:root { color-scheme: dark; }
* { box-sizing: border-box; margin: 0; padding: 0; }
body {
    font-family: "Noto Sans JP", "Inter", system-ui, -apple-system, sans-serif;
    background: #121212;
    color: #fff;
    line-height: 1.7;
}
.container { max-width: 760px; margin: 0 auto; padding: 32px 20px 64px; }
nav.top {
    display: flex; justify-content: space-between; align-items: center;
    padding: 12px 20px;
    background: rgba(18, 18, 18, 0.95);
    border-bottom: 1px solid rgba(255, 255, 255, 0.08);
    position: sticky; top: 0; z-index: 10;
}
.logo { font-weight: 800; letter-spacing: 1.5px; font-size: 1.05rem; }
.top-cta {
    background: linear-gradient(135deg, #1dfbde, #b026ff);
    color: #121212; text-decoration: none; font-weight: 700;
    padding: 8px 18px; border-radius: 999px; font-size: 0.85rem;
}
.hero { text-align: center; padding: 32px 0 24px; }
.hero h1 {
    font-size: 1.85rem; font-weight: 800; letter-spacing: 0.3px;
    margin-bottom: 14px; line-height: 1.35;
}
.hero p.lead {
    color: rgba(255, 255, 255, 0.7); font-size: 0.98rem;
    max-width: 600px; margin: 0 auto;
}
.cta-row {
    display: flex; justify-content: center; gap: 12px;
    margin: 28px 0 8px; flex-wrap: wrap;
}
.btn-primary, .btn-secondary {
    text-decoration: none; font-weight: 700;
    padding: 14px 24px; border-radius: 999px; font-size: 0.95rem;
    display: inline-flex; align-items: center; gap: 8px;
}
.btn-primary {
    background: linear-gradient(135deg, #1dfbde, #b026ff);
    color: #121212;
}
.btn-secondary {
    background: rgba(255, 255, 255, 0.06);
    color: #fff;
    border: 1px solid rgba(255, 255, 255, 0.12);
}
.note { color: rgba(255, 255, 255, 0.5); font-size: 0.82rem; margin-top: 12px; }
h2 {
    margin-top: 40px; margin-bottom: 14px;
    font-size: 1.3rem; font-weight: 700;
    padding-bottom: 8px;
    border-bottom: 1px solid rgba(29, 251, 222, 0.25);
}
h3 {
    margin-top: 24px; margin-bottom: 10px;
    font-size: 1.05rem; font-weight: 700; color: #1dfbde;
}
p { margin-bottom: 14px; color: rgba(255, 255, 255, 0.85); }
ul, ol { padding-left: 22px; margin-bottom: 14px; }
li { margin-bottom: 6px; color: rgba(255, 255, 255, 0.85); }
.toc {
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid rgba(255, 255, 255, 0.06);
    border-radius: 12px; padding: 16px 18px; margin-bottom: 24px;
}
.toc h4 { font-size: 0.85rem; color: rgba(255, 255, 255, 0.6); margin-bottom: 8px; font-weight: 600; }
.toc ul { padding-left: 18px; margin: 0; }
.toc a { color: #d4d4d4; text-decoration: none; font-size: 0.92rem; }
.toc a:hover { color: #1dfbde; }
.card-grid {
    display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 12px; margin: 16px 0 24px;
}
.info-card {
    padding: 16px;
    background: rgba(255, 255, 255, 0.04);
    border: 1px solid rgba(255, 255, 255, 0.08);
    border-radius: 12px;
}
.info-card strong { display: block; margin-bottom: 6px; color: #fff; }
.info-card span { color: rgba(255, 255, 255, 0.75); font-size: 0.88rem; }
.faq { margin-top: 16px; }
.faq details {
    background: rgba(255, 255, 255, 0.04);
    border: 1px solid rgba(255, 255, 255, 0.07);
    border-radius: 10px; padding: 14px 16px; margin-bottom: 8px;
}
.faq summary { cursor: pointer; font-weight: 600; color: #fff; }
.faq details[open] summary { color: #1dfbde; }
.faq p { margin-top: 10px; color: rgba(255, 255, 255, 0.8); font-size: 0.92rem; }
.related {
    margin-top: 40px; padding: 20px;
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid rgba(255, 255, 255, 0.06);
    border-radius: 12px;
}
.related h3 { margin-top: 0; color: #fff; font-size: 1rem; }
.related ul { margin: 0; padding-left: 18px; }
.related a { color: #1dfbde; text-decoration: none; font-size: 0.9rem; }
.related a:hover { text-decoration: underline; }
footer.foot {
    margin-top: 48px; padding-top: 20px;
    border-top: 1px solid rgba(255, 255, 255, 0.08);
    color: rgba(255, 255, 255, 0.5); font-size: 0.85rem; text-align: center;
}
footer.foot a { color: #1dfbde; text-decoration: none; }
.center { text-align: center; margin: 28px 0; }