/* Shared styles for English problem statements */
:root {
    --bg: #f5f5f5;
    --surface: #ffffff;
    --surface-2: #f0f0f0;
    --text: #1a1a1a;
    --muted: #666666;
    --border: #e5e5e5;
    --accent: #111111;
    --accent-soft: #eeeeee;
    --amber: #1a1a1a;
    --link: #2563eb;
    --shadow: 0 1px 3px rgba(16, 24, 40, 0.06), 0 8px 24px rgba(16, 24, 40, 0.06);
    --nav-bg: rgba(245, 245, 245, 0.85);
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    line-height: 1.65;
    color: var(--text);
    background-color: var(--bg);
    transition: background-color 0.3s, color 0.3s;
}

.mono {
    font-family: 'JetBrains Mono', ui-monospace, monospace;
}

nav {
    position: sticky;
    top: 0;
    z-index: 100;
    background: var(--nav-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border);
}

.nav-inner {
    max-width: 860px;
    margin: 0 auto;
    padding: 14px 24px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
}

.nav-name {
    font-family: 'JetBrains Mono', ui-monospace, monospace;
    font-weight: 700;
    font-size: 0.95em;
    color: var(--text);
    text-decoration: none;
    white-space: nowrap;
}

.nav-name span {
    color: var(--accent);
}

.nav-links {
    display: flex;
    gap: 4px;
    align-items: center;
}

.nav-links a {
    color: var(--muted);
    text-decoration: none;
    font-size: 0.85em;
    font-weight: 500;
    padding: 6px 10px;
    border-radius: 8px;
    transition: color 0.2s, background-color 0.2s;
}

.nav-links a:hover {
    color: var(--link);
    background-color: var(--accent-soft);
}

.container {
    max-width: 860px;
    margin: 0 auto;
    padding: 40px 24px 60px;
}

.prob-head {
    border-bottom: 1px solid var(--border);
    padding-bottom: 20px;
    margin-bottom: 28px;
}

.prob-head h1 {
    font-size: 2em;
    font-weight: 800;
    letter-spacing: -0.02em;
}

.prob-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-top: 14px;
    align-items: center;
}

.chip {
    font-family: 'JetBrains Mono', ui-monospace, monospace;
    font-size: 0.75em;
    background: var(--surface-2);
    border: 1px solid var(--border);
    color: var(--muted);
    padding: 4px 12px;
    border-radius: 8px;
    white-space: nowrap;
}

.prob-meta a {
    font-family: 'JetBrains Mono', ui-monospace, monospace;
    font-size: 0.75em;
    color: var(--link);
    text-decoration: none;
    font-weight: 700;
    padding: 4px 12px;
    border: 1px dashed var(--link);
    border-radius: 8px;
    white-space: nowrap;
}

.prob-meta a:hover {
    background: var(--accent-soft);
}

.stmt h2 {
    font-size: 1.15em;
    font-weight: 800;
    margin: 32px 0 14px;
    padding-bottom: 8px;
    border-bottom: 1px solid var(--border);
}

.stmt p {
    margin-bottom: 14px;
}

.stmt ul, .stmt ol {
    margin: 0 0 14px 22px;
}

.stmt li {
    margin-bottom: 6px;
}

.stmt code, .stmt pre {
    font-family: 'JetBrains Mono', ui-monospace, monospace;
    font-size: 0.85em;
}

.stmt code {
    background: var(--surface-2);
    border: 1px solid var(--border);
    border-radius: 6px;
    padding: 2px 6px;
}

.stmt pre {
    background: var(--surface-2);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 14px 18px;
    overflow-x: auto;
    margin-bottom: 14px;
    line-height: 1.5;
}

.stmt pre code {
    background: none;
    border: none;
    padding: 0;
}

.stmt table {
    border-collapse: collapse;
    margin: 0 auto 14px;
    font-size: 0.9em;
}

.stmt th, .stmt td {
    border: 1px solid var(--border);
    padding: 8px 14px;
    text-align: center;
}

.stmt th {
    background: var(--surface-2);
    font-weight: 700;
}

.stmt .io {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 14px;
    margin-bottom: 14px;
}

.stmt .io-label {
    display: block;
    font-family: 'JetBrains Mono', ui-monospace, monospace;
    font-size: 0.7em;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.07em;
    color: var(--muted);
    margin-bottom: 6px;
}

.stmt .io pre {
    margin-bottom: 0;
    height: 100%;
    box-sizing: border-box;
}

.stmt img {
    max-width: 100%;
    border-radius: 10px;
    border: 1px solid var(--border);
    display: block;
    margin: 14px auto;
}

.stmt .note {
    background: var(--surface-2);
    border-left: 4px solid var(--amber);
    border-radius: 8px;
    padding: 12px 16px;
    font-size: 0.9em;
    margin-bottom: 14px;
}

footer {
    margin-top: 60px;
    padding: 24px;
    border-top: 1px solid var(--border);
    text-align: center;
    color: var(--muted);
    font-size: 0.8em;
}

@media (max-width: 640px) {
    .nav-inner {
        padding: 10px 16px;
    }

    .prob-head h1 {
        font-size: 1.5em;
    }

    .container {
        padding: 28px 16px 48px;
    }
}