styles.css

*{
    margin: 0;
    padding: 0;
}

.container{
    margin: 0 auto;
    text-align: center;
}

.display{
    width: 100%;
    padding: 5px 0;
    margin: 15px 0;
}

.controllers{
    width: 100%;
    padding: 5px 0;
    margin-top: 15px;
    margin-bottom: 35px;
}

button{
    padding-top: 0.25rem;
    padding-bottom: 0.25rem;
    padding-right: 0.75rem;
    padding-left: 0.75rem;
    margin-right: 0.5rem;
    margin-left: 0.1rem;
    font-size: 16px;
    background-color: #ffffff;
    color: #000000;
    border: 1px solid rgba(49, 51, 63, 0.2);
    border-radius: 0.25rem;
    margin-top: 0.75rem;
    margin-bottom: 0.25rem;
}

button:hover{
    padding-top: 0.25rem;
    padding-bottom: 0.25rem;
    padding-right: 0.75rem;
    padding-left: 0.75rem;
    margin-right: 0.5rem;
    margin-left: 0.1rem;
    font-size: 16px;
    background-color: #ffffff;
    color: #ff4c4b;
    border: 1px solid #ff4c4b;
    border-radius: 0.25rem;
    margin-top: 0.75rem;
    margin-bottom: 0.25rem;
}

audio {
  width: 450px;
  height: 45px;
}