.pay-bill-button {
    position: fixed;
    top: 75%;
    right: 0;
    padding: 20px 10px;
    background-color: #ff0000;
    color: #ffffff;
    border-radius: 5px;
    text-decoration: none;
    z-index: 999;
    display: inline-flex;
    justify-content: center;
    align-items: center;
    font-size: 15px;
    font-weight: bold; /* Makes the text bold */
    overflow: hidden; /* Ensure the animated span stays within the button */
}

.pay-bill-button:hover {
    background-color: #0088ff;
}

.pay-bill-button span {
    position: absolute;
    width: 0;
    height: 0;
    background-color: #0088ff;
    transition: width 0.5s, height 0.5s;
    z-index: -1;
    border-radius: 5px;
}

.pay-bill-button:hover span {
    width: 100%;
    height: 100%;
    z-index: -1;
}