.btn {
    color: #FFF;
    background-color: #4AC764;
    border: none;
    height: 40px;
    padding: 0 10px;
    cursor: pointer;
    border-radius: 0px 10px 10px 0px;
}

.btn:hover {
    transform: scale(1.05);
}

.circle {
    margin: 10px;
    background-color: black;
    color: white;
    padding: 10px;
    border-radius: 15px;
}

body {
    background-color: #ffffff;
    overflow-y: hidden;
    margin: 0;
}

h3 {
    font-family: sans-serif;
    font-weight: bolder;
    margin: 0px;
}

div.container {
    display: flex;
    padding: 10px;
    flex-direction: column;
    align-items: center;
    gap: .5rem;
}

.input-row {
    display: flex;
    gap: .5rem;
}

input {
    border-width: 1px;
    border-radius: 10px 0px 0px 10px;
    height: 35px;
}

.btn i {
    display: inline-block;
}

/* animação de tocar */
.btn i.ringing {
    animation: ring 1s infinite;
}

@keyframes ring {
    0% {
        transform: rotate(0);
    }

    10% {
        transform: rotate(15deg);
    }

    20% {
        transform: rotate(-15deg);
    }

    30% {
        transform: rotate(15deg);
    }

    40% {
        transform: rotate(-15deg);
    }

    50% {
        transform: rotate(0);
    }

    100% {
        transform: rotate(0);
    }
}