.index-banner{
	text-align: center;
}
img, video {
	height: auto;
}

/* YouTube埋め込みレスポンシブ対応 */
.embed-responsive {
    position: relative;
    display: block;
    width: 100%;
    padding: 0;
    overflow: hidden;
}

.embed-responsive::before {
    display: block;
    content: "";
}

.embed-responsive-16by9::before {
    padding-top: 56.25%; /* 16:9 アスペクト比 */
}

.embed-responsive-item,
.embed-responsive iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border: 0;
}

.mb-3 {
    margin-bottom: 1rem;
}