.header-btn{
    background-image: url(../img/downarrow.png);
    background-position: center center;
    background-size: cover;
    border-radius: 100%;
    bottom: 50px;
    cursor: pointer;
    height: 40px;
    left: 0;
    margin: auto;
    position: absolute;
    right: 0;
    width: 40px;
    z-index: 5;

    -webkit-transition: background 0.3s ease-in-out;
    -moz-transition: background 0.3s ease-in-out;
    transition: background 0.3s ease-in-out;
}


.btn-circle:hover,
.btn-circle:focus {
    outline: none;
    color: white;
}
.btn-circle:hover{

    opacity: 0.8;
}
.btn-circle{
    -webkit-animation-name: pulse;
    -moz-animation-name: pulse;
    -webkit-animation-duration: 2s;
    -moz-animation-duration: 2s;
    -webkit-animation-iteration-count: infinite;
    -moz-animation-iteration-count: infinite;
    -webkit-animation-timing-function: linear;
    -moz-animation-timing-function: linear;
}
@-webkit-keyframes pulse {
    0% {
        -webkit-transform: scale(1);
        transform: scale(1);
    }
    50% {
        -webkit-transform: scale(1.2);
        transform: scale(1.2);
    }
    100% {
        -webkit-transform: scale(1);
        transform: scale(1);
    }
}
@-moz-keyframes pulse {
    0% {
        -moz-transform: scale(1);
        transform: scale(1);
    }
    50% {
        -moz-transform: scale(1.2);
        transform: scale(1.2);
    }
    100% {
        -moz-transform: scale(1);
        transform: scale(1);
    }
}