html,
body {
    font-size: 1em;
    margin: 0;
    padding: 0;
    background-color: rgb(13, 17, 23);
    color: rgb(201, 209, 217);
    font-family: sans-serif;
}

header {
    background-color: rgb(22, 27, 34);
    height: 62px;
    display: flex;
    align-items: center;
    justify-content: center;
    border: 5px solid transparent;
    box-sizing: border-box;
    font-size: 2em;
    font-weight: bold;
}

div {
    width: 500px;
    text-align: left;
    margin-left: auto;
    margin-right: auto;
}

button {
    background-color: hsl(212, 12%, 21%);
    border: 1px solid rgba(115, 115, 115, 0.4);
    outline: none;
    transition: all ease 100ms;
    width: 200px;
    height: 65px;
    color: aliceblue;
    font-size: 20px;
}

button:hover {
    border: 1px solid rgba(115, 115, 115, 0.9);
}

button:active {
    background-color: hsl(212, 12%, 15%);
}

a:visited {
    color: inherit;
}