/*body
{
    margin: 0;
    padding: 0;
    background: #262626;
}
.center 
{
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
}
.pulse
{
    width: 100px;
    height: 100px;
    background: #177c80;
    border-radius: 50%;
    color: #fff;
    font-size: 20px;
    text-align: center;
    line-height: 100px;
    font-family: verdana;
    text-transform: uppercase;
    animation: animate 3s linear infinite;
    text-align: center;
}
@keyframes animate
{
    0%
    {
        box-shadow: 0 0 0 0 rgba(55, 209, 201, 0.7), 0 0 0 0 rgba(24, 153, 104, 0.7);
    }
    40%
    {
        box-shadow: 0 0 0 50px rgba(55, 209, 201, 0), 0 0 0 0 rgba(55, 209, 201, 0.7);
    }
    80%
    {
        box-shadow: 0 0 0 50px rgba(55, 209, 201, 0), 0 0 0 30px rgba(55, 209, 201, 0);
    }
    100%
    {
        box-shadow: 0 0 0 0 rgba(55, 209, 201, 0), 0 0 0 30px rgba(55, 209, 201, 0);
    }
}*/

body {
    padding: 0;
    margin: 0;
    height: 100vh;
    width: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
    background-color: #131c1f;
}
#challenge5 .center {
    width: 100px;
    height: 100px;
    position: relative;
}
#challenge5 .pulse-effect {
    position: absolute;
    width: 50%;
    height: 50%;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    background: #009191b5;
    border-radius: 50%;
    animation: pulseanimation linear 2s infinite;
}

#challenge5 .pulse-button {
    font-size: 13px;
    color: #FFF;
    background: #009191;
    border-radius: 50%;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 50%;
    height: 50%;
    border: none;
    font-weight: 700;
    text-align: center;
    cursor: pointer;
    transition: 1s;
}

#challenge5 .pulse-button:hover {
    background-color: #fff;
    color: #009191;
}
@keyframes pulseanimation {
    0% {
        width: 50%;
        height: 50%;
        opacity: 0;
    }
    50% {
        width: 100%;
        height: 100%;
        opacity: 1;
    }
    100% { 
        width: 50%;
        height: 50%;
        opacity: 0;
    }
}