* {
    box-sizing: border-box;
}

body {
    margin: 0;
    background-color: green;
    font-size: 16px;
}

h1 {
    font-size: 3rem;
    font-family: helvetica, sans-serif;
}

main {
    position: relative;
    margin: 0 auto;
    width: 100%;
    height: 60vh;
    background-color: deepskyblue;
}

@media only screen and (min-width: 481px) {
    .be_true_through_and_through {
        font-size: 5rem;
    }
}

@media only screen and (min-width: 1025x) {
    .be_true_through_and_through {
        font-size: 7rem;
    }
}

@media only screen and (min-width: 1601px) {
    .be_true_through_and_through{
        font-size: 9rem;
    }
}

@keyframes shine_bright {
    from {text-shadow: 0 0 0 lightyellow;}
    to {text-shadow: 0 0 2000px lightyellow;}
}

.be_true_through_and_through {
    position: absolute;
    margin-bottom: 0;
    padding-bottom: 0;
    width: 100%;
    bottom: 0;
    text-align: center;
    color: yellow;
    animation-name: shine_bright;
    animation-delay: 1s;
    animation-duration: 2s;
    animation-iteration-count: 1;
    animation-timing-function: ease-in;
}