:root {
    --bg-color: #1a1a2e;
    --card-bg: #16213e;
    --text-main: #e0e0e0;
    --text-muted: #a0a0a0;
    --accent-color: #0f3460;
    --highlight-color: #e94560;
    --link-color: #4da8da;
    --font-main: 'Inter', 'Noto Sans JP', sans-serif;
    --spacing-unit: 1rem;
    --border-radius: 12px;
    --transition-speed: 0.3s;
}

body {
    background-color: var(--bg-color);
    color: var(--text-main);
    font-family: var(--font-main);
    margin: 0;
    padding: 0;
    line-height: 1.6;
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
}

a {
    color: var(--link-color);
    text-decoration: none;
    transition: color var(--transition-speed) ease;
}

a:hover {
    color: var(--highlight-color);
}

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 2rem 1.5rem;
}

header {
    text-align: center;
    margin-bottom: 3rem;
    padding: 2rem 0;
    border-bottom: 1px solid var(--accent-color);
}

header h1 {
    font-size: 2rem;
    margin: 0;
    font-weight: 700;
    color: var(--text-main);
}

main {
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.intro-section {
    text-align: center;
    margin-bottom: 2rem;
    padding: 1.5rem;
    background: var(--card-bg);
    border-radius: var(--border-radius);
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

.important-link {
    display: inline-block;
    margin-top: 1rem;
    padding: 0.75rem 1.5rem;
    background-color: var(--highlight-color);
    color: #fff;
    border-radius: 50px;
    font-weight: bold;
    box-shadow: 0 4px 15px rgba(233, 69, 96, 0.4);
    transition: transform var(--transition-speed) ease, box-shadow var(--transition-speed) ease;
}

.important-link:hover {
    color: #fff;
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(233, 69, 96, 0.6);
}

section h2 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: var(--text-main);
    border-left: 4px solid var(--highlight-color);
    padding-left: 1rem;
}

.links-list {
    list-style: none;
    padding: 0;
    display: grid;
    grid-template-columns: 1fr;
    gap: 1rem;
}

.link-card {
    background: var(--card-bg);
    border-radius: var(--border-radius);
    padding: 1.25rem;
    transition: transform var(--transition-speed) ease, background-color var(--transition-speed) ease;
    border: 1px solid transparent;
}

.link-card:hover {
    transform: translateY(-3px);
    background-color: #1a264a;
    border-color: var(--accent-color);
}

.link-card h3 {
    margin: 0 0 1rem 0;
    font-size: 1.1rem;
    border-bottom: 1px solid var(--accent-color);
    padding-bottom: 0.5rem;
}

.link-card ul {
    list-style: disc;
    padding-left: 1.5rem;
    margin-top: 0.5rem;
}

.link-card li {
    margin-bottom: 0.5rem;
    font-size: 0.95rem;
}

.link-card li a {
    display: block;
    padding: 0.25rem 0;
    color: var(--text-muted);
}

.link-card li a:hover {
    color: var(--link-color);
    padding-left: 4px;
}

footer {
    text-align: center;
    margin-top: 4rem;
    padding: 2rem 0;
    font-size: 0.9rem;
    color: var(--text-muted);
}

@media (max-width: 600px) {
    .container {
        padding: 1rem;
    }

    header h1 {
        font-size: 1.75rem;
    }

    .links-list {
        grid-template-columns: 1fr;
    }
}