Центральный дивинг no meio da tela
.center-box {
display: flex;
align-items: center;
justify-content: center;
}
Thyago Mac
.center-box {
display: flex;
align-items: center;
justify-content: center;
}
.flex-box {
display: flex;
align-items: center;
justify-content: center;
}