/* cssアニメーション */
.fade-in {
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

.fade-in.visible {
    opacity: 1;
    transform: translateY(0);
}

/* ホバーアニメーション */
nav a {
    position: relative;
    display: inline-block;
    padding-bottom: 2px;
    transition: color 0.3s ease;
}

nav a::after {
    content: '';
    position: absolute;
    left: 0;
    bottom: 0;
    width: 100%;
    height: 2px;
    background-color: #000; /* 下線の色 */
    transform: scaleX(0);
    transform-origin: bottom right;
    transition: transform 0.3s ease;
}

nav a:hover::after {
    transform: scaleX(1);
    transform-origin: bottom left;
}