/* ==========================================================================
   VERCEL / APPLE STYLE DEVELOPER PORTFOLIO
   Developer: Laxman — Computer Engineering Student
   Design Tokens:
     - Pure Dark Background: #000000 / #050505
     - Pure Light Background: #ffffff (via toggle)
     - Primary Text: #ffffff / #0a0a0a
     - Secondary Text: #888888 / #666666
     - Hairline Border: rgba(255, 255, 255, 0.08) / #222222
     - Surface Gray: #0a0a0a / #f5f5f5
     - Single Accent: #0070f3 (Vercel Blue)
   Typography: Inter (-0.04em letter-spacing) & JetBrains Mono
   ========================================================================== */

/* --------------------------------------------------------------------------
   01. DESIGN TOKENS & CSS VARIABLES
   -------------------------------------------------------------------------- */
:root {
    --bg-dark: #000000;
    --bg-surface: #0a0a0a;
    --bg-surface-hover: #121212;
    --bg-glass: rgba(0, 0, 0, 0.75);

    --primary-accent: #0070f3;
    --primary-glow: rgba(0, 112, 243, 0.25);

    --text-main: #ffffff;
    --text-sub: #888888;
    --text-muted: #555555;

    --border-hairline: rgba(255, 255, 255, 0.08);
    --border-hover: rgba(255, 255, 255, 0.25);

    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-mono: 'JetBrains Mono', monospace;

    --radius-full: 9999px;
    --radius-xl: 12px;
    --radius-lg: 8px;
    --radius-md: 6px;

    --transition-fast: all 0.2s cubic-bezier(0.16, 1, 0.3, 1);
    --transition-smooth: all 0.35s cubic-bezier(0.16, 1, 0.3, 1);
}

/* Light Theme Variables */
[data-theme="light"] {
    --bg-dark: #ffffff;
    --bg-surface: #f5f5f5;
    --bg-surface-hover: #ebebeb;
    --bg-glass: rgba(255, 255, 255, 0.85);

    --text-main: #0a0a0a;
    --text-sub: #666666;
    --text-muted: #999999;

    --border-hairline: #eaeaea;
    --border-hover: #cccccc;
}

/* --------------------------------------------------------------------------
   02. RESET & BASE STYLES
   -------------------------------------------------------------------------- */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    scroll-padding-top: 80px;
}

body {
    background-color: var(--bg-dark);
    color: var(--text-main);
    font-family: var(--font-sans);
    font-size: 16px;
    line-height: 1.6;
    overflow-x: hidden;
    min-height: 100vh;
    transition: background-color 0.3s ease, color 0.3s ease;
    -webkit-font-smoothing: antialiased;
}

/* Scroll Progress Bar */
#scroll-progress-bar {
    position: fixed;
    top: 0;
    left: 0;
    height: 2px;
    width: 0%;
    background: var(--primary-accent);
    z-index: 10000;
}

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

button {
    cursor: pointer;
    border: none;
    background: none;
    font-family: inherit;
}

/* --------------------------------------------------------------------------
   03. BUTTONS & UTILITIES
   -------------------------------------------------------------------------- */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    font-family: var(--font-sans);
    font-weight: 500;
    font-size: 0.92rem;
    padding: 12px 24px;
    border-radius: var(--radius-lg);
    transition: var(--transition-smooth);
    cursor: pointer;
}

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

.btn-primary:hover {
    background: var(--primary-accent);
    color: #ffffff;
    border-color: var(--primary-accent);
    transform: translateY(-1px);
}

.btn-secondary {
    background: transparent;
    color: var(--text-main);
    border: 1px solid var(--border-hairline);
}

.btn-secondary:hover {
    border-color: var(--border-hover);
    background: var(--bg-surface);
    transform: translateY(-1px);
}

.btn-sm {
    padding: 7px 16px;
    font-size: 0.85rem;
    border-radius: var(--radius-md);
}

.w-full { width: 100%; }
.text-center { text-align: center; }

/* Code tags */
.mono-tag {
    font-family: var(--font-mono);
    font-size: 0.78rem;
    color: var(--text-sub);
    background: var(--bg-surface);
    border: 1px solid var(--border-hairline);
    padding: 4px 10px;
    border-radius: var(--radius-md);
    display: inline-block;
}

/* --------------------------------------------------------------------------
   04. STICKY GLASS NAVBAR
   -------------------------------------------------------------------------- */
.glass-navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    padding: 18px 0;
    transition: var(--transition-smooth);
}

.glass-navbar.scrolled {
    background: var(--bg-glass);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-bottom: 1px solid var(--border-hairline);
    padding: 14px 0;
}

.nav-container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 24px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-logo {
    font-size: 1.15rem;
    font-weight: 700;
    letter-spacing: -0.04em;
    color: var(--text-main);
}

.logo-dot { color: var(--primary-accent); }

.nav-links-desktop {
    display: flex;
    align-items: center;
    gap: 28px;
}

.nav-link {
    font-size: 0.88rem;
    font-weight: 400;
    color: var(--text-sub);
    transition: color 0.2s ease;
}

.nav-link:hover, .nav-link.active {
    color: var(--text-main);
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: 12px;
}

.icon-btn {
    width: 36px;
    height: 36px;
    border-radius: var(--radius-md);
    border: 1px solid var(--border-hairline);
    color: var(--text-sub);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.95rem;
    transition: var(--transition-fast);
}

.icon-btn:hover {
    color: var(--text-main);
    border-color: var(--border-hover);
}

.sun-icon { display: none; }
[data-theme="light"] .moon-icon { display: none; }
[data-theme="light"] .sun-icon { display: block; }

.mobile-menu-btn {
    display: none;
    flex-direction: column;
    gap: 5px;
    padding: 6px;
}

.mobile-menu-btn span {
    width: 22px;
    height: 2px;
    background: var(--text-main);
    transition: var(--transition-fast);
}

/* Mobile Drawer */
.mobile-drawer {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background: var(--bg-dark);
    z-index: 999;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition-smooth);
}

.mobile-drawer.open {
    opacity: 1;
    visibility: visible;
}

.mobile-drawer-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 24px;
    width: 80%;
    max-width: 300px;
}

.mobile-nav-link {
    font-size: 1.25rem;
    font-weight: 500;
    color: var(--text-sub);
}

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

/* --------------------------------------------------------------------------
   05. HERO SECTION (CENTER-ALIGNED APPLE/VERCEL STYLE)
   -------------------------------------------------------------------------- */
.hero-section {
    min-height: 90vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 140px 0 80px;
    text-align: center;
}

.hero-container {
    max-width: 900px;
    margin: 0 auto;
    padding: 0 24px;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    font-family: var(--font-mono);
    font-size: 0.8rem;
    color: var(--text-sub);
    background: var(--bg-surface);
    border: 1px solid var(--border-hairline);
    padding: 6px 16px;
    border-radius: var(--radius-full);
    margin-bottom: 28px;
}

.badge-status-dot {
    width: 6px;
    height: 6px;
    background-color: var(--primary-accent);
    border-radius: 50%;
}

.hero-headline {
    font-size: clamp(2.8rem, 6.2vw, 5rem);
    font-weight: 800;
    line-height: 1.08;
    letter-spacing: -0.04em;
    color: var(--text-main);
    margin-bottom: 24px;
}

.hero-subheading {
    font-size: clamp(1.05rem, 1.4vw, 1.25rem);
    color: var(--text-sub);
    line-height: 1.65;
    max-width: 680px;
    margin-bottom: 36px;
    font-weight: 400;
}

.hero-actions {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 16px;
    margin-bottom: 60px;
}

.arrow-icon {
    transition: transform 0.2s ease;
}

.btn-secondary:hover .arrow-icon {
    transform: translateX(4px);
}

/* SIGNATURE VISUAL (System Interactive Terminal) */
.signature-visual-wrapper {
    width: 100%;
    max-width: 820px;
    margin-top: 20px;
}

.browser-frame {
    background: var(--bg-surface);
    border: 1px solid var(--border-hairline);
    border-radius: var(--radius-xl);
    overflow: hidden;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.4);
    text-align: left;
}

.browser-header {
    background: rgba(255, 255, 255, 0.03);
    border-bottom: 1px solid var(--border-hairline);
    padding: 12px 18px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.browser-dots {
    display: flex;
    gap: 6px;
}

.dot {
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background: var(--text-muted);
}
.dot.red { background: #ff5f56; }
.dot.yellow { background: #ffbd2e; }
.dot.green { background: #27c93f; }

.browser-title {
    font-family: var(--font-mono);
    font-size: 0.76rem;
    color: var(--text-sub);
}

.browser-status {
    font-family: var(--font-mono);
    font-size: 0.72rem;
    color: var(--primary-accent);
}

.terminal-body {
    padding: 24px;
    font-family: var(--font-mono);
    font-size: 0.85rem;
    line-height: 1.7;
    color: var(--text-sub);
}

.terminal-line { margin-bottom: 12px; }
.t-prompt { color: var(--primary-accent); font-weight: 600; }
.t-cmd { color: var(--text-main); }
.t-key { color: var(--primary-accent); }
.t-str { color: #a1a1a1; }
.t-cursor { animation: blink 1s infinite; color: var(--primary-accent); }

@keyframes blink { 0%, 100% { opacity: 1; } 50% { opacity: 0; } }

/* --------------------------------------------------------------------------
   06. TARGET COMPANIES STRIP
   -------------------------------------------------------------------------- */
.target-companies-section {
    padding: 40px 0;
    border-top: 1px solid var(--border-hairline);
    border-bottom: 1px solid var(--border-hairline);
}

.companies-label {
    font-family: var(--font-mono);
    font-size: 0.76rem;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.1em;
    text-align: center;
    margin-bottom: 20px;
}

.companies-row {
    display: flex;
    align-items: center;
    justify-content: center;
    flex-wrap: wrap;
    gap: 16px;
}

.company-tag {
    font-family: var(--font-sans);
    font-size: 0.88rem;
    font-weight: 500;
    color: var(--text-sub);
    background: var(--bg-surface);
    border: 1px solid var(--border-hairline);
    padding: 8px 18px;
    border-radius: var(--radius-full);
    display: flex;
    align-items: center;
    gap: 8px;
    transition: var(--transition-fast);
}

.company-tag:hover {
    color: var(--text-main);
    border-color: var(--border-hover);
}

/* --------------------------------------------------------------------------
   07. SECTION LAYOUT & SPACING (HUGE WHITESPACE 130PX+)
   -------------------------------------------------------------------------- */
.section-padding {
    padding: 140px 0;
}

.border-top {
    border-top: 1px solid var(--border-hairline);
}

.section-container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 24px;
}

.section-label {
    font-family: var(--font-mono);
    font-size: 0.78rem;
    font-weight: 600;
    color: var(--primary-accent);
    letter-spacing: 0.1em;
    text-transform: uppercase;
    display: block;
    margin-bottom: 12px;
}

.section-headline {
    font-size: clamp(2rem, 3.5vw, 2.8rem);
    font-weight: 700;
    letter-spacing: -0.03em;
    color: var(--text-main);
    margin-bottom: 50px;
}

/* --------------------------------------------------------------------------
   08. ABOUT SECTION
   -------------------------------------------------------------------------- */
.about-statement {
    font-size: clamp(1.4rem, 2.4vw, 2rem);
    font-weight: 500;
    letter-spacing: -0.02em;
    color: var(--text-main);
    line-height: 1.4;
    max-width: 900px;
    margin-bottom: 40px;
}

.about-text-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 40px;
    margin-bottom: 60px;
}

.about-paragraph {
    font-size: 1.05rem;
    color: var(--text-sub);
    line-height: 1.7;
}

.about-stats-row {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 20px;
    padding-top: 40px;
    border-top: 1px solid var(--border-hairline);
}

.stat-item {
    display: flex;
    flex-direction: column;
}

.stat-num {
    font-size: 2.2rem;
    font-weight: 800;
    letter-spacing: -0.03em;
    color: var(--text-main);
}

.stat-lbl {
    font-family: var(--font-mono);
    font-size: 0.78rem;
    color: var(--text-sub);
    margin-top: 4px;
}

/* --------------------------------------------------------------------------
   09. SELECTED WORK / PROJECTS
   -------------------------------------------------------------------------- */
.projects-list {
    display: flex;
    flex-direction: column;
    gap: 80px;
}

.project-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 50px;
    align-items: center;
    padding-bottom: 80px;
    border-bottom: 1px solid var(--border-hairline);
}

.project-row:last-child {
    padding-bottom: 0;
    border-bottom: none;
}

.project-row-left {
    display: flex;
    flex-direction: column;
}

.project-meta-tag {
    font-family: var(--font-mono);
    font-size: 0.76rem;
    color: var(--primary-accent);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 8px;
}

.project-name {
    font-size: 2rem;
    font-weight: 700;
    letter-spacing: -0.03em;
    color: var(--text-main);
    margin-bottom: 12px;
}

.project-summary {
    font-size: 1.05rem;
    color: var(--text-sub);
    line-height: 1.6;
    margin-bottom: 24px;
}

.project-detail-box {
    display: flex;
    flex-direction: column;
    gap: 16px;
    margin-bottom: 24px;
    background: var(--bg-surface);
    border: 1px solid var(--border-hairline);
    padding: 20px;
    border-radius: var(--radius-lg);
}

.detail-group {}

.detail-label {
    font-family: var(--font-mono);
    font-size: 0.72rem;
    color: var(--text-muted);
    letter-spacing: 0.08em;
    display: block;
    margin-bottom: 4px;
}

.detail-val {
    font-size: 0.9rem;
    color: var(--text-sub);
    line-height: 1.5;
}

.feature-bullets {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 6px;
    margin-top: 4px;
}

.feature-bullets li {
    font-size: 0.88rem;
    color: var(--text-sub);
    position: relative;
    padding-left: 14px;
}

.feature-bullets li::before {
    content: '•';
    position: absolute;
    left: 0;
    color: var(--primary-accent);
}

.project-tech-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-bottom: 24px;
}

.project-links {
    display: flex;
    align-items: center;
    gap: 20px;
}

.project-link {
    font-size: 0.92rem;
    font-weight: 500;
    color: var(--text-main);
    display: inline-flex;
    align-items: center;
    gap: 6px;
}

.project-link .arrow {
    transition: transform 0.2s ease;
}

.project-link:hover .arrow {
    transform: translateX(4px);
}

.browser-frame-preview {
    background: var(--bg-surface);
    border: 1px solid var(--border-hairline);
    border-radius: var(--radius-xl);
    overflow: hidden;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.project-row:hover .browser-frame-preview {
    transform: scale(1.015);
    box-shadow: 0 15px 35px rgba(0, 0, 0, 0.3);
}

.browser-bar {
    background: rgba(255, 255, 255, 0.03);
    border-bottom: 1px solid var(--border-hairline);
    padding: 10px 14px;
    display: flex;
    align-items: center;
    gap: 12px;
}

.browser-bar .dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: var(--text-muted);
}

.bar-url {
    font-family: var(--font-mono);
    font-size: 0.72rem;
    color: var(--text-muted);
}

.project-img {
    width: 100%;
    aspect-ratio: 16/10;
    object-fit: cover;
    display: block;
}

/* --------------------------------------------------------------------------
   10. TECHNICAL SKILLS
   -------------------------------------------------------------------------- */
.skills-clean-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 30px;
}

.skill-category-box {
    background: var(--bg-surface);
    border: 1px solid var(--border-hairline);
    border-radius: var(--radius-xl);
    padding: 30px;
}

.category-name {
    font-size: 1.15rem;
    font-weight: 600;
    color: var(--text-main);
    margin-bottom: 18px;
    letter-spacing: -0.02em;
}

.skills-flex {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

/* --------------------------------------------------------------------------
   11. EXPERIENCE & ACHIEVEMENTS
   -------------------------------------------------------------------------- */
.experience-list {
    display: flex;
    flex-direction: column;
    gap: 32px;
}

.exp-item {
    display: grid;
    grid-template-columns: 220px 1fr;
    gap: 30px;
    padding-bottom: 32px;
    border-bottom: 1px solid var(--border-hairline);
}

.exp-item:last-child {
    border-bottom: none;
}

.exp-left {
    display: flex;
    flex-direction: column;
    gap: 6px;
}

.exp-date {
    font-family: var(--font-mono);
    font-size: 0.85rem;
    color: var(--text-sub);
}

.exp-badge {
    font-family: var(--font-mono);
    font-size: 0.75rem;
    color: var(--primary-accent);
}

.exp-badge.winner {
    font-weight: 600;
}

.exp-title {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-main);
    letter-spacing: -0.02em;
    margin-bottom: 4px;
}

.exp-org {
    font-family: var(--font-mono);
    font-size: 0.82rem;
    color: var(--text-muted);
    margin-bottom: 10px;
}

.exp-desc {
    font-size: 0.95rem;
    color: var(--text-sub);
    line-height: 1.6;
}

/* --------------------------------------------------------------------------
   12. EDUCATION & CERTIFICATIONS
   -------------------------------------------------------------------------- */
.two-col-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 50px;
}

.col-title {
    font-size: 1.6rem;
    font-weight: 700;
    letter-spacing: -0.03em;
    color: var(--text-main);
    margin-bottom: 30px;
}

.edu-box {
    background: var(--bg-surface);
    border: 1px solid var(--border-hairline);
    border-radius: var(--radius-xl);
    padding: 30px;
}

.edu-degree {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--text-main);
    margin-bottom: 6px;
}

.edu-period {
    font-family: var(--font-mono);
    font-size: 0.82rem;
    color: var(--primary-accent);
    margin-bottom: 14px;
}

.edu-text {
    font-size: 0.95rem;
    color: var(--text-sub);
    line-height: 1.6;
    margin-bottom: 20px;
}

.coursework-list {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.cert-list {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.cert-item {
    background: var(--bg-surface);
    border: 1px solid var(--border-hairline);
    border-radius: var(--radius-lg);
    padding: 20px;
    display: flex;
    flex-direction: column;
}

.cert-name {
    font-size: 1.02rem;
    font-weight: 600;
    color: var(--text-main);
    margin-bottom: 4px;
}

.cert-meta {
    font-family: var(--font-mono);
    font-size: 0.8rem;
    color: var(--text-sub);
}

/* --------------------------------------------------------------------------
   13. GITHUB ACTIVITY
   -------------------------------------------------------------------------- */
.github-panel {
    background: var(--bg-surface);
    border: 1px solid var(--border-hairline);
    border-radius: var(--radius-xl);
    padding: 30px;
}

.github-panel-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 24px;
    flex-wrap: wrap;
    gap: 16px;
}

.user-meta {
    display: flex;
    align-items: center;
    gap: 14px;
}

.gh-icon {
    font-size: 2rem;
    color: var(--text-main);
}

.user-handle {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--text-main);
    display: block;
}

.user-sub {
    font-size: 0.85rem;
    color: var(--text-sub);
}

.heatmap-container {
    background: var(--bg-dark);
    border: 1px solid var(--border-hairline);
    border-radius: var(--radius-lg);
    padding: 20px;
}

.heatmap-top {
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-family: var(--font-mono);
    font-size: 0.78rem;
    color: var(--text-sub);
    margin-bottom: 16px;
}

.heatmap-legend {
    display: flex;
    align-items: center;
    gap: 4px;
}

.sq {
    width: 10px;
    height: 10px;
    border-radius: 2px;
}

.sq-0 { background: #161b22; }
.sq-1 { background: #0e4429; }
.sq-2 { background: #006d32; }
.sq-3 { background: #26a641; }
.sq-4 { background: #39d353; }

.heatmap-grid {
    display: grid;
    grid-template-columns: repeat(52, 1fr);
    gap: 4px;
    overflow-x: auto;
}

.heatmap-cell {
    width: 100%;
    aspect-ratio: 1;
    border-radius: 2px;
}

/* --------------------------------------------------------------------------
   14. CONTACT SECTION
   -------------------------------------------------------------------------- */
.contact-box {
    text-align: left;
    max-width: 800px;
}

.contact-headline {
    font-size: clamp(2.2rem, 4vw, 3.4rem);
    font-weight: 800;
    letter-spacing: -0.04em;
    color: var(--text-main);
    line-height: 1.15;
    margin-bottom: 20px;
}

.contact-text {
    font-size: 1.1rem;
    color: var(--text-sub);
    line-height: 1.65;
    margin-bottom: 36px;
}

.contact-links {
    display: flex;
    align-items: center;
    flex-wrap: wrap;
    gap: 16px;
}

/* --------------------------------------------------------------------------
   15. FOOTER & BACK TO TOP
   -------------------------------------------------------------------------- */
.site-footer {
    border-top: 1px solid var(--border-hairline);
    padding: 40px 0;
}

.footer-container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 24px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 20px;
}

.footer-brand {
    font-weight: 700;
    font-size: 1.05rem;
    color: var(--text-main);
    display: block;
}

.footer-copy {
    font-family: var(--font-mono);
    font-size: 0.78rem;
    color: var(--text-muted);
}

.footer-links {
    display: flex;
    align-items: center;
    gap: 24px;
}

.footer-links a {
    font-size: 0.88rem;
    color: var(--text-sub);
}

.footer-links a:hover { color: var(--text-main); }

.back-to-top-btn {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 40px;
    height: 40px;
    border-radius: var(--radius-lg);
    background: var(--bg-surface);
    border: 1px solid var(--border-hairline);
    color: var(--text-main);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1rem;
    z-index: 900;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition-smooth);
}

.back-to-top-btn.visible {
    opacity: 1;
    visibility: visible;
}

.back-to-top-btn:hover {
    border-color: var(--border-hover);
    transform: translateY(-2px);
}

/* Scroll Reveal */
.reveal-element {
    opacity: 0;
    transform: translateY(12px);
    transition: opacity 0.6s cubic-bezier(0.16, 1, 0.3, 1), transform 0.6s cubic-bezier(0.16, 1, 0.3, 1);
}

.reveal-element.active {
    opacity: 1;
    transform: translateY(0);
}

/* Respect reduced motion */
@media (prefers-reduced-motion: reduce) {
    .reveal-element {
        opacity: 1;
        transform: none;
        transition: none;
    }
}

/* Responsive */
@media (max-width: 900px) {
    .about-text-grid { grid-template-columns: 1fr; }
    .about-stats-row { grid-template-columns: repeat(2, 1fr); gap: 30px; }
    .project-row { grid-template-columns: 1fr; gap: 30px; }
    .skills-clean-grid { grid-template-columns: 1fr; }
    .two-col-grid { grid-template-columns: 1fr; }
    .exp-item { grid-template-columns: 1fr; gap: 8px; }
}

@media (max-width: 768px) {
    .nav-links-desktop { display: none; }
    .mobile-menu-btn { display: flex; }
    .hero-section { padding-top: 110px; }
    .section-padding { padding: 90px 0; }
    .footer-container { flex-direction: column; text-align: center; }
}