/* ===== CSS Variables & Reset ===== */
:root {
    --color-bg: #0f172a;
    --color-bg-alt: #1e293b;
    --color-surface: #334155;
    --color-primary: #38bdf8;
    --color-primary-dark: #0284c7;
    --color-accent: #22d3ee;
    --color-text: #e2e8f0;
    --color-text-muted: #94a3b8;
    --color-text-heading: #f1f5f9;
    --color-border: #475569;
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --max-width: 1100px;
    --radius: 12px;
    --transition: 0.3s ease;
}

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

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

body {
    font-family: var(--font-family);
    background-color: var(--color-bg);
    color: var(--color-text);
    line-height: 1.7;
    -webkit-font-smoothing: antialiased;
}

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

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

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

/* ===== Layout ===== */
.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 24px;
}

.section {
    padding: 100px 0;
}

.section-alt {
    background-color: var(--color-bg-alt);
}

.section-title {
    font-size: 2rem;
    font-weight: 700;
    color: var(--color-text-heading);
    margin-bottom: 48px;
    position: relative;
    display: inline-block;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -8px;
    left: 0;
    width: 60px;
    height: 3px;
    background: linear-gradient(90deg, var(--color-primary), var(--color-accent));
    border-radius: 2px;
}

/* ===== Navbar ===== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(15, 23, 42, 0.85);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid rgba(71, 85, 105, 0.3);
    transition: background var(--transition);
}

.nav-container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 24px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
}

.nav-logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--color-primary);
    letter-spacing: -0.5px;
}

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

.nav-links {
    display: flex;
    list-style: none;
    gap: 32px;
}

.nav-links a {
    color: var(--color-text-muted);
    font-size: 0.9rem;
    font-weight: 500;
    transition: color var(--transition);
    position: relative;
}

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

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

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

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
}

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

/* ===== Hero ===== */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 120px 24px 80px;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -20%;
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, rgba(56, 189, 248, 0.08) 0%, transparent 70%);
    pointer-events: none;
}

.hero::after {
    content: '';
    position: absolute;
    bottom: -30%;
    left: -10%;
    width: 500px;
    height: 500px;
    background: radial-gradient(circle, rgba(34, 211, 238, 0.06) 0%, transparent 70%);
    pointer-events: none;
}

.hero-content {
    max-width: 720px;
    position: relative;
    z-index: 1;
}

.hero-greeting {
    font-size: 1.1rem;
    color: var(--color-primary);
    font-weight: 500;
    margin-bottom: 8px;
    letter-spacing: 0.5px;
}

.hero-name {
    font-size: 3.5rem;
    font-weight: 700;
    color: var(--color-text-heading);
    line-height: 1.15;
    margin-bottom: 12px;
}

.hero-title-suffix {
    color: var(--color-text-muted);
    font-weight: 400;
    font-size: 2rem;
}

.hero-tagline {
    font-size: 1.2rem;
    color: var(--color-primary);
    margin-bottom: 24px;
    font-weight: 500;
}

.hero-description {
    font-size: 1.05rem;
    color: var(--color-text-muted);
    line-height: 1.8;
    margin-bottom: 36px;
    max-width: 600px;
}

.hero-actions {
    display: flex;
    gap: 16px;
    flex-wrap: wrap;
}

/* ===== Buttons ===== */
.btn {
    display: inline-flex;
    align-items: center;
    padding: 12px 28px;
    border-radius: 8px;
    font-size: 0.95rem;
    font-weight: 600;
    transition: all var(--transition);
    cursor: pointer;
    border: none;
    text-decoration: none;
}

.btn-primary {
    background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
    color: var(--color-bg);
}

.btn-primary:hover {
    color: var(--color-bg);
    transform: translateY(-2px);
    box-shadow: 0 8px 24px rgba(56, 189, 248, 0.25);
}

.btn-secondary {
    background: transparent;
    color: var(--color-primary);
    border: 1px solid var(--color-primary);
}

.btn-secondary:hover {
    background: rgba(56, 189, 248, 0.1);
    color: var(--color-accent);
    transform: translateY(-2px);
}

/* ===== About ===== */
.about-grid {
    display: grid;
    grid-template-columns: 1.5fr 1fr;
    gap: 48px;
    align-items: start;
}

.about-text p {
    margin-bottom: 16px;
    color: var(--color-text-muted);
}

.about-text strong {
    color: var(--color-text);
}

.about-highlights {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
}

.highlight-card {
    background: var(--color-bg-alt);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 20px;
    text-align: center;
    transition: transform var(--transition), border-color var(--transition);
}

.highlight-card:hover {
    transform: translateY(-4px);
    border-color: var(--color-primary);
}

.highlight-icon {
    font-size: 1.8rem;
    display: block;
    margin-bottom: 8px;
}

.highlight-card h3 {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--color-text-heading);
    margin-bottom: 4px;
}

.highlight-card p {
    font-size: 0.8rem;
    color: var(--color-text-muted);
}

/* ===== Timeline ===== */
.timeline {
    position: relative;
    padding-left: 40px;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 8px;
    top: 0;
    bottom: 0;
    width: 2px;
    background: linear-gradient(to bottom, var(--color-primary), var(--color-accent), transparent);
}

.timeline-item {
    position: relative;
    margin-bottom: 48px;
}

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

.timeline-marker {
    position: absolute;
    left: -40px;
    top: 6px;
    width: 18px;
    height: 18px;
    border-radius: 50%;
    background: var(--color-bg-alt);
    border: 3px solid var(--color-primary);
    z-index: 1;
}

.timeline-content {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 28px;
    transition: border-color var(--transition), transform var(--transition);
}

.timeline-content:hover {
    border-color: var(--color-primary);
    transform: translateX(4px);
}

.timeline-date {
    font-size: 0.85rem;
    color: var(--color-primary);
    font-weight: 600;
    letter-spacing: 0.5px;
}

.timeline-content h3 {
    font-size: 1.3rem;
    color: var(--color-text-heading);
    margin-top: 4px;
}

.timeline-content h4 {
    font-size: 1rem;
    color: var(--color-text-muted);
    font-weight: 400;
    margin-bottom: 12px;
}

.timeline-content ul {
    list-style: none;
    padding: 0;
}

.timeline-content li {
    position: relative;
    padding-left: 20px;
    margin-bottom: 8px;
    color: var(--color-text-muted);
    font-size: 0.95rem;
}

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

/* ===== Skills ===== */
.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 24px;
}

.skill-category {
    background: var(--color-bg-alt);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 24px;
    transition: border-color var(--transition);
}

.skill-category:hover {
    border-color: var(--color-primary);
}

.skill-category h3 {
    font-size: 0.95rem;
    color: var(--color-text-heading);
    margin-bottom: 14px;
    font-weight: 600;
}

.skill-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.skill-tag {
    background: rgba(56, 189, 248, 0.1);
    color: var(--color-primary);
    padding: 6px 14px;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 500;
    border: 1px solid rgba(56, 189, 248, 0.2);
    transition: all var(--transition);
}

.skill-tag:hover {
    background: rgba(56, 189, 248, 0.2);
    border-color: var(--color-primary);
}

/* ===== Education ===== */
.education-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 20px;
}

.education-card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 24px;
    transition: border-color var(--transition), transform var(--transition);
}

.education-card:hover {
    border-color: var(--color-primary);
    transform: translateY(-4px);
}

.education-year {
    font-size: 0.85rem;
    color: var(--color-primary);
    font-weight: 600;
}

.education-card h3 {
    font-size: 1.1rem;
    color: var(--color-text-heading);
    margin-top: 4px;
}

.education-card h4 {
    font-size: 0.9rem;
    color: var(--color-text-muted);
    font-weight: 400;
    margin-bottom: 4px;
}

.thesis-title {
    font-size: 0.88rem;
    color: var(--color-text-muted);
    margin-top: 8px;
    line-height: 1.5;
}

/* ===== Engagement ===== */
.engagement-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 20px;
}

.engagement-card {
    background: var(--color-bg-alt);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 24px;
    text-align: center;
    transition: border-color var(--transition), transform var(--transition);
}

.engagement-card:hover {
    border-color: var(--color-primary);
    transform: translateY(-4px);
}

.engagement-icon {
    font-size: 2.2rem;
    display: block;
    margin-bottom: 12px;
}

.engagement-card h3 {
    font-size: 1.05rem;
    color: var(--color-text-heading);
    margin-bottom: 4px;
}

.engagement-date {
    font-size: 0.8rem;
    color: var(--color-primary);
    font-weight: 600;
    display: block;
    margin-bottom: 8px;
}

.engagement-card p {
    font-size: 0.9rem;
    color: var(--color-text-muted);
    line-height: 1.6;
}

/* ===== Contact ===== */
.contact-content {
    text-align: center;
    max-width: 600px;
    margin: 0 auto;
}

.contact-text {
    font-size: 1.05rem;
    color: var(--color-text-muted);
    margin-bottom: 36px;
    line-height: 1.8;
}

.contact-links {
    display: flex;
    flex-direction: column;
    gap: 16px;
    align-items: center;
}

.contact-link {
    display: inline-flex;
    align-items: center;
    gap: 12px;
    padding: 14px 28px;
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    color: var(--color-text);
    transition: all var(--transition);
    min-width: 300px;
    justify-content: center;
}

.contact-link:hover {
    border-color: var(--color-primary);
    background: rgba(56, 189, 248, 0.05);
    color: var(--color-primary);
    transform: translateY(-2px);
}

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

/* ===== Footer ===== */
.footer {
    text-align: center;
    padding: 24px;
    border-top: 1px solid var(--color-border);
    color: var(--color-text-muted);
    font-size: 0.85rem;
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
    .nav-toggle {
        display: flex;
    }

    .nav-links {
        position: fixed;
        top: 64px;
        left: 0;
        right: 0;
        background: rgba(15, 23, 42, 0.98);
        backdrop-filter: blur(12px);
        flex-direction: column;
        padding: 24px;
        gap: 20px;
        transform: translateY(-120%);
        transition: transform var(--transition);
        border-bottom: 1px solid var(--color-border);
    }

    .nav-links.active {
        transform: translateY(0);
    }

    .hero-name {
        font-size: 2.4rem;
    }

    .hero-title-suffix {
        font-size: 1.4rem;
    }

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

    .about-highlights {
        grid-template-columns: 1fr 1fr;
    }

    .timeline {
        padding-left: 30px;
    }

    .timeline-marker {
        left: -30px;
        width: 14px;
        height: 14px;
    }

    .timeline-content {
        padding: 20px;
    }

    .contact-link {
        min-width: auto;
        width: 100%;
    }

    .section {
        padding: 64px 0;
    }
}

@media (max-width: 480px) {
    .hero-name {
        font-size: 1.8rem;
    }

    .hero-title-suffix {
        font-size: 1.1rem;
        display: block;
    }

    .about-highlights {
        grid-template-columns: 1fr;
    }

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

    .btn {
        width: 100%;
        justify-content: center;
    }
}

/* ===== Animations ===== */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.fade-in {
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

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