.box {
    padding: 5px;
    margin: 5px;
}

.available {
    background-color: lightgray;
}

.completed {
    background-color: lightgreen;
}

.locked {
    background-color: lightsalmon;
}

.centered-div {
    text-align: center;
}

.left-div {
    text-align: left;
}

a {
    color: inherit;
    text-decoration: none;
}

a:hover {
    color: inherit;
    text-decoration: none;
}