styles.css

/** OVERRIDES **/
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
body {
    font-family: Arial, Helvetica, sans-serif;
    font-size: 16px;
    color: #5d4037;
}
button[type='button'] {
    border-radius: 3rem;
    padding: .5rem 1rem;
    font-size: 1rem;
    font-weight: bold;
    cursor: pointer;
    border: none;
    transition: opacity .3s ease-in;
}
button[type='button']:hover {
    opacity: .8;
}
h1 {
    font-size: 5rem;
}
button[disabled] {
    background-color: #e0e0e0;
    pointer-events: none;
}

/** STATE **/
.-hidden {
    display: none;
}

/** WELCOME SCREEN **/
.welcome-screen {
    width: 100%;
    padding: 3rem;
}
.welcome-screen [type='button'] {
    margin: 1rem 0;
}
.welcome-screen p {
    color: #8d6e63;
}

/** GAME **/
main {
    margin: auto;
    padding: 3rem;
    display: block;
}
header {
    display: flex;
    margin-bottom: 2rem;
    justify-content: space-between;
}
footer {
    display: flex;
    justify-content: center;
    margin-top: 3rem;
}
footer button {
    margin-right: 1rem;
}
footer button:last-child {
    margin: 0;
}
.-reset {
    background-color: #ba68c8;
}
.-stop {
    background-color: #e57373;
}
.-start {
    background-color: #aed581;
}
.group {
    margin-right: 1rem;
}
.playing-field {
    display: flex;
    flex-wrap: wrap;
    position: relative;
}
.hole {
    height: 80px;
    background: url('./img/hole.svg') center bottom no-repeat;
    background-size: contain;
    flex: 1 0 33%;
    position: relative;
    margin-bottom: 3rem;
}
.mole {
    position: absolute;
    width: 80px;
    top: 5rem;
    opacity: 0;
    transition: opacity .2s ease-in-out, top .5s ease-in-out;
    cursor: pointer;
    left: 50%;
    margin-left: -40px;
}
.-up {
    top: -2rem;
    opacity: 1;
}