body {
    background-color: #c0ffee;
}

.nanimonai {
    font-size: 50px;
    font-family: 'Zen Old Mincho', '游明朝';
    animation: falling 2s ease-out forwards;
    position: relative;
}

.nanimonai span {
    user-select: none;
    cursor: text;
}

.nanimonai span::after{
    content: "";
    display: block;
    width: 0;
    height: 2px;
    background: #000;
    position: absolute;
    bottom: 2px;
    left: 0;
    right: 0;
    margin: auto;
    transition: .8s;
}
.nanimonai span:hover::after{
    width: 450px;
}

@keyframes falling {
    0% {
        transform: translateY(-50px);
        opacity: 0;
    }
    45% {
        opacity: 0.6;
    }
    100% {
        transform: translateY(25vh);
        opacity: 1;
    }
}