/* ===== CSS Variables ===== */
:root {
    /* Colors - Light Mode */
    --bg-primary: #ffffff;
    --bg-secondary: #f8fafc;
    --text-primary: #0f172a;
    --text-secondary: #475569;
    --text-muted: #94a3b8;
    --accent: #0d9488;
    --accent-hover: #0f766e;
    --border: #e2e8f0;
    --card-bg: #ffffff;
    --card-shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --card-shadow-hover: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);
    
    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    
    /* Spacing */
    --container-max: 1200px;
    --section-padding: 6rem;
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 300ms ease;
}

/* Dark Mode */
[data-theme="dark"] {
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --text-primary: #f1f5f9;
    --text-secondary: #cbd5e1;
    --text-muted: #64748b;
    --accent: #14b8a6;
    --accent-hover: #2dd4bf;
    --border: #334155;
    --card-bg: #1e293b;
    --card-shadow: 0 4px 6px -1px rgb(0 0 0 / 0.3), 0 2px 4px -2px rgb(0 0 0 / 0.3);
    --card-shadow-hover: 0 20px 25px -5px rgb(0 0 0 / 0.3), 0 8px 10px -6px rgb(0 0 0 / 0.3);
}

/* ===== Reset & Base ===== */
*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
    scroll-padding-top: 80px;
}

body {
    font-family: var(--font-family);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color var(--transition-normal), color var(--transition-normal);
}

a {
    color: inherit;
    text-decoration: none;
}

ul {
    list-style: none;
}

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

/* ===== Utilities ===== */
.container {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 1.5rem;
}

.section-title {
    font-size: clamp(1.75rem, 5vw, 2.5rem);
    font-weight: 700;
    margin-bottom: 3rem;
    position: relative;
    display: inline-block;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -0.5rem;
    left: 0;
    width: 3rem;
    height: 3px;
    background-color: var(--accent);
    border-radius: 2px;
}

/* ===== Buttons ===== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.875rem 1.75rem;
    font-size: 1rem;
    font-weight: 500;
    border-radius: 8px;
    border: 2px solid transparent;
    cursor: pointer;
    transition: all var(--transition-fast);
}

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

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

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

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

.btn-large {
    padding: 1rem 2.5rem;
    font-size: 1.125rem;
}

/* ===== Navigation ===== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background-color: var(--bg-primary);
    border-bottom: 1px solid var(--border);
    transition: background-color var(--transition-normal), border-color var(--transition-normal);
}

.nav-container {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 1rem 1.5rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--accent);
}

.nav-menu {
    display: flex;
    align-items: center;
    gap: 2rem;
}

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

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

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

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

/* Theme Toggle */
.theme-toggle {
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
    color: var(--text-secondary);
    transition: color var(--transition-fast);
    display: flex;
    align-items: center;
    justify-content: center;
}

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

.sun-icon {
    display: none;
}

[data-theme="dark"] .sun-icon {
    display: block;
}

[data-theme="dark"] .moon-icon {
    display: none;
}

/* Mobile Nav Toggle */
.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
}

.nav-toggle span {
    width: 24px;
    height: 2px;
    background-color: var(--text-primary);
    transition: all var(--transition-fast);
}

/* Mobile Navigation */
@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        top: 65px;
        left: 0;
        right: 0;
        background-color: var(--bg-primary);
        flex-direction: column;
        padding: 2rem;
        gap: 1.5rem;
        border-bottom: 1px solid var(--border);
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: all var(--transition-normal);
    }

    .nav-menu.active {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }

    .nav-toggle {
        display: flex;
    }

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

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

    .nav-toggle.active span:nth-child(3) {
        transform: rotate(-45deg) translate(5px, -5px);
    }
}

/* ===== Hero Section ===== */
.hero {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    padding: 6rem 1.5rem 2rem;
    position: relative;
}

.hero-content {
    text-align: center;
    max-width: 800px;
}

.hero-greeting {
    font-size: 1.125rem;
    color: var(--accent);
    font-weight: 500;
    margin-bottom: 0.5rem;
}

.hero-title {
    font-size: clamp(2.5rem, 8vw, 4.5rem);
    font-weight: 700;
    line-height: 1.1;
    margin-bottom: 0.5rem;
}

.hero-subtitle {
    font-size: clamp(1.5rem, 4vw, 2.5rem);
    font-weight: 600;
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
}

.hero-description {
    font-size: 1.125rem;
    color: var(--text-secondary);
    max-width: 500px;
    margin: 0 auto 2rem;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
    margin-bottom: 2.5rem;
}

.hero-social {
    display: flex;
    gap: 1.5rem;
    justify-content: center;
}

.hero-social a {
    color: var(--text-muted);
    transition: color var(--transition-fast), transform var(--transition-fast);
}

.hero-social a:hover {
    color: var(--accent);
    transform: translateY(-3px);
}

/* Scroll Indicator */
.scroll-indicator {
    position: absolute;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
    color: var(--text-muted);
    font-size: 0.875rem;
    animation: bounce 2s infinite;
}

.scroll-arrow {
    width: 1px;
    height: 2rem;
    background: linear-gradient(to bottom, var(--text-muted), transparent);
}

@keyframes bounce {
    0%, 20%, 50%, 80%, 100% {
        transform: translateX(-50%) translateY(0);
    }
    40% {
        transform: translateX(-50%) translateY(-10px);
    }
    60% {
        transform: translateX(-50%) translateY(-5px);
    }
}

/* ===== About Section ===== */
.about {
    padding: var(--section-padding) 0;
    background-color: var(--bg-secondary);
}

.about-content {
    display: grid;
    gap: 3rem;
}

.about-text {
    max-width: 600px;
}

.about-text p {
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.about-text p:last-child {
    margin-bottom: 0;
}

.skills h3 {
    font-size: 1.25rem;
    margin-bottom: 1.5rem;
}

.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 2rem;
}

.skill-category h4 {
    font-size: 0.875rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--accent);
    margin-bottom: 0.75rem;
}

.skill-category ul {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.skill-category li {
    color: var(--text-secondary);
    font-size: 0.9375rem;
}

/* ===== Projects Section ===== */
.projects {
    padding: var(--section-padding) 0;
}

.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 2rem;
}

.project-card {
    background-color: var(--card-bg);
    border-radius: 12px;
    overflow: hidden;
    box-shadow: var(--card-shadow);
    transition: transform var(--transition-normal), box-shadow var(--transition-normal);
    border: 1px solid var(--border);
}

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

.project-image {
    aspect-ratio: 16 / 10;
    background-color: var(--bg-secondary);
    display: flex;
    align-items: center;
    justify-content: center;
}

.project-placeholder {
    color: var(--text-muted);
}

.project-content {
    padding: 1.5rem;
}

.project-content h3 {
    font-size: 1.25rem;
    margin-bottom: 0.75rem;
}

.project-content p {
    color: var(--text-secondary);
    font-size: 0.9375rem;
    margin-bottom: 1rem;
}

.project-tech {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1.25rem;
}

.project-tech span {
    font-size: 0.75rem;
    padding: 0.25rem 0.75rem;
    background-color: var(--bg-secondary);
    color: var(--text-secondary);
    border-radius: 9999px;
}

.project-links {
    display: flex;
    gap: 1.5rem;
}

.project-link {
    display: inline-flex;
    align-items: center;
    gap: 0.375rem;
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--text-secondary);
    transition: color var(--transition-fast);
}

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

/* ===== Contact Section ===== */
.contact {
    padding: var(--section-padding) 0;
    background-color: var(--bg-secondary);
}

.contact-content {
    text-align: center;
    max-width: 500px;
    margin: 0 auto;
}

.contact-content p {
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

.contact-social {
    display: flex;
    gap: 1.5rem;
    justify-content: center;
    margin-top: 2rem;
}

.contact-social a {
    color: var(--text-muted);
    transition: color var(--transition-fast), transform var(--transition-fast);
}

.contact-social a:hover {
    color: var(--accent);
    transform: translateY(-3px);
}

/* ===== Experience Section ===== */
.experience {
    padding: var(--section-padding) 0;
}

.timeline {
    position: relative;
    max-width: 800px;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 2px;
    background-color: var(--border);
}

.timeline-item {
    position: relative;
    padding-left: 2rem;
    padding-bottom: 2.5rem;
}

.timeline-item:last-child {
    padding-bottom: 0;
}

.timeline-marker {
    position: absolute;
    left: -5px;
    top: 0.375rem;
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background-color: var(--accent);
    border: 2px solid var(--bg-primary);
}

.timeline-content {
    background-color: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 1.25rem;
    transition: box-shadow var(--transition-normal);
}

.timeline-content:hover {
    box-shadow: var(--card-shadow);
}

.timeline-header {
    display: flex;
    flex-wrap: wrap;
    align-items: baseline;
    gap: 0.5rem;
    margin-bottom: 0.25rem;
}

.timeline-header h3 {
    font-size: 1.125rem;
    font-weight: 600;
    margin: 0;
}

.timeline-company {
    color: var(--accent);
    font-weight: 500;
}

.timeline-date {
    display: block;
    font-size: 0.875rem;
    color: var(--text-muted);
    margin-bottom: 0.25rem;
}

.timeline-location {
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-bottom: 0.75rem;
}

.timeline-description {
    color: var(--text-secondary);
    font-size: 0.9375rem;
    margin: 0;
}

.timeline-tech {
    font-size: 0.8125rem;
    color: var(--accent);
    font-weight: 500;
    margin-bottom: 0.75rem;
}

.timeline-list {
    margin: 0;
    padding-left: 1.25rem;
    color: var(--text-secondary);
    font-size: 0.9375rem;
}

.timeline-list li {
    margin-bottom: 0.375rem;
    list-style: disc;
}

.timeline-list li:last-child {
    margin-bottom: 0;
}

/* Education */
.education {
    margin-top: 3rem;
    padding-top: 2rem;
    border-top: 1px solid var(--border);
}

.education h3 {
    font-size: 1.25rem;
    margin-bottom: 1rem;
}

.education-item h4 {
    font-size: 1.0625rem;
    font-weight: 600;
    margin-bottom: 0.25rem;
}

.education-item p {
    color: var(--text-secondary);
    margin-bottom: 0.25rem;
}

.education-details {
    font-size: 0.875rem;
    color: var(--text-muted);
}

/* ===== Footer ===== */
.footer {
    padding: 2rem 0;
    text-align: center;
    border-top: 1px solid var(--border);
}

.footer p {
    color: var(--text-muted);
    font-size: 0.875rem;
}

.footer-year {
    margin-top: 0.25rem;
}

/* ===== Animations ===== */
@media (prefers-reduced-motion: no-preference) {
    .fade-in {
        opacity: 0;
        transform: translateY(20px);
        transition: opacity 0.6s ease, transform 0.6s ease;
    }

    .fade-in.visible {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ===== Responsive Adjustments ===== */
@media (max-width: 640px) {
    :root {
        --section-padding: 4rem;
    }

    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }

    .btn {
        width: 100%;
        max-width: 280px;
    }

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

    .skills-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}