:root {
    --color-bg: #fafafa;
    --color-surface: #ffffff;
    --color-primary: #3d7341;
    --color-primary-light: #4a8a50;
    --color-text: #333333;
    --color-text-muted: #666666;
    --color-border: #e0e0e0;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.1);
    --radius: 8px;
    --font-main: 'Segoe UI', system-ui, -apple-system, sans-serif;
    --font-mono: 'SF Mono', 'Consolas', monospace;
}

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

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-main);
    background-color: var(--color-bg);
    color: var(--color-text);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.container {
    width: 100%;
    max-width: 800px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

.container-wide {
    max-width: 1200px;
}

header {
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-light) 100%);
    color: white;
    padding: 2.5rem 0;
    text-align: center;
}

header h1 {
    font-size: 2rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    letter-spacing: -0.5px;
}

header .subtitle {
    font-size: 1.1rem;
    opacity: 0.9;
    font-style: italic;
}

main {
    flex: 1;
    padding: 3rem 0 2rem 0;
}

.content-section {
    background: var(--color-surface);
    border-radius: var(--radius);
    padding: 2rem;
    box-shadow: var(--shadow-sm);
}

.content-section .intro {
    font-size: 1.05rem;
    color: var(--color-text-muted);
    margin-bottom: 2rem;
}

.table-wrapper {
    overflow-x: auto;
    margin: 1.5rem 0;
    width: 100%;
}

.alphabet-table {
    width: 100%;
    min-width: 100%;
    border-collapse: collapse;
    font-size: 0.95rem;
    border: 1px solid var(--color-border);
}

.alphabet-table th,
.alphabet-table td {
    padding: 0.5rem 0.35rem;
    text-align: center;
    border: 1px solid var(--color-border);
    white-space: nowrap;
}

.alphabet-table th {
    background: var(--color-bg);
    font-weight: 600;
    color: var(--color-text-muted);
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 0.4px;
    writing-mode: vertical-rl;
    transform: rotate(180deg);
    vertical-align: bottom;
    height: 9.5rem;
    padding: 0.75rem 0.25rem;
}

.alphabet-table td:first-child {
    font-size: 1.3rem;
    font-weight: 500;
}

.alphabet-table td:nth-child(2) {
    color: var(--color-primary);
    font-weight: 600;
    font-size: 1.1rem;
}

.alphabet-table tbody tr:hover {
    background: rgba(61, 115, 65, 0.05);
}

.alphabet-table td.freq {
    font-size: 0.85rem;
    color: var(--color-text-muted);
    font-family: var(--font-mono);
}

.note {
    background: var(--color-bg);
    border-radius: var(--radius);
    padding: 1.25rem;
    margin-top: 2rem;
}

.note h3 {
    font-size: 1rem;
    color: var(--color-text-muted);
    margin-bottom: 0.75rem;
}

.note ul {
    margin-left: 1.5rem;
    margin-bottom: 0;
}

.note li {
    font-size: 0.9rem;
    color: var(--color-text-muted);
    margin-bottom: 0.5rem;
}

footer {
    background: var(--color-surface);
    border-top: 1px solid var(--color-border);
    padding: 1.5rem 0;
    text-align: center;
    font-size: 0.9rem;
    color: var(--color-text-muted);
}

footer p {
    margin: 0.25rem 0;
}

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

footer a:hover {
    text-decoration: underline;
}

@media (max-width: 600px) {
    header {
        padding: 2rem 0;
    }

    header h1 {
        font-size: 1.5rem;
    }

    header .subtitle {
        font-size: 1rem;
    }

    .container {
        padding: 0 1rem;
    }

    .content-section {
        padding: 1.25rem;
    }

    .alphabet-table {
        font-size: 0.85rem;
    }

    .alphabet-table th,
    .alphabet-table td {
        padding: 0.4rem 0.25rem;
    }

    .alphabet-table th {
        height: 8rem;
        font-size: 0.75rem;
        padding: 0.5rem 0.15rem;
    }

    .alphabet-table td:first-child {
        font-size: 1.1rem;
    }

    .alphabet-table td:nth-child(2) {
        font-size: 1rem;
    }
}

@media (min-width: 1200px) {
    .alphabet-table {
        font-size: 1rem;
    }

    .alphabet-table th,
    .alphabet-table td {
        padding: 0.6rem 0.4rem;
    }

    .alphabet-table th {
        height: 10rem;
        padding: 0.85rem 0.3rem;
    }
}