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

:root {
    --bg: #ffffff;
    --text: #2d3748;
    --text-lt: #4a5568;
    --text-muted: #718096;
    --blue: #2563eb;
    --border: #e2e8f0;
    --radius: 8px;
}

html {
    scroll-behavior: smooth;
    scroll-padding-top: 40px;
}

body {
    font-family: 'Montserrat', sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

h1,
h2,
h3,
h4 {
    color: #1a202c;
    margin-top: 2rem;
    margin-bottom: 1rem;
    line-height: 1.2;
}

h1 {
    font-size: 2.25rem;
    font-weight: 700;
    border-bottom: 2px solid var(--border);
    padding-bottom: 1rem;
}

h2 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-top: 2.5rem;
}

a {
    color: var(--blue);
    text-decoration: none;
}

a:hover {
    text-decoration: underline;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 3rem 1.5rem;
}

.back-link {
    display: inline-block;
    margin-bottom: 2rem;
    font-size: 0.9rem;
    color: var(--text-muted);
}

.updated {
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-bottom: 2rem;
}

.section {
    margin-bottom: 2rem;
}

.section p {
    margin-bottom: 1rem;
}

ul {
    margin-left: 1.5rem;
    margin-bottom: 1rem;
}

li {
    margin-bottom: 0.5rem;
}

.note {
    background: #f7fafc;
    border-left: 4px solid var(--blue);
    padding: 1rem;
    margin: 1.5rem 0;
    font-style: italic;
}

table {
    width: 100%;
    border-collapse: collapse;
    margin: 1rem 0;
    font-size: 0.9rem;
}

th {
    background: #edf2f7;
    text-align: left;
    padding: 0.75rem;
    border: 1px solid var(--border);
}

td {
    padding: 0.75rem;
    border: 1px solid var(--border);
}

footer {
    margin-top: 4rem;
    padding-top: 2rem;
    border-top: 1px solid var(--border);
    text-align: center;
    font-size: 0.85rem;
    color: var(--text-muted);
}

.toc {
    background: #f8fafc;
    padding: 1.5rem;
    border-radius: var(--radius);
    margin-bottom: 3rem;
    border: 1px solid var(--border);
}

.toc-title {
    font-weight: 700;
    margin-bottom: 1rem;
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.toc ul {
    list-style: none;
    margin-left: 0;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 0.5rem 1rem;
}

.toc a {
    font-size: 0.85rem;
    color: var(--text-lt);
}

@media (max-width: 640px) {
    h1 {
        font-size: 1.75rem;
    }

    .toc ul {
        grid-template-columns: 1fr;
    }
}