.main-div
{
    text-align: center;
}

.page-div
{
    min-height: calc(90vh - 60px);
    position: relative;
}

.page-content {
    text-align: center;
    width: 100%;
    padding: 100px 0;
}

input { 
    text-align: center; 
}

.explain-text {
    width: 720px;
    max-width: 90%;
    display: inline-block;
}