/* --- Global Styles & Variables [LIGHT THEME V3] --- */
:root {
    --bg-light: #F8F9FA;
    --bg-white: #FFFFFF;
    --border-color: #E9ECEF;
    --text-dark: #212529;
    --text-muted: #6C757D;
    --accent-color: #28A3F4; /* Lighter Marrow Blue */
    --accent-hover: #1E90DB; /* Darker Light Blue */
    --footer-dark: #212529;
    --font-family: 'Inter', sans-serif;
    --shadow-sm: 0 4px 8px rgba(0, 0, 0, 0.04);
    --shadow-md: 0 10px 20px rgba(0, 0, 0, 0.08);
}

/* --- DARK THEME VARIABLES --- */
body[data-theme="dark"] {
    --bg-light: #111827;
    --bg-white: #1F2937;
    --border-color: #374151;
    --text-dark: #F9FAFB;
    --text-muted: #9CA3AF;
    --footer-dark: #111827;
}


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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    background-color: var(--bg-light);
    color: var(--text-dark);
    line-height: 1.7;
    -webkit-font-smoothing: antialiased;
    transition: background-color 0.3s ease, color 0.3s ease;
}

.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 2rem;
}

section {
    padding-top: 6rem;
    padding-bottom: 6rem;
}

h1, h2, h3, h4 {
    font-weight: 700;
    color: var(--text-dark);
}

h2 {
    font-size: 2.25rem;
    margin-top: 2rem;
    margin-bottom: 2.5rem;
    text-align: center;
}

h2, .experience-card h3, .research-card h3 {
    color: var(--accent-color);
}


/* --- Header & Navigation --- */
header {
    width: 100%;
    padding: 1.5rem 0;
    position: fixed;
    top: 0;
    left: 0;
    z-index: 1000;
    background-color: rgba(255, 255, 255, 0.85);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    transition: background-color 0.3s ease, border-color 0.3s ease;
}
body[data-theme="dark"] header {
    background-color: rgba(17, 24, 39, 0.8);
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.25rem;
    font-weight: 600;
    text-decoration: none;
    color: var(--text-dark);
}

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

.nav-links a {
    text-decoration: none;
    color: var(--text-muted);
    font-weight: 600;
    transition: color 0.3s ease;
}

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

.header-controls {
    display: flex;
    align-items: center;
    gap: 1.5rem;
}

.hamburger {
    display: none;
    font-size: 1.5rem;
    cursor: pointer;
    z-index: 1001;
    color: var(--text-dark);
}

/* --- Theme Switch --- */
.theme-switch-wrapper {
    display: flex;
    align-items: center;
}
.theme-switch {
    position: relative;
    display: inline-block;
    width: 50px;
    height: 26px;
}
.theme-switch input {
    opacity: 0;
    width: 0;
    height: 0;
}
.slider {
    position: absolute;
    cursor: pointer;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: #ccc;
    transition: .4s;
    border-radius: 34px;
}
.slider:before {
    position: absolute;
    content: "";
    height: 18px;
    width: 18px;
    left: 4px;
    bottom: 4px;
    background-color: white;
    transition: .4s;
    border-radius: 50%;
}
input:checked + .slider {
    background-color: var(--accent-color);
}
input:checked + .slider:before {
    transform: translateX(24px);
}

/* --- Hero Section --- */
#hero {
    display: grid;
    grid-template-columns: 1fr 1fr;
    align-items: center;
    gap: 4rem;
    padding-top: 12rem;
    padding-bottom: 6rem;
}

.hero-intro {
    display: block;
    font-weight: 600;
    color: var(--accent-color);
    margin-bottom: 1rem;
    letter-spacing: 1px;
    font-size: 0.9rem;
}

.hero-text h1 {
    font-size: 3rem;
    line-height: 1.2;
    margin-bottom: 1.5rem;
}

.hero-text p {
    font-size: 1.1rem;
    color: var(--text-muted);
    margin-bottom: 2rem;
    max-width: 500px;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
}

.btn {
    display: inline-block;
    padding: 0.85rem 1.75rem;
    border-radius: 8px;
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s ease;
    border: none;
    cursor: pointer;
}

.btn-primary {
    background-color: var(--accent-color);
    color: var(--bg-white);
    box-shadow: 0 4px 10px rgba(40, 163, 244, 0.3);
}
.btn-primary:hover {
    background-color: var(--accent-hover);
    transform: translateY(-3px);
    box-shadow: 0 6px 15px rgba(40, 163, 244, 0.4);
}

.btn-secondary {
    background-color: var(--bg-white);
    color: var(--accent-color);
    border: 1px solid var(--border-color);
}
.btn-secondary:hover {
    background-color: #f0f0f0;
    border-color: #ccc;
}
body[data-theme="dark"] .btn-secondary {
    background-color: var(--bg-medium);
    color: var(--text-primary);
}


.hero-image img {
    width: 100%;
    max-width: 380px;
    border-radius: 50%;
    border: 8px solid var(--bg-white);
    box-shadow: var(--shadow-md);
}

/* --- Mission Section --- */
#mission {
    background-color: var(--bg-white);
    text-align: center;
    border-top: 1px solid var(--border-color);
    border-bottom: 1px solid var(--border-color);
}

.mission-statement {
    font-size: 1.4rem;
    line-height: 1.7;
    font-style: italic;
    max-width: 800px;
    margin: 0 auto;
    color: var(--text-muted);
}

/* --- About Section --- */
#about .about-content {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 3rem;
    align-items: flex-start;
}
#about .about-text h2 {
    text-align: left;
    margin-top: 0;
}
#about .about-text p {
    color: var(--text-muted);
    margin-bottom: 1rem;
    text-align: justify;
}
#about .linkedin-badge {
    padding-top: 1rem;
}
/* This new rule hides the text link above the LinkedIn badge */
.LI-profile-badge a.LI-simple-link {
    display: none !important;
}


/* --- Featured Project Section --- */
#featured-project {
    background-color: var(--bg-white);
    border-top: 3px solid var(--accent-color);
    border-bottom: 1px solid var(--border-color);
    position: relative;
}
.flagship-badge {
    display: inline-block;
    background: var(--accent-color);
    color: #fff;
    font-size: 0.75rem;
    font-weight: 700;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    padding: 0.35rem 0.9rem;
    border-radius: 999px;
    margin-bottom: 1rem;
}
.project-cta {
    margin-top: 2rem;
    padding: 1.5rem;
    border-radius: 12px;
    background: var(--bg-light);
    border: 1px solid var(--border-color);
}
.project-cta p {
    text-align: left !important;
    color: var(--text-dark) !important;
    margin-bottom: 1rem;
    font-weight: 500;
}
.project-content {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: 3rem;
    align-items: center;
}
.project-image img {
    width: 100%;
    border-radius: 12px;
    box-shadow: var(--shadow-md);
}
.project-details h3 {
    font-size: 1.75rem;
    margin-bottom: 2rem;
}
.project-item {
    margin-bottom: 1.5rem;
}
.project-item h4 {
    font-size: 1.1rem;
    margin-bottom: 0.5rem;
    color: var(--text-dark);
}
.project-item p {
    color: var(--text-muted);
    text-align: justify;
}


/* --- Core Research Areas --- */
.research-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 2rem;
}
.research-card {
    background-color: var(--bg-white);
    padding: 2.5rem;
    border: 1px solid var(--border-color);
    border-radius: 12px;
    text-align: center;
    transition: all 0.3s ease;
    box-shadow: var(--shadow-sm);
}
.research-card:hover {
    border-color: var(--accent-color);
    transform: translateY(-5px);
    box-shadow: var(--shadow-md);
}
.research-card i {
    font-size: 2.5rem;
    color: var(--accent-color);
    margin-bottom: 1.5rem;
}
.research-card h3 {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
}
.research-card p {
    color: var(--text-muted);
}

/* --- Blog Section --- */
#blog {
    background-color: var(--bg-white);
    border-top: 1px solid var(--border-color);
}
.blog-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}
.blog-post-card {
    background-color: var(--bg-light);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    overflow: hidden;
    text-decoration: none;
    color: var(--text-dark);
    transition: all 0.3s ease;
    box-shadow: var(--shadow-sm);
}
.blog-post-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-md);
}
.blog-post-card img {
    width: 100%;
    height: 200px;
    object-fit: cover;
}
.blog-post-content {
    padding: 1.5rem;
}
.blog-post-content h3 {
    color: var(--accent-color);
    margin-bottom: 0.5rem;
}
.blog-post-content p {
    color: var(--text-muted);
    font-size: 0.9rem;
}


/* --- Presentations Section --- */
#presentations {
    border-top: 1px solid var(--border-color);
    border-bottom: 1px solid var(--border-color);
}
.presentation-list {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
}
.presentation-item {
    background-color: var(--bg-white);
    border: 1px solid var(--border-color);
    padding: 1.5rem;
    border-radius: 8px;
    border-left: 4px solid var(--accent-color);
}
.presentation-role {
    font-weight: 700;
    font-size: 1.1rem;
    margin-bottom: 0.25rem;
}
.presentation-event {
    color: var(--text-muted);
}

/* --- Experience Section --- */
.experience-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1.5rem;
}

.experience-card {
    background-color: var(--bg-white);
    padding: 2rem;
    border-left: 4px solid var(--border-color);
    border-radius: 0 8px 8px 0;
    transition: all 0.3s ease;
}
.experience-card:hover {
    border-left-color: var(--accent-color);
    transform: translateX(5px);
    box-shadow: var(--shadow-sm);
}
.experience-details {
    color: var(--text-dark);
    font-weight: 600;
    margin-bottom: 0.5rem;
}
.experience-card p:last-child {
    color: var(--text-muted);
    text-align: justify;
}

/* --- Research Publications Section --- */
.toggle-buttons {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 2rem;
}
.toggle-btn {
    background: var(--bg-white);
    border: 1px solid var(--border-color);
    color: var(--text-muted);
    padding: 0.5rem 1rem;
    border-radius: 50px;
    cursor: pointer;
    font-weight: 600;
    transition: all 0.3s ease;
}
.toggle-btn.active, .toggle-btn:hover {
    background-color: var(--accent-color);
    color: var(--bg-white);
    border-color: var(--accent-color);
}
.research-content { display: none; }
.research-content.active { display: block; }

.publication-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background-color: var(--bg-white);
    padding: 1rem 1.5rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    margin-bottom: 1rem;
    box-shadow: var(--shadow-sm);
    flex-wrap: wrap;
}
.publication-info {
    flex: 1;
    min-width: 300px;
    padding-right: 1rem;
}
.publication-links {
    display: flex;
    gap: 0.5rem;
}
.publication-links a {
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 600;
    padding: 0.4rem 0.8rem;
    border-radius: 6px;
    transition: all 0.3s ease;
}
.link-btn {
    color: var(--accent-color);
    border: 1px solid var(--accent-color);
}
.link-btn:hover {
    background-color: var(--accent-color);
    color: var(--bg-white);
}
.download-btn {
    color: var(--text-muted);
    border: 1px solid var(--border-color);
}
.download-btn:hover {
    background-color: var(--text-muted);
    color: var(--bg-white);
    border-color: var(--text-muted);
}


.ongoing-item {
    display: block;
    background-color: var(--bg-white);
    padding: 1rem 1.5rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    margin-bottom: 1rem;
    box-shadow: var(--shadow-sm);
}


/* --- Footer & Contact Form --- */
footer {
    background-color: var(--footer-dark);
    color: #F8F9FA;
    text-align: center;
    padding-top: 6rem;
    padding-bottom: 4rem;
}
footer h2 { 
    color: var(--bg-white);
    margin-bottom: 1rem; 
}
footer p {
    color: var(--text-muted);
    max-width: 600px;
    margin: 0 auto 2rem auto;
}

.contact-form {
    max-width: 600px;
    margin: 0 auto 3rem auto;
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.form-group {
    display: flex;
    gap: 1rem;
}

.contact-form input, .contact-form textarea {
    width: 100%;
    padding: 0.75rem;
    background-color: #2c3e50;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    color: var(--bg-light);
    font-family: var(--font-family);
    transition: border-color 0.3s ease;
}

.contact-form input:focus, .contact-form textarea:focus {
    outline: none;
    border-color: var(--accent-color);
}

.contact-form input::placeholder, .contact-form textarea::placeholder {
    color: var(--text-muted);
}

.contact-links {
    display: flex;
    justify-content: center;
    gap: 2rem;
    margin-top: 2.5rem;
}
.contact-links a {
    color: var(--text-muted);
    font-size: 2rem;
    transition: color 0.3s ease, transform 0.3s ease;
}
.contact-links a:hover { 
    color: var(--accent-color);
    transform: translateY(-3px);
}
.copyright {
    margin-top: 3rem;
    font-size: 0.9rem;
}

/* --- Back to Top Button --- */
.back-to-top-btn {
    position: fixed;
    bottom: 30px;
    right: 30px;
    background-color: var(--accent-color);
    color: var(--bg-white);
    width: 50px;
    height: 50px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    text-decoration: none;
    box-shadow: var(--shadow-md);
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.4s, visibility 0.4s, transform 0.4s;
}
.back-to-top-btn.show {
    opacity: 1;
    visibility: visible;
}
.back-to-top-btn:hover {
    background-color: var(--accent-hover);
    transform: translateY(-5px);
}


/* --- Scroll Animation --- */
.animated-section {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}
.animated-section.visible {
    opacity: 1;
    transform: translateY(0);
}


/* --- Responsive Design & Mobile Menu --- */
@media (max-width: 992px) {
    #about .about-content {
        grid-template-columns: 1fr;
    }
}


@media (max-width: 768px) {
    h2 { font-size: 2rem; }

    .hamburger { display: block; }
    .nav-links {
        position: fixed;
        right: -100%;
        top: 0;
        height: 100vh;
        width: 70%;
        background: var(--bg-white);
        flex-direction: column;
        align-items: center;
        justify-content: center;
        transition: right 0.4s ease-in-out;
        box-shadow: -5px 0 15px rgba(0,0,0,0.1);
        gap: 0;
        z-index: 1000;
    }
    body[data-theme="dark"] .nav-links {
        background: var(--bg-white);
    }
    .nav-links.nav-active { right: 0; }
    .nav-links li { margin: 2rem 0; }

    #hero {
        grid-template-columns: 1fr;
        text-align: center;
        padding-top: 8rem;
    }
    .hero-image { grid-row: 1; margin-bottom: 2rem; }
    .hero-image img { margin: 0 auto; max-width: 280px; }
    .hero-text h1 { font-size: 2.5rem; }
    .hero-text p { margin-left: auto; margin-right: auto; }

    #about .about-content {
        text-align: center;
    }
    #about .about-content h2 { text-align: center; }
    #about .about-text p { text-align: left; }

    .project-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
    .project-content h3 { text-align: center; }
    .project-item p { text-align: left; }
    .project-image { margin-bottom: 2rem; }

    .research-grid, .presentation-list { grid-template-columns: 1fr; }
    .experience-card p:last-child { text-align: left; }
    .form-group { flex-direction: column; }
    .publication-item { flex-direction: column; align-items: flex-start; }
    .publication-links { margin-top: 1rem; }
}