.youtube-list {
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
    list-style: none;
    padding: 0;
    margin: 0 20px; /* ← ここだけ追加！左右に余白 */
    justify-content: flex-start;
}
.youtube-list li {
    width: 380px;
}
.youtube-16-9 {
    width: 100%;
    aspect-ratio: 16 / 9;
    border: none;
}
.youtube-title {
    font-weight: bold;
    margin-top: 0.5em;
}
.video-category {
    margin-bottom: 3rem;
}
.video-category h3 {
    background-color: #004080;
    color: #fff;
    padding: 0.75em 1em;
    margin: 2rem 0 1rem;
    font-size: 1.25rem;
    border-left: 8px solid #00bfff;
    border-radius: 4px;
    scroll-margin-top: 170px;
}

.tag-nav {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin: 2rem 0;
    justify-content: flex-start;
}

.tag-button {
    display: inline-block;
    background: #00bfff;
    color: white !important;
    padding: 0.5em 1em;
    border-radius: 6px;
    text-decoration: none;
    font-weight: 600;
    transition: background 0.3s;
}

.tag-button:hover {
    background: #008fcc;
    color: white !important;
}

.back-to-top-inline {
    text-align: right;
    margin-top: 10px;
    margin-bottom: 2rem;
}
.top-inline-button {
    background: #f0f0f0;
    color: #333;
    padding: 0.4em 0.7em;
    font-size: 0.9rem;
    border-radius: 4px;
    text-decoration: none;
    border: 1px solid #ccc;
}
.top-inline-button:hover {
    background: #e0e0e0;
}