.w3-button w3-block w3-blue {
  position: relative;
  margin: auto;	
  background-color: #777;
  color: white;
  cursor: pointer;
  padding: 18px;
  max-width: 300px;
  border: none;
  text-align: left;
  outline: none;
  font-size: 15px;
}

.active, .w3-button w3-block w3-blue:hover {
  background-color: #555;
}

.w3-button w3-block w3-blue:after {
  content: '\002B';
  color: white;
  font-weight: bold;
  float: right;
  margin-left: 5px;
}

.active:after {
  content: "\2212";
  float: right;
}


.w3-bar w3-blue{
   width: 300px;
   position: relative;
   margin: auto;	
}

.content {
  max-width: 300px;
  position: relative;
  margin: auto;	
  padding: 0 18px;
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.2s ease-out;
  background-color: #f1f1f1;
}

<!-- // Proba za otvarajuci sadrzaj -->



img {
  width: 100%;
  height: auto;
}

* {box-sizing: border-box}

.mySlides {display: none}
img {vertical-align: middle;}

/* Slideshow container */
.slideshow-container {
  max-width: 300px;
  position: relative;
  margin: auto;
}
.responsive {
  width: 100%;
  height: auto;
  
}
.content {
  max-width: 300px;
  position: relative;
  margin: auto;	
  }
.video {
  max-width: 300px;
  position: relative;
  margin: auto;	
}

/* Next & previous buttons */
.prev, .next {
  cursor: pointer;
  position: absolute;
  top: 50%;
  width: auto;
  padding: 16px;
  margin-top: -22px;
  color: white;
  font-weight: bold;
  font-size: 18px;
  transition: 0.6s ease;
  border-radius: 0 3px 3px 0;
  user-select: none;
}

/* Position the "next button" to the right */
.next {
  right: 0;
  border-radius: 3px 0 0 3px;
}

/* On hover, add a black background color with a little bit see-through */
.prev:hover, .next:hover {
  background-color: rgba(0,0,0,0.8);
  
  
  /* Fading animation */
.fade {
  -webkit-animation-name: fade;
  -webkit-animation-duration: 1.5s;
  animation-name: fade;
  animation-duration: 1.5s;
}

@-webkit-keyframes fade {
  from {opacity: .4} 
  to {opacity: 1}
}

@keyframes fade {
  from {opacity: .4} 
  to {opacity: 1}
}

/* On smaller screens, decrease text size */
@media only screen and (max-width: 300px) {
  .prev, .next,.text {font-size: 11px}
}