/* ============================================
   CSS CUSTOM PROPERTIES / DESIGN TOKENS
   ============================================ */
:root {
    /* Colors - Dark Theme */
    --color-bg: #0a0e14;
    --color-bg-secondary: #12171f;
    --color-bg-elevated: #1a2029;
    --color-border: #2a3341;
    --color-border-hover: #3d4b5c;
    
    --color-text-primary: #e6e8eb;
    --color-text-secondary: #a0a8b5;
    --color-text-muted: #6b7280;
    
    --color-accent: #60a5fa;
    --color-accent-hover: #3b82f6;
    --color-accent-dim: #1e3a5f;
    
    --color-highlight: #22d3ee;
    
    /* Typography */
    --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', sans-serif;
    --font-mono: 'SF Mono', 'Monaco', 'Cascadia Code', 'Roboto Mono', 'Courier New', monospace;
    
    --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;
    
    /* Spacing */
    --spacing-1: 0.25rem;
    --spacing-2: 0.5rem;
    --spacing-3: 0.75rem;
    --spacing-4: 1rem;
    --spacing-5: 1.25rem;
    --spacing-6: 1.5rem;
    --spacing-8: 2rem;
    --spacing-10: 2.5rem;
    --spacing-12: 3rem;
    --spacing-16: 4rem;
    --spacing-20: 5rem;
    
    /* Layout */
    --max-width-content: 1200px;
    --max-width-narrow: 800px;
    --header-height: 70px;
    
    /* Border radius */
    --radius-sm: 0.25rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4), 0 2px 4px -1px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.5), 0 4px 6px -2px rgba(0, 0, 0, 0.4);
    
    /* Transitions */
    --transition-base: 0.2s ease-in-out;
    --transition-slow: 0.3s ease-in-out;
}

/* ============================================
   RESET & BASE STYLES
   ============================================ */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
}

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

body {
    font-family: var(--font-sans);
    font-size: var(--font-size-base);
    line-height: 1.6;
    color: var(--color-text-primary);
    background-color: var(--color-bg);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

h1, h2, h3, h4, h5, h6 {
    line-height: 1.2;
    font-weight: 600;
}

a {
    color: var(--color-accent);
    text-decoration: none;
    transition: color var(--transition-base);
}

a:hover {
    color: var(--color-accent-hover);
}

a:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
    border-radius: var(--radius-sm);
}

ul {
    list-style: none;
}

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

/* ============================================
   UTILITY CLASSES
   ============================================ */
.container {
    max-width: var(--max-width-content);
    margin: 0 auto;
    padding: 0 var(--spacing-6);
}

@media (max-width: 768px) {
    .container {
        padding: 0 var(--spacing-4);
    }
}

/* Skip link for accessibility */
.skip-link {
    position: absolute;
    top: -100px;
    left: var(--spacing-4);
    background: var(--color-accent);
    color: var(--color-bg);
    padding: var(--spacing-3) var(--spacing-5);
    border-radius: var(--radius-md);
    font-weight: 600;
    z-index: 100;
}

.skip-link:focus {
    top: var(--spacing-4);
}

/* ============================================
   HEADER & NAVIGATION
   ============================================ */
.header {
    position: sticky;
    top: 0;
    background-color: rgba(10, 14, 20, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--color-border);
    z-index: 50;
    height: var(--header-height);
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 100%;
}

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

.brand:hover {
    color: var(--color-accent);
}

.brand-name {
    position: relative;
}

.nav-list {
    display: flex;
    gap: var(--spacing-8);
    align-items: center;
}

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

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

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--color-accent);
    transition: width var(--transition-base);
}

.nav-link:hover::after {
    width: 100%;
}

.nav-link-download {
    padding: var(--spacing-2) var(--spacing-4);
    background-color: var(--color-accent-dim);
    border-radius: var(--radius-md);
    color: var(--color-accent);
}

.nav-link-download:hover {
    background-color: var(--color-accent);
    color: var(--color-bg);
}

.nav-link-download::after {
    display: none;
}

/* Mobile menu toggle */
.nav-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: var(--spacing-2);
    z-index: 51;
}

.hamburger {
    display: block;
    width: 24px;
    height: 2px;
    background-color: var(--color-text-primary);
    position: relative;
    transition: background-color var(--transition-base);
}

.hamburger::before,
.hamburger::after {
    content: '';
    position: absolute;
    width: 24px;
    height: 2px;
    background-color: var(--color-text-primary);
    transition: transform var(--transition-base);
}

.hamburger::before {
    top: -8px;
}

.hamburger::after {
    top: 8px;
}

@media (max-width: 768px) {
    .nav-toggle {
        display: block;
    }
    
    .nav-list {
        position: fixed;
        top: var(--header-height);
        right: -100%;
        width: 80%;
        max-width: 300px;
        height: calc(100vh - var(--header-height));
        background-color: var(--color-bg-secondary);
        border-left: 1px solid var(--color-border);
        flex-direction: column;
        gap: 0;
        padding: var(--spacing-6) 0;
        transition: right var(--transition-slow);
        align-items: flex-start;
    }
    
    .nav-list.active {
        right: 0;
    }
    
    .nav-list li {
        width: 100%;
    }
    
    .nav-link {
        display: block;
        padding: var(--spacing-4) var(--spacing-6);
        width: 100%;
    }
    
    .nav-link::after {
        display: none;
    }
    
    .nav-link-download {
        margin: var(--spacing-4) var(--spacing-6);
        width: calc(100% - var(--spacing-12));
        text-align: center;
    }
    
    .nav-toggle[aria-expanded="true"] .hamburger {
        background-color: transparent;
    }
    
    .nav-toggle[aria-expanded="true"] .hamburger::before {
        transform: rotate(45deg) translate(5px, 5px);
    }
    
    .nav-toggle[aria-expanded="true"] .hamburger::after {
        transform: rotate(-45deg) translate(6px, -6px);
    }
}

/* ============================================
   HERO SECTION
   ============================================ */
.hero {
    min-height: calc(45vh - var(--header-height));
    display: flex;
    align-items: center;
    padding: var(--spacing-10) 0;
}

.hero-content {
    max-width: var(--max-width-narrow);
}

.hero-title {
    font-size: var(--font-size-5xl);
    margin-bottom: var(--spacing-4);
}

.highlight {
    color: var(--color-highlight);
}

.hero-role {
    font-size: var(--font-size-2xl);
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-6);
}

.hero-tagline {
    font-size: var(--font-size-lg);
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-8);
    line-height: 1.7;
}

.hero-actions {
    display: flex;
    gap: var(--spacing-4);
    margin-bottom: var(--spacing-8);
    flex-wrap: wrap;
}

.btn {
    display: inline-flex;
    align-items: center;
    padding: var(--spacing-3) var(--spacing-6);
    border-radius: var(--radius-md);
    font-weight: 600;
    transition: all var(--transition-base);
    border: 2px solid transparent;
}

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

.btn-primary:hover {
    background-color: var(--color-accent-hover);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background-color: transparent;
    border-color: var(--color-accent);
    color: var(--color-accent);
}

.btn-secondary:hover {
    background-color: var(--color-accent-dim);
    transform: translateY(-2px);
}

.hero-social {
    display: flex;
    gap: var(--spacing-4);
}

.social-link {
    display: flex;
    align-items: center;
    gap: var(--spacing-2);
    padding: var(--spacing-2);
    color: var(--color-text-secondary);
    transition: all var(--transition-base);
}

.social-link:hover {
    color: var(--color-accent);
    transform: translateY(-2px);
}

.social-link svg {
    flex-shrink: 0;
}

@media (max-width: 768px) {
    .hero {
        padding: var(--spacing-10) 0;
    }
    
    .hero-title {
        font-size: var(--font-size-3xl);
    }
    
    .hero-role {
        font-size: var(--font-size-xl);
    }
    
    .hero-tagline {
        font-size: var(--font-size-base);
    }
}

/* ============================================
   SECTIONS
   ============================================ */
.section {
    padding: var(--spacing-20) 0;
}

.section-title {
    font-size: var(--font-size-4xl);
    margin-bottom: var(--spacing-12);
    text-align: center;
    position: relative;
}

.section-title::after {
    content: '';
    display: block;
    width: 60px;
    height: 4px;
    background: linear-gradient(90deg, var(--color-accent), var(--color-highlight));
    margin: var(--spacing-4) auto 0;
    border-radius: var(--radius-sm);
}

@media (max-width: 768px) {
    .section {
        padding: var(--spacing-12) 0;
    }
    
    .section-title {
        font-size: var(--font-size-3xl);
    }
}

/* ============================================
   ABOUT SECTION
   ============================================ */
.section-about {
    background-color: var(--color-bg-secondary);
}

.about-content {
    max-width: var(--max-width-narrow);
    margin: 0 auto;
}

.about-intro {
    font-size: var(--font-size-lg);
    color: var(--color-text-secondary);
    line-height: 1.8;
    margin-bottom: var(--spacing-12);
    text-align: center;
}

.about-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-6);
}

.card {
    background-color: var(--color-bg-elevated);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-6);
    transition: all var(--transition-base);
}

.card:hover {
    border-color: var(--color-border-hover);
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
}

.card-title {
    font-size: var(--font-size-xl);
    margin-bottom: var(--spacing-4);
    color: var(--color-accent);
}

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

.card-list li {
    padding: var(--spacing-2) 0;
    padding-left: var(--spacing-6);
    position: relative;
    color: var(--color-text-secondary);
}

.card-list li::before {
    content: '▹';
    position: absolute;
    left: 0;
    color: var(--color-accent);
    font-weight: bold;
}

.tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-2);
}

.tag {
    padding: var(--spacing-2) var(--spacing-3);
    background-color: var(--color-accent-dim);
    color: var(--color-accent);
    border-radius: var(--radius-md);
    font-size: var(--font-size-sm);
    font-weight: 500;
    transition: all var(--transition-base);
}

.tag:hover {
    background-color: var(--color-accent);
    color: var(--color-bg);
}

.tag-small {
    padding: var(--spacing-1) var(--spacing-2);
    font-size: 0.8rem;
}

/* ============================================
   PROJECTS SECTION
   ============================================ */
.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: var(--spacing-6);
    max-width: var(--max-width-content);
    margin: 0 auto;
}

.project-card {
    background-color: var(--color-bg-elevated);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-6);
    display: flex;
    flex-direction: column;
    transition: all var(--transition-base);
}

.project-card:hover {
    border-color: var(--color-border-hover);
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.project-title {
    font-size: var(--font-size-xl);
    margin-bottom: var(--spacing-3);
    color: var(--color-text-primary);
}

.project-description {
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-4);
    line-height: 1.7;
}

.project-highlights {
    list-style: none;
    margin-bottom: var(--spacing-4);
    flex-grow: 1;
}

.project-highlights li {
    padding: var(--spacing-2) 0;
    padding-left: var(--spacing-5);
    position: relative;
    color: var(--color-text-secondary);
    font-size: var(--font-size-sm);
}

.project-highlights li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--color-highlight);
    font-weight: bold;
}

.project-tags {
    margin-bottom: var(--spacing-4);
}

.project-link {
    display: inline-flex;
    align-items: center;
    color: var(--color-accent);
    font-weight: 600;
    margin-top: auto;
    transition: all var(--transition-base);
}

.project-link:hover {
    color: var(--color-accent-hover);
    transform: translateX(4px);
}

@media (max-width: 768px) {
    .projects-grid {
        grid-template-columns: 1fr;
    }
}

/* ============================================
   CONTACT SECTION
   ============================================ */
.section-contact {
    background-color: var(--color-bg-secondary);
}

.contact-content {
    max-width: var(--max-width-narrow);
    margin: 0 auto;
    text-align: center;
}

.contact-intro {
    font-size: var(--font-size-lg);
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-8);
    line-height: 1.8;
}

.contact-info {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-6);
}

.contact-email {
    font-size: var(--font-size-2xl);
    font-weight: 600;
    color: var(--color-accent);
    padding: var(--spacing-4) var(--spacing-8);
    border: 2px solid var(--color-accent);
    border-radius: var(--radius-lg);
    transition: all var(--transition-base);
}

.contact-email:hover {
    background-color: var(--color-accent-dim);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.contact-social {
    display: flex;
    gap: var(--spacing-6);
}

.contact-social .social-link {
    padding: var(--spacing-3) var(--spacing-5);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    background-color: var(--color-bg-elevated);
}

.contact-social .social-link:hover {
    border-color: var(--color-accent);
    background-color: var(--color-accent-dim);
}

@media (max-width: 768px) {
    .contact-email {
        font-size: var(--font-size-xl);
        padding: var(--spacing-3) var(--spacing-6);
    }
    
    .contact-social {
        flex-direction: column;
        width: 100%;
    }
    
    .contact-social .social-link {
        width: 100%;
        justify-content: center;
    }
}

/* ============================================
   FOOTER
   ============================================ */
.footer {
    background-color: var(--color-bg-secondary);
    border-top: 1px solid var(--color-border);
    padding: var(--spacing-8) 0;
    text-align: center;
}

.footer-text {
    color: var(--color-text-muted);
    font-size: var(--font-size-sm);
}