:root {
    --bg-color: #ffffff;
    --text-color: #333333;
    --text-secondary: #666666;
    --accent-color: #0056b3;
    --card-bg: #f8f9fa;
    --border-color: #e9ecef;
    --nav-bg: rgba(255, 255, 255, 0.95);
    --shadow: 0 2px 4px rgba(0,0,0,0.1);
    --transition: all 0.3s ease;
}

[data-theme="dark"] {
    --bg-color: #121212;
    --text-color: #e0e0e0;
    --text-secondary: #a0a0a0;
    --accent-color: #4da3ff;
    --card-bg: #1e1e1e;
    --border-color: #333333;
    --nav-bg: rgba(18, 18, 18, 0.95);
    --shadow: 0 2px 4px rgba(0,0,0,0.3);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    transition: var(--transition);
}

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

a:hover {
    text-decoration: underline;
}

.container {
    max-width: 960px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Loader */
.loader-container {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: var(--bg-color);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
    transition: opacity 0.5s ease, visibility 0.5s;
}

.loader {
    border: 4px solid var(--border-color);
    border-top: 4px solid var(--accent-color);
    border-radius: 50%;
    width: 40px;
    height: 40px;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

.loader-hidden {
    opacity: 0;
    visibility: hidden;
}

/* Navbar */
.navbar {
    position: sticky;
    top: 0;
    background-color: var(--nav-bg);
    box-shadow: var(--shadow);
    padding: 1rem 0;
    z-index: 100;
    backdrop-filter: blur(10px);
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--text-color);
    text-decoration: none;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 20px;
}

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

.nav-links a:hover {
    color: var(--accent-color);
    text-decoration: none;
}

.theme-btn {
    background: none;
    border: none;
    color: var(--text-color);
    cursor: pointer;
    font-size: 1.2rem;
    padding: 5px;
    margin-left: 20px;
}

.hamburger {
    display: none;
    flex-direction: column;
    cursor: pointer;
    gap: 5px;
}

.hamburger span {
    width: 25px;
    height: 3px;
    background-color: var(--text-color);
    transition: var(--transition);
}

/* Sections */
.section {
    padding: 60px 0;
}

.section-title {
    font-size: 2rem;
    margin-bottom: 30px;
    color: var(--text-color);
    border-bottom: 2px solid var(--accent-color);
    display: inline-block;
    padding-bottom: 5px;
}

hr {
    border: 0;
    border-top: 1px solid var(--border-color);
    margin: 0;
}

/* Profile */
.profile-content {
    display: flex;
    align-items: center;
    gap: 40px;
}

.profile-image-container {
    flex-shrink: 0;
}

.profile-img {
    width: 200px;
    height: 200px;
    border-radius: 50%;
    object-fit: cover;
    border: 4px solid var(--card-bg);
    box-shadow: var(--shadow);
}

.profile-info h1 {
    font-size: 2.5rem;
    margin-bottom: 5px;
}

.profile-info h2 {
    font-size: 1.2rem;
    color: var(--text-secondary);
    font-weight: normal;
    margin-bottom: 10px;
}

.affiliation {
    color: var(--text-secondary);
    margin-bottom: 20px;
    font-style: italic;
}

.bio {
    margin-bottom: 20px;
}

.highlight {
    color: #ff0000;
    font-weight: bold;
}

.social-links {
    display: flex;
    gap: 15px;
}

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

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

/* Experience */
.timeline {
    position: relative;
    border-left: 2px solid var(--border-color);
    padding-left: 20px;
    margin-left: 10px;
}

.timeline-item {
    margin-bottom: 30px;
    position: relative;
}

.timeline-item::before {
    content: '';
    position: absolute;
    left: -26px;
    top: 5px;
    width: 10px;
    height: 10px;
    background-color: var(--accent-color);
    border-radius: 50%;
}

.timeline-role {
    font-weight: bold;
    font-size: 1.1rem;
}

.timeline-company {
    color: var(--text-secondary);
}

.timeline-period {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-top: 5px;
}

/* Publications */
.publication-item {
    margin-bottom: 25px;
    padding-bottom: 15px;
    border-bottom: 1px solid var(--border-color);
}

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

.pub-title {
    font-weight: bold;
    font-size: 1.1rem;
    margin-bottom: 5px;
}

.pub-authors {
    margin-bottom: 5px;
    color: var(--text-secondary);
}

.pub-venue {
    font-style: italic;
    color: var(--accent-color);
    margin-bottom: 5px;
}

.pub-award {
    color: #d9534f;
    font-weight: bold;
    margin-left: 10px;
}

.pub-links {
    margin-top: 5px;
}

.pub-links a {
    display: inline-block;
    margin-right: 10px;
    font-size: 0.9rem;
    border: 1px solid var(--accent-color);
    padding: 2px 8px;
    border-radius: 4px;
}

.pub-links a:hover {
    background-color: var(--accent-color);
    color: #fff;
    text-decoration: none;
}

/* Services */
.services-list {
    list-style: none;
}

.services-list li {
    margin-bottom: 15px;
}

.service-role {
    font-weight: bold;
}

/* Footer */
.footer {
    padding: 20px 0;
    text-align: center;
    color: var(--text-secondary);
    border-top: 1px solid var(--border-color);
    margin-top: 40px;
}

/* Responsive */
@media (max-width: 768px) {
    .profile-content {
        flex-direction: column;
        text-align: center;
        gap: 20px;
    }

    .profile-img {
        width: 150px;
        height: 150px;
    }
    
    .nav-links {
        display: none;
        flex-direction: column;
        position: absolute;
        top: 60px;
        left: 0;
        width: 100%;
        background-color: var(--nav-bg);
        box-shadow: var(--shadow);
        padding: 20px;
        text-align: center;
    }

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

    .hamburger {
        display: flex;
    }
}