* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    display: flex;
    min-height: 100vh;
    flex-direction: column;
}

main {
    flex: 1 0 auto;
    min-height: 70vh;
}

div.background {
    position: relative;
    /* width: 100%;
    height: 100vh; */
    background: #c51162;
    /* overflow: hidden; */
}

div.background .air {
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 100px;
    background: url(../img/wave.png);
    background-size: 1000px 100px;
}

div.background .air.air1 {
    animation: wave 30s linear infinite;
    z-index: 1000;
    opacity: 1;
    animation-delay: 0s;
    bottom: 0;
}

div.background .air.air2 {
    animation: wave2 15s linear infinite;
    z-index: 999;
    opacity: 0.5;
    animation-delay: -5s;
    bottom: 10px;
}

div.background .air.air3 {
    animation: wave 30s linear infinite;
    z-index: 998;
    opacity: 0.2;
    animation-delay: -2s;
    bottom: 15px;
}

div.background .air.air4 {
    animation: wave2 5s linear infinite;
    z-index: 997;
    opacity: 0.7;
    animation-delay: -5s;
    bottom: 20px;
}

@keyframes wave {
    0% {
        background-position-x: 0px;
    }

    100% {
        background-position-x: 1000px;
    }
}

@keyframes wave2 {
    0% {
        background-position-x: 0px;
    }

    100% {
        background-position-x: -1000px;
    }
}