header {
    background-color: #333;
    color: #fff;
    padding: 10px 0;
    text-align: center;
}

ul {
    width: 100%;
    overflow-x: auto;
    list-style-type: none;
    padding: 0;
}
li {
    height: 5rem;
    display: flex;
    text-align: center;
    justify-content: center;
    align-items: center;
    border-radius: 25px;
    border: 1px solid;
    margin: 0rem 1rem 1rem 1rem;
}
li:nth-child(even) {
    background-color: #474747;
    border-color: #1F1F1F;
    color: #fff;
    filter: grayscale(0.75);
}
a {
    display: flex;
    text-align: center;
    justify-content: center;
    align-items: center;
    color: #a9c7d4;
}
li:nth-child(odd) {
    background-color: #1F1F1F;
    border-color: #474747;
    color: #fff;
    filter: grayscale(1);
}