html, body {
    margin: 0;
    padding: 0;
}

:root { 
    --white: #fff;
    --red: #FF0002;
}

body{
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
}

.flag{
    width: 300px;
    height: 300px;
    background: var(--red);
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    grid-template-rows: repeat(5, 1fr);
}

.cross{
    background: var(--white);
}

.cross1{
    grid-row: 2/5;
    grid-column: 3/4;
}

.cross2{
    grid-row: 3/4;
    grid-column: 2/5;
}