* {box-sizing: border-box;} 

body, html {
  overflow: hidden;
  width: 100%;
  height: 100%;
  margin: 0;
  font: 400 15px/1.8 "Lato", sans-serif;
  color: #777;
}

.main {
  overflow: auto;
  position: fixed;
  opacity: 100%;
  background-attachment: fixed;
  background-size: ;
  background-color:;
  left:0px;
  top:0px;
  width:100%;
  height:100%
    
}



.bottom {
  position: relative;
  opacity: 0.65;
  background-attachment: fixed;
  background-size: cover;
  background-color:black;
}

.topnav {
  z-index:4;
  position: fixed;
  top: 0px;
  right: 0px;
  overflow: hidden;
  background-color: #333;
}


/* MENU OZELLIKLERI */
.topnav a {
  float: left;
  display: block;
  color: #f2f2f2;
  text-align: center;
  padding: 14px 6px;
  text-decoration: none;
  font-size: 14px;
}


.topnav a:hover {
  background-color: #555;
  color: white;
}



.active {
  background-color: #4CAF50;
  height:100%;
  color: white;
}

.topnav .icon {
  display: none;
  height:14px;
}

.grid-container {
  display:grid;
  width:100%;
  float:left;
  grid-template-columns: auto auto auto ;
  grid-gap: 4px;
  background-color: #f1f1f1;
  padding: 1px;
}

#toggle {
  display: none;
}

#collapseContent {
  display: none;
}

#toggle:checked ~ #collapseContent {
  display: block;
}