.background {
  background-color:black;
  /* margin: 0;
  padding: 0; */
  /* display: flex; */
  /* height: 100vh; */
  /* align-items: center; */
  /* justify-content: center; */
}


/* center div */
.section {
  margin: auto;
  width: 80%;
  color: white;
  background-color:black;
  padding: 10px;
}

.section-center {
  margin: auto;
  width: 50%;
  color: white;
  background-color:black;
  padding: 10px;
  text-align: center;
}

/* button CSS */
.button-54 {
  /* font-family: "Open Sans", sans-serif; */
  /* font-family: 'Times New Roman', Times, serif;; */
  font-size: 16px;
  letter-spacing: 2px;
  text-decoration: none;
  text-transform: uppercase;
  color: white;
  background-color: black;
  cursor: pointer;
  border: 3px solid;
  padding: 0.25em 0.5em;
  margin-left: 10px;
  margin-right: 10px;
  /* box-shadow: 1px 1px 0px 0px, 2px 2px 0px 0px, 3px 3px 0px 0px, 4px 4px 0px 0px, 5px 5px 0px 0px; */
  /* box-shadow: 1px 1px 0px 0px; */
  position: relative;
  user-select: none;
  -webkit-user-select: none;
  touch-action: manipulation;
}

.button-54:active {
  box-shadow: 0px 0px 0px 0px;
  top: 2px;
  left: 2px;
}

@media (min-width: 768px) {
  .button-54 {
    padding: 0.25em 0.75em;
  }
}



/* CSS */
.button-title {
  width: 300px;
  height: 45px;
  font-size: 23px;
  cursor: pointer;
  border: none;
  outline: none;
  background: transparent;
  color: white;
  margin-top: 5px;
  margin-bottom: 5px;
  /* font-family: 'Times New Roman', Times, serif; */
  /* font-family: 'Times New Roman', Times, serif; */
  font-weight: 700;
  position: relative;
  -webkit-transition: all 0.5s;
  transition: all 0.5s;
  z-index: 1;
 }
 
 .button-title::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 5px;
  height: 100%;
  background-color: white;
  z-index: -1;
  -webkit-transition: all 0.5s;
  transition: all 0.5s;
 }
 
 .button-title:hover::before {
  width: 100%;
 }
 
 .button-title:hover {
  color: black;
 }
 
 .button-title:active:before {
  background: #b9b9b9;
 }


/* button 翻转 */
 span{
  position: relative;
  display: inline-flex;
  width: 180px;
  height: 55px;
  margin: 0 15px;
  perspective: 1000px;
}
span a{
  font-size: 19px;
  letter-spacing: 1px;
  transform-style: preserve-3d;
  transform: translateZ(-25px);
  transition: transform .25s;
  font-family: 'Montserrat', sans-serif;
  
}
span a:before,
span a:after{
  position: absolute;
  content: "BUTTON";
  height: 55px;
  width: 180px;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 5px solid black;
  box-sizing: border-box;
  border-radius: 5px;
}
span a:before{
  color: #fff;
  background: #000;
  transform: rotateY(0deg) translateZ(25px);
}
span a:after{
  color: #000;
  transform: rotateX(90deg) translateZ(25px);
}
span a:hover{
  transform: translateZ(-25px) rotateX(-90deg);
}