/* ===================================
   CSS Variables
   =================================== */
:root {
    --bg-primary: #0a0a0a;
    --bg-secondary: #111111;
    --bg-surface: #181818;
    --bg-card: #131313;
    --text-primary: #ededed;
    --text-secondary: #888888;
    --text-muted: #555555;
    --accent: #00d9ff;
    --accent-dim: rgba(0, 217, 255, 0.12);
    --accent-hover: #00b8db;
    --border: #222222;
    --border-light: #2a2a2a;

    --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-mono: 'Fira Code', 'JetBrains Mono', 'Consolas', monospace;

    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 5rem;

    --radius: 6px;
    --radius-lg: 10px;
    --transition: 200ms ease;
    --transition-slow: 350ms ease;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-body);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.65;
    font-size: 16px;
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
}

a {
    color: inherit;
    text-decoration: none;
}

/* ===================================
   Top Brand Bar
   =================================== */
.top-bar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--accent) 0%, #0077ff 100%);
    z-index: 100;
}

/* ===================================
   Container
   =================================== */
.container {
    max-width: 1040px;
    margin: 0 auto;
    padding: var(--spacing-xl) var(--spacing-lg);
    padding-top: calc(var(--spacing-xl) + 3px);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* ===================================
   Header
   =================================== */
header {
    padding: var(--spacing-xl) 0 var(--spacing-lg);
    border-bottom: 1px solid var(--border);
    margin-bottom: var(--spacing-lg);
}

.brand {
    margin-bottom: var(--spacing-lg);
}

.site-title {
    font-family: var(--font-mono);
    font-size: clamp(2.2rem, 5vw, 3.5rem);
    font-weight: 500;
    letter-spacing: -0.03em;
    line-height: 1.1;
    margin-bottom: 0.5rem;
    background: linear-gradient(135deg, #ffffff 0%, #c0c0c0 60%, var(--accent) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.site-subtitle {
    font-family: var(--font-mono);
    font-size: 0.9rem;
    color: var(--text-muted);
    letter-spacing: 0.08em;
    text-transform: uppercase;
    font-weight: 400;
}

/* ===================================
   About Panel
   =================================== */
.about-panel {
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    gap: var(--spacing-lg);
    padding: var(--spacing-md) 0;
    border-top: 1px solid var(--border);
}

.about-bio {
    font-size: 1rem;
    color: var(--text-secondary);
    line-height: 1.7;
    max-width: 540px;
    flex: 1;
}

.about-links {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
    flex-shrink: 0;
    align-items: flex-end;
}

.about-link {
    font-family: var(--font-mono);
    font-size: 0.85rem;
    color: var(--text-secondary);
    transition: color var(--transition);
    white-space: nowrap;
}

.about-link:hover {
    color: var(--accent);
}

/* ===================================
   Tab Navigation
   =================================== */
.tab-navigation {
    display: flex;
    gap: 0;
    border-bottom: 1px solid var(--border);
    margin-bottom: var(--spacing-xl);
    overflow-x: auto;
    scrollbar-width: none;
}

.tab-navigation::-webkit-scrollbar {
    display: none;
}

.tab-button {
    background: none;
    border: none;
    color: var(--text-muted);
    font-family: var(--font-mono);
    font-size: 0.9rem;
    font-weight: 500;
    padding: var(--spacing-sm) var(--spacing-md);
    cursor: pointer;
    position: relative;
    transition: color var(--transition);
    white-space: nowrap;
    letter-spacing: 0.02em;
}

.tab-button:hover {
    color: var(--text-secondary);
}

.tab-button.active {
    color: var(--text-primary);
}

.tab-button.active::after {
    content: '';
    position: absolute;
    bottom: -1px;
    left: 0;
    right: 0;
    height: 2px;
    background: var(--accent);
    border-radius: 2px 2px 0 0;
}

/* ===================================
   Tab Content
   =================================== */
.content {
    flex: 1;
}

.tab-content {
    display: none;
    animation: fadeUp 0.25s ease;
}

.tab-content.active {
    display: block;
}

@keyframes fadeUp {
    from {
        opacity: 0;
        transform: translateY(8px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ===================================
   Section Headers
   =================================== */
.section-header {
    display: flex;
    align-items: baseline;
    justify-content: space-between;
    margin-bottom: var(--spacing-lg);
}

.section-header h2 {
    font-family: var(--font-mono);
    font-size: 1.8rem;
    font-weight: 500;
    color: var(--text-primary);
    letter-spacing: -0.02em;
}

.section-cta {
    font-family: var(--font-mono);
    font-size: 0.85rem;
    color: var(--accent);
    transition: color var(--transition);
}

.section-cta:hover {
    color: var(--accent-hover);
}

.subsection-title {
    font-family: var(--font-mono);
    font-size: 0.8rem;
    font-weight: 500;
    color: var(--text-muted);
    letter-spacing: 0.1em;
    text-transform: uppercase;
    margin-bottom: var(--spacing-md);
    padding-bottom: var(--spacing-xs);
    border-bottom: 1px solid var(--border);
}

.subsection {
    margin-bottom: var(--spacing-xl);
}

/* ===================================
   Channel Banner (Videos)
   =================================== */
.channel-banner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    background: var(--bg-surface);
    border: 1px solid var(--border-light);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg) var(--spacing-xl);
    margin-bottom: var(--spacing-xl);
    transition: border-color var(--transition), background var(--transition);
    cursor: pointer;
    gap: var(--spacing-lg);
}

.channel-banner:hover {
    border-color: var(--accent);
    background: var(--bg-card);
}

.channel-info {
    display: flex;
    flex-direction: column;
    gap: 0.35rem;
}

.channel-label {
    font-family: var(--font-mono);
    font-size: 0.75rem;
    color: var(--text-muted);
    letter-spacing: 0.1em;
    text-transform: uppercase;
}

.channel-name {
    font-family: var(--font-mono);
    font-size: 1.5rem;
    font-weight: 500;
    color: var(--text-primary);
    letter-spacing: -0.02em;
}

.channel-desc {
    font-size: 0.95rem;
    color: var(--text-secondary);
}

.subscribe-btn {
    flex-shrink: 0;
    padding: 0.6rem 1.4rem;
    background: var(--accent);
    color: var(--bg-primary);
    border-radius: var(--radius);
    font-family: var(--font-mono);
    font-size: 0.85rem;
    font-weight: 500;
    transition: background var(--transition), transform var(--transition);
}

.channel-banner:hover .subscribe-btn {
    background: var(--accent-hover);
    transform: translateY(-1px);
}

/* ===================================
   Video Grid
   =================================== */
.video-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(290px, 1fr));
    gap: var(--spacing-lg);
}

.video-card {
    background: var(--bg-surface);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border);
    overflow: hidden;
    transition: transform var(--transition), border-color var(--transition);
}

.video-card:hover {
    transform: translateY(-3px);
    border-color: var(--border-light);
}

.video-thumbnail {
    width: 100%;
    aspect-ratio: 16 / 9;
    background: var(--bg-secondary);
    overflow: hidden;
}

.placeholder {
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-muted);
    font-family: var(--font-mono);
    font-size: 0.8rem;
    letter-spacing: 0.05em;
}

.video-card h3 {
    font-family: var(--font-body);
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-primary);
    padding: var(--spacing-md) var(--spacing-md) var(--spacing-xs);
}

.video-card p {
    color: var(--text-secondary);
    font-size: 0.9rem;
    padding: 0 var(--spacing-md) var(--spacing-md);
    line-height: 1.55;
}

/* ===================================
   Book Card (Writing)
   =================================== */
.book-card {
    background: var(--bg-surface);
    border: 1px solid var(--border-light);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    margin-bottom: var(--spacing-xl);
    position: relative;
}

.book-status-row {
    margin-bottom: var(--spacing-sm);
}

.status-badge {
    font-family: var(--font-mono);
    font-size: 0.75rem;
    font-weight: 500;
    color: var(--accent);
    background: var(--accent-dim);
    padding: 0.25rem 0.65rem;
    border-radius: 20px;
    letter-spacing: 0.05em;
    text-transform: uppercase;
}

.book-title {
    font-family: var(--font-body);
    font-size: 1.6rem;
    font-weight: 600;
    color: var(--text-primary);
    letter-spacing: -0.02em;
    margin-bottom: 0.35rem;
}

.book-genre {
    font-family: var(--font-mono);
    font-size: 0.8rem;
    color: var(--text-muted);
    letter-spacing: 0.05em;
    margin-bottom: var(--spacing-md);
}

.book-desc {
    font-size: 1rem;
    color: var(--text-secondary);
    line-height: 1.75;
}

/* ===================================
   Writing List
   =================================== */
.writing-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.writing-item {
    background: var(--bg-surface);
    border-radius: var(--radius);
    padding: var(--spacing-lg);
    border: 1px solid var(--border);
    transition: border-color var(--transition);
}

.writing-item:hover {
    border-color: var(--border-light);
}

.writing-meta {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-sm);
    font-family: var(--font-mono);
    font-size: 0.8rem;
}

.date {
    color: var(--text-muted);
}

.tag {
    color: var(--accent);
    background: var(--accent-dim);
    padding: 0.15rem 0.5rem;
    border-radius: 3px;
    font-size: 0.75rem;
}

.writing-item h3 {
    font-size: 1.05rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: var(--spacing-xs);
    font-family: var(--font-body);
}

.writing-item p {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: var(--spacing-sm);
    line-height: 1.6;
}

.read-more {
    font-family: var(--font-mono);
    font-size: 0.82rem;
    color: var(--accent);
    transition: color var(--transition);
}

.read-more:hover {
    color: var(--accent-hover);
}

/* ===================================
   Project Grid (Fun)
   =================================== */
.project-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
    gap: var(--spacing-md);
}

.project-card {
    background: var(--bg-surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: var(--spacing-md);
    transition: border-color var(--transition), transform var(--transition);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.project-card:hover {
    border-color: var(--border-light);
    transform: translateY(-2px);
}

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

.project-header h4 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-primary);
    font-family: var(--font-body);
}

.project-link {
    font-size: 1.1rem;
    color: var(--text-muted);
    transition: color var(--transition);
    line-height: 1;
}

.project-link:hover {
    color: var(--accent);
}

.project-card p {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.55;
    flex: 1;
}

/* ===================================
   Tech Tags
   =================================== */
.tech-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.4rem;
    margin-top: var(--spacing-xs);
}

.tech-tag {
    font-family: var(--font-mono);
    font-size: 0.75rem;
    color: var(--text-muted);
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    padding: 0.2rem 0.55rem;
    border-radius: 3px;
}

/* ===================================
   Work Cards
   =================================== */
.work-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.work-card {
    background: var(--bg-surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: var(--spacing-lg);
    transition: border-color var(--transition);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.work-card:hover {
    border-color: var(--border-light);
}

.work-header {
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    gap: var(--spacing-md);
}

.work-title-group {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
}

.work-title-group h3 {
    font-size: 1.05rem;
    font-weight: 600;
    color: var(--text-primary);
    font-family: var(--font-body);
    letter-spacing: -0.01em;
}

.work-company {
    font-family: var(--font-mono);
    font-size: 0.8rem;
    color: var(--accent);
}

.work-date {
    font-family: var(--font-mono);
    font-size: 0.8rem;
    color: var(--text-muted);
    white-space: nowrap;
    flex-shrink: 0;
    padding-top: 0.15rem;
}

.work-desc {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.65;
}

.work-links {
    display: flex;
    gap: var(--spacing-md);
    padding-top: var(--spacing-xs);
}

.work-link {
    font-family: var(--font-mono);
    font-size: 0.82rem;
    color: var(--text-muted);
    transition: color var(--transition);
}

.work-link:hover {
    color: var(--accent);
}

/* ===================================
   Footer
   =================================== */
footer {
    margin-top: var(--spacing-2xl);
    padding: var(--spacing-lg) 0;
    border-top: 1px solid var(--border);
}

footer p {
    color: var(--text-muted);
    font-family: var(--font-mono);
    font-size: 0.8rem;
}

/* ===================================
   Responsive
   =================================== */
@media (max-width: 768px) {
    .container {
        padding: var(--spacing-lg) var(--spacing-md);
        padding-top: calc(var(--spacing-lg) + 3px);
    }

    .about-panel {
        flex-direction: column;
        gap: var(--spacing-md);
    }

    .about-links {
        flex-direction: row;
        flex-wrap: wrap;
        align-items: flex-start;
        gap: var(--spacing-md);
    }

    .channel-banner {
        flex-direction: column;
        align-items: flex-start;
        padding: var(--spacing-md);
    }

    .subscribe-btn {
        align-self: flex-start;
    }

    .video-grid {
        grid-template-columns: 1fr;
    }

    .project-grid {
        grid-template-columns: 1fr;
    }

    .work-header {
        flex-direction: column;
        gap: var(--spacing-xs);
    }

    .work-date {
        color: var(--text-muted);
    }
}

@media (max-width: 480px) {
    .site-title {
        font-size: 2rem;
    }

    .tab-button {
        padding: var(--spacing-sm) var(--spacing-sm);
        font-size: 0.85rem;
    }

    .book-card {
        padding: var(--spacing-md);
    }
}