/* 背景 曇らせる (blur) */
body.dimmed::before {
    content: "";
    position: fixed;
    left: 0;
    right: 0;
    top: 0;
    bottom: 0;
    background-color: rgba(255, 255, 255, 0.75);
    -webkit-backdrop-filter: blur(5px);
    backdrop-filter: blur(5px);
    z-index: 100;
}