/* 拡張説明ページ */
.extension-hero {
    display: grid;
    grid-template-columns: minmax(0, 0.86fr) minmax(500px, 1.14fr);
    align-items: center;
    gap: 48px;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-large);
    padding: clamp(28px, 5vw, 64px);
    background:
        radial-gradient(circle at 10% 12%, rgba(37, 99, 235, 0.14), transparent 36%),
        var(--color-surface);
    box-shadow: var(--shadow-soft);
}

.extension-benefits {
    display: grid;
    gap: 8px;
    margin: 24px 0;
    padding: 0;
    list-style: none;
}

.extension-benefits li {
    position: relative;
    padding-left: 30px;
    font-weight: 700;
}

.extension-benefits li::before {
    position: absolute;
    top: 0;
    left: 0;
    color: var(--color-primary);
    content: "✓";
    font-weight: 900;
}

.extension-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
}

.btn-extension-store {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-height: 52px;
    border: 2px solid var(--color-primary);
    border-radius: var(--radius-small);
    padding: 10px 18px;
    background: var(--color-primary);
    color: #fff;
    font-weight: 800;
    text-decoration: none;
}

.btn-extension-store:hover {
    background: var(--color-primary-strong);
    color: #fff;
}

.btn-extension-firefox {
    border-color: var(--color-foreground);
    background: var(--color-foreground);
}

.extension-supported {
    margin-bottom: 0;
    color: var(--color-muted);
    font-weight: 700;
}

.extension-hero-figure,
.extension-media figure {
    margin: 0;
}

.extension-hero-figure img,
.extension-media img {
    display: block;
    width: 100%;
    height: auto;
    aspect-ratio: 8 / 5;
    object-fit: contain;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-medium);
    background: #eef2f7;
    box-shadow: var(--shadow-item);
}

.extension-hero-figure figcaption,
.extension-media figcaption {
    margin-top: 10px;
    color: var(--color-muted);
}

.extension-page-nav {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 8px;
    margin: 28px 0 0;
    border-bottom: 1px solid var(--color-border);
    padding-bottom: 28px;
}

.extension-page-nav a {
    display: inline-flex;
    align-items: center;
    min-height: 44px;
    border-radius: var(--radius-small);
    padding: 8px 14px;
    color: var(--color-foreground);
    font-weight: 800;
    text-decoration: none;
}

.extension-page-nav a:hover {
    background: var(--color-surface-blue);
    color: var(--color-primary);
}

.extension-section {
    padding-block: clamp(56px, 8vw, 92px);
    scroll-margin-top: 24px;
}

.extension-section + .extension-section {
    border-top: 1px solid var(--color-border);
}

.extension-section > h2,
.extension-media h2,
.extension-bottom h2 {
    margin: 0 0 24px;
    font-size: clamp(1.8rem, 4vw, 3rem);
    line-height: 1.25;
}

.extension-feature-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 18px;
}

.extension-feature-grid article {
    border: 1px solid var(--color-border);
    border-radius: var(--radius-medium);
    padding: 24px;
    background: var(--color-surface);
    box-shadow: var(--shadow-item);
}

.extension-feature-grid strong {
    color: var(--color-primary);
    font-size: 1.5rem;
}

.extension-feature-grid h3 {
    margin: 12px 0 8px;
}

.extension-feature-grid p {
    margin-bottom: 0;
    color: var(--color-muted);
}

.extension-media {
    display: grid;
    grid-template-columns: minmax(0, 0.92fr) minmax(420px, 1.08fr);
    align-items: center;
    gap: 48px;
}

.extension-steps {
    display: grid;
    gap: 18px;
    margin: 28px 0 0;
    padding: 0;
    list-style: none;
}

.extension-steps li {
    display: grid;
    grid-template-columns: 48px 1fr;
    gap: 14px;
}

.extension-steps li > span {
    display: grid;
    width: 48px;
    height: 48px;
    place-items: center;
    border-radius: 50%;
    background: var(--color-primary);
    color: #fff;
    font-weight: 900;
}

.extension-steps h3,
.extension-steps p {
    margin: 0;
}

.extension-steps p {
    color: var(--color-muted);
}

.extension-faq-list {
    display: grid;
    gap: 12px;
}

.extension-faq-list details {
    border: 1px solid var(--color-border);
    border-radius: var(--radius-small);
    padding: 16px 20px;
    background: var(--color-surface);
}

.extension-faq-list summary {
    min-height: 44px;
    cursor: pointer;
    font-weight: 800;
}

.extension-faq-list p {
    margin: 10px 0 0;
    color: var(--color-muted);
}

.extension-bottom {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 28px;
    border-radius: var(--radius-large);
    padding: clamp(28px, 5vw, 48px);
    background: var(--color-primary-strong);
    color: #fff;
}

.extension-bottom .eyebrow,
.extension-bottom h2 {
    color: #fff;
}

.extension-bottom h2 {
    margin-bottom: 0;
}

.extension-bottom .btn-extension-store {
    border-color: #fff;
}

@media (max-width: 960px) {
    .extension-hero,
    .extension-media {
        grid-template-columns: 1fr;
    }

    .extension-hero-figure {
        order: -1;
    }

    .extension-feature-grid {
        grid-template-columns: 1fr;
    }

    .extension-bottom {
        align-items: stretch;
        flex-direction: column;
    }
}

@media (max-width: 560px) {
    .extension-hero {
        gap: 28px;
        padding: 22px 16px;
    }

    .extension-actions,
    .extension-actions a {
        width: 100%;
    }

    .extension-page-nav {
        justify-content: flex-start;
    }

    .extension-section {
        padding-block: 48px;
    }

    .extension-media {
        gap: 28px;
    }

    .extension-bottom {
        padding: 24px 18px;
    }
}