:root {
    --primary-color: #2c3e50;
    --secondary-color: #3498db;
    --text-color: #333;
    --background-color: #f5f6fa;
    --section-bg: #ffffff;
    --font-family: "PT Serif", serif;
    --card-bg: rgba(255, 255, 255, 0.1);
    --shadow-color: rgba(0, 0, 0, 0.1);
}

[data-theme="dark"] {
    --primary-color: #fff;
    --secondary-color: #4da3ff;
    --background-color: #1a1a1a;
    --text-color: #fff;
    --section-bg: #1a1a1a;
    --card-bg: rgba(255, 255, 255, 0.05);
    --shadow-color: rgba(255, 255, 255, 0.1);
}

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

body {
    font-family: 'PT Serif',serif， 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--background-color);
    transition: all 0.3s ease;
}

/* Header and Navigation */
header {
    background-color: var(--section-bg);
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    position: fixed;
    width: 100%;
    top: 0;
    z-index: 1000;
}

nav {
    font-size: 1.1rem;

    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 5%;
    max-width: 1200px;
    margin: 0 auto;
}

.logo {
    font-size: 1.8rem;
    font-weight: bold;
    color: var(--primary-color);
}

.nav-items {
    display: flex;
    align-items: center;
    gap: 2rem;
}

.nav-links {
    display: flex;
    gap: 2rem;
    list-style: none;
    margin: 0;
    padding: 0;
}

.nav-links li {
    margin-left: 2rem;
}

.nav-links a {
    text-decoration: none;
    color: var(--primary-color);
    font-weight: 500;
    transition: color 0.3s ease;
    position: relative;
    display: inline-block;
}

.nav-links a::after {
    content: '';
    position: absolute;
    width: 0;
    height: 2px;
    bottom: 0;
    left: 0;
    background-color: var(--secondary-color);
    transition: width 0.3s ease;
}

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

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

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

.theme-switch-wrapper {
    display: flex;
    align-items: center;
    margin-left: 1rem;
}

/* Main Content */
main {
    max-width: 1200px;
    margin: 80px auto 0;
    padding: 2rem;
}

.section {
    background-color: var(--section-bg);
    border-radius: 10px;
    padding: 2rem;
    margin-bottom: 2rem;
    box-shadow: 0 2px 5px rgba(0,0,0,0.05);
}

h2 {
    color: var(--primary-color);
    margin-bottom: 1.5rem;
    font-size: 2rem;
}

/* About Section */
.about-content {
    display: flex;
    gap: 2rem;
    align-items: center;
}

.profile-image {
    flex: 0 0 200px;
}

.profile-pic {
    width: 100%;
    border-radius: 50%;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

.profile-pic {
    width: 200px; /* Adjust as needed for the size */
    height: 200px; /* Same value as width for a perfect circle */
    object-fit: cover; /* Ensures the image scales properly without distortion */
    border-radius: 50%;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}


.about-text {
    flex: 1;
}

/* Research Interests */
.interests-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 2rem;
    max-width: 900px;
    margin: 0 auto;
    padding: 1rem;
}

.interest-item {
    background: rgba(255, 255, 255, 0.05);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 8px;
    padding: 1.2rem;
    text-align: center;
    transition: all 0.3s ease;
    transform-style: preserve-3d;
    transform: perspective(1000px);
    box-shadow: 0 8px 32px 0 rgba(31, 38, 135, 0.08);
}

.interest-item:hover {
    background: rgba(0, 123, 255, 0.85);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    color: white;
    box-shadow: 0 8px 32px 0 rgba(31, 38, 135, 0.15);
}

.interest-item:hover i {
    color: rgba(255, 255, 255, 1);
}

.interest-item:hover h3 {
    color: rgba(255, 255, 255, 1);
}

.interest-item:hover p {
    color: rgba(255, 255, 255, 0.9);
}

.interest-item i {
    font-size: 2rem;
    margin-bottom: 0.8rem;
    color: rgba(102, 102, 102, 0.9);
    transition: color 0.3s ease;
}

.interest-item h3 {
    margin-bottom: 0.5rem;
    font-size: 1.2rem;
    transition: color 0.3s ease;
    color: rgba(0, 0, 0, 0.8);
}

.interest-item p {
    font-size: 0.9rem;
    color: rgba(102, 102, 102, 0.9);
    line-height: 1.4;
    transition: color 0.3s ease;
}

/* Make it responsive for mobile */
@media (max-width: 768px) {
    .interests-grid {
        grid-template-columns: 1fr;
    }
}

/* Publications */
.publication {
    margin-bottom: 1.5rem;
}

.publication ul {
    list-style: none;
}

.publication li {
    margin-bottom: 1rem;
    padding: 1rem;
    background-color: #f8f9fa;
    border-radius: 8px;
}

.pub-title {
    display: block;
    font-weight: bold;
    color: var(--primary-color);
}

.pub-authors {
    display: block;
    font-style: italic;
    color: #666;
    margin: 0.5rem 0;
}

.pub-links a {
    display: inline-block;
    margin-right: 1rem;
    color: var(--secondary-color);
    text-decoration: none;
}

/* Software Projects */
.software-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.software-item {
    background-color:  #f8f9fa;
    border-radius: 8px;
    padding: 1.5rem;
    transition: transform 0.3s ease;
    position: relative;
    overflow: hidden;
}

.software-icon {
    position: absolute;
    right: 20px;
    bottom: 20px;
    font-size: 520px;
    opacity: 0.08;
    transform: rotate(-15deg);
    pointer-events: none;
}

.software-item:hover {
    transform: translateY(-5px);
}

.software-links {
    margin-top: 1rem;
}

.software-links a {
    display: inline-block;
    margin-right: 1rem;
    color: var(--secondary-color);
    text-decoration: none;
}

/* Footer */
footer {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    border-top: 1px solid rgba(255, 255, 255, 0.2);
    padding: 3rem 0 1.5rem;
    margin-top: 4rem;
    box-shadow: 0 -4px 32px 0 rgba(31, 38, 135, 0.15);
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    justify-content: center;
}

.footer-section {
    display: flex;
    flex-direction: column;
}

.footer-section h3 {
    color: #333;
    margin-bottom: 1rem;
    font-size: 1.2rem;
    font-weight: 600;
    text-align: left;
}

.social-links {
    display: flex;
    gap: 1.5rem;
    margin-top: 0.5rem;
}

.footer-nav {
    display: flex;
    flex-direction: column;
    gap: 0.8rem;
    margin-top: 0.5rem;
}

.footer-nav a {
    color: #666;
    text-decoration: none;
    text-align: left;
    font-size: 1.2rem;
    /* padding: 0.5rem; */
    position: relative;
    display: inline-block;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    margin-left: -0.5rem;
    padding: 0.5rem 0.5rem 0.5rem 1.5rem;  /* increased left padding */
    margin-left: -1.5rem; 
}

.footer-nav a::before {
    content: '→';
    position: absolute;
    left: -15px;
    opacity: 0;
    transition: all 0.3s ease;
}

.footer-nav a:hover {
    color: #007bff;
    transform: translateX(25px) scale(1.05);
    text-shadow: 0 0 15px rgba(0, 123, 255, 0.3);
}

.footer-nav a:hover::before {
    opacity: 1;
    left: 0;
}

.footer-bottom {
    text-align: center;
    margin-top: 3rem;
    padding-top: 1.5rem;
    border-top: 1px solid rgba(0, 0, 0, 0.1);
}

.footer-section h3 {
    color: #333;
    margin-bottom: 1rem;
    font-size: 1.2rem;
    font-weight: 600;
}

.social-link {
    color: #666;
    font-size: 1.5rem;
    transition: all 0.3s ease;
}

.social-link:hover {
    color: #007bff;
    transform: translateY(-3px);
}

.footer-nav a {
    color: #666;
    text-decoration: none;
    transition: all 0.3s ease;
}

.footer-nav a:hover {
    color: #007bff;
    transform: translateX(5px);
}

.footer-bottom p {
    color: #666;
    font-size: 0.9rem;
}

@media (max-width: 768px) {
    .footer-content {
        grid-template-columns: 1fr;
        gap: 2rem;
        text-align: center;
    }
    
    .footer-section {
        align-items: center;
    }
    
    .footer-section h3 {
        text-align: center;
    }
    
    .social-links {
        justify-content: center;
    }
    
    .footer-nav {
        align-items: center;
    }
    
    .footer-nav a {
        text-align: center;
    }
}

@media (max-width: 768px) {
    .footer-nav a {
        margin-left: 0;
        padding: 0.5rem 1rem;
    }
    
    .footer-nav a:hover {
        transform: translateX(20px) scale(1.05);
    }
}

/* Responsive Design */
@media screen and (max-width: 768px) {
    .nav-items {
        display: none;
    }
    
    .nav-items.active {
        display: flex;
        flex-direction: column;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: var(--background-color);
        padding: 1rem;
        box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    }
    
    .nav-links {
        flex-direction: column;
        align-items: center;
        gap: 1rem;
    }
    
    .theme-switch-wrapper {
        margin: 1rem 0;
    }
    
    .about-content {
        flex-direction: column;
        text-align: center;
    }
    
    .profile-image {
        margin-bottom: 1rem;
    }
}

/* Burger Menu */
.burger {
    display: none;
    cursor: pointer;
}

.burger div {
    width: 25px;
    height: 3px;
    background-color: var(--primary-color);
    margin: 5px;
    transition: all 0.3s ease;
}

.certification-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    padding: 1rem;
}

.certification-item {
    background: #ffffff;
    border-radius: 8px;
    padding: 1.5rem;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    transition: transform 0.3s ease;
    position: relative;
    overflow: hidden;
}

.certification-item::before {
    content: '\f0a3';  /* Font Awesome certificate icon unicode */
    font-family: 'Font Awesome 5 Free';
    font-weight: 900;
    position: absolute;
    right: -20px;
    bottom: -20px;
    font-size: 120px;
    opacity: 0.03;
    transform: rotate(-15deg);
    pointer-events: none;
}

.certification-item:hover {
    transform: translateY(-5px);
}

.certification-item h3 {
    color: #333;
    margin-bottom: 0.5rem;
}

.cert-institution {
    color: #666;
    font-weight: bold;
    margin-bottom: 0.5rem;
}

.cert-date {
    color: #888;
    font-size: 0.9rem;
    margin-bottom: 1rem;
}

.cert-details {
    color: #555;
    margin-bottom: 0.5rem;
    line-height: 1.4;
}

.cert-instructor {
    color: #666;
    font-style: italic;
    margin-bottom: 1rem;
}

.cert-link {
    display: inline-block;
    padding: 0.5rem 1rem;
    background-color: #007bff;
    color: white;
    text-decoration: none;
    border-radius: 4px;
    transition: background-color 0.3s ease;
}

.cert-link:hover {
    background-color: #0056b3;
}

/* Theme Switch Styles */
.theme-switch-wrapper {
    display: flex;
    align-items: center;
    margin-left: 1rem;
}

.theme-switch {
    display: inline-block;
    height: 34px;
    position: relative;
    width: 60px;
}

.theme-switch input {
    display: none;
}

.slider {
    background-color: #ccc;
    bottom: 0;
    cursor: pointer;
    left: 0;
    position: absolute;
    right: 0;
    top: 0;
    transition: .4s;
    border-radius: 34px;
}

.slider:before {
    background-color: #fff;
    bottom: 4px;
    content: "";
    height: 26px;
    left: 4px;
    position: absolute;
    transition: .4s;
    width: 26px;
    border-radius: 50%;
}

.slider i {
    color: #fff;
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    transition: .4s;
    font-size: 0.9rem;
}

.slider .fa-sun {
    right: 8px;
}

.slider .fa-moon {
    left: 8px;
    opacity: 0;
}

input:checked + .slider {
    background-color: #2196F3;
}

input:checked + .slider:before {
    transform: translateX(26px);
}

input:checked + .slider .fa-sun {
    opacity: 0;
}

input:checked + .slider .fa-moon {
    opacity: 1;
}

.slider.round {
    border-radius: 34px;
}

.slider.round:before {
    border-radius: 50%;
}