:root {
    /* Light Mode (Default) */
    --primary-color: #0f172a; /* Navy Blue */
    --secondary-color: #3b82f6; /* Bright Blue */
    --accent-color: #f59e0b; /* Amber/Gold for highlights */
    --text-color: #334155; /* Slate Gray */
    --light-bg: #f8fafc; /* Very Light Gray */
    --white: #ffffff;
    --dark-bg: #1e293b;
    --border-color: #e2e8f0;
    --font-family: 'Inter', sans-serif;
    --transition: all 0.3s ease;

    /* Semantic Variables */
    --body-bg: var(--white);
    --card-bg: var(--white);
    --nav-bg: var(--white);
    --footer-bg: var(--light-bg);
    --hero-bg: linear-gradient(135deg, #f8fafc 0%, #e2e8f0 100%);
    --muted-text: #64748b;
    --nav-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --card-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05);
    --card-hover-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
}

[data-theme="dark"] {
    /* Dark Mode Overrides */
    --primary-color: #f8fafc;
    --secondary-color: #60a5fa;
    --accent-color: #fbbf24;
    --text-color: #cbd5e1;
    --light-bg: #0f172a;
    --white: #1e293b;
    --dark-bg: #020617;
    --border-color: #334155;

    /* Semantic Overrides */
    --body-bg: var(--dark-bg);
    --card-bg: var(--white);
    --nav-bg: var(--white);
    --footer-bg: var(--light-bg);
    --hero-bg: linear-gradient(135deg, #1e293b 0%, #0f172a 100%);
    --muted-text: #94a3b8;
    --nav-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.3);
    --card-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.2);
    --card-hover-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.4);
}

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

html {
    scroll-behavior: smooth;
}

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

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

ul {
    list-style: none;
}

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

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

/* Buttons */
.btn-primary, .btn-secondary {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border-radius: 6px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
}

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

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

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

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

/* Header & Nav */
header {
    background-color: var(--nav-bg);
    box-shadow: var(--nav-shadow);
    position: sticky;
    top: 0;
    z-index: 1000;
    padding: 1rem 0;
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--primary-color);
    letter-spacing: -0.5px;
}

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

.nav-links {
    display: flex;
    gap: 2rem;
    align-items: center;
    margin-left: auto;
    margin-right: 1rem;
}

.theme-toggle {
    cursor: pointer;
    font-size: 1.25rem;
    color: var(--text-color);
    transition: var(--transition);
    padding: 0.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
}

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

.nav-links a {
    font-weight: 500;
    color: var(--text-color);
}

.nav-links a.btn-primary,
.nav-links a.btn-primary:hover {
    color: var(--white);
}

.nav-links a:hover {
    color: var(--secondary-color);
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-right: -1rem;
}

.hamburger {
    display: none;
    font-size: 1.5rem;
    cursor: pointer;
}

/* Hero Section */
#hero {
    padding: 8rem 0 6rem;
    background: var(--hero-bg);
    text-align: center;
}

.hero-content {
    max-width: 800px;
    margin: 0 auto;
}

.tagline {
    display: block;
    font-size: 0.875rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--secondary-color);
    margin-bottom: 1rem;
}

#hero h1 {
    font-size: 3.5rem;
    line-height: 1.2;
    color: var(--primary-color);
    margin-bottom: 1.5rem;
    font-weight: 800;
}

#hero p {
    font-size: 1.25rem;
    color: var(--muted-text);
    margin-bottom: 2.5rem;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.hero-btns {
    display: flex;
    gap: 1rem;
    justify-content: center;
}

/* Sections General */
section {
    padding: 6rem 0;
}

.section-header {
    text-align: center;
    margin-bottom: 4rem;
}

.section-header h2 {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.section-header p {
    font-size: 1.125rem;
    color: var(--muted-text);
}

/* Skills */
#skills {
    background-color: var(--white);
}

.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.skill-card {
    background: var(--card-bg);
    padding: 2.5rem;
    border-radius: 12px;
    border: 1px solid var(--border-color);
    transition: var(--transition);
}

.skill-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--card-hover-shadow);
    border-color: var(--secondary-color);
}

.icon-box {
    width: 60px;
    height: 60px;
    background-color: rgba(59, 130, 246, 0.1);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1.5rem;
}

.icon-box i {
    font-size: 1.75rem;
    color: var(--secondary-color);
}

.skill-card h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: var(--primary-color);
}

.skill-list {
    margin-top: 1.5rem;
    padding-left: 1.25rem;
    list-style-type: disc;
}

.skill-list li {
    margin-bottom: 0.5rem;
    color: var(--muted-text);
}

/* About / Meet the Expert */
#about {
    background-color: var(--light-bg);
}

.about-container {
    display: grid;
    grid-template-columns: 1fr;
    gap: 4rem;
}

.section-subtitle {
    font-size: 0.875rem;
    font-weight: 700;
    color: var(--secondary-color);
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 0.5rem;
    display: block;
}

.about-content h2 {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.about-content h3 {
    font-size: 1.25rem;
    color: var(--muted-text);
    font-weight: 500;
    margin-bottom: 1.5rem;
}

.about-content p {
    margin-bottom: 1.5rem;
    color: var(--text-color);
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
    margin-top: 2rem;
    padding-top: 2rem;
    border-top: 1px solid var(--border-color);
}

.stat-item {
    text-align: center;
}

.stat-number {
    display: block;
    font-size: 2rem;
    font-weight: 800;
    color: var(--secondary-color);
}

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

/* Experience Timeline */
#expertise {
    background-color: var(--white);
}

.timeline {
    position: relative;
    max-width: 800px;
    margin: 0 auto;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    height: 100%;
    width: 2px;
    background-color: var(--border-color);
}

.timeline-item {
    position: relative;
    padding-left: 2rem;
    margin-bottom: 3rem;
}

.timeline-item::before {
    content: '';
    position: absolute;
    left: -5px;
    top: 0;
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background-color: var(--secondary-color);
    border: 2px solid var(--white);
}

.timeline-date {
    font-size: 0.875rem;
    color: var(--muted-text);
    margin-bottom: 0.5rem;
    font-weight: 600;
}

.timeline-content h3 {
    font-size: 1.25rem;
    color: var(--primary-color);
    margin-bottom: 0.25rem;
}

.timeline-content h4 {
    font-size: 1rem;
    color: var(--secondary-color);
    margin-bottom: 1rem;
}

/* Projects */
#projects {
    background-color: var(--light-bg);
}

.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 2rem;
}

.project-card {
    background: var(--card-bg);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--card-shadow);
    transition: var(--transition);
    display: flex;
    flex-direction: column;
}

.project-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--card-hover-shadow);
}

.project-header {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1rem;
}

.project-header i {
    font-size: 1.5rem;
    color: var(--secondary-color);
}

.project-header h3 {
    font-size: 1.25rem;
    color: var(--primary-color);
    flex-grow: 1;
}

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

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

.project-card p {
    color: var(--muted-text);
    margin-bottom: 1.5rem;
    flex-grow: 1;
}

.tech-stack {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.tech-stack span {
    background-color: var(--light-bg);
    color: var(--text-color);
    padding: 0.25rem 0.75rem;
    border-radius: 9999px;
    font-size: 0.75rem;
    font-weight: 600;
}

/* Contact */
#contact {
    background-color: var(--white);
    color: var(--text-color);
    padding: 6rem 0;
}

.contact-wrapper {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 4rem;
}

.contact-header {
    text-align: center;
    max-width: 700px;
}

.contact-header h2 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    color: var(--primary-color);
}

.contact-header p {
    color: var(--muted-text);
    font-size: 1.125rem;
}

.contact-cards {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
    width: 100%;
    max-width: 1000px;
}

.contact-card {
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    padding: 2.5rem 2rem;
    border-radius: 16px;
    text-align: center;
    transition: var(--transition);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1rem;
    box-shadow: var(--card-shadow);
}

.contact-card:hover {
    transform: translateY(-10px);
    border-color: var(--secondary-color);
    box-shadow: var(--card-hover-shadow);
}

.card-icon {
    width: 64px;
    height: 64px;
    background-color: rgba(59, 130, 246, 0.1);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 0.5rem;
    transition: var(--transition);
}

.contact-card:hover .card-icon {
    background-color: var(--secondary-color);
}

.contact-card:hover .card-icon i {
    color: var(--white);
}

.contact-card:hover h3,
.contact-card:hover span,
.contact-card:hover a {
    color: var(--secondary-color);
}

.card-icon i {
    font-size: 1.75rem;
    color: var(--secondary-color);
    transition: var(--transition);
}

.contact-card h3 {
    font-size: 1.25rem;
    color: var(--primary-color);
    font-weight: 600;
}

.contact-card a, .contact-card span {
    color: var(--muted-text);
    font-size: 1rem;
}

.contact-card a:hover {
    color: var(--secondary-color);
}

.social-links {
    display: flex;
    gap: 2rem;
    margin-top: 1rem;
}

.social-links a {
    width: 50px;
    height: 50px;
    background-color: var(--light-bg);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
    border: 1px solid var(--border-color);
}

.social-links a:hover {
    background-color: var(--secondary-color);
    transform: scale(1.1);
    border-color: var(--secondary-color);
}

.social-links i {
    font-size: 1.5rem;
    color: var(--text-color);
}

.social-links a:hover i {
    color: var(--white);
}


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

.footer-logo {
    font-weight: 800;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

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

/* Responsive */
@media (max-width: 968px) {
    #hero h1 {
        font-size: 2.5rem;
    }

    .contact-cards {
        grid-template-columns: 1fr;
        max-width: 500px;
    }
}

@media (max-width: 768px) {
    .nav-links {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        width: 100%;
        background-color: var(--white);
        flex-direction: column;
        padding: 1rem 0;
        box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
        margin-left: 0;
        margin-right: 0;
    }

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

    .hamburger {
        display: block;
    }

    .theme-toggle {
        margin-right: 0.5rem;
    }

    #hero {
        padding: 6rem 0 4rem;
    }

    .stats-grid {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }
    
    .timeline::before {
        left: 0;
    }
    
    .timeline-item {
        padding-left: 1.5rem;
    }
}