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

:root {
    --primary-color: #1a365d;
    --secondary-color: #2b77ad;
    --accent-color: #3182ce;
    --text-dark: #2d3748;
    --text-light: #4a5568;
    --text-muted: #718096;
    --bg-light: #f7fafc;
    --bg-white: #ffffff;
    --border-color: #e2e8f0;
    --gradient: linear-gradient(135deg, #1a365d 0%, #2b77ad 100%);
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--text-dark);
    background: var(--bg-white);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Header */
header {
    background: var(--gradient);
    color: white;
    padding: 60px 0;
    position: relative;
    overflow: hidden;
}

header::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100"><defs><pattern id="grid" width="10" height="10" patternUnits="userSpaceOnUse"><path d="M 10 0 L 0 0 0 10" fill="none" stroke="rgba(255,255,255,0.05)" stroke-width="1"/></pattern></defs><rect width="100" height="100" fill="url(%23grid)"/></svg>');
    opacity: 0.3;
}

.header-content {
    position: relative;
    z-index: 2;
    display: grid;
    grid-template-columns: 1fr 300px;
    gap: 40px;
    align-items: center;
}

.hero-text h1 {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 10px;
    line-height: 1.2;
}

.hero-text .subtitle {
    font-size: 1.3rem;
    font-weight: 300;
    margin-bottom: 20px;
    opacity: 0.9;
}

.hero-text .summary {
    font-size: 1.1rem;
    line-height: 1.7;
    opacity: 0.85;
    max-width: 600px;
}

.contact-card {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 15px;
    padding: 30px;
}

.contact-item {
    display: flex;
    align-items: center;
    margin-bottom: 15px;
    font-size: 1rem;
}

.contact-item i {
    width: 25px;
    margin-right: 15px;
    opacity: 0.8;
}

.contact-item a {
    color: white;
    text-decoration: none;
    transition: opacity 0.3s;
}

.contact-item a:hover {
    opacity: 0.8;
}

/* Navigation */
nav {
    background: var(--bg-white);
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav-container {
    display: flex;
    justify-content: center;
    padding: 0;
}

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

.nav-links li {
    margin: 0;
}

.nav-links a {
    display: block;
    padding: 20px 30px;
    text-decoration: none;
    color: var(--text-dark);
    font-weight: 500;
    transition: all 0.3s;
    border-bottom: 3px solid transparent;
}

.nav-links a:hover,
.nav-links a.active {
    color: var(--accent-color);
    border-bottom-color: var(--accent-color);
}

/* Main Content */
main {
    padding: 60px 0;
}

.section {
    margin-bottom: 80px;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 40px;
    text-align: center;
    position: relative;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 4px;
    background: var(--accent-color);
    border-radius: 2px;
}

/* Experience Section */
.timeline {
    position: relative;
    padding-left: 30px;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 15px;
    top: 0;
    bottom: 0;
    width: 2px;
    background: var(--accent-color);
}

.timeline-item {
    position: relative;
    background: var(--bg-white);
    border: 1px solid var(--border-color);
    border-radius: 15px;
    padding: 30px;
    margin-bottom: 30px;
    margin-left: 30px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.08);
    transition: transform 0.3s, box-shadow 0.3s;
}

.timeline-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 25px rgba(0,0,0,0.15);
}

.timeline-item::before {
    content: '';
    position: absolute;
    left: -45px;
    top: 30px;
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: var(--accent-color);
    border: 3px solid var(--bg-white);
}

.job-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 15px;
    flex-wrap: wrap;
    gap: 10px;
}

.job-title {
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 5px;
}

.company {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--accent-color);
}

.job-period {
    background: var(--bg-light);
    padding: 8px 16px;
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-light);
    white-space: nowrap;
}

.job-location {
    font-style: italic;
    color: var(--text-muted);
    margin-bottom: 15px;
}

.job-description {
    margin-bottom: 20px;
    line-height: 1.7;
}

.achievements {
    background: var(--bg-light);
    border-radius: 10px;
    padding: 20px;
}

.achievements h4 {
    color: var(--primary-color);
    margin-bottom: 15px;
    font-size: 1.1rem;
}

.achievements ul {
    list-style: none;
    padding-left: 0;
}

.achievements li {
    position: relative;
    padding-left: 25px;
    margin-bottom: 10px;
    line-height: 1.6;
}

.achievements li::before {
    content: '▶';
    position: absolute;
    left: 0;
    color: var(--accent-color);
    font-size: 0.8rem;
}

/* Skills & Languages Grid */
.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 40px;
    margin-top: 40px;
}

.skill-category {
    background: var(--bg-white);
    border: 1px solid var(--border-color);
    border-radius: 15px;
    padding: 30px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.08);
}

.skill-category h3 {
    color: var(--primary-color);
    margin-bottom: 20px;
    font-size: 1.3rem;
    text-align: center;
}

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

.skill-item {
    display: flex;
    align-items: center;
    padding: 12px 0;
    border-bottom: 1px solid var(--border-color);
}

.skill-item:last-child {
    border-bottom: none;
}

.skill-item i {
    margin-right: 15px;
    color: var(--accent-color);
    width: 20px;
}

/* Education & Publications */
.education-item,
.publication-item {
    background: var(--bg-white);
    border: 1px solid var(--border-color);
    border-radius: 15px;
    padding: 25px;
    margin-bottom: 20px;
    box-shadow: 0 3px 10px rgba(0,0,0,0.05);
}

.education-item h3,
.publication-item h3 {
    color: var(--primary-color);
    margin-bottom: 10px;
}

.education-meta,
.publication-meta {
    color: var(--text-muted);
    font-style: italic;
}

/* Footer */
footer {
    background: var(--primary-color);
    color: white;
    text-align: center;
    padding: 40px 0;
}

/* Responsive Design */
@media (max-width: 768px) {
    .header-content {
        grid-template-columns: 1fr;
        gap: 30px;
        text-align: center;
    }

    .hero-text h1 {
        font-size: 2.2rem;
    }

    .hero-text .subtitle {
        font-size: 1.1rem;
    }

    .nav-links {
        flex-wrap: wrap;
        justify-content: center;
    }

    .nav-links a {
        padding: 15px 20px;
    }

    .job-header {
        flex-direction: column;
        align-items: flex-start;
    }

    .timeline {
        padding-left: 0;
    }

    .timeline::before {
        display: none;
    }

    .timeline-item {
        margin-left: 0;
    }

    .timeline-item::before {
        display: none;
    }

    .skills-grid {
        grid-template-columns: 1fr;
        gap: 20px;
    }
}

/* Smooth scrolling */
html {
    scroll-behavior: smooth;
}

/* Animation for elements coming into view */
.fade-in {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.6s, transform 0.6s;
}

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