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

:root {
    --bg-primary: #0a0a0b;
    --bg-secondary: #111113;
    --bg-tertiary: #18181b;
    --bg-code: #0d0d0f;
    --border: #27272a;
    --border-hover: #3f3f46;
    --text-primary: #fafafa;
    --text-secondary: #a1a1aa;
    --text-muted: #71717a;
    --accent: #60a5fa;
    --accent-hover: #93c5fd;
    --accent-glow: rgba(96, 165, 250, 0.15);
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    --font-mono: 'JetBrains Mono', 'Courier New', monospace;
}

html { scroll-behavior: smooth; }

body {
    background: var(--bg-primary);
    color: var(--text-primary);
    font-family: var(--font-sans);
    line-height: 1.6;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

body::before {
    content: '';
    position: fixed;
    inset: 0;
    background-image:
        linear-gradient(rgba(255,255,255,0.015) 1px, transparent 1px),
        linear-gradient(90deg, rgba(255,255,255,0.015) 1px, transparent 1px);
    background-size: 50px 50px;
    pointer-events: none;
    z-index: 0;
}

main { flex: 1; position: relative; z-index: 2; }

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

.container-narrow {
    max-width: 820px;
}

a { color: var(--accent); transition: color 0.2s; }
a:hover { color: var(--accent-hover); }

/* ============ NAVBAR ============ */
.navbar {
    position: fixed;
    top: 0; left: 0; right: 0;
    background: rgba(10, 10, 11, 0.85);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border);
    z-index: 100;
    padding: 1rem 0;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo {
    font-family: var(--font-mono);
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-primary);
    text-decoration: none;
}

.logo-bracket { color: var(--accent); }
.logo-suffix { color: var(--text-muted); font-weight: 400; }

.nav-links {
    display: flex;
    gap: 1.75rem;
    list-style: none;
}

.nav-links a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 500;
}

.nav-links a:hover { color: var(--text-primary); }
.nav-external { color: var(--accent) !important; }

/* ============ HERO ============ */
.hero-small {
    padding: 8rem 2rem 4rem;
    text-align: center;
    border-bottom: 1px solid var(--border);
}

.hero-greeting {
    font-family: var(--font-mono);
    color: var(--accent);
    font-size: 0.9rem;
    margin-bottom: 1rem;
}

.hero-title {
    font-size: clamp(2.5rem, 6vw, 4rem);
    font-weight: 700;
    letter-spacing: -2px;
    margin-bottom: 1rem;
}

.hero-subtitle {
    color: var(--text-secondary);
    font-size: 1.05rem;
}

.accent { color: var(--accent); font-weight: 500; }

.back-link {
    display: inline-block;
    color: var(--text-muted);
    text-decoration: none;
    font-family: var(--font-mono);
    font-size: 0.85rem;
    margin-bottom: 1.5rem;
    transition: color 0.2s;
}

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

/* ============ FILTER BAR ============ */
.filter-bar {
    padding: 2rem 0;
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 60px;
    z-index: 50;
    backdrop-filter: blur(12px);
}

.filter-bar .container {
    display: flex;
    flex-wrap: wrap;
    gap: 1.5rem;
    align-items: center;
    justify-content: space-between;
}

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

.filter-btn {
    background: var(--bg-tertiary);
    border: 1px solid var(--border);
    color: var(--text-secondary);
    padding: 0.5rem 0.9rem;
    border-radius: 6px;
    cursor: pointer;
    font-family: var(--font-sans);
    font-size: 0.85rem;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    transition: all 0.2s;
}

.filter-btn:hover {
    border-color: var(--border-hover);
    color: var(--text-primary);
}

.filter-btn.active {
    background: var(--accent);
    color: var(--bg-primary);
    border-color: var(--accent);
}

.filter-btn.active .filter-count {
    background: rgba(0,0,0,0.2);
    color: var(--bg-primary);
}

.filter-icon { font-size: 1rem; }

.filter-count {
    background: var(--bg-primary);
    color: var(--text-muted);
    padding: 0.1rem 0.45rem;
    border-radius: 3px;
    font-family: var(--font-mono);
    font-size: 0.7rem;
}

.search-wrap {
    flex: 1;
    min-width: 200px;
    max-width: 320px;
}

.search-input {
    width: 100%;
    background: var(--bg-tertiary);
    border: 1px solid var(--border);
    color: var(--text-primary);
    padding: 0.55rem 0.9rem;
    border-radius: 6px;
    font-family: var(--font-mono);
    font-size: 0.85rem;
    transition: border-color 0.2s;
}

.search-input:focus {
    outline: none;
    border-color: var(--accent);
}

.search-input::placeholder { color: var(--text-muted); }

/* ============ WRITEUPS GRID ============ */
.writeups-section { padding: 3rem 0 5rem; }

.writeups-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1.25rem;
}

.writeup-card {
    background: var(--bg-tertiary);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 1.5rem;
    text-decoration: none;
    color: inherit;
    display: flex;
    flex-direction: column;
    transition: all 0.25s;
    position: relative;
    overflow: hidden;
}

.writeup-card::before {
    content: '';
    position: absolute;
    top: 0; left: 0;
    width: 100%; height: 2px;
    background: linear-gradient(90deg, transparent, var(--accent), transparent);
    transform: translateX(-100%);
    transition: transform 0.4s;
}

.writeup-card:hover {
    border-color: var(--accent);
    transform: translateY(-4px);
    box-shadow: 0 10px 30px rgba(0,0,0,0.3);
}

.writeup-card:hover::before {
    transform: translateX(100%);
}

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
}

.card-category {
    font-family: var(--font-mono);
    font-size: 0.75rem;
    font-weight: 500;
    letter-spacing: 0.5px;
}

.card-difficulty {
    font-family: var(--font-mono);
    font-size: 0.75rem;
    letter-spacing: 1px;
}

.card-difficulty.difficulty-easy { color: #34d399; }
.card-difficulty.difficulty-medium { color: #fbbf24; }
.card-difficulty.difficulty-hard { color: #fb923c; }
.card-difficulty.difficulty-insane { color: #f87171; }
.card-difficulty .dim { color: var(--border); }

.card-title {
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: 0.4rem;
    line-height: 1.3;
    color: var(--text-primary);
}

.card-ctf {
    color: var(--text-muted);
    font-size: 0.85rem;
    margin-bottom: 1rem;
    font-family: var(--font-mono);
}

.card-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.4rem;
    margin-bottom: 1rem;
}

.tag {
    font-family: var(--font-mono);
    font-size: 0.7rem;
    background: var(--bg-primary);
    color: var(--text-secondary);
    padding: 0.2rem 0.55rem;
    border-radius: 3px;
    border: 1px solid var(--border);
}

.card-footer {
    margin-top: auto;
    padding-top: 1rem;
    border-top: 1px solid var(--border);
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.8rem;
    color: var(--text-muted);
    font-family: var(--font-mono);
}

.card-arrow {
    color: var(--text-muted);
    transition: all 0.2s;
}

.writeup-card:hover .card-arrow {
    color: var(--accent);
    transform: translateX(4px);
}

.no-results {
    text-align: center;
    color: var(--text-muted);
    font-family: var(--font-mono);
    padding: 3rem;
}

/* ============ EMPTY STATE ============ */
.empty-state {
    padding: 4rem 0 6rem;
}

.empty-card {
    background: var(--bg-tertiary);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 3rem 2rem;
    text-align: center;
    max-width: 700px;
    margin: 0 auto;
}

.empty-icon {
    font-family: var(--font-mono);
    font-size: 3rem;
    color: var(--accent);
    margin-bottom: 1rem;
}

.empty-card h2 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
}

.empty-card p {
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

.empty-card code {
    background: var(--bg-primary);
    color: var(--accent);
    padding: 0.15rem 0.4rem;
    border-radius: 3px;
    font-family: var(--font-mono);
    font-size: 0.85em;
}

.empty-code {
    background: var(--bg-code);
    border: 1px solid var(--border);
    border-radius: 6px;
    padding: 1.5rem;
    text-align: left;
    font-family: var(--font-mono);
    font-size: 0.85rem;
    line-height: 1.7;
    color: var(--text-secondary);
    overflow-x: auto;
}

.empty-code .comment { color: var(--text-muted); }
.empty-code .key { color: var(--accent); }
.empty-code .str { color: #a78bfa; }
.empty-code .punct { color: var(--text-muted); }

/* ============ WRITEUP PAGE ============ */
.writeup { padding-top: 5rem; }

.writeup-header {
    padding: 2rem 0 3rem;
    border-bottom: 1px solid var(--border);
}

.writeup-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    margin-bottom: 1.5rem;
    align-items: center;
}

.meta-item {
    font-family: var(--font-mono);
    font-size: 0.8rem;
    color: var(--text-muted);
    padding: 0.25rem 0.6rem;
    background: var(--bg-tertiary);
    border: 1px solid var(--border);
    border-radius: 4px;
}

.writeup-title {
    font-size: clamp(1.8rem, 5vw, 3rem);
    font-weight: 700;
    letter-spacing: -1.5px;
    line-height: 1.15;
    margin-bottom: 0.5rem;
}

.writeup-ctf {
    color: var(--text-secondary);
    font-family: var(--font-mono);
    font-size: 1rem;
    margin-bottom: 1.25rem;
}

.writeup-body { padding: 3rem 0; }

/* ============ PROSE (markdown content) ============ */
.prose {
    color: var(--text-secondary);
    font-size: 1.02rem;
    line-height: 1.75;
}

.prose h1, .prose h2, .prose h3, .prose h4 {
    color: var(--text-primary);
    font-weight: 600;
    line-height: 1.3;
    margin: 2.5rem 0 1rem;
    scroll-margin-top: 5rem;
}

.prose h1 { font-size: 2rem; letter-spacing: -1px; }
.prose h2 {
    font-size: 1.6rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px solid var(--border);
}
.prose h3 { font-size: 1.25rem; color: var(--accent); }
.prose h4 { font-size: 1.05rem; }

.prose p { margin-bottom: 1.25rem; }

.prose strong { color: var(--text-primary); font-weight: 600; }
.prose em { color: var(--text-primary); }

.prose a {
    color: var(--accent);
    text-decoration: underline;
    text-decoration-color: rgba(96, 165, 250, 0.4);
    text-underline-offset: 3px;
}

.prose a:hover { text-decoration-color: var(--accent); }

.prose ul, .prose ol {
    margin: 0 0 1.25rem 1.5rem;
}

.prose li { margin-bottom: 0.4rem; }

.prose ul li::marker { color: var(--accent); }

.prose blockquote {
    border-left: 3px solid var(--accent);
    padding: 0.5rem 1.25rem;
    margin: 1.5rem 0;
    background: var(--bg-tertiary);
    border-radius: 0 6px 6px 0;
    color: var(--text-secondary);
    font-style: italic;
}

.prose blockquote p:last-child { margin-bottom: 0; }

.prose code {
    background: var(--bg-tertiary);
    color: #f0abfc;
    padding: 0.15rem 0.4rem;
    border-radius: 3px;
    font-family: var(--font-mono);
    font-size: 0.88em;
    border: 1px solid var(--border);
}

.prose pre {
    background: var(--bg-code);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 1.25rem;
    overflow-x: auto;
    margin: 1.5rem 0;
    font-size: 0.88rem;
    line-height: 1.6;
}

.prose pre code {
    background: transparent;
    padding: 0;
    border: none;
    color: var(--text-primary);
    font-size: inherit;
}

.copy-btn {
    position: absolute;
    top: 0.5rem;
    right: 0.5rem;
    background: var(--bg-tertiary);
    color: var(--text-secondary);
    border: 1px solid var(--border);
    border-radius: 4px;
    padding: 0.25rem 0.6rem;
    font-family: var(--font-mono);
    font-size: 0.7rem;
    cursor: pointer;
    opacity: 0;
    transition: opacity 0.2s, background 0.2s;
}

.prose pre:hover .copy-btn { opacity: 1; }
.copy-btn:hover { background: var(--accent); color: var(--bg-primary); border-color: var(--accent); }

.prose img {
    max-width: 100%;
    border-radius: 8px;
    margin: 1.5rem 0;
    border: 1px solid var(--border);
}

.prose hr {
    border: none;
    border-top: 1px solid var(--border);
    margin: 2.5rem 0;
}

.prose table {
    width: 100%;
    border-collapse: collapse;
    margin: 1.5rem 0;
    font-size: 0.92rem;
}

.prose th, .prose td {
    text-align: left;
    padding: 0.7rem 1rem;
    border: 1px solid var(--border);
}

.prose th {
    background: var(--bg-tertiary);
    color: var(--text-primary);
    font-weight: 600;
}

.prose td { background: var(--bg-secondary); }

/* ============ WRITEUP FOOTER ============ */
.writeup-footer {
    padding: 2rem 0 4rem;
    border-top: 1px solid var(--border);
    margin-top: 3rem;
}

.btn-back {
    display: inline-block;
    color: var(--text-secondary);
    text-decoration: none;
    font-family: var(--font-mono);
    font-size: 0.9rem;
    padding: 0.6rem 1.2rem;
    border: 1px solid var(--border);
    border-radius: 6px;
    transition: all 0.2s;
}

.btn-back:hover {
    border-color: var(--accent);
    color: var(--accent);
}

/* ============ ERROR PAGE ============ */
.error-page {
    padding: 8rem 0;
    text-align: center;
}

.error-code {
    font-family: var(--font-mono);
    font-size: clamp(5rem, 15vw, 9rem);
    color: var(--accent);
    line-height: 1;
    font-weight: 700;
    letter-spacing: -3px;
}

.error-title {
    font-size: 1.75rem;
    margin: 1rem 0 0.5rem;
}

.error-message {
    color: var(--text-secondary);
    margin-bottom: 2rem;
    font-family: var(--font-mono);
}

.error-message .comment { color: var(--text-muted); }

.btn {
    display: inline-block;
    padding: 0.85rem 1.75rem;
    border-radius: 6px;
    text-decoration: none;
    font-weight: 500;
    font-size: 0.95rem;
    transition: all 0.2s;
}

.btn-primary {
    background: var(--accent);
    color: var(--bg-primary);
}

.btn-primary:hover {
    background: var(--accent-hover);
    transform: translateY(-2px);
}

/* ============ FOOTER ============ */
.footer {
    background: var(--bg-secondary);
    border-top: 1px solid var(--border);
    padding: 3rem 0 2rem;
    position: relative;
    z-index: 2;
    margin-top: auto;
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    flex-wrap: wrap;
    gap: 2rem;
    padding-bottom: 2rem;
    border-bottom: 1px solid var(--border);
    margin-bottom: 1.5rem;
}

.footer-brand { font-family: var(--font-mono); font-size: 1rem; font-weight: 600; }

.footer-brand p {
    font-family: var(--font-sans);
    font-weight: 400;
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-top: 0.5rem;
}

.footer-links { display: flex; gap: 1.5rem; }

.footer-links a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.9rem;
}

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

.footer-bottom {
    display: flex;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 0.5rem;
    font-size: 0.8rem;
    color: var(--text-muted);
}

.footer-mono { font-family: var(--font-mono); }

/* ============ RESPONSIVE ============ */
@media (max-width: 768px) {
    .container { padding: 0 1.25rem; }
    .nav-container { padding: 0 1.25rem; }
    .filter-bar .container { flex-direction: column; align-items: stretch; }
    .search-wrap { max-width: none; }
    .writeups-grid { grid-template-columns: 1fr; }
    .filter-bar { top: 56px; }
}