.circle {
    width: 50px;
    height: 50px;
    border-radius: 50%;
}

.circle:hover {
    opacity: 50%;
}

section {
    position: fixed;
    top: 0px;
    left: 10px;
    z-index: 999;
}

input {
    height: 20px;
}

article {
    padding: 5px;
}

button {
    width: 100px;
    padding: 3px;
    background-color: #75a586;
    border-radius: 5px;
    border: solid 2px;
    font-size: 18px;
}