/* ==========================================================================
   ICPC Competitive Programming Subpage Styles
   Theme: Dark Space & Stardust Gold / Astral Cyan
   ========================================================================== */

:root {
    --bg-color: #06060c;
    --section-bg: #0e0f1b;
    --surface-color: #111224;
    --border-color: rgba(130, 142, 230, 0.12);
    --border-hover: rgba(255, 183, 50, 0.35);
    
    --text-primary: #f1f3fc;
    --text-secondary: #9fa4c7;
    --text-muted: #676b8a;
    
    --accent-gold: #ffb732;
    --accent-glow: rgba(255, 183, 50, 0.15);
    --sec-cyan: #64d4ff;
    --sec-cyan-glow: rgba(100, 212, 255, 0.15);
    
    --code-bg: #070810;
    --code-border: rgba(100, 212, 255, 0.2);
    
    --font-serif: 'Cinzel', Georgia, serif;
    --font-sans: 'Plus Jakarta Sans', system-ui, -apple-system, sans-serif;
    --font-mono: 'IBM Plex Mono', monospace;
}

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

body {
    background-color: var(--bg-color);
    color: var(--text-primary);
    font-family: var(--font-sans);
    line-height: 1.6;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
}

/* Navigation Bar */
.nav-bar {
    position: fixed;
    top: 0;
    width: 100%;
    z-index: 1000;
    background-color: rgba(6, 6, 12, 0.85);
    border-bottom: 1px solid var(--border-color);
    backdrop-filter: blur(16px);
    padding: 1rem 5%;
}

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

.back-link {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--text-secondary);
    text-decoration: none;
    font-family: var(--font-mono);
    font-size: 0.82rem;
    transition: color 0.3s ease;
}

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

.logo {
    display: flex;
    flex-direction: column;
}

.logo-text {
    font-family: var(--font-serif);
    font-size: 1.3rem;
    color: var(--text-primary);
}

.logo-sub {
    font-family: var(--font-mono);
    font-size: 0.65rem;
    color: var(--text-muted);
}

.nav-status {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-family: var(--font-mono);
    font-size: 0.72rem;
    color: var(--text-secondary);
}

.status-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background-color: var(--accent-gold);
    box-shadow: 0 0 10px var(--accent-gold);
    animation: statusPulse 2s infinite ease-in-out;
}

@keyframes statusPulse {
    0%, 100% { opacity: 0.6; transform: scale(0.9); }
    50% { opacity: 1; transform: scale(1.1); box-shadow: 0 0 14px var(--accent-gold); }
}

/* Page Hero */
.page-hero {
    padding: 8rem 5% 4rem;
    border-bottom: 1px solid var(--border-color);
    background: radial-gradient(circle at 50% 20%, rgba(255, 183, 50, 0.05) 0%, transparent 70%);
}

.hero-container {
    max-width: 1000px;
    margin: 0 auto;
    text-align: center;
}

.hero-badge {
    display: inline-block;
    font-family: var(--font-mono);
    font-size: 0.75rem;
    color: var(--accent-gold);
    background: rgba(255, 183, 50, 0.1);
    border: 1px solid rgba(255, 183, 50, 0.25);
    padding: 0.35rem 1rem;
    border-radius: 20px;
    margin-bottom: 1.25rem;
    letter-spacing: 1px;
}

.hero-title {
    font-family: var(--font-serif);
    font-size: 2.8rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1rem;
    line-height: 1.2;
}

.hero-subtitle {
    font-size: 1.05rem;
    color: var(--text-secondary);
    max-width: 760px;
    margin: 0 auto 2.5rem;
    font-weight: 300;
}

.hero-actions {
    display: flex;
    justify-content: center;
    gap: 1.25rem;
    margin-bottom: 2rem;
}

.hero-prob-shortcuts {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 3rem;
    flex-wrap: wrap;
}

.shortcut-lbl {
    font-family: var(--font-mono);
    font-size: 0.72rem;
    color: var(--text-muted);
    margin-right: 0.3rem;
}

.prob-shortcut-btn {
    width: 34px;
    height: 34px;
    border-radius: 6px;
    background-color: var(--section-bg);
    border: 1px solid var(--border-color);
    color: var(--accent-gold);
    font-family: var(--font-mono);
    font-size: 0.85rem;
    font-weight: 600;
    text-decoration: none;
    display: flex;
    justify-content: center;
    align-items: center;
    transition: all 0.3s ease;
}

.prob-shortcut-btn:hover {
    background-color: var(--accent-gold);
    color: #06060c;
    border-color: var(--accent-gold);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px var(--accent-glow);
}

.btn {
    font-family: var(--font-mono);
    font-size: 0.85rem;
    padding: 0.8rem 1.8rem;
    border-radius: 6px;
    text-decoration: none;
    transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

.btn.primary {
    background-color: var(--accent-gold);
    color: #06060c;
    border: 1px solid var(--accent-gold);
    font-weight: 600;
}

.btn.primary:hover {
    background-color: #ffc965;
    transform: translateY(-2px);
    box-shadow: 0 6px 18px var(--accent-glow);
}

.btn.secondary {
    background-color: transparent;
    color: var(--sec-cyan);
    border: 1px solid var(--sec-cyan);
}

.btn.secondary:hover {
    background-color: rgba(100, 212, 255, 0.1);
    transform: translateY(-2px);
    box-shadow: 0 6px 18px var(--sec-cyan-glow);
}

/* Stats Bar */
.stats-bar {
    display: flex;
    justify-content: space-around;
    align-items: center;
    padding: 1.5rem;
    background-color: var(--section-bg);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    max-width: 800px;
    margin: 0 auto;
}

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

.stat-val {
    font-family: var(--font-mono);
    font-size: 1.4rem;
    font-weight: 600;
    color: var(--accent-gold);
}

.stat-lbl {
    font-size: 0.75rem;
    color: var(--text-muted);
    font-family: var(--font-mono);
}

.stat-divider {
    width: 1px;
    height: 30px;
    background-color: var(--border-color);
}

/* Main Container & Filter Section */
.main-container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 4rem 5%;
}

.filter-section {
    margin-bottom: 3rem;
}

.filter-label {
    font-family: var(--font-mono);
    font-size: 0.78rem;
    color: var(--accent-gold);
    margin-bottom: 0.8rem;
}

.filter-tabs {
    display: flex;
    flex-wrap: wrap;
    gap: 0.6rem;
}

.tab-btn {
    background-color: var(--section-bg);
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    padding: 0.5rem 1.2rem;
    border-radius: 6px;
    font-family: var(--font-mono);
    font-size: 0.8rem;
    cursor: pointer;
    transition: all 0.3s ease;
}

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

.tab-btn.active {
    background-color: var(--accent-gold);
    color: #06060c;
    border-color: var(--accent-gold);
    font-weight: 600;
}

/* Problem Cards */
.problem-list {
    display: flex;
    flex-direction: column;
    gap: 3rem;
}

.glass-card {
    background-color: var(--section-bg);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    overflow: hidden;
    transition: border-color 0.3s ease, box-shadow 0.3s ease;
}

.glass-card:hover {
    border-color: var(--border-hover);
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.4);
}

.prob-header {
    padding: 2rem 2.5rem;
    background-color: rgba(17, 18, 36, 0.6);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
}

.prob-title-group {
    display: flex;
    align-items: center;
    gap: 1.25rem;
}

.prob-letter {
    width: 48px;
    height: 48px;
    border-radius: 10px;
    background-color: rgba(255, 183, 50, 0.1);
    border: 1px solid var(--accent-gold);
    color: var(--accent-gold);
    font-family: var(--font-serif);
    font-size: 1.5rem;
    font-weight: 700;
    display: flex;
    justify-content: center;
    align-items: center;
}

.prob-name {
    font-family: var(--font-serif);
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-primary);
}

.prob-tag {
    font-family: var(--font-mono);
    font-size: 0.72rem;
    color: var(--sec-cyan);
}

.prob-limits {
    display: flex;
    gap: 1rem;
    font-family: var(--font-mono);
    font-size: 0.78rem;
    color: var(--text-muted);
}

.prob-body {
    padding: 2.5rem;
}

.prob-body h3 {
    font-family: var(--font-serif);
    font-size: 1.15rem;
    color: var(--accent-gold);
    margin-bottom: 0.8rem;
}

.prob-body p {
    font-size: 0.98rem;
    color: var(--text-secondary);
    line-height: 1.7;
    margin-bottom: 1.25rem;
    font-weight: 300;
}

.prob-body ul {
    margin-left: 1.5rem;
    margin-bottom: 1.25rem;
    color: var(--text-secondary);
    font-size: 0.95rem;
}

.spec-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
    margin: 2rem 0;
}

.spec-box {
    background-color: #080914;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 1.25rem;
}

.spec-box h4 {
    font-family: var(--font-mono);
    font-size: 0.8rem;
    color: var(--sec-cyan);
    margin-bottom: 0.5rem;
}

.spec-box p {
    font-size: 0.88rem;
    color: var(--text-secondary);
    margin-bottom: 0;
}

/* Examples Block */
.examples-block {
    margin: 2rem 0;
}

.examples-block h4 {
    font-family: var(--font-mono);
    font-size: 0.82rem;
    color: var(--accent-gold);
    margin-bottom: 0.8rem;
}

.example-item {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
    margin-bottom: 1rem;
}

.ex-col {
    display: flex;
    flex-direction: column;
}

.ex-hdr {
    font-family: var(--font-mono);
    font-size: 0.72rem;
    color: var(--text-muted);
    margin-bottom: 0.3rem;
}

.code-box {
    background-color: var(--code-bg);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    padding: 0.8rem 1rem;
    font-family: var(--font-mono);
    font-size: 0.85rem;
    color: #e2e4f0;
    overflow-x: auto;
    white-space: pre;
}

.note-box {
    background-color: rgba(100, 212, 255, 0.04);
    border-left: 3px solid var(--sec-cyan);
    padding: 1rem 1.25rem;
    border-radius: 0 6px 6px 0;
    font-size: 0.9rem;
    color: var(--text-secondary);
}

/* Solution Reveal Block */
.solution-wrapper {
    border-top: 1px solid var(--border-color);
    background-color: #070812;
}

.reveal-btn {
    width: 100%;
    background-color: transparent;
    border: none;
    padding: 1.25rem 2.5rem;
    color: var(--accent-gold);
    font-family: var(--font-mono);
    font-size: 0.9rem;
    font-weight: 500;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: background-color 0.3s ease;
}

.reveal-btn:hover {
    background-color: rgba(255, 183, 50, 0.08);
}

.chevron {
    transition: transform 0.3s ease;
}

.reveal-btn.active .chevron {
    transform: rotate(180deg);
}

.solution-content {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.5s cubic-bezier(0.16, 1, 0.3, 1);
}

.solution-content.open {
    max-height: 2000px;
}

.sol-inner {
    padding: 0 2.5rem 2.5rem;
}

.sol-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background-color: #0d0e1c;
    border: 1px solid var(--border-color);
    border-bottom: none;
    border-radius: 8px 8px 0 0;
    padding: 0.6rem 1.2rem;
}

.sol-lang {
    font-family: var(--font-mono);
    font-size: 0.75rem;
    color: var(--sec-cyan);
}

.copy-btn {
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    padding: 0.25rem 0.75rem;
    border-radius: 4px;
    font-family: var(--font-mono);
    font-size: 0.72rem;
    cursor: pointer;
    transition: all 0.3s ease;
}

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

.source-code {
    background-color: var(--code-bg);
    border: 1px solid var(--border-color);
    border-radius: 0 0 8px 8px;
    padding: 1.25rem;
    overflow-x: auto;
    margin-bottom: 1.5rem;
}

.source-code code {
    font-family: var(--font-mono);
    font-size: 0.85rem;
    line-height: 1.6;
    color: #e4e7fb;
}

.approach-box {
    background-color: rgba(255, 183, 50, 0.05);
    border: 1px solid rgba(255, 183, 50, 0.2);
    border-radius: 8px;
    padding: 1.25rem;
}

.approach-box strong {
    font-family: var(--font-mono);
    font-size: 0.82rem;
    color: var(--accent-gold);
    display: block;
    margin-bottom: 0.4rem;
}

.approach-box p {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: 0;
}

/* Site Footer */
.site-footer {
    border-top: 1px solid var(--border-color);
    padding: 3rem 5%;
    text-align: center;
    background-color: #040409;
}

.footer-content p {
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.footer-sub {
    font-family: var(--font-mono);
    font-size: 0.75rem;
    color: var(--text-muted);
    margin-top: 0.4rem;
}

/* Toast */
.toast {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    background-color: var(--accent-gold);
    color: #06060c;
    padding: 0.8rem 1.5rem;
    border-radius: 6px;
    font-family: var(--font-mono);
    font-size: 0.82rem;
    font-weight: 600;
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.5);
    opacity: 0;
    transform: translateY(20px);
    transition: all 0.3s ease;
    pointer-events: none;
    z-index: 2000;
}

.toast.show {
    opacity: 1;
    transform: translateY(0);
}

/* Responsive */
@media (max-width: 768px) {
    .hero-title { font-size: 2rem; }
    .spec-grid, .example-item { grid-template-columns: 1fr; }
    .stats-bar { flex-direction: column; gap: 1rem; }
    .stat-divider { display: none; }
    .prob-header { flex-direction: column; align-items: flex-start; }
}