:root {
    --primary-color: #2c3e50;
    --secondary-color: #3498db;
    --accent-color: #e74c3c;
    --light-color: #ecf0f1;
    --dark-color: #2c3e50;
    --text-color: #333;
    --background-color: #f9f9f9;
    --card-background: #ffffff;
    --border-color: #dddddd;
    --shadow-color: rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
}

/* Dark Theme */
[data-theme="dark"] {
    --primary-color: #3498db;
    --secondary-color: #2980b9;
    --accent-color: #e74c3c;
    --light-color: #34495e;
    --dark-color: #ecf0f1;
    --text-color: #ecf0f1;
    --background-color: #1a1a1a;
    --card-background: #2c2c2c;
    --border-color: #444444;
    --shadow-color: rgba(0, 0, 0, 0.3);
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--background-color);
    overflow-x: hidden;
    transition: var(--transition);
}

/* Header and Navigation */
header {
    background: linear-gradient(90deg, rgba(44, 62, 80, 0.95), rgba(52, 73, 94, 0.95));
    color: white;
    padding: 1rem 0;
    position: fixed;
    width: 100%;
    top: 0;
    z-index: 1000;
    box-shadow: 0 2px 10px var(--shadow-color);
    transition: var(--transition);
    backdrop-filter: blur(10px);
}

header.scrolled {
    background: linear-gradient(90deg, rgba(44, 62, 80, 0.98), rgba(52, 73, 94, 0.98));
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.15);
    padding: 0.5rem 0;
}

.header-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

.logo {
    font-size: 1.5rem;
    font-weight: bold;
    display: flex;
    align-items: center;
    transition: var(--transition);
    position: relative;
    z-index: 2;
}

.logo:hover {
    transform: scale(1.05);
}

.logo i {
    margin-right: 0.5rem;
    color: var(--secondary-color);
    transition: var(--transition);
    font-size: 1.8rem;
    display: inline-block;
}

.logo:hover i {
    color: var(--accent-color);
    animation: logoRotate 0.6s ease-in-out;
}

@keyframes logoRotate {
    0% {
        transform: rotate(0deg);
    }

    100% {
        transform: rotate(360deg);
    }
}

.nav-toggle {
    display: none;
    background: none;
    border: none;
    color: white;
    font-size: 1.5rem;
    cursor: pointer;
    transition: var(--transition);
    position: relative;
    z-index: 2;
}

.nav-toggle:hover {
    color: var(--secondary-color);
    transform: scale(1.1);
}

.nav-toggle.active {
    color: var(--accent-color);
}

nav {
    position: relative;
    z-index: 1;
}

nav ul {
    display: flex;
    list-style: none;
    transition: var(--transition);
}

nav ul li {
    margin-left: 1.5rem;
    position: relative;
}

nav ul li a {
    color: white;
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
    position: relative;
    padding: 0.5rem 0;
    display: inline-block;
}

nav ul li a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: linear-gradient(90deg, var(--secondary-color), var(--accent-color));
    transition: var(--transition);
}

nav ul li a:hover::after,
nav ul li a.active::after {
    width: 100%;
}

nav ul li a.active {
    color: var(--secondary-color);
}

/* Theme Switcher */
.theme-switcher {
    display: flex;
    align-items: center;
    margin-left: 1rem;
    background: rgba(255, 255, 255, 0.1);
    padding: 0.3rem;
    border-radius: 20px;
    transition: var(--transition);
    position: relative;
    z-index: 2;
}

.theme-switcher:hover {
    background: rgba(255, 255, 255, 0.2);
}

.theme-option {
    width: 24px;
    height: 24px;
    border-radius: 50%;
    margin: 0 3px;
    cursor: pointer;
    border: 2px solid transparent;
    transition: var(--transition);
    position: relative;
}

.theme-option:hover {
    transform: scale(1.2);
}

.theme-option.active {
    border-color: white;
    box-shadow: 0 0 10px rgba(255, 255, 255, 0.5);
}

.theme-option.active::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 8px;
    height: 8px;
    background-color: white;
    border-radius: 50%;
}

.theme-light {
    background: linear-gradient(135deg, #f5f5f5, #e0e0e0);
}

.theme-dark {
    background: linear-gradient(135deg, #424242, #212121);
}

/* Navigation Background Effect */
.nav-bg {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
    opacity: 0;
    transition: opacity 0.5s ease;
}

nav:hover .nav-bg {
    opacity: 1;
}

/* Main Content */
main {
    margin-top: 80px;
    min-height: calc(100vh - 80px);
}

.section {
    display: none;
    padding: 2rem 0;
    animation: fadeIn 0.5s ease-in-out;
}

.section.active {
    display: block;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

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



/* Home Section */
.about-me {
    background: var(--card-background);
    padding: 2rem;
    border-radius: 8px;
    box-shadow: 0 5px 15px var(--shadow-color);
    margin-bottom: 2rem;
    transition: var(--transition);
}

.about-me h2 {
    color: var(--primary-color);
    margin-bottom: 1.5rem;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid var(--secondary-color);
    font-size: 1.8rem;
}

.about-me img {
    max-width: 200px;
    border-radius: 50%;
    float: left;
    margin-right: 1.5rem;
    margin-bottom: 1rem;
    border: 4px solid var(--secondary-color);
    transition: var(--transition);
}

.about-me img:hover {
    transform: scale(1.05);
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
}

.about-me p {
    margin-bottom: 1rem;
    text-align: justify;
}

/* Education Section */
.education-section {
    background: var(--card-background);
    padding: 2rem;
    border-radius: 8px;
    box-shadow: 0 5px 15px var(--shadow-color);
    margin-bottom: 2rem;
    transition: var(--transition);
}

.education-section h2 {
    color: var(--primary-color);
    margin-bottom: 1.5rem;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid var(--secondary-color);
    font-size: 1.8rem;
    display: flex;
    align-items: center;
}

.education-section h2 i {
    margin-right: 0.5rem;
    color: var(--secondary-color);
}

.education-item {
    padding: 1.5rem;
    margin-bottom: 1.5rem;
    background-color: var(--background-color);
    border-radius: 6px;
    border-left: 4px solid var(--secondary-color);
    transition: var(--transition);
}

.education-item:hover {
    background-color: var(--border-color);
    transform: translateX(5px);
}

.education-item h3 {
    color: var(--primary-color);
    margin-bottom: 0.5rem;
    font-size: 1.2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.education-item .period {
    color: var(--accent-color);
    font-size: 0.9rem;
    font-weight: 500;
}

.education-item .institution {
    color: var(--secondary-color);
    font-weight: 500;
    margin-bottom: 0.5rem;
}

.education-item .description {
    margin-bottom: 0.5rem;
    font-size: 0.95rem;
}

.education-item .details {
    list-style-type: none;
    margin-top: 0.5rem;
}

.education-item .details li {
    padding: 0.3rem 0;
    padding-left: 1.5rem;
    position: relative;
    font-size: 0.9rem;
}

.education-item .details li::before {
    content: '▶';
    position: absolute;
    left: 0;
    color: var(--secondary-color);
}

/* News Section */
.news-section {
    background: var(--card-background);
    padding: 2rem;
    border-radius: 8px;
    box-shadow: 0 5px 15px var(--shadow-color);
    margin-bottom: 2rem;
    transition: var(--transition);
}

.news-section h2 {
    color: var(--primary-color);
    margin-bottom: 1.5rem;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid var(--secondary-color);
    font-size: 1.8rem;
}

.news-list {
    max-height: 400px;
    overflow-y: auto;
    padding-right: 10px;
}

.news-list::-webkit-scrollbar {
    width: 8px;
}

.news-list::-webkit-scrollbar-track {
    background: var(--border-color);
    border-radius: 4px;
}

.news-list::-webkit-scrollbar-thumb {
    background: var(--secondary-color);
    border-radius: 4px;
}

.news-item {
    padding: 1.2rem;
    margin-bottom: 1.2rem;
    background-color: var(--background-color);
    border-radius: 6px;
    border-left: 4px solid var(--secondary-color);
    transition: var(--transition);
}

.news-item:hover {
    background-color: var(--border-color);
    transform: translateX(5px);
}

.news-item h3 {
    color: var(--primary-color);
    margin-bottom: 0.5rem;
    font-size: 1.1rem;
}

.news-item p {
    font-size: 0.95rem;
    color: var(--text-color);
    opacity: 0.8;
}

.news-item .date {
    font-size: 0.85rem;
    color: var(--accent-color);
    margin-top: 0.5rem;
    font-weight: 500;
}

/* Students Sections */
.student-section {
    background: var(--card-background);
    padding: 2rem;
    border-radius: 8px;
    box-shadow: 0 5px 15px var(--shadow-color);
    margin-bottom: 2rem;
    transition: var(--transition);
}

.student-section h2 {
    color: var(--primary-color);
    margin-bottom: 1.5rem;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid var(--secondary-color);
    font-size: 1.8rem;
    display: flex;
    align-items: center;
}

.student-section h2 i {
    margin-right: 0.5rem;
    color: var(--secondary-color);
}

.student-section ul {
    list-style-type: none;
}

.student-section ul li {
    padding: 0.6rem 0;
    border-bottom: 1px solid var(--border-color);
    font-size: 0.95rem;
}

.student-section ul li:last-child {
    border-bottom: none;
}

.student-section .student-info {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
}

.student-section .student-details {
    flex: 1;
}

.student-section .student-current {
    flex: 1;
    margin-left: 1rem;
    padding-left: 1rem;
    border-left: 1px solid var(--border-color);
}

.student-section .student-current h4 {
    color: var(--secondary-color);
    font-size: 0.9rem;
    margin-bottom: 0.3rem;
}

.student-section .student-current p {
    font-size: 0.85rem;
    color: var(--text-color);
    opacity: 0.8;
}

.student-section p {
    margin-bottom: 1rem;
    font-size: 0.95rem;
    text-align: justify;
}

/* Experience Section */
.experience-section {
    background: var(--card-background);
    padding: 2rem;
    border-radius: 8px;
    box-shadow: 0 5px 15px var(--shadow-color);
    margin-bottom: 2rem;
    transition: var(--transition);
}

.experience-section h2 {
    color: var(--primary-color);
    margin-bottom: 1.5rem;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid var(--secondary-color);
    font-size: 1.8rem;
    display: flex;
    align-items: center;
}

.experience-section h2 i {
    margin-right: 0.5rem;
    color: var(--secondary-color);
}

.experience-tabs {
    display: flex;
    margin-bottom: 1.5rem;
    border-bottom: 1px solid var(--border-color);
}

.experience-tab {
    padding: 0.8rem 1.5rem;
    cursor: pointer;
    border-bottom: 2px solid transparent;
    transition: var(--transition);
    font-weight: 500;
    color: var(--text-color);
    opacity: 0.7;
}

.experience-tab.active {
    color: var(--secondary-color);
    border-bottom-color: var(--secondary-color);
    opacity: 1;
}

.experience-tab:hover {
    color: var(--primary-color);
    opacity: 1;
}

.experience-content {
    display: none;
}

.experience-content.active {
    display: block;
}

.experience-item {
    padding: 1.5rem;
    margin-bottom: 1.5rem;
    background-color: var(--background-color);
    border-radius: 6px;
    border-left: 4px solid var(--secondary-color);
    transition: var(--transition);
}

.experience-item:hover {
    background-color: var(--border-color);
    transform: translateX(5px);
}

.experience-item h3 {
    color: var(--primary-color);
    margin-bottom: 0.5rem;
    font-size: 1.2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.experience-item .period {
    color: var(--accent-color);
    font-size: 0.9rem;
    font-weight: 500;
}

.experience-item .institution {
    color: var(--secondary-color);
    font-weight: 500;
    margin-bottom: 0.5rem;
}

.experience-item .description {
    margin-bottom: 0.5rem;
    font-size: 0.95rem;
}

.experience-item .achievements {
    list-style-type: none;
    margin-top: 0.5rem;
}

.experience-item .achievements li {
    padding: 0.3rem 0;
    padding-left: 1.5rem;
    position: relative;
    font-size: 0.9rem;
}

.experience-item .achievements li::before {
    content: '▶';
    position: absolute;
    left: 0;
    color: var(--secondary-color);
}

/* Research Section */
.research-summary {
    background: var(--card-background);
    padding: 2rem;
    border-radius: 8px;
    box-shadow: 0 5px 15px var(--shadow-color);
    margin-bottom: 3rem;
    transition: var(--transition);
}

.research-summary h2 {
    color: var(--primary-color);
    margin-bottom: 1rem;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid var(--secondary-color);
}

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

.research-card {
    background: var(--card-background);
    border-radius: 8px;
    overflow: hidden;
    box-shadow: 0 5px 15px var(--shadow-color);
    transition: var(--transition);
}

.research-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 25px var(--shadow-color);
}

.research-card img {
    width: 100%;
    height: 200px;
    object-fit: cover;
}

.research-card-content {
    padding: 1.5rem;
}

.research-card-content h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.research-card-content ul {
    list-style-type: none;
    padding-left: 0;
}

.research-card-content ul li {
    padding: 0.5rem 0;
    padding-left: 1.5rem;
    position: relative;
}

.research-card-content ul li::before {
    content: '▶';
    position: absolute;
    left: 0;
    color: var(--secondary-color);
}

/* Publications Section */
.publications-container {
    background: var(--card-background);
    padding: 2rem;
    border-radius: 8px;
    box-shadow: 0 5px 15px var(--shadow-color);
    transition: var(--transition);
}

.publications-container h2 {
    color: var(--primary-color);
    margin-bottom: 1.5rem;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid var(--secondary-color);
}

/* Year Filter */
.year-filter {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border-color);
}

.year-filter button {
    padding: 0.5rem 1rem;
    background-color: var(--background-color);
    border: 1px solid var(--border-color);
    border-radius: 4px;
    color: var(--text-color);
    cursor: pointer;
    transition: var(--transition);
    font-weight: 500;
}

.year-filter button:hover {
    background-color: var(--secondary-color);
    color: white;
    border-color: var(--secondary-color);
}

.year-filter button.active {
    background-color: var(--secondary-color);
    color: white;
    border-color: var(--secondary-color);
}

.publication-list {
    max-height: 600px;
    overflow-y: auto;
    padding-right: 15px;
    list-style-type: none;
}

.publication-list::-webkit-scrollbar {
    width: 10px;
}

.publication-list::-webkit-scrollbar-track {
    background: var(--border-color);
    border-radius: 5px;
}

.publication-list::-webkit-scrollbar-thumb {
    background: var(--secondary-color);
    border-radius: 5px;
}

.publication-list::-webkit-scrollbar-thumb:hover {
    background: var(--primary-color);
}

.publication-item {
    padding: 1.5rem;
    margin-bottom: 1.5rem;
    background-color: var(--background-color);
    border-radius: 6px;
    border-left: 4px solid var(--secondary-color);
    transition: var(--transition);
    display: none;
}

.publication-item.show {
    display: block;
}

.publication-item:hover {
    background-color: var(--border-color);
    transform: translateX(5px);
}

.publication-item h3 {
    color: var(--primary-color);
    margin-bottom: 0.5rem;
    font-size: 1.1rem;
}

.publication-item .authors {
    font-style: italic;
    margin-bottom: 0.5rem;
    color: var(--text-color);
    opacity: 0.8;
}

.publication-item .venue {
    color: var(--accent-color);
    margin-bottom: 0.5rem;
    font-weight: 500;
}

.publication-item .links {
    margin-top: 0.5rem;
    display: flex;
    flex-wrap: wrap;
    gap: 0.8rem;
}

.publication-item .links a {
    display: inline-flex;
    align-items: center;
    color: var(--secondary-color);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
    font-size: 0.9rem;
}

.publication-item .links a:hover {
    color: var(--primary-color);
}

.publication-item .links a i {
    margin-right: 0.3rem;
}

.publication-item .abstract {
    margin-top: 1rem;
    padding: 1rem;
    background-color: var(--card-background);
    border-radius: 6px;
    border-left: 3px solid var(--secondary-color);
    display: none;
}

.publication-item .abstract.show {
    display: block;
    animation: slideDown 0.3s ease-in-out;
}

@keyframes slideDown {
    from {
        opacity: 0;
        max-height: 0;
        transform: translateY(-10px);
    }

    to {
        opacity: 1;
        max-height: 500px;
        transform: translateY(0);
    }
}

.publication-item .bibtex {
    margin-top: 1rem;
    padding: 1rem;
    background-color: var(--card-background);
    border-radius: 6px;
    border-left: 3px solid var(--accent-color);
    font-family: 'Courier New', monospace;
    font-size: 0.9rem;
    white-space: pre-wrap;
    display: none;
    overflow-x: auto;
}

.publication-item .bibtex.show {
    display: block;
    animation: slideDown 0.3s ease-in-out;
}

.btn-expand {
    background: none;
    border: 1px solid var(--secondary-color);
    color: var(--secondary-color);
    padding: 0.3rem 0.6rem;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.8rem;
    transition: var(--transition);
    display: inline-flex;
    align-items: center;
}

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

.btn-expand i {
    margin-right: 0.3rem;
}

/* Download Section */
.downloads-container {
    background: var(--card-background);
    padding: 2rem;
    border-radius: 8px;
    box-shadow: 0 5px 15px var(--shadow-color);
    transition: var(--transition);
}

.downloads-container h2 {
    color: var(--primary-color);
    margin-bottom: 1.5rem;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid var(--secondary-color);
}

.download-list {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1.5rem;
}

.download-item {
    background-color: var(--background-color);
    border-radius: 6px;
    padding: 1.5rem;
    border-left: 4px solid var(--secondary-color);
    transition: var(--transition);
}

.download-item:hover {
    background-color: var(--border-color);
    transform: translateY(-3px);
}

.download-item h3 {
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.download-item p {
    margin-bottom: 1rem;
    font-size: 0.9rem;
}

.download-item .links {
    display: flex;
    gap: 1rem;
}

.download-item .links a {
    display: inline-flex;
    align-items: center;
    color: var(--secondary-color);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
}

.download-item .links a:hover {
    color: var(--primary-color);
}

.download-item .links a i {
    margin-right: 0.3rem;
}

/* Teaching Section */
.teaching-container {
    background: var(--card-background);
    padding: 2rem;
    border-radius: 8px;
    box-shadow: 0 5px 15px var(--shadow-color);
    transition: var(--transition);
}

.teaching-container h2 {
    color: var(--primary-color);
    margin-bottom: 1.5rem;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid var(--secondary-color);
}

.teaching-list {
    list-style-type: none;
}

.teaching-item {
    padding: 1.5rem;
    margin-bottom: 1.5rem;
    background-color: var(--background-color);
    border-radius: 6px;
    border-left: 4px solid var(--secondary-color);
    transition: var(--transition);
}

.teaching-item h3 {
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.teaching-item .course-code {
    color: var(--accent-color);
    font-weight: bold;
    margin-bottom: 0.5rem;
}

.teaching-item .semester {
    font-style: italic;
    margin-bottom: 0.5rem;
}

.teaching-item .description {
    margin-bottom: 0.5rem;
}

/* Contact Section */
.contact-container {
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.contact-info {
    background: var(--card-background);
    padding: 2rem;
    border-radius: 8px;
    box-shadow: 0 5px 15px var(--shadow-color);
    transition: var(--transition);
}

.contact-info h2 {
    color: var(--primary-color);
    margin-bottom: 1.5rem;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid var(--secondary-color);
}

.contact-item {
    display: flex;
    align-items: flex-start;
    margin-bottom: 1.5rem;
}

.contact-item i {
    font-size: 1.2rem;
    color: var(--secondary-color);
    margin-right: 1rem;
    margin-top: 0.2rem;
}

.contact-item .contact-text {
    flex: 1;
}

.contact-item .contact-text h3 {
    color: var(--primary-color);
    margin-bottom: 0.3rem;
    font-size: 1rem;
}

.contact-item .contact-text p {
    margin: 0;
}

/* Academic Profiles Section */
.academic-profiles {
    margin-top: 1.5rem;
    padding-top: 1.5rem;
    border-top: 1px solid var(--border-color);
}

.academic-profiles h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
    font-size: 1.1rem;
}

.profile-links {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
}

.profile-link {
    display: inline-flex;
    align-items: center;
    padding: 0.6rem 1rem;
    background-color: var(--background-color);
    border-radius: 6px;
    color: var(--secondary-color);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
    border: 1px solid var(--border-color);
}

.profile-link:hover {
    background-color: var(--secondary-color);
    color: var(--card-background);
    transform: translateY(-3px);
    box-shadow: 0 5px 15px var(--shadow-color);
}

.profile-link i {
    margin-right: 0.5rem;
    font-size: 1.1rem;
}

.contact-form {
    background: var(--card-background);
    padding: 2rem;
    border-radius: 8px;
    box-shadow: 0 5px 15px var(--shadow-color);
    transition: var(--transition);
}

.contact-form h2 {
    color: var(--primary-color);
    margin-bottom: 1.5rem;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid var(--secondary-color);
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    color: var(--primary-color);
    font-weight: 500;
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 0.8rem;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    font-family: inherit;
    background-color: var(--background-color);
    color: var(--text-color);
    transition: var(--transition);
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--secondary-color);
    box-shadow: 0 0 0 2px rgba(52, 152, 219, 0.2);
}

.form-group textarea {
    resize: vertical;
    min-height: 150px;
}

.btn {
    display: inline-block;
    background-color: var(--secondary-color);
    color: white;
    padding: 0.8rem 1.5rem;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-weight: 500;
    transition: var(--transition);
}

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

/* Footer */
footer {
    background-color: var(--primary-color);
    color: white;
    text-align: center;
    padding: 2rem 0;
    margin-top: 3rem;
    transition: var(--transition);
}

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

.social-links {
    margin-bottom: 1rem;
}

.social-links a {
    display: inline-block;
    margin: 0 0.5rem;
    color: white;
    font-size: 1.2rem;
    transition: var(--transition);
}

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

/* Responsive Design */
@media (max-width: 992px) {
    .contact-container {
        flex-direction: column;
    }
}

@media (max-width: 768px) {
    .nav-toggle {
        display: block;
    }

    nav ul {
        position: fixed;
        top: 0;
        right: -100%;
        width: 70%;
        height: 100vh;
        background: linear-gradient(180deg, rgba(44, 62, 80, 0.98), rgba(52, 73, 94, 0.98));
        flex-direction: column;
        align-items: flex-start;
        padding: 5rem 2rem 2rem;
        transition: right 0.3s ease;
        box-shadow: -5px 0 15px rgba(0, 0, 0, 0.1);
        z-index: 1;
    }

    nav ul.active {
        right: 0;
    }

    nav ul li {
        margin: 0.5rem 0;
        width: 100%;
    }

    nav ul li a {
        display: block;
        padding: 1rem 0;
        font-size: 1.1rem;
    }

    .research-interests {
        grid-template-columns: 1fr;
    }

    .experience-tabs {
        flex-direction: column;
        border-bottom: none;
        border-right: 1px solid var(--border-color);
    }

    .experience-tab {
        border-bottom: 1px solid var(--border-color);
        border-right: none;
    }

    .profile-links {
        justify-content: center;
    }

    .student-section .student-info {
        flex-direction: column;
    }

    .student-section .student-current {
        margin-left: 0;
        margin-top: 0.5rem;
        padding-left: 0;
        border-left: none;
        border-top: 1px solid var(--border-color);
        padding-top: 0.5rem;
    }
}

@media (max-width: 576px) {
    .container {
        padding: 0 1rem;
    }

    .about-me img {
        float: none;
        display: block;
        margin: 0 auto 1rem;
    }

    .download-list {
        grid-template-columns: 1fr;
    }

    .profile-links {
        flex-direction: column;
        align-items: center;
    }

    .profile-link {
        width: 80%;
        justify-content: center;
    }

    .year-filter {
        justify-content: center;
    }

    .publication-item .links {
        flex-direction: column;
        gap: 0.5rem;
    }
}