CSS/filterを使った背景

*::before,
* {
    -webkit-box-sizing: border-box;
    -moz-box-sizing: border-box;
    box-sizing: border-box;
}

.panela-in::before,
.panel {
    background: url("../img/m4.jpg") no-repeat center;
    -webkit-background-size: cover;
    background-size: cover;
    margin-bottom: 30px;
    margin-left: 30px;
    position: relative;
}

.panel-main {
    padding: 30px;
    z-index: 30;
    position: relative;
    margin-bottom: 0;
    border: solid 1px rgba(255,255,255,0.4);
    background: rgba(255,255,255,0.4);
}

.panela-in::before {
    content: "";
    position: absolute;
    background-clip: content-box;
    width: 100%;
    height: 100%;
    padding: 30px;
    top: 0;
    left: 0;
    -webkit-filter: blur(6px);
    filter: blur(6px);
}
.panela-in {
    padding: 30px;
    position: relative;
}

.panelb-in {
    padding: 30px;
    position: relative;
}
.panelb-in::before{
    background: url("../img/m4.jpg") no-repeat center;
    -webkit-background-size: cover;
    background-size: cover;
    content: "";
    position: absolute;
    background-clip: content-box;
    width: 100%;
    height: 100%;
    padding: 30px;
    top: 0;
    left: 0;
    -webkit-filter: hue-rotate(180deg);
    filter: hue-rotate(180deg);
}

.panelc-in::before{
    background: url("../img/m4.jpg") no-repeat center;
    -webkit-background-size: cover;
    background-size: cover;
    content: "";
    position: absolute;
    background-clip: content-box;
    width: 100%;
    height: 100%;
    padding: 30px;
    top: 0;
    left: 0;
    -webkit-filter: contrast(50%);
    filter: contrast(50%);
}
.panelc-in {
    padding: 30px;
    position: relative;
}

.paneld-in::before{
    background: url("../img/m4.jpg") no-repeat center;
    -webkit-background-size: cover;
    background-size: cover;
    content: "";
    position: absolute;
    background-clip: content-box;
    width: 100%;
    height: 100%;
    padding: 30px;
    top: 0;
    left: 0;
    -webkit-filter: sepia(50%);
    filter: sepia(50%);
}
.paneld-in {
    padding: 30px;
    position: relative;
}

/*背景画像の設定をする*/
.bgImage{
  background: url("../../img/code.jpg") no-repeat center;
  background-size: cover;
  position: relative;
  z-index: 0;
  overflow: hidden;/*ブラー効果でボヤけた部分を非表示*/
}

/*:beforeにぼかし効果を設定する*/
.bgImage:before{
  content: '';
  background: inherit;/*.bgImageで設定した背景画像を継承する*/
  -webkit-filter: blur(5px);
  -moz-filter: blur(5px);
  -o-filter: blur(5px);
  -ms-filter: blur(5px);
  filter: blur(5px);
  position: absolute;
  /*ブラー効果で画像の端がボヤけた分だけ位置を調整*/
  top: -5px;
  left: -5px;
  right: -5px;
  bottom: -5px;
  z-index: -1;/*重なり順序を一番下にしておく*/
}
p{
  margin: 150px 0 200px;
  text-align: center;
  font-family: 'Cinzel', serif;
  font-size: 34px;
  color: #fff;
  text-shadow: 0 0 10px rgba(0,0,0,.4);
}
	

#s3Img {
	width: 300px;
	animation: haunted 3s infinite;
}

@keyframes haunted {
  0% {
    filter: brightness(20%);
  }
  48% {
    filter: brightness(20%);
  }
  50% {
    filter: sepia(1) contrast(2) brightness(200%);
  }
  60% {
    filter: sepia(1) contrast(2) brightness(200%);
  }
  62% {
    filter: brightness(20%);
  }
  96% {
    filter: brightness(20%);
  }
  96% {
    filter: brightness(400%);
  }
}