*, *::before, *::after{
    box-sizing: border-box;
}

*{
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    margin: 0;
    padding: 0;    
}

html, body{
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}

.test{
    width: 80%;
    height: 80%;
    background-color: yellowgreen;
}