* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

.samplebox {
    height: 400px;
    background: lightblue;
}

.color01 {
    background-color: white;
}

.color02 {
    background-color: rgb(209, 218, 223);
}

.color03 {
    background-color: rgb(175, 183, 187);
}