:root {
    --max-width: 1200px;
    --accent: #2c7a3f;
    --border: #ddd;
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family:
        system-ui,
        -apple-system,
        BlinkMacSystemFont,
        "Segoe UI",
        sans-serif;
    background: #fafafa;
    color: #222;
    line-height: 1.5;
}

.site-header {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 1rem;
    text-align: center;
}

.site-header h1 {
    margin: 0 0 1rem;
}

.period-nav {
    display: flex;
    justify-content: center;
    gap: 0.75rem;
    flex-wrap: wrap;
}

.period-nav a,
.period-nav .active {
    padding: 0.4rem 0.8rem;
    border-radius: 999px;
    text-decoration: none;
}

.period-nav a {
    color: var(--accent);
    border: 1px solid var(--accent);
}

.period-nav a:hover {
    background: var(--accent);
    color: white;
}

.period-nav .active {
    background: var(--accent);
    color: white;
}

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 1rem;
}

.graph {
    margin: 0 0 1.5rem;
    text-align: center;
}

.graph img {
    display: inline-block;
    max-width: 100%;
    height: auto;
    border: 1px solid var(--border);
    border-radius: 8px;
    background: white;
}