style.css

.block {
    width: 150px;
    height: 150px;
    background: linear-gradient(to top, #333 0%, #666 30%, #333 100%);
    box-shadow: inset 2px 2px 5px 2px #333;
    border-radius: 10px;
    display: inline-block;
    vertical-align: top;
    color: #fff;
}
h3 {
    font-family: Arial;
    font-size: 18px;
    text-align: center;
}
.vertical {
    width: 75px;
    height: 75px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto;
}
.vertical input {
    transform: rotate(90deg);
    width: 75px;
}
.vertical label {
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    height: 75px;
}
.horizontal {
    width: 100px;
    margin: 0 auto;
}
.horizontal input {
    width: 100px;
}
.horizontal label {
    width: 100px;
    display: flex;
    justify-content: space-between;
}
.center {
    height: 70px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}
#ok-shape {
    margin-top: 10px;
}
.hex-container {
    width: 100px;
    margin: 40px auto 0;
}
#hex {
    width: 80px;
}
.rgba-container {
    width: 100px;
    margin: 0 auto;
}
.rgba-container input {
    width: 80px;
}
.container {
    margin-top: 20px;
    position: relative;
}

/* Uses CSS selectors to style a div tag */
#block {
    width: 150px;
    height: 150px;
    background-color: #f00;
    position: absolute;
    left: 0;
    top: 0;
}