@keyframes bgca{ 0%,20%,100%{background:#83ccd290;} 25%,45%{background:#89c3eb90;} 50%,70%{background:#a0d8ef90;} 75%,95%{background:#bce2e890;} } .bgc{ border: 1px solid; animation: bgca 15s linear infinite; } 夕焼け 今頃の海は穏やかです…