/* Main CSS */
    @import url('https://fonts.googleapis.com/css2?family=Poppins:wght@300;400;500;600;700&display=swap');

    :root {
        --primary-color: #4a6fa5;
        --secondary-color: #166d3b;
        --accent-color: #ff7e5f;
        --dark-color: #333333;
        --light-color: #f9f9f9;
        --text-color: #4a4a4a;
        --text-light: #777777;
        --transition: all 0.3s ease;
    }

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

    body {
        font-family: 'Poppins', sans-serif;
        background-color: var(--light-color);
        color: var(--text-color);
        line-height: 1.6;
    }

    .container {
        width: 100%;
        max-width: 1200px;
        margin: 0 auto;
        padding: 0 20px;
    }

    h1, h2, h3, h4 {
        margin-bottom: 15px;
        color: var(--dark-color);
    }

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

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

    ul {
        list-style: none;
    }

    section {
        padding: 80px 0;
    }

    /* Header Styles */
    header {
        background-color: rgba(255, 255, 255, 0.95);
        position: fixed;
        width: 100%;
        top: 0;
        left: 0;
        z-index: 1000;
        box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
        transition: var(--transition);
    }

    header.scrolled {
        padding: 10px 0;
        background-color: rgba(255, 255, 255, 0.98);
    }

    .header-container {
        display: flex;
        justify-content: space-between;
        align-items: center;
        padding: 20px 0;
    }

    .logo {
        font-size: 24px;
        font-weight: 700;
        color: var(--primary-color);
    }

    .nav-items {
        display: flex;
    }

    .nav-items li {
        margin-left: 30px;
    }

    .nav-items a {
        font-weight: 500;
        padding: 8px 0;
        position: relative;
    }

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

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

    .hamburger {
        display: none;
        cursor: pointer;
        background: none;
        border: none;
        font-size: 24px;
        color: var(--dark-color);
    }

    /* Hero Section */
    .hero {
        height: 100vh;
        background: linear-gradient(135deg, rgba(74, 111, 165, 0.1) 0%, rgba(255, 126, 95, 0.1) 100%);
        display: flex;
        align-items: center;
        position: relative;
        overflow: hidden;
    }

    .hero-content {
        max-width: 600px;
    }

    .hero h1 {
        font-size: 48px;
        margin-bottom: 20px;
        animation: fadeInUp 1s ease;
    }

    .hero h3 {
        font-size: 24px;
        color: var(--primary-color);
        margin-bottom: 30px;
        animation: fadeInUp 1s ease 0.2s forwards;
        opacity: 0;
    }

    .hero p {
        font-size: 18px;
        margin-bottom: 40px;
        animation: fadeInUp 1s ease 0.4s forwards;
        opacity: 0;
    }

    .cta-buttons {
        display: flex;
        gap: 20px;
        animation: fadeInUp 1s ease 0.6s forwards;
        opacity: 0;
    }

    .btn {
        padding: 12px 30px;
        border-radius: 30px;
        font-weight: 500;
        text-transform: uppercase;
        letter-spacing: 1px;
        transition: var(--transition);
        display: inline-block;
    }

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

    .btn-primary:hover {
        background-color: var(--secondary-color);
        color: white;
        transform: translateY(-3px);
    }

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

    .btn-outline:hover {
        background-color: var(--primary-color);
        color: white;
        transform: translateY(-3px);
    }

    .social-links {
        display: flex;
        gap: 15px;
        margin-top: 30px;
        animation: fadeInUp 1s ease 0.8s forwards;
        opacity: 0;
    }

    .social-links a {
        width: 40px;
        height: 40px;
        border-radius: 50%;
        display: flex;
        align-items: center;
        justify-content: center;
        background-color: var(--primary-color);
        color: white;
        transition: var(--transition);
    }

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

    /* About Section */
    .about {
        background-color: white;
    }

    .about-content {
        display: flex;
        align-items: center;
        gap: 50px;
    }

    .about-image {
        flex: 1;
        position: relative;
    }

    .about-image img {
        width: 100%;
        border-radius: 10px;
        box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    }

    .about-image::before {
        content: '';
        position: absolute;
        width: 100%;
        height: 100%;
        border: 3px solid var(--accent-color);
        border-radius: 10px;
        top: 20px;
        left: 20px;
        z-index: -1;
    }

    .about-text {
        flex: 1;
    }

    .about-text h2 {
        position: relative;
        display: inline-block;
        margin-bottom: 30px;
    }

    .about-text h2::after {
        content: '';
        position: absolute;
        width: 60px;
        height: 3px;
        background-color: var(--accent-color);
        bottom: -10px;
        left: 0;
    }

    .about-text p {
        margin-bottom: 20px;
    }

    /* Experience Section */
    .experience .section-title {
        text-align: center;
        margin-bottom: 60px;
        position: relative;
    }

    .section-title::after {
        content: '';
        position: absolute;
        width: 60px;
        height: 3px;
        background-color: var(--accent-color);
        bottom: -15px;
        left: 50%;
        transform: translateX(-50%);
    }

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

    .timeline::after {
        content: '';
        position: absolute;
        width: 3px;
        background-color: var(--primary-color);
        top: 0;
        bottom: 0;
        left: 50%;
        margin-left: -1.5px;
    }

    .timeline-item {
        position: relative;
        margin-bottom: 50px;
    }

    .timeline-item::after {
        content: '';
        display: table;
        clear: both;
    }

    .timeline-content {
        width: 45%;
        padding: 20px;
        background-color: white;
        border-radius: 10px;
        box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
        position: relative;
        transition: var(--transition);
    }

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

    .timeline-item:nth-child(even) .timeline-content {
        float: right;
    }

    .timeline-item:nth-child(odd) .timeline-content {
        float: left;
    }

    .timeline-content::before {
        content: '';
        position: absolute;
        top: 20px;
        width: 20px;
        height: 20px;
        background-color: white;
        transform: rotate(45deg);
    }

    .timeline-item:nth-child(odd) .timeline-content::before {
        right: -10px;
    }

    .timeline-item:nth-child(even) .timeline-content::before {
        left: -10px;
    }

    .timeline-date {
        top: 20px;
        font-size: 14px;
        font-weight: 500;
        color: var(--text-light);
    }

    .timeline-item:nth-child(odd) .timeline-date {
        right: -120px;
    }

    .timeline-item:nth-child(even) .timeline-date {
        left: -120px;
    }

    .timeline-dot {
        position: absolute;
        width: 16px;
        height: 16px;
        background-color: var(--primary-color);
        border-radius: 50%;
        top: 25px;
        left: 50%;
        margin-left: -8px;
        z-index: 1;
    }

    .timeline-title {
        margin-bottom: 10px;
        font-size: 18px;
        color: var(--primary-color);
    }

    .timeline-subtitle {
        margin-bottom: 10px;
        font-size: 14px;
        color: var(--accent-color);
    }

    /* Education Section */
    .education {
        background-color: white;
    }

    .education .section-title {
        text-align: center;
        margin-bottom: 60px;
        position: relative;
    }

    .education-cards {
        display: flex;
        flex-wrap: wrap;
        gap: 30px;
        justify-content: center;
    }

    .education-card {
        background-color: var(--light-color);
        border-radius: 10px;
        padding: 30px;
        box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
        flex: 1;
        min-width: 300px;
        max-width: 380px;
        transition: var(--transition);
    }

    .education-card:hover {
        transform: translateY(-5px);
        box-shadow: 0 10px 25px rgba(0, 0, 0, 0.1);
    }

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

    .education-card h4 {
        color: var(--accent-color);
        font-size: 16px;
        margin-bottom: 15px;
    }

    .education-card p {
        color: var(--text-light);
        font-size: 14px;
        margin-bottom: 15px;
    }

    .courses {
        margin-top: 15px;
    }

    .courses strong {
        color: var(--dark-color);
    }

    /* Skills Section */
    .skills .section-title {
        text-align: center;
        margin-bottom: 60px;
        position: relative;
    }

    .skills-container {
        display: flex;
        flex-wrap: wrap;
        gap: 50px;
        justify-content: center;
    }

    .skills-category {
        flex: 1;
        min-width: 300px;
    }

    .skills-category h3 {
        margin-bottom: 20px;
        color: var(--primary-color);
        position: relative;
        display: inline-block;
    }

    .skills-category h3::after {
        content: '';
        position: absolute;
        width: 40px;
        height: 2px;
        background-color: var(--accent-color);
        bottom: -8px;
        left: 0;
    }

    .skill-item {
        margin-bottom: 20px;
    }

    .skill-info {
        display: flex;
        justify-content: space-between;
        margin-bottom: 8px;
    }

    .skill-name {
        font-weight: 500;
    }

    .skill-level {
        color: var(--text-light);
    }

    .skill-bar {
        height: 6px;
        background-color: #e0e0e0;
        border-radius: 3px;
        overflow: hidden;
    }

    .skill-progress {
        height: 100%;
        background-color: var(--primary-color);
        border-radius: 3px;
        width: 0;
        transition: width 1.5s ease-in-out;
    }

    /* Research Section */
    .research {
        background-color: white;
    }

    .research .section-title {
        text-align: center;
        margin-bottom: 60px;
        position: relative;
    }

    .research-cards {
        display: flex;
        flex-wrap: wrap;
        gap: 30px;
        justify-content: center;
    }

    .research-card {
        background-color: var(--light-color);
        border-radius: 10px;
        padding: 30px;
        box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
        flex: 1;
        min-width: 300px;
        max-width: 500px;
        transition: var(--transition);
    }

    .research-card:hover {
        transform: translateY(-5px);
        box-shadow: 0 10px 25px rgba(0, 0, 0, 0.1);
    }

    .research-card h3 {
        color: var(--primary-color);
        margin-bottom: 10px;
    }

    .research-date {
        color: var(--accent-color);
        font-size: 14px;
        margin-bottom: 15px;
        display: block;
    }

    .research-journal {
        font-style: italic;
        margin-bottom: 15px;
        color: var(--text-light);
    }

    .research-doi {
        margin-top: 15px;
        font-size: 14px;
    }

    .research-doi a {
        word-break: break-all;
    }

    /* Contact Section */
    .contact {
        background: linear-gradient(135deg, rgba(74, 111, 165, 0.1) 0%, rgba(255, 126, 95, 0.1) 100%);
    }

    .contact .section-title {
        text-align: center;
        margin-bottom: 60px;
        position: relative;
    }

    .contact-container {
        display: flex;
        flex-wrap: wrap;
        gap: 50px;
    }

    .contact-info {
        flex: 1;
        min-width: 300px;
    }

    .contact-form {
        flex: 1;
        min-width: 300px;
    }

    .contact-item {
        display: flex;
        align-items: flex-start;
        margin-bottom: 30px;
    }

    .contact-icon {
        margin-right: 15px;
        width: 40px;
        height: 40px;
        background-color: var(--primary-color);
        color: white;
        border-radius: 50%;
        display: flex;
        align-items: center;
        justify-content: center;
    }

    .contact-text h4 {
        margin-bottom: 5px;
    }

    .contact-text p, .contact-text a {
        color: var(--text-light);
    }

    .form-group {
        margin-bottom: 20px;
    }

    .form-control {
        width: 100%;
        padding: 12px 15px;
        border: 1px solid #e0e0e0;
        border-radius: 5px;
        font-family: 'Poppins', sans-serif;
        font-size: 16px;
        transition: var(--transition);
    }

    .form-control:focus {
        outline: none;
        border-color: var(--primary-color);
    }

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

    .btn-submit {
        background-color: var(--primary-color);
        color: white;
        border: none;
        cursor: pointer;
        padding: 12px 30px;
        border-radius: 30px;
        font-weight: 500;
        text-transform: uppercase;
        letter-spacing: 1px;
        transition: var(--transition);
        width: 100%;
    }

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

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

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

    .footer-social {
        margin-bottom: 20px;
    }

    .footer-social a {
        margin: 0 10px;
        color: white;
        font-size: 18px;
        transition: var(--transition);
    }

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

    .footer-text {
        margin-top: 20px;
        color: rgba(255, 255, 255, 0.7);
        font-size: 14px;
    }

    /* 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);
    }

    /* Responsive Styles */
    @media (max-width: 991px) {
        .about-content {
            flex-direction: column;
        }

        .about-image::before {
            display: none;
        }

        .timeline::after {
            left: 31px;
        }

        .timeline-content {
            width: calc(100% - 80px);
        }

        .timeline-item:nth-child(even) .timeline-content,
        .timeline-item:nth-child(odd) .timeline-content {
            float: right;
        }

        .timeline-item:nth-child(even) .timeline-content::before,
        .timeline-item:nth-child(odd) .timeline-content::before {
            left: -10px;
        }

        .timeline-dot {
            left: 31px;
        }

        .timeline-item:nth-child(odd) .timeline-date,
        .timeline-item:nth-child(even) .timeline-date {
            right: auto;
            left: -80px;
            top: 5px;
            font-size: 12px;
            width: 100px;
            text-align: right;
        }
    }

    @media (max-width: 768px) {
        .header-container {
            padding: 15px 0;
        }

        .nav-items {
            position: fixed;
            top: 70px;
            left: 0;
            background-color: white;
            width: 100%;
            padding: 20px;
            box-shadow: 0 5px 10px rgba(0, 0, 0, 0.1);
            flex-direction: column;
            transform: translateY(-150%);
            transition: transform 0.3s ease;
            z-index: 999;
        }

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

        .nav-items li {
            margin: 15px 0;
        }

        .hamburger {
            display: block;
        }

        .hero h1 {
            font-size: 36px;
        }

        .hero h3 {
            font-size: 20px;
        }

        .hero p {
            font-size: 16px;
        }

        .btn {
            padding: 10px 25px;
        }

        .timeline-content {
            padding: 15px;
        }

        .timeline-item:nth-child(odd) .timeline-date,
        .timeline-item:nth-child(even) .timeline-date {
            position: relative;
            left: auto;
            right: auto;
            top: auto;
            margin-bottom: 10px;
            text-align: left;
        }

        .timeline::after {
            display: none;
        }

        .timeline-dot {
            display: none;
        }

        .timeline-content {
            width: 100%;
        }

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