/* ==========================================================================
   Pankaj Saha Academic Portfolio - Design System & Stylesheet
   ========================================================================== */

/* --------------------------------------------------------------------------
   1. CSS Custom Properties & Design Tokens
   -------------------------------------------------------------------------- */
:root {
    /* Color Palette - Dark Theme (Default) */
    --bg-main: #07090e;
    --bg-secondary: #0f1420;
    --bg-card: rgba(18, 24, 38, 0.7);
    --bg-card-hover: rgba(28, 37, 56, 0.85);
    --bg-glass: rgba(255, 255, 255, 0.03);
    --border-color: rgba(255, 255, 255, 0.08);
    --border-highlight: rgba(99, 102, 241, 0.4);

    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;

    /* Accent & Brand Colors */
    --accent-primary: #6366f1;
    --accent-secondary: #8b5cf6;
    --accent-cyan: #06b6d4;
    --accent-emerald: #10b981;
    --accent-gradient: linear-gradient(135deg, #6366f1 0%, #8b5cf6 50%, #06b6d4 100%);
    --card-glow: rgba(99, 102, 241, 0.15);

    /* Fonts */
    --font-sans: 'Inter', system-ui, -apple-system, sans-serif;
    --font-serif: 'Newsreader', Georgia, serif;
    --font-code: 'Fira Code', monospace;

    /* Layout & Shadows */
    --shadow-sm: 0 4px 6px -1px rgba(0, 0, 0, 0.2);
    --shadow-lg: 0 10px 30px -5px rgba(0, 0, 0, 0.5);
    --shadow-glow: 0 0 25px rgba(99, 102, 241, 0.25);
    --radius-sm: 8px;
    --radius-md: 14px;
    --radius-lg: 20px;

    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Light Theme Variables */
[data-theme="light"] {
    --bg-main: #f8fafc;
    --bg-secondary: #f1f5f9;
    --bg-card: rgba(255, 255, 255, 0.85);
    --bg-card-hover: rgba(255, 255, 255, 0.98);
    --bg-glass: rgba(0, 0, 0, 0.02);
    --border-color: rgba(0, 0, 0, 0.08);
    --border-highlight: rgba(99, 102, 241, 0.5);

    --text-primary: #0f172a;
    --text-secondary: #475569;
    --text-muted: #64748b;

    --card-glow: rgba(99, 102, 241, 0.08);
    --shadow-lg: 0 10px 30px -5px rgba(0, 0, 0, 0.08);
}

/* --------------------------------------------------------------------------
   2. Reset & Global Base
   -------------------------------------------------------------------------- */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-sans);
    background-color: var(--bg-main);
    color: var(--text-primary);
    line-height: 1.6;
    overflow-x: hidden;
    transition: background-color var(--transition-normal), color var(--transition-normal);
}

#stochasticCanvas {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    z-index: -1;
    pointer-events: none;
    opacity: 0.6;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

.section-padding {
    padding: 5rem 0;
}

h1, h2, h3, h4 {
    color: var(--text-primary);
    line-height: 1.25;
}

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

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

.glass-card {
    background: var(--bg-card);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
    transition: transform var(--transition-normal), border-color var(--transition-normal), box-shadow var(--transition-normal);
}

.glass-card:hover {
    border-color: var(--border-highlight);
    box-shadow: var(--shadow-lg), var(--shadow-glow);
}

/* --------------------------------------------------------------------------
   3. Navigation Header
   -------------------------------------------------------------------------- */
.site-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(7, 9, 14, 0.75);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border-color);
    transition: background-color var(--transition-normal);
}

[data-theme="light"] .site-header {
    background: rgba(248, 250, 252, 0.85);
}

.nav-container {
    max-width: 1240px;
    margin: 0 auto;
    padding: 0.85rem 1.5rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.brand-logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.brand-symbol {
    font-family: var(--font-serif);
    font-size: 2.2rem;
    font-weight: 600;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.brand-text {
    display: flex;
    flex-direction: column;
}

.brand-name {
    font-weight: 700;
    font-size: 1.1rem;
    color: var(--text-primary);
    letter-spacing: -0.01em;
}

.brand-sub {
    font-size: 0.75rem;
    color: var(--text-muted);
}

.nav-menu {
    display: flex;
    align-items: center;
    gap: 1.5rem;
}

.nav-link {
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-secondary);
    position: relative;
    padding: 0.3rem 0;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0%;
    height: 2px;
    background: var(--accent-gradient);
    transition: width var(--transition-normal);
    border-radius: 2px;
}

.nav-link:hover {
    color: var(--text-primary);
}

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

.nav-actions {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.icon-btn {
    background: var(--bg-glass);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.icon-btn:hover {
    border-color: var(--accent-primary);
    color: var(--accent-primary);
    transform: scale(1.05);
}

.mobile-toggle {
    display: none;
    background: none;
    border: none;
    color: var(--text-primary);
    font-size: 1.3rem;
    cursor: pointer;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.65rem 1.3rem;
    font-size: 0.9rem;
    font-weight: 600;
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all var(--transition-normal);
    border: none;
}

.btn-primary {
    background: var(--accent-gradient);
    color: #ffffff;
    box-shadow: 0 4px 15px rgba(99, 102, 241, 0.3);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(99, 102, 241, 0.5);
    color: #ffffff;
}

.btn-secondary {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
}

.btn-secondary:hover {
    border-color: var(--accent-primary);
    background: var(--bg-card-hover);
    transform: translateY(-2px);
}

.btn-outline {
    background: transparent;
    border: 1px solid var(--border-highlight);
    color: var(--accent-primary);
}

.btn-outline:hover {
    background: var(--accent-primary);
    color: #ffffff;
}

.btn-block {
    width: 100%;
    justify-content: center;
}

/* --------------------------------------------------------------------------
   4. Hero Section
   -------------------------------------------------------------------------- */
.hero-section {
    padding-top: 8.5rem;
    padding-bottom: 4rem;
    min-height: 90vh;
    display: flex;
    align-items: center;
}

.hero-grid {
    display: grid;
    grid-template-columns: 340px 1fr;
    gap: 3rem;
    align-items: center;
}

.avatar-card {
    padding: 1.8rem;
    text-align: center;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1.2rem;
}

.avatar-wrapper {
    position: relative;
    width: 180px;
    height: 180px;
    border-radius: 50%;
    padding: 4px;
    background: var(--accent-gradient);
}

.profile-img {
    width: 100%;
    height: 100%;
    border-radius: 50%;
    object-fit: cover;
    object-position: top center;
    background: var(--bg-secondary);
}

.status-pill {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.4rem 0.9rem;
    background: rgba(16, 185, 129, 0.12);
    border: 1px solid rgba(16, 185, 129, 0.3);
    color: var(--accent-emerald);
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 600;
}

.status-dot {
    width: 8px;
    height: 8px;
    background-color: var(--accent-emerald);
    border-radius: 50%;
    box-shadow: 0 0 8px var(--accent-emerald);
    animation: pulse 2s infinite;
}

@keyframes pulse {
    0% { transform: scale(0.95); opacity: 0.8; }
    50% { transform: scale(1.15); opacity: 1; }
    100% { transform: scale(0.95); opacity: 0.8; }
}

.hero-quick-links {
    display: flex;
    gap: 0.75rem;
}

.quick-link-btn {
    width: 38px;
    height: 38px;
    border-radius: 50%;
    background: var(--bg-glass);
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1rem;
    transition: all var(--transition-fast);
}

.quick-link-btn:hover {
    color: var(--text-primary);
    border-color: var(--accent-primary);
    background: var(--accent-primary);
}

/* Hero Content */
.badge-tag {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.35rem 0.85rem;
    background: var(--bg-glass);
    border: 1px solid var(--border-color);
    border-radius: 20px;
    font-size: 0.85rem;
    color: var(--accent-primary);
    margin-bottom: 1rem;
    font-weight: 500;
}

.hero-title {
    font-size: 3rem;
    font-weight: 800;
    letter-spacing: -0.02em;
    margin-bottom: 0.2rem;
    background: linear-gradient(135deg, var(--text-primary) 60%, var(--accent-primary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero-subtitle {
    font-family: var(--font-serif);
    font-size: 1.6rem;
    font-weight: 400;
    color: var(--accent-cyan);
    margin-bottom: 1.2rem;
}

.hero-bio {
    font-size: 1.05rem;
    color: var(--text-secondary);
    max-width: 680px;
    margin-bottom: 1.5rem;
    line-height: 1.7;
}

.math-banner {
    padding: 1rem 1.25rem;
    margin-bottom: 1.8rem;
    border-left: 3px solid var(--accent-primary);
}

.math-formula {
    overflow-x: auto;
    font-size: 1.1rem;
    color: var(--text-primary);
}

.math-caption {
    font-size: 0.78rem;
    color: var(--text-muted);
    display: block;
    margin-top: 0.3rem;
}

.hero-actions {
    display: flex;
    gap: 1rem;
    margin-bottom: 2rem;
    flex-wrap: wrap;
}

.stats-bar {
    display: flex;
    gap: 2.5rem;
    padding-top: 1.5rem;
    border-top: 1px solid var(--border-color);
}

.stat-num {
    display: block;
    font-size: 2rem;
    font-weight: 800;
    color: var(--accent-primary);
    font-family: var(--font-code);
}

.stat-label {
    font-size: 0.8rem;
    color: var(--text-muted);
    font-weight: 500;
}

/* --------------------------------------------------------------------------
   5. Section Headers & Badges
   -------------------------------------------------------------------------- */
.section-header {
    margin-bottom: 3.5rem;
}

.text-center {
    text-align: center;
}

.section-badge {
    display: inline-block;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    font-size: 0.75rem;
    font-weight: 700;
    color: var(--accent-primary);
    margin-bottom: 0.5rem;
}

.section-title {
    font-size: 2.3rem;
    font-weight: 800;
    letter-spacing: -0.01em;
    margin-bottom: 0.75rem;
}

.section-description {
    font-size: 1.05rem;
    color: var(--text-secondary);
    max-width: 650px;
    margin: 0 auto;
}

/* --------------------------------------------------------------------------
   6. Research Interests Section
   -------------------------------------------------------------------------- */
.research-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 1.5rem;
}

.research-card {
    padding: 1.8rem;
    display: flex;
    flex-direction: column;
    gap: 0.8rem;
    height: 100%;
}

.card-icon {
    width: 48px;
    height: 48px;
    border-radius: var(--radius-sm);
    background: var(--bg-glass);
    border: 1px solid var(--border-color);
    color: var(--accent-primary);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.3rem;
}

.research-card h3 {
    font-size: 1.2rem;
    font-weight: 700;
}

.research-card p {
    font-size: 0.92rem;
    color: var(--text-secondary);
    flex-grow: 1;
}

.katex-box {
    padding: 0.6rem 0.8rem;
    background: rgba(0, 0, 0, 0.2);
    border-radius: var(--radius-sm);
    border: 1px solid var(--border-color);
    overflow-x: auto;
    font-size: 0.95rem;
}

[data-theme="light"] .katex-box {
    background: rgba(0, 0, 0, 0.03);
}

/* --------------------------------------------------------------------------
   7. Academic Projects Section
   -------------------------------------------------------------------------- */
.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(480px, 1fr));
    gap: 2rem;
}

.project-card {
    padding: 2rem;
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

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

.project-tag {
    font-size: 0.75rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    padding: 0.25rem 0.65rem;
    background: var(--accent-gradient);
    color: #ffffff;
    border-radius: 4px;
}

.project-date {
    font-size: 0.82rem;
    color: var(--text-muted);
}

.project-title {
    font-size: 1.3rem;
    font-weight: 700;
    line-height: 1.35;
}

.project-supervisor {
    font-size: 0.88rem;
    color: var(--accent-cyan);
    font-weight: 500;
}

.project-summary {
    font-size: 0.95rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

.project-math-highlight {
    margin: 0.5rem 0;
}

.project-keywords {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.project-keywords span {
    font-size: 0.78rem;
    padding: 0.25rem 0.6rem;
    background: var(--bg-glass);
    border: 1px solid var(--border-color);
    border-radius: 20px;
    color: var(--text-secondary);
}

/* --------------------------------------------------------------------------
   8. Education Timeline Section
   -------------------------------------------------------------------------- */
.timeline {
    position: relative;
    max-width: 800px;
    margin: 0 auto;
}

.timeline::before {
    content: '';
    position: absolute;
    top: 0;
    bottom: 0;
    left: 20px;
    width: 2px;
    background: var(--border-color);
}

.timeline-item {
    position: relative;
    padding-left: 60px;
    margin-bottom: 2.5rem;
}

.timeline-dot {
    position: absolute;
    left: 11px;
    top: 24px;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--accent-primary);
    border: 4px solid var(--bg-main);
    box-shadow: 0 0 10px var(--accent-primary);
}

.timeline-content {
    padding: 1.8rem;
}

.timeline-badge {
    display: inline-block;
    font-size: 0.75rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    padding: 0.2rem 0.6rem;
    background: var(--bg-glass);
    border: 1px solid var(--border-color);
    border-radius: 4px;
    color: var(--accent-primary);
    margin-bottom: 0.5rem;
}

.badge-active {
    background: var(--accent-emerald);
    color: #ffffff;
    border: none;
}

.timeline-date {
    float: right;
    font-size: 0.82rem;
    color: var(--text-muted);
}

.timeline-title {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 0.3rem;
}

.timeline-institution {
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--accent-cyan);
    margin-bottom: 0.75rem;
}

.timeline-desc {
    font-size: 0.92rem;
    color: var(--text-secondary);
}

.score-chip {
    display: inline-block;
    margin-top: 0.5rem;
    padding: 0.3rem 0.75rem;
    background: rgba(99, 102, 241, 0.1);
    border: 1px solid var(--border-highlight);
    border-radius: 6px;
    color: var(--text-primary);
    font-size: 0.85rem;
}

/* --------------------------------------------------------------------------
   9. Achievements & Exams Section
   -------------------------------------------------------------------------- */
.achievements-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 1.5rem;
}

.achievement-card {
    padding: 1.8rem;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.achieve-year {
    position: absolute;
    top: 1rem;
    right: 1.2rem;
    font-size: 0.8rem;
    font-weight: 700;
    color: var(--accent-primary);
    font-family: var(--font-code);
}

.achieve-icon {
    font-size: 2.2rem;
    color: var(--accent-primary);
    margin-bottom: 1rem;
}

.achievement-card h3 {
    font-size: 1.3rem;
    font-weight: 800;
    margin-bottom: 0.3rem;
}

.achieve-name {
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
    min-height: 2.6rem;
}

.achieve-status {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    font-size: 0.78rem;
    font-weight: 600;
    color: var(--accent-emerald);
}

/* --------------------------------------------------------------------------
   10. Academic Activities Section
   -------------------------------------------------------------------------- */
.activities-list {
    display: flex;
    flex-direction: column;
    gap: 1.25rem;
    max-width: 900px;
    margin: 0 auto;
}

.activity-card {
    padding: 1.5rem 1.8rem;
    display: flex;
    gap: 1.8rem;
    align-items: center;
}

.activity-date-badge {
    min-width: 140px;
    text-align: center;
    padding: 0.6rem 0.8rem;
    background: var(--bg-glass);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-family: var(--font-code);
    font-size: 0.82rem;
    font-weight: 600;
    color: var(--accent-cyan);
}

.activity-info h3 {
    font-size: 1.1rem;
    font-weight: 700;
    margin-bottom: 0.2rem;
}

.activity-org {
    font-size: 0.85rem;
    color: var(--accent-primary);
    margin-bottom: 0.4rem;
}

.activity-desc {
    font-size: 0.9rem;
    color: var(--text-secondary);
}

/* --------------------------------------------------------------------------
   11. Coursework & Skills Explorer
   -------------------------------------------------------------------------- */
.tab-filters {
    display: flex;
    justify-content: center;
    gap: 0.75rem;
    margin-bottom: 2.5rem;
    flex-wrap: wrap;
}

.tab-btn {
    padding: 0.6rem 1.2rem;
    border-radius: 30px;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    font-size: 0.88rem;
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.tab-btn:hover, .tab-btn.active {
    background: var(--accent-gradient);
    color: #ffffff;
    border-color: transparent;
    box-shadow: 0 4px 15px rgba(99, 102, 241, 0.3);
}

.course-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 1.5rem;
}

.course-category-card {
    padding: 1.8rem;
}

.course-category-card h3 {
    font-size: 1.2rem;
    font-weight: 700;
    margin-bottom: 1.2rem;
    display: flex;
    align-items: center;
    gap: 0.6rem;
    color: var(--accent-primary);
}

.tags-container {
    display: flex;
    flex-wrap: wrap;
    gap: 0.6rem;
}

.course-tag {
    padding: 0.4rem 0.85rem;
    background: var(--bg-glass);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-size: 0.85rem;
    color: var(--text-primary);
}

.lang-tag {
    background: rgba(6, 182, 212, 0.1);
    border-color: rgba(6, 182, 212, 0.3);
}

.skill-bar-item {
    margin-bottom: 1rem;
}

.skill-info {
    display: flex;
    justify-content: space-between;
    font-size: 0.88rem;
    margin-bottom: 0.3rem;
}

.skill-level {
    color: var(--text-muted);
    font-size: 0.8rem;
}

.skill-progress {
    height: 6px;
    background: var(--bg-glass);
    border-radius: 3px;
    overflow: hidden;
}

.skill-fill {
    height: 100%;
    background: var(--accent-gradient);
    border-radius: 3px;
    transition: width 1s ease-in-out;
}

/* --------------------------------------------------------------------------
   12. Contact Section
   -------------------------------------------------------------------------- */
.contact-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2.5rem;
}

.contact-info-cards {
    display: flex;
    flex-direction: column;
    gap: 1.2rem;
}

.contact-card {
    padding: 1.3rem 1.6rem;
    display: flex;
    align-items: center;
    gap: 1.2rem;
}

.contact-icon {
    width: 44px;
    height: 44px;
    border-radius: 50%;
    background: var(--bg-glass);
    border: 1px solid var(--border-color);
    color: var(--accent-primary);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
}

.contact-details h4 {
    font-size: 0.8rem;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.contact-val {
    font-size: 0.98rem;
    font-weight: 600;
    color: var(--text-primary);
    display: block;
    word-break: break-all;
}

.copy-btn {
    margin-top: 0.25rem;
    background: none;
    border: none;
    color: var(--accent-primary);
    font-size: 0.78rem;
    cursor: pointer;
    font-weight: 500;
}

.copy-btn:hover {
    text-decoration: underline;
}

/* Contact Form */
.contact-form-container {
    padding: 2rem;
}

.contact-form-container h3 {
    font-size: 1.3rem;
    font-weight: 700;
    margin-bottom: 1.2rem;
}

.form-group {
    margin-bottom: 1.2rem;
}

.form-group label {
    display: block;
    font-size: 0.85rem;
    font-weight: 600;
    margin-bottom: 0.4rem;
    color: var(--text-secondary);
}

.form-group input, .form-group textarea {
    width: 100%;
    padding: 0.75rem 1rem;
    background: var(--bg-main);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    color: var(--text-primary);
    font-family: var(--font-sans);
    font-size: 0.92rem;
    transition: border-color var(--transition-fast);
}

.form-group input:focus, .form-group textarea:focus {
    outline: none;
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.2);
}

.alert-success {
    margin-top: 1rem;
    padding: 0.8rem 1rem;
    background: rgba(16, 185, 129, 0.15);
    border: 1px solid rgba(16, 185, 129, 0.3);
    color: var(--accent-emerald);
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.hidden {
    display: none !important;
}

/* --------------------------------------------------------------------------
   13. Modal Dialog
   -------------------------------------------------------------------------- */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 2000;
    background: rgba(0, 0, 0, 0.75);
    backdrop-filter: blur(8px);
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 1.5rem;
    opacity: 0;
    pointer-events: none;
    transition: opacity var(--transition-normal);
}

.modal-overlay.active {
    opacity: 1;
    pointer-events: auto;
}

.modal-card {
    max-width: 680px;
    width: 100%;
    padding: 2.2rem;
    position: relative;
    max-height: 85vh;
    overflow-y: auto;
}

.modal-close {
    position: absolute;
    top: 1.2rem;
    right: 1.2rem;
    background: var(--bg-glass);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    width: 36px;
    height: 36px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
}

.modal-close:hover {
    background: var(--accent-primary);
    color: #ffffff;
}

/* --------------------------------------------------------------------------
   14. Footer
   -------------------------------------------------------------------------- */
.site-footer {
    border-top: 1px solid var(--border-color);
    padding: 2.5rem 0;
    background: var(--bg-secondary);
}

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

.footer-title {
    font-weight: 700;
    font-size: 1.1rem;
}

.footer-brand p {
    font-size: 0.85rem;
    color: var(--text-muted);
}

/* --------------------------------------------------------------------------
   15. Responsive Breakpoints
   -------------------------------------------------------------------------- */
@media (max-width: 992px) {
    .hero-grid {
        grid-template-columns: 1fr;
        text-align: center;
    }
    .avatar-card {
        max-width: 320px;
        margin: 0 auto;
    }
    .hero-bio {
        margin: 0 auto 1.5rem;
    }
    .hero-actions {
        justify-content: center;
    }
    .stats-bar {
        justify-content: center;
    }
    .contact-grid {
        grid-template-columns: 1fr;
    }
    .projects-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        top: 70px;
        left: 0;
        right: 0;
        background: var(--bg-secondary);
        flex-direction: column;
        padding: 2rem;
        border-bottom: 1px solid var(--border-color);
        transform: translateY(-150%);
        transition: transform var(--transition-normal);
    }
    .nav-menu.active {
        transform: translateY(0);
    }
    .mobile-toggle {
        display: block;
    }
    .nav-cv-btn {
        display: none;
    }
    .hero-title {
        font-size: 2.2rem;
    }
    .activity-card {
        flex-direction: column;
        align-items: flex-start;
        gap: 0.75rem;
    }
    .activity-date-badge {
        width: 100%;
        text-align: left;
    }
    .footer-container {
        flex-direction: column;
        gap: 1rem;
        text-align: center;
    }
}