/*
 * Deepak Vaid - Portfolio
 * Main Stylesheet
 */

/* ====== BASE STYLES ====== */
:root {
    /* Light Theme Colors */
    --primary-color-light: #1e293b;
    --secondary-color-light: #3b82f6;
    --accent-color-light: #6366f1;
    --bg-color-light: #ffffff;
    --text-color-light: #1e293b;
    --text-light-light: #64748b;
    --card-bg-light: #ffffff;
    --border-light: #e2e8f0;

    /* Dark Theme Colors */
    --primary-color-dark: #1a1f37;
    --secondary-color-dark: #4F7EFF;
    --accent-color-dark: #6366F1;
    --bg-color-dark: linear-gradient(135deg, #1a1f37 0%, #0f1629 30%, #0f1629 70%, #1a1f37 100%);
    --text-color-dark: #e2e8f0;
    --text-light-dark: #94a3b8;
    --card-bg-dark: linear-gradient(135deg, rgba(255, 255, 255, 0.1) 0%, rgba(255, 255, 255, 0.05) 100%);
    --border-dark: rgba(255, 255, 255, 0.1);

    /* Default to light theme */
    --primary-color: var(--primary-color-light);
    --secondary-color: var(--secondary-color-light);
    --accent-color: var(--accent-color-light);
    --bg-color: var(--bg-color-light);
    --text-color: var(--text-color-light);
    --text-light: var(--text-light-light);
    --card-bg: var(--card-bg-light);
    --border-color: var(--border-light);

    /* Shared colors */
    --light-color: #F8FAFC;
    --dark-color: #0f1629;
    --quantum-color-1: #8B5CF6;
    --quantum-color-2: #10B981;
    --quantum-color-3: #F59E0B;

    /* Fonts */
    --heading-font: 'Playfair Display', serif;
    --body-font: 'Inter', sans-serif;

    /* Spacing */
    --section-spacing: 40px;
    --element-spacing: 20px;
    --card-padding: 24px;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--body-font);
    color: var(--text-color);
    line-height: 1.6;
    background: var(--bg-color);
    min-height: 100vh;
    transition: all 0.3s ease;
}

body.dark-theme {
    background: var(--bg-color-dark);
}

h1, h2, h3, h4, h5, h6 {
    font-family: var(--heading-font);
    font-weight: 700;
    margin-bottom: 20px;
    color: var(--text-color);
    transition: color 0.3s ease;
}

p {
    margin-bottom: 15px;
}

a {
    color: var(--secondary-color);
    text-decoration: none;
    transition: color 0.3s ease;
}

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

ul {
    list-style: none;
}

.container {
    width: 90%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

.section {
    padding: var(--section-spacing) 0;
}

.section-alt {
    background: linear-gradient(135deg, rgba(26, 31, 55, 0.8) 0%, rgba(15, 22, 41, 0.9) 100%);
}

.section-subtle {
    background: linear-gradient(135deg, rgba(26, 31, 55, 0.6) 0%, rgba(15, 22, 41, 0.7) 100%);
}

.section-title {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 50px;
    position: relative;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -15px;
    left: 50%;
    transform: translateX(-50%);
    width: 70px;
    height: 3px;
    background-color: var(--secondary-color);
}

.hero-title {
    text-align: center;
    font-size: 3rem;
    margin-bottom: 20px;
    position: relative;
}

.hero-title::after {
    content: '';
    position: absolute;
    bottom: -15px;
    left: 50%;
    transform: translateX(-50%);
    width: 100px;
    height: 3px;
    background-color: var(--secondary-color);
}

.btn {
    display: inline-block;
    padding: 12px 24px;
    background-color: var(--secondary-color);
    color: white;
    border-radius: 4px;
    text-transform: uppercase;
    font-weight: 600;
    font-size: 0.9rem;
    letter-spacing: 0.5px;
    transition: all 0.3s ease;
}

.btn:hover {
    background-color: var(--primary-color);
    color: white;
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
}

.btn-alt {
    background-color: transparent;
    color: var(--secondary-color);
    border: 2px solid var(--secondary-color);
}

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

.more-link {
    text-align: center;
    margin-top: 40px;
}

.tag {
    display: inline-block;
    background-color: var(--light-color);
    color: var(--text-color);
    padding: 4px 8px;
    border-radius: 4px;
    font-size: 0.8rem;
    margin-right: 5px;
    margin-bottom: 5px;
}

/* Dark theme override */
body.dark-theme {
    --primary-color: var(--primary-color-dark);
    --secondary-color: var(--secondary-color-dark);
    --accent-color: var(--accent-color-dark);
    --bg-color: var(--bg-color-dark);
    --text-color: var(--text-color-dark);
    --text-light: var(--text-light-dark);
    --card-bg: var(--card-bg-dark);
    --border-color: var(--border-dark);
}

/* ====== THEME TOGGLE ====== */
.theme-toggle {
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 50%;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    cursor: pointer;
    transition: all 0.3s ease;
    backdrop-filter: blur(10px);
}

.theme-toggle:hover {
    background: rgba(255, 255, 255, 0.2);
    transform: scale(1.1);
}

.theme-toggle i {
    font-size: 18px;
    transition: transform 0.3s ease;
}

/* ====== HEADER & NAVIGATION ====== */
.header {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--dark-color) 50%, #0a0f1c 100%);
    color: white;
    padding: 20px 0 80px;
    position: relative;
    overflow: hidden;
}

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

.logo {
    font-family: var(--heading-font);
    font-size: 2rem;
    font-weight: 700;
    color: white;
}

.logo img {
    height: 48px;
    width: 48px;
    display: block;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 50%;
    padding: 4px;
    backdrop-filter: blur(10px);
    transition: all 0.3s ease;
}

.logo img:hover {
    background: rgba(255, 255, 255, 0.15);
    transform: scale(1.05);
}

.nav-links {
    display: flex;
}

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

.nav-links a {
    color: white;
    font-weight: 500;
    position: relative;
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--secondary-color);
    transition: width 0.3s ease;
}

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

/* Hamburger menu toggle */
.nav-toggle {
    display: none;
    background: none;
    border: none;
    color: white;
    font-size: 1.5rem;
    cursor: pointer;
    padding: 8px;
    z-index: 1001;
}

/* Mobile nav overlay */
.nav-links.mobile-open {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(15, 22, 41, 0.98);
    flex-direction: column;
    justify-content: center;
    align-items: center;
    gap: 24px;
    z-index: 1000;
    margin: 0;
    padding: 0;
}

.nav-links.mobile-open li {
    margin: 0;
}

.nav-links.mobile-open a {
    font-size: 1.5rem;
    padding: 12px 24px;
}

.nav-links.mobile-open .theme-toggle {
    margin-top: 20px;
    font-size: 1.5rem;
}

.hero {
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 80px 0;
    text-align: center;
    min-height: 60vh;
}

.hero-content {
    width: 100%;
    max-width: 800px;
    position: relative;
}

.hero-content h1 {
    font-size: 4.5rem;
    color: white;
    margin-bottom: 15px;
    font-weight: 800;
    letter-spacing: -0.02em;
}

.hero-content h2 {
    font-size: 2.5rem;
    color: var(--secondary-color);
    margin-bottom: 25px;
    font-weight: 600;
}

.tagline {
    font-size: 1.4rem;
    color: var(--light-color);
    margin-bottom: 40px;
    line-height: 1.6;
    opacity: 0.95;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.social-links {
    display: flex;
    gap: 30px;
    justify-content: center;
    margin-top: 40px;
}

.social-links a {
    color: white;
    font-size: 2rem;
    transition: all 0.3s ease;
    padding: 15px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.2);
}

.social-links a:hover {
    color: var(--secondary-color);
    transform: translateY(-5px) scale(1.1);
    background: rgba(255, 255, 255, 0.2);
    box-shadow: 0 10px 30px rgba(0,0,0,0.3);
}

.hero-visual {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: -1;
}

.physics-animation {
    position: relative;
    width: 100%;
    height: 100%;
    margin: 0 auto;
    perspective: 1000px;
    overflow: hidden;
}

.quantum-particle {
    position: absolute;
    width: 25px;
    height: 25px;
    border-radius: 50%;
    animation: float 3s infinite ease-in-out;
    box-shadow: 0 0 20px currentColor;
    opacity: 0.8;
}

.quantum-particle:nth-child(1) {
    background-color: var(--quantum-color-1);
    top: 20%;
    left: 15%;
    animation-duration: 4s;
    animation-delay: 0s;
}

.quantum-particle:nth-child(2) {
    background-color: var(--quantum-color-2);
    top: 60%;
    right: 20%;
    animation-duration: 6s;
    animation-delay: 0.5s;
}

.quantum-particle:nth-child(3) {
    background-color: var(--quantum-color-3);
    bottom: 30%;
    left: 25%;
    animation-duration: 5s;
    animation-delay: 1s;
}

.quantum-particle:nth-child(4) {
    background-color: var(--secondary-color);
    top: 40%;
    right: 35%;
    animation-duration: 7s;
    animation-delay: 1.5s;
}

.quantum-particle:nth-child(5) {
    background-color: var(--accent-color);
    bottom: 15%;
    right: 15%;
    animation-duration: 5.5s;
    animation-delay: 2s;
}

@keyframes float {
    0%, 100% {
        transform: translateY(0) scale(1) rotate(0deg);
        opacity: 0.6;
    }
    25% {
        transform: translateY(-30px) scale(1.1) rotate(90deg);
        opacity: 0.9;
    }
    50% {
        transform: translateY(-40px) scale(1.3) rotate(180deg);
        opacity: 1;
        box-shadow: 0 15px 40px rgba(0,0,0,0.3);
    }
    75% {
        transform: translateY(-30px) scale(1.1) rotate(270deg);
        opacity: 0.9;
    }
}

/* ====== ABOUT SECTION ====== */
.about-grid {
    display: grid;
    grid-template-columns: 1.2fr 0.8fr;
    gap: 60px;
    align-items: start;
    margin-top: 40px;
}

.about-content {
    padding-right: 20px;
}

.about-content p {
    margin-bottom: 25px;
    font-size: 1.1rem;
    line-height: 1.7;
    color: var(--text-color);
}

.about-content p:first-child {
    font-size: 1.2rem;
    font-weight: 500;
    color: var(--primary-color);
}

.about-stats {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 25px;
}

.stat-box {
    background: var(--card-bg);
    backdrop-filter: blur(10px);
    border: 1px solid var(--border-color);
    padding: 30px 20px;
    border-radius: 12px;
    text-align: center;
    box-shadow: 0 8px 25px rgba(0,0,0,0.08);
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.stat-box::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--secondary-color), var(--accent-color));
}

body.dark-theme .stat-box {
    box-shadow: 0 8px 25px rgba(0,0,0,0.3);
}

.stat-box:hover {
    transform: translateY(-8px);
    box-shadow: 0 15px 35px rgba(0,0,0,0.15);
}

body.dark-theme .stat-box:hover {
    box-shadow: 0 15px 35px rgba(0,0,0,0.4);
}

.stat-number {
    display: block;
    font-size: 3rem;
    font-weight: 800;
    color: var(--secondary-color);
    margin-bottom: 8px;
    line-height: 1;
}

.stat-label {
    font-size: 0.85rem;
    color: var(--text-light);
    text-transform: uppercase;
    letter-spacing: 1.2px;
    font-weight: 600;
}

/* ====== RESEARCH SECTION ====== */
.research-areas {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 40px;
    margin-top: 50px;
}

.research-card {
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.15) 0%, rgba(255, 255, 255, 0.08) 100%);
    backdrop-filter: blur(15px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    padding: 40px 35px;
    border-radius: 16px;
    box-shadow: 0 8px 32px rgba(0,0,0,0.3);
    transition: all 0.3s ease;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.research-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--quantum-color-1), var(--quantum-color-2), var(--quantum-color-3));
}

.research-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 20px 50px rgba(0,0,0,0.4);
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.2) 0%, rgba(255, 255, 255, 0.12) 100%);
}

.research-icon {
    font-size: 3.5rem;
    color: var(--secondary-color);
    margin-bottom: 25px;
    display: block;
    transition: all 0.3s ease;
}

.research-card:hover .research-icon {
    transform: scale(1.1);
    color: white;
}

.research-card h3 {
    margin-bottom: 20px;
    font-size: 1.5rem;
    color: white;
    font-weight: 700;
}

.research-card p {
    color: rgba(255, 255, 255, 0.9);
    line-height: 1.6;
    font-size: 1rem;
}

/* ====== PUBLICATIONS SECTION ====== */
.publications-list {
    display: flex;
    flex-direction: column;
    gap: 30px;
}

.publication {
    background-color: white;
    padding: 30px;
    border-radius: 12px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.05);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    border-left: 4px solid var(--secondary-color);
    position: relative;
    overflow: hidden;
}

.publication::before {
    content: '';
    position: absolute;
    top: 0;
    right: 0;
    width: 50px;
    height: 50px;
    background: linear-gradient(135deg, var(--secondary-color), var(--quantum-color-1));
    opacity: 0.1;
    border-radius: 0 12px 0 50px;
}

.publication:hover {
    transform: translateY(-5px);
    box-shadow: 0 15px 30px rgba(0,0,0,0.1);
}

.publication h3 {
    margin-bottom: 15px;
    font-size: 1.5rem;
    line-height: 1.4;
    color: var(--primary-color);
}

.publication-authors {
    color: var(--text-light);
    margin-bottom: 8px;
    font-size: 1.1rem;
}

.publication-journal {
    color: var(--secondary-color);
    font-style: italic;
    font-weight: 600;
    font-size: 1.1rem;
}

.publication-year {
    position: absolute;
    top: 15px;
    right: 15px;
    background-color: var(--secondary-color);
    color: white;
    padding: 4px 12px;
    border-radius: 12px;
    font-size: 0.8rem;
    font-weight: 600;
}

/* ====== TEACHING SECTION ====== */
.teaching-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 50px;
}

.youtube-stats {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
    margin-top: 30px;
}

.yt-stat {
    text-align: center;
    background: linear-gradient(135deg, #5b7de1, #d0caec);
    color: white;
    padding: 20px 15px;
    border-radius: 12px;
    box-shadow: 0 5px 15px rgba(255, 0, 0, 0.2);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.yt-stat:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 20px rgba(255, 0, 0, 0.3);
}

.yt-number {
    display: block;
    font-size: 2.2rem;
    font-weight: 700;
    color: white;
    margin-bottom: 5px;
}

.yt-label {
    font-size: 0.85rem;
    color: rgba(255, 255, 255, 0.9);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.lecture-list {
    background-color: white;
    border-radius: 8px;
    overflow: hidden;
    box-shadow: 0 5px 15px rgba(0,0,0,0.05);
}

.lecture-list li {
    border-bottom: 1px solid var(--light-color);
}

.lecture-list li:last-child {
    border-bottom: none;
}

.lecture-list a {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 20px;
    color: var(--text-color);
    transition: background-color 0.3s ease;
}

.lecture-list a:hover {
    background-color: rgba(52, 152, 219, 0.1);
    color: var(--secondary-color);
}

.lecture-title {
    font-weight: 500;
}

.lecture-views {
    color: var(--text-light);
    font-size: 0.9rem;
}

.top-lectures h3 {
    margin-bottom: 20px;
}

/* ====== BLOG SECTION ====== */
.blog-subtitle {
    text-align: center;
    color: var(--text-light);
    font-style: italic;
    margin-top: -30px;
    margin-bottom: 40px;
}

.blog-posts {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
}

.blog-post {
    background-color: white;
    border-radius: 8px;
    overflow: hidden;
    box-shadow: 0 5px 15px rgba(0,0,0,0.05);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    padding: 30px;
}

.blog-post:hover {
    transform: translateY(-5px);
    box-shadow: 0 15px 30px rgba(0,0,0,0.1);
}

.blog-post h3 {
    font-size: 1.3rem;
    margin-bottom: 10px;
}

.post-date {
    color: var(--text-light);
    font-size: 0.9rem;
    margin-bottom: 15px;
}

.post-excerpt {
    color: var(--text-color);
    margin-bottom: 20px;
}

.read-more {
    font-weight: 600;
    position: relative;
}

.read-more::after {
    content: '→';
    margin-left: 5px;
    transition: transform 0.3s ease;
}

.read-more:hover::after {
    transform: translateX(5px);
}

/* ====== PROJECT CARD ENHANCEMENTS ====== */
.card-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 10px;
    gap: 10px;
}

.card-header h3 {
    margin-bottom: 0;
    flex: 1;
}

.status-badge {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    padding: 3px 10px;
    border-radius: 12px;
    font-size: 0.7rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    white-space: nowrap;
    flex-shrink: 0;
}

.status-badge::before {
    content: '';
    width: 6px;
    height: 6px;
    border-radius: 50%;
    display: inline-block;
}

.status-badge.live {
    background: rgba(16, 185, 129, 0.15);
    color: #059669;
}

.status-badge.live::before {
    background: #10b981;
    box-shadow: 0 0 4px #10b981;
}

body.dark-theme .status-badge.live {
    background: rgba(16, 185, 129, 0.2);
    color: #34d399;
}

.status-badge.wip {
    background: rgba(245, 158, 11, 0.15);
    color: #d97706;
}

.status-badge.wip::before {
    background: #f59e0b;
    box-shadow: 0 0 4px #f59e0b;
}

body.dark-theme .status-badge.wip {
    background: rgba(245, 158, 11, 0.2);
    color: #fbbf24;
}

.status-badge.archived {
    background: rgba(100, 116, 139, 0.15);
    color: #64748b;
}

.status-badge.archived::before {
    background: #94a3b8;
}

body.dark-theme .status-badge.archived {
    background: rgba(148, 163, 184, 0.2);
    color: #cbd5e1;
}

/* Live card glow */
.repo-card.live {
    border: 1px solid rgba(16, 185, 129, 0.3);
    position: relative;
}

.repo-card.live::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, #10b981, #34d399);
    border-radius: 8px 8px 0 0;
}

body.dark-theme .repo-card.live {
    border-color: rgba(16, 185, 129, 0.4);
    box-shadow: 0 5px 15px rgba(16, 185, 129, 0.05);
}

body.dark-theme .repo-card.live:hover {
    box-shadow: 0 15px 30px rgba(16, 185, 129, 0.1);
}

/* Color-coded tags */
.tag.tag-js { background: rgba(247, 223, 30, 0.2); color: #854d0e; }
.tag.tag-python { background: rgba(59, 130, 246, 0.15); color: #1d4ed8; }
.tag.tag-ts { background: rgba(49, 120, 198, 0.15); color: #1e40af; }
.tag.tag-ai { background: rgba(139, 92, 246, 0.15); color: #7c3aed; }
.tag.tag-game { background: rgba(236, 72, 153, 0.15); color: #be185d; }
.tag.tag-data { background: rgba(14, 165, 233, 0.15); color: #0369a1; }
.tag.tag-automation { background: rgba(245, 158, 11, 0.15); color: #b45309; }
.tag.tag-3d { background: rgba(99, 102, 241, 0.15); color: #4338ca; }
.tag.tag-gis { background: rgba(16, 185, 129, 0.15); color: #047857; }
.tag.tag-writing { background: rgba(244, 63, 94, 0.15); color: #be123c; }
.tag.tag-sql { background: rgba(100, 116, 139, 0.15); color: #475569; }

body.dark-theme .tag.tag-js { background: rgba(247, 223, 30, 0.15); color: #facc15; }
body.dark-theme .tag.tag-python { background: rgba(59, 130, 246, 0.2); color: #60a5fa; }
body.dark-theme .tag.tag-ts { background: rgba(49, 120, 198, 0.2); color: #93c5fd; }
body.dark-theme .tag.tag-ai { background: rgba(139, 92, 246, 0.2); color: #a78bfa; }
body.dark-theme .tag.tag-game { background: rgba(236, 72, 153, 0.2); color: #f472b6; }
body.dark-theme .tag.tag-data { background: rgba(14, 165, 233, 0.2); color: #38bdf8; }
body.dark-theme .tag.tag-automation { background: rgba(245, 158, 11, 0.2); color: #fbbf24; }
body.dark-theme .tag.tag-3d { background: rgba(99, 102, 241, 0.2); color: #818cf8; }
body.dark-theme .tag.tag-gis { background: rgba(16, 185, 129, 0.2); color: #34d399; }
body.dark-theme .tag.tag-writing { background: rgba(244, 63, 94, 0.2); color: #fb7185; }
body.dark-theme .tag.tag-sql { background: rgba(100, 116, 139, 0.2); color: #94a3b8; }

/* Section icon styling */
.project-categories h2 {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-top: 50px;
    margin-bottom: 30px;
    padding-bottom: 15px;
    border-bottom: 2px solid var(--border-color);
}

.project-categories h2:first-child {
    margin-top: 0;
}

.project-categories h2 i {
    color: var(--secondary-color);
    font-size: 1.3rem;
}

/* Section description */
.section-description {
    text-align: center;
    color: var(--text-light);
    font-size: 1.1rem;
    max-width: 700px;
    margin: -30px auto 40px;
}

/* ====== CODE SECTION ====== */
.github-info {
    text-align: center;
    max-width: 700px;
    margin: 0 auto 50px;
}

.github-stats {
    display: flex;
    justify-content: center;
    gap: 50px;
    margin-top: 30px;
}

.github-number {
    display: block;
    font-size: 2rem;
    font-weight: 700;
    color: var(--dark-color);
}

.github-label {
    font-size: 0.9rem;
    color: var(--text-light);
}

.repo-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
}

.repo-card {
    background-color: white;
    padding: 25px;
    border-radius: 8px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.05);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    display: flex;
    flex-direction: column;
}

.repo-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 15px 30px rgba(0,0,0,0.1);
}

.repo-card h3 {
    font-size: 1.2rem;
    margin-bottom: 10px;
}

.repo-card .card-header h3 {
    margin-bottom: 0;
}

.repo-card p {
    color: var(--text-color);
    font-size: 0.95rem;
    margin-bottom: 15px;
    flex-grow: 1;
}

.repo-tags {
    margin-bottom: 20px;
}

.repo-link {
    font-weight: 600;
    display: flex;
    align-items: center;
    justify-content: center;
    border-top: 1px solid var(--light-color);
    padding-top: 15px;
}

.repo-link i {
    margin-right: 10px;
}

/* ====== CONTACT SECTION ====== */
.contact-content {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
}

.contact-content p {
    font-size: 1.2rem;
    margin-bottom: 50px;
    line-height: 1.7;
    color: var(--text-color);
}

.contact-links {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 25px;
    margin-top: 40px;
}

.contact-link {
    display: flex;
    align-items: center;
    gap: 15px;
    padding: 20px 25px;
    background: var(--card-bg);
    backdrop-filter: blur(10px);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    box-shadow: 0 8px 25px rgba(0,0,0,0.08);
    color: var(--text-color);
    transition: all 0.3s ease;
    text-align: left;
    position: relative;
    overflow: hidden;
}

.contact-link::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 4px;
    height: 100%;
    background: var(--secondary-color);
    transform: scaleY(0);
    transition: transform 0.3s ease;
}

.contact-link:hover::before {
    transform: scaleY(1);
}

.contact-link:hover {
    transform: translateY(-5px);
    box-shadow: 0 15px 35px rgba(0,0,0,0.15);
    color: var(--secondary-color);
    border-color: var(--secondary-color);
}

body.dark-theme .contact-link {
    box-shadow: 0 8px 25px rgba(0,0,0,0.3);
}

body.dark-theme .contact-link:hover {
    box-shadow: 0 15px 35px rgba(0,0,0,0.4);
}

.contact-link i {
    font-size: 1.5rem;
    color: var(--secondary-color);
    min-width: 24px;
    transition: all 0.3s ease;
}

.contact-link:hover i {
    transform: scale(1.2);
    color: var(--accent-color);
}

/* ====== FOOTER ====== */
.footer {
    background: linear-gradient(135deg, var(--dark-color) 0%, var(--primary-color) 50%, #0a0f1c 100%);
    color: white;
    padding: 40px 0;
}

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

.footer-logo {
    font-family: var(--heading-font);
    font-size: 1.8rem;
    font-weight: 700;
}

.footer-logo img {
    height: 36px;
    width: 36px;
    display: block;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 50%;
    padding: 4px;
    transition: all 0.3s ease;
}

.footer-logo img:hover {
    background: rgba(255, 255, 255, 0.15);
    transform: scale(1.05);
}

.footer-copyright {
    color: var(--text-light);
    font-size: 0.9rem;
}

.footer-links {
    display: flex;
    gap: 20px;
}

.footer-links a {
    color: white;
    font-size: 1.2rem;
    transition: all 0.3s ease;
}

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

/* ====== RESPONSIVE STYLES ====== */
@media screen and (max-width: 1024px) {
    .hero {
        padding: 60px 0;
        min-height: 50vh;
    }

    .hero-content h1 {
        font-size: 3.5rem;
    }

    .hero-content h2 {
        font-size: 2rem;
    }

    .about-grid {
        grid-template-columns: 1fr;
        gap: 40px;
        text-align: center;
    }

    .about-content {
        padding-right: 0;
    }

    .about-stats {
        grid-template-columns: repeat(2, 1fr);
        max-width: 400px;
        margin: 0 auto;
    }

    .research-areas {
        grid-template-columns: 1fr;
        gap: 30px;
    }

    .contact-links {
        grid-template-columns: 1fr;
        gap: 20px;
    }
}

@media screen and (max-width: 768px) {
    .nav {
        flex-direction: column;
    }

    .nav-links {
        margin-top: 20px;
    }

    .nav-links li {
        margin: 0 10px;
    }

    .hero-content h1 {
        font-size: 3rem;
    }

    .hero-content h2 {
        font-size: 1.8rem;
    }

    .tagline {
        font-size: 1.2rem;
    }

    .social-links {
        gap: 20px;
    }

    .social-links a {
        font-size: 1.5rem;
        padding: 12px;
    }

    .section-title {
        font-size: 2.2rem;
    }

    .about-stats {
        grid-template-columns: 1fr 1fr;
    }

    .stat-box {
        padding: 25px 15px;
    }

    .stat-number {
        font-size: 2.5rem;
    }

    .research-card {
        padding: 30px 25px;
    }

    .research-icon {
        font-size: 3rem;
    }

    .contact-link {
        justify-content: center;
        text-align: center;
    }

    .footer-content {
        flex-direction: column;
        text-align: center;
        gap: 20px;
    }
}

@media screen and (max-width: 480px) {
    .nav-toggle {
        display: block;
    }

    .nav-links {
        display: none;
        position: fixed;
        top: 0;
        left: 0;
        right: 0;
        bottom: 0;
        background: rgba(15, 22, 41, 0.98);
        flex-direction: column;
        justify-content: center;
        align-items: center;
        gap: 20px;
        z-index: 1000;
        margin: 0;
        padding: 0;
    }

    .nav-links.mobile-open {
        display: flex;
    }

    .nav-links li {
        margin: 0;
    }

    .nav-links a {
        font-size: 1.3rem;
        padding: 10px 20px;
    }

    .hero-content h1 {
        font-size: 2.5rem;
    }

    .hero-content h2 {
        font-size: 1.5rem;
    }

    .tagline {
        font-size: 1.1rem;
    }

    .social-links {
        gap: 15px;
    }

    .social-links a {
        font-size: 1.3rem;
        padding: 10px;
    }

    .nav-links {
        flex-wrap: wrap;
        justify-content: center;
    }

    .nav-links li {
        margin: 5px 10px;
    }

    .about-stats {
        grid-template-columns: 1fr;
        gap: 20px;
    }

    .stat-box {
        padding: 20px 15px;
    }

    .research-card {
        padding: 25px 20px;
    }

    .research-icon {
        font-size: 2.5rem;
    }

    .contact-link {
        padding: 15px 20px;
        font-size: 0.9rem;
    }
}

/* ====== ANIMATIONS ====== */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ====== COLLAPSIBLE PROJECT CATEGORIES ====== */
.project-category {
    margin-bottom: 2rem;
}

.category-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    cursor: pointer;
    padding: 0.75rem 0;
    margin: 0;
    border-bottom: 2px solid var(--border-color);
    transition: color 0.2s ease, border-color 0.2s ease;
    user-select: none;
}

.category-header:hover {
    color: var(--secondary-color);
    border-bottom-color: var(--secondary-color);
}

.category-header .header-text {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.category-header .chevron {
    transition: transform 0.3s ease;
    font-size: 0.875rem;
    color: var(--text-light);
    transform: rotate(-90deg);
}

.category-header.active .chevron {
    transform: rotate(0deg);
}

.category-content {
    overflow: hidden;
    transition: max-height 0.4s ease, opacity 0.3s ease, padding 0.3s ease;
    max-height: 2000px;
    opacity: 1;
    padding-top: 1.5rem;
}

.category-content.collapsed {
    max-height: 0;
    opacity: 0;
    padding-top: 0;
}

/* When explicitly expanded via active header */
.category-header.active + .category-content {
    max-height: 2000px;
    opacity: 1;
    padding-top: 1.5rem;
}

/* Mobile adjustments */
@media (max-width: 768px) {
    .project-category {
        margin-bottom: 1.5rem;
    }

    .category-header {
        padding: 0.5rem 0;
        font-size: 1.25rem;
    }
}


/* ====== FILTER CHIPS ====== */
.filter-chips {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 2rem;
    padding: 0.5rem 0;
}

.chip {
    padding: 0.5rem 1rem;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 500;
    white-space: nowrap;
    border: 1px solid var(--border-color);
    background: var(--card-bg);
    color: var(--text-light);
    cursor: pointer;
    transition: all 0.2s ease;
    font-family: 'Inter', sans-serif;
}

.chip:hover {
    border-color: var(--secondary-color);
    color: var(--secondary-color);
}

.chip.active {
    background: var(--secondary-color);
    color: white;
    border-color: var(--secondary-color);
}

.chip .count {
    font-size: 0.7rem;
    opacity: 0.7;
    margin-left: 4px;
}

@media (max-width: 768px) {
    .filter-chips {
        flex-wrap: nowrap;
        overflow-x: auto;
        -webkit-overflow-scrolling: touch;
        scrollbar-width: none;
        gap: 0.5rem;
        padding-bottom: 0.5rem;
    }
    .filter-chips::-webkit-scrollbar {
        display: none;
    }
}

/* ===== T30: Card-Based Design System ===== */

/* Section header - collapsible */
.section-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 16px 12px;
  cursor: pointer;
  user-select: none;
  -webkit-tap-highlight-color: transparent;
  border-bottom: 2px solid var(--border-color);
  margin: 0 16px;
}

.section-header h2 {
  font-family: var(--heading-font);
  font-size: 1.15rem;
  display: flex;
  align-items: center;
  gap: 10px;
  margin: 0;
  color: var(--text-color);
}

.section-header h2 i {
  color: var(--secondary-color);
  font-size: 1.1rem;
}

.chevron {
  color: var(--text-light);
  font-size: 0.9rem;
  transition: transform 0.25s ease;
}

.section-header.collapsed .chevron {
  transform: rotate(-90deg);
}

/* Horizontal scroll row */
.scroll-row {
  display: flex;
  gap: 16px;
  overflow-x: auto;
  padding: 16px;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
  scroll-snap-type: x mandatory;
}

.scroll-row::-webkit-scrollbar { display: none; }

/* Cards */
.card {
  flex: 0 0 85vw;
  max-width: 340px;
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 24px;
  box-shadow: 0 5px 15px rgba(0,0,0,0.05);
  scroll-snap-align: start;
  display: flex;
  flex-direction: column;
  position: relative;
}

body.dark-theme .card {
  box-shadow: 0 5px 15px rgba(0,0,0,0.2);
}

.card.live {
  border-top: 3px solid #10b981;
}

body.dark-theme .card.live {
  border-color: rgba(255,255,255,0.1);
  border-top: 3px solid #10b981;
}

.card-header-row {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 10px;
  gap: 10px;
}

.card h3 {
  font-family: var(--heading-font);
  font-size: 1.2rem;
  margin: 0;
  flex: 1;
  color: var(--text-color);
}

.status-badge {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 3px 10px;
  border-radius: 12px;
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  white-space: nowrap;
  flex-shrink: 0;
}

.status-badge.live {
  background: rgba(16, 185, 129, 0.15);
  color: #059669;
}

body.dark-theme .status-badge.live {
  background: rgba(16, 185, 129, 0.2);
  color: #34d399;
}

.status-badge.wip {
  background: rgba(245, 158, 11, 0.15);
  color: #d97706;
}

body.dark-theme .status-badge.wip {
  background: rgba(245, 158, 11, 0.2);
  color: #fbbf24;
}

.card p {
  color: var(--text-color);
  font-size: 0.95rem;
  margin-bottom: 15px;
  flex-grow: 1;
  line-height: 1.6;
}

.card .tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-bottom: 15px;
}

.card .tag {
  display: inline-block;
  background: var(--light-color);
  color: var(--text-color);
  padding: 4px 8px;
  border-radius: 4px;
  font-size: 0.8rem;
  font-weight: 500;
}

body.dark-theme .card .tag {
  background: rgba(255,255,255,0.08);
  color: var(--text-light);
}

/* Color-coded tags */
.card .tag.tag-js { background: rgba(247,223,30,0.15); color: #854d0e; }
.card .tag.tag-ts { background: rgba(49,120,198,0.15); color: #1e40af; }
.card .tag.tag-py { background: rgba(59,130,246,0.15); color: #1d4ed8; }
.card .tag.tag-ai { background: rgba(139,92,246,0.15); color: #7c3aed; }
.card .tag.tag-game { background: rgba(236,72,153,0.15); color: #be185d; }
.card .tag.tag-data { background: rgba(14,165,233,0.15); color: #0369a1; }
.card .tag.tag-gis { background: rgba(20,184,166,0.15); color: #0f766e; }
.card .tag.tag-auto { background: rgba(245,158,11,0.15); color: #b45309; }
.card .tag.tag-sql { background: rgba(100,116,139,0.15); color: #475569; }

body.dark-theme .card .tag.tag-js { background: rgba(247,223,30,0.12); color: #facc15; }
body.dark-theme .card .tag.tag-ts { background: rgba(49,120,198,0.15); color: #60a5fa; }
body.dark-theme .card .tag.tag-py { background: rgba(59,130,246,0.15); color: #60a5fa; }
body.dark-theme .card .tag.tag-ai { background: rgba(139,92,246,0.15); color: #a78bfa; }
body.dark-theme .card .tag.tag-game { background: rgba(236,72,153,0.15); color: #f472b6; }
body.dark-theme .card .tag.tag-data { background: rgba(14,165,233,0.15); color: #38bdf8; }
body.dark-theme .card .tag.tag-gis { background: rgba(20,184,166,0.15); color: #2dd4bf; }
body.dark-theme .card .tag.tag-auto { background: rgba(245,158,11,0.15); color: #fbbf24; }
body.dark-theme .card .tag.tag-sql { background: rgba(100,116,139,0.15); color: #94a3b8; }

.card .links {
  display: flex;
  gap: 16px;
  margin-top: auto;
  border-top: 1px solid var(--border-color);
  padding-top: 15px;
}

.card .links a {
  font-weight: 600;
  font-size: 0.9rem;
  display: flex;
  align-items: center;
  gap: 6px;
  color: var(--secondary-color);
}

.card .links a i {
  font-size: 0.85rem;
}

.card .repo-note {
  color: var(--text-light);
  font-size: 0.85rem;
}

/* Scroll hint dots */
.scroll-hint {
  display: flex;
  justify-content: center;
  gap: 6px;
  padding: 4px 0 16px;
}

.scroll-hint .dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--border-color);
  transition: background 0.2s;
}

.scroll-hint .dot.active {
  background: var(--secondary-color);
}

/* Collapsed state */
.scroll-row.collapsed,
.scroll-hint.collapsed {
  display: none;
}

/* Responsive card widths */
@media (min-width: 480px) {
  .card {
    flex: 0 0 calc(50vw - 24px);
  }
}

@media (min-width: 768px) {
  .card {
    flex: 0 0 calc(33.333vw - 24px);
    max-width: 300px;
  }
}

/* Projects page specific overrides */
#projects .container {
  width: 100%;
  max-width: none;
  padding: 0;
  margin: 0;
}

#projects.section {
  padding: 0;
}

#projects .section-title {
  text-align: center;
  font-size: 2rem;
  margin: 30px 16px 10px;
  position: relative;
}

#projects .section-title::after {
  content: '';
  position: absolute;
  bottom: -10px;
  left: 50%;
  transform: translateX(-50%);
  width: 60px;
  height: 3px;
  background: var(--secondary-color);
}

#projects .section-description {
  text-align: center;
  color: var(--text-light);
  font-size: 1rem;
  margin: 20px 16px 10px;
}

/* Hide old filter chips and grid on projects page */
#projects .filter-chips,
#projects .repo-grid,
#projects .project-category {
  display: none;
}

/* Ensure project-section is visible */
#projects .project-section {
  display: block;
  margin-bottom: 1rem;
}