125rem 0.375rem;
    border-radius: var(--radius-sm);
}

/* ===========================
   Container & Layout
   =========================== */

.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.section-title {
    text-align: center;
    margin-bottom: var(--spacing-3xl);
    position: relative;
    padding-bottom: var(--spacing-lg);
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 4px;
    background: linear-gradient(90deg, var(--primary), var(--secondary));
    border-radius: var(--radius-full);
}

/* ===========================
   Navigation
   =========================== */

.navbar {
    background: var(--bg-primary);
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: var(--shadow-sm);
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md) var(--spacing-lg);
}

.nav-brand a {
    font-size: var(--font-size-xl);
    font-weight: 700;
    color: var(--text-primary);
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: var(--spacing-2xl);
    align-items: center;
}

.nav-link {
    color: var(--text-secondary);
    font-weight: 500;
    position: relative;
    transition: color var(--transition-fast);
}

.nav-link:hover,
.nav-link.active {
    color: var(--primary);
}

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: -8px;
    left: 0;
    right: 0;
    height: 3px;
    background: var(--primary);
    border-radius: var(--radius-full);
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 6px;
    cursor: pointer;
}

.nav-toggle span {
    width: 25px;
    height: 3px;
    background: var(--text-primary);
    border-radius: var(--radius-full);
    transition: all var(--transition-fast);
}

/* ===========================
   Dark Mode Toggle
   =========================== */

.dark-mode-toggle {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    margin-left: var(--spacing-lg);
}

.theme-toggle {
    background: transparent;
    border: 2px solid var(--border);
    border-radius: var(--radius-full);
    width: 44px;
    height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    font-size: 1.25rem;
    transition: all var(--transition-normal);
    color: var(--text-primary);
}

.theme-toggle:hover {
    background: var(--bg-secondary);
    border-color: var(--primary);
    transform: scale(1.1);
}

.theme-toggle:focus {
    outline: none;
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

/* ===========================
   Hero Section
   =========================== */

.hero {
    padding: var(--spacing-4xl) var(--spacing-lg);
    background: linear-gradient(135deg, rgba(37, 99, 235, 0.1) 0%, rgba(124, 58, 237, 0.05) 100%);
}

.hero .container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-3xl);
    align-items: center;
}

.hero-title {
    font-size: var(--font-size-5xl);
    margin-bottom: var(--spacing-lg);
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: var(--font-size-lg);
    color: var(--text-secondary);
    margin-bottom: var(--spacing-2xl);
    line-height: var(--line-height-relaxed);
}

.hero-cta {
    display: flex;
    gap: var(--spacing-lg);
    flex-wrap: wrap;
}

.hero-avatar {
    width: 200px;
    height: 200px;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    border-radius: var(--radius-2xl);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 4rem;
    font-weight: 700;
    color: var(--bg-primary);
    box-shadow: var(--shadow-xl);
}

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

/* ===========================
   Buttons
   =========================== */

.btn {
    padding: var(--spacing-md) var(--spacing-2xl);
    border: none;
    border-radius: var(--radius-lg);
    font-size: var(--font-size-base);
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-normal);
    display: inline-block;
    text-align: center;
}

.btn-primary {
    background: var(--primary);
    color: var(--bg-primary);
}

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

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

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

.btn-large {
    padding: var(--spacing-lg) var(--spacing-3xl);
    font-size: var(--font-size-lg);
}

/* ===========================
   Featured Section
   =========================== */

.featured {
    padding: var(--spacing-4xl) var(--spacing-lg);
    background: var(--bg-secondary);
}

.featured-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-2xl);
}

.featured-card {
    background: var(--bg-primary);
    padding: var(--spacing-2xl);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow);
    transition: all var(--transition-normal);
    text-align: center;
}

.featured-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
}

.feature-icon {
    font-size: 3rem;
    margin-bottom: var(--spacing-md);
}

.featured-card h3 {
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

.featured-card p {
    color: var(--text-secondary);
    margin-bottom: 0;
}

/* ===========================
   Projects Section
   =========================== */

.recent-projects {
    padding: var(--spacing-4xl) var(--spacing-lg);
}

.projects-preview {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-2xl);
}

.project-preview-card {
    background: var(--bg-secondary);
    padding: var(--spacing-2xl);
    border-radius: var(--radius-xl);
    border-left: 4px solid var(--primary);
    transition: all var(--transition-normal);
}

.project-preview-card:hover {
    transform: translateX(8px);
    box-shadow: var(--shadow-lg);
}

.project-preview-card h3 {
    margin-bottom: var(--spacing-md);
    font-size: var(--font-size-xl);
}

.project-preview-card p {
    margin-bottom: var(--spacing-lg);
}

.link-arrow {
    font-weight: 600;
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    color: var(--primary);
}

.link-arrow:hover {
    gap: var(--spacing-md);
}

/* ===========================
   Highlights Section
   =========================== */

.highlights {
    padding: var(--spacing-4xl) var(--spacing-lg);
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    color: var(--bg-primary);
}

.highlights .container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-2xl);
}

.highlight-item h3 {
    margin-bottom: var(--spacing-md);
    color: var(--bg-primary);
}

.highlight-item p {
    color: rgba(255, 255, 255, 0.9);
}

/* ===========================
   CTA Section
   =========================== */

.cta-section {
    padding: var(--spacing-4xl) var(--spacing-lg);
    text-align: center;
    background: var(--bg-secondary);
}

.cta-section h2 {
    margin-bottom: var(--spacing-lg);
    color: var(--text-primary);
}

.cta-section p {
    font-size: var(--font-size-lg);
    margin-bottom: var(--spacing-2xl);
    color: var(--text-secondary);
}

.social-links {
    margin-top: var(--spacing-2xl);
    display: flex;
    justify-content: center;
    gap: var(--spacing-lg);
    flex-wrap: wrap;
}

.social-links a {
    padding: var(--spacing-md) var(--spacing-lg);
    background: var(--bg-primary);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    transition: all var(--transition-fast);
}

.social-links a:hover {
    background: var(--primary);
    color: var(--bg-primary);
    border-color: var(--primary);
}

/* ===========================
   Footer
   =========================== */

.footer {
    background: var(--text-primary);
    color: var(--bg-primary);
    padding: var(--spacing-2xl) var(--spacing-lg);
    text-align: center;
}

.footer p {
    color: rgba(255, 255, 255, 0.8);
    margin-bottom: var(--spacing-sm);
}

/* ===========================
   Page Content Sections
   =========================== */

.page-content-section {
    padding: var(--spacing-4xl) var(--spacing-lg);
    border-top: 1px solid var(--border);
}

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

.content-subsection {
    margin-top: var(--spacing-3xl);
    padding-top: var(--spacing-3xl);
    border-top: 1px solid var(--border);
}

.content-section {
    margin-bottom: var(--spacing-3xl);
}

.content-section h2 {
    margin-top: var(--spacing-3xl);
    margin-bottom: var(--spacing-xl);
    padding-bottom: var(--spacing-lg);
    border-bottom: 2px solid var(--border);
}

.content-section h3 {
    margin-top: var(--spacing-2xl);
    margin-bottom: var(--spacing-md);
    color: var(--primary);
}

.content-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-2xl);
    margin: var(--spacing-2xl) 0;
}

.content-card {
    background: var(--bg-secondary);
    padding: var(--spacing-2xl);
    border-radius: var(--radius-xl);
    border: 1px solid var(--border);
}

.content-card h4 {
    color: var(--primary);
    margin-bottom: var(--spacing-md);
}

.skill-tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
    margin: var(--spacing-lg) 0;
}

.skill-tag {
    background: var(--primary);
    color: var(--bg-primary);
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-full);
    font-size: var(--font-size-sm);
    font-weight: 600;
}

.tech-list {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-lg);
    margin: var(--spacing-2xl) 0;
}

.tech-item {
    background: var(--bg-secondary);
    padding: var(--spacing-lg);
    border-radius: var(--radius-lg);
    border-left: 3px solid var(--secondary);
}

.tech-item h4 {
    color: var(--secondary);
    margin-bottom: var(--spacing-sm);
}

.tech-item p {
    font-size: var(--font-size-sm);
    margin-bottom: 0;
}

.quote {
    border-left: 4px solid var(--primary);
    padding-left: var(--spacing-lg);
    margin: var(--spacing-2xl) 0;
    font-style: italic;
    color: var(--text-secondary);
}

/* ===========================
   Images
   =========================== */

img {
    max-width: 100%;
    height: auto;
    display: block;
}

.hero-profile-img {
    transition: transform var(--transition-normal);
}

.hero-profile-img:hover {
    transform: scale(1.05);
}

.content-card img {
    transition: opacity var(--transition-normal);
}

.content-card:hover img {
    opacity: 0.9;
}

.highlight-item img {
    opacity: 0.8;
    transition: opacity var(--transition-normal);
}

.highlight-item:hover img {
    opacity: 1;
}

@media (max-width: 768px) {
    :root {
        --font-size-5xl: 2.25rem;
        --font-size-4xl: 1.875rem;
        --spacing-4xl: 3rem;
    }

    .nav-menu {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        flex-direction: column;
        background: var(--bg-primary);
        border-bottom: 1px solid var(--border);
        gap: var(--spacing-md);
        padding: var(--spacing-lg);
        border-top: 1px solid var(--border);
    }

    .nav-menu.active {
        display: flex;
    }

    .nav-toggle {
        display: flex;
    }

    .hero .container {
        grid-template-columns: 1fr;
    }

    .hero-avatar {
        width: 150px;
        height: 150px;
        font-size: 3rem;
    }

    .hero-cta {
        flex-direction: column;
    }

    .btn {
        width: 100%;
    }

    .featured-grid {
        grid-template-columns: 1fr;
    }

    .projects-preview {
        grid-template-columns: 1fr;
    }

    .content-grid {
        grid-template-columns: 1fr;
    }

    .tech-list {
        grid-template-columns: 1fr;
    }

    h1 {
        font-size: var(--font-size-3xl);
    }

    h2 {
        font-size: var(--font-size-2xl);
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 var(--spacing-md);
    }

    .nav-menu {
        gap: var(--spacing-sm);
    }

    .hero-title {
        font-size: var(--font-size-3xl);
    }

    .section-title {
        margin-bottom: var(--spacing-2xl);
    }

    h1 {
        font-size: var(--font-size-2xl);
    }

    .hero-cta {
        flex-direction: column;
    }

    .social-links {
        flex-direction: column;
    }

    .social-links a {
        width: 100%;
    }
}