*{ box-sizing: border-box; }

.container{ width: 100%; margin-bottom: 10px; cursor: pointer;  }
.photo, .advertisement, .posters, .design{
  width: 100%;
  padding-bottom: 90%;
  background-size: cover;
  position:relative;
  background-position: center;
}
section{ display: block; }
.photo{
  background-image: url("image/a.jpg");
}

.advertisement{
  background-image: url("image/b.jpg");
}
.posters{
  background-image: url("image/c.jpg");
}
.design{
  background-image: url("image/d.jpg");
}


.photo div, .advertisement div, .posters div, .design div, {
  transition: background-color 1s, opacity 1s;
}
.photo:hover div, .advertisement:hover div, .posters:hover div, .design:hover div {
  opacity: 1;
  background-color: white;
  transition: background-color 1s, opacity 1s;
}
.content{
  text-align:center;
  width: 100%;
 position: absolute;
  left:0;
  top:20vw;
  opacity: 0;
  transition: opacity;
}


@media (min-width:700px){
   section{
       width: calc( 50% - 10px );
        display: inline-block;
   }
  .container { margin-bottom: 0px; }
  
}

.toptxt{ 
  font-weight: 800;
  font-size: calc( 22px + 1vw ); 
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
  text-shadow: 0 0 3px white;
}
.grey{
  text-transform: uppercase;
  color: #777;
  text-shadow: 0 0 3px white;
}

.wrapper{ width: 100%; max-width: 1120px; margin: 0 auto; }

@font-face {
  font-family: "Milkshake";
  src: url("font/Milkshake.ttf");
}

 h1{
  font-family: "Milkshake";
}

ul.topnav {
  list-style-type: none;
  margin: 0;
  padding: 0;
  overflow: hidden;
  background-color: white;
}

ul.topnav li {float:right;}

ul.topnav li a {
  display: block;
  color: black;
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
  font-size: 18px;
  text-align:center;
  padding: 14px 16px;
  text-decoration: none;
}

ul.topnav li a:hover:not(.active) {color:grey}

ul.topnav li a.active {color:grey;}

ul.topnav li.right {float: right;}

@media screen and (max-width: 500px) {
  ul.topnav li.right, 
  ul.topnav li {float:none;}
  
  
  
}