.my-class {
    color: red;
    background-color: blue;
    font-size: 16px;
}

#my-id {
    margin: 10px;
}

div.special {
    padding: 5px;
}

* {
    box-sizing: border-box;
}

.parent > .child {
    display: block;
}

a:hover {
    color: green;
}