Less than 4 slides?

[Sinthaesia]

I'm using the slider-def.css file and I was wondering how to manage to get less than 4 slides, in particular 2.
I'm genuinely hoping you check this issue in less than a year's time.

#slider{
  width:200%;
  height:500px;
  position:relative;
  overflow:hidden;
}
@keyframes load{
  from{left:-100%;}
  to{left:0;}
}
.slides{
  width:200%;
  height:100%;
  position:relative;
  -webkit-animation:slide 30s infinite;
  -moz-animation:slide 30s infinite;
  animation:slide 30s infinite;
}
.slider{
  width:50%;
  height:100%;
  float:left;
  position:relative;
  overflow:hidden;
}
.slide img{
  width:100%;
  height:100%;
}
.image{
  width:100%;
  height:100%;
max-width: 100%;
    height: auto;
    width: auto\9; /* ie8 */
    -moz-box-shadow:    inset 0 0 10px #0d1010;
   -webkit-box-shadow: inset 0 0 10px #0d1010;
   box-shadow:         inset 0 0 10px #0d1010;
}
.images img{
}
.image img{
  width:100%;
  height:100%;
max-width: 100%;
    height: auto;
    width: auto\9; /* ie8 */
}

/* Legend */
.legend{
  border:500px solid transparent;
  border-left:800px solid rgba(218,165,33,0.7);
  border-bottom:0;
  position:absolute;
  bottom:0;
}

/* Contents */
.content{
  width:100%;
  height:100%;
  position:absolute;
  overflow:hidden;
background-size: contain;
}
.content-txt{
  width:400px;
  height:150px;
  float:left;
  position:relative;
  top:300px;
  -webkit-animation:content-s 7.5s infinite;
  -moz-animation:content-s 7.5s infinite;
  animation:content-s 7.5s infinite;
}
.content-txt h1{
  font-family:'BebaBold';
  font-size:75px;
  color:rgb(13,16,16);
  text-align:left;
  margin-left:30px;
  padding-bottom:2px;
}
.content-txt h2{
  font-family:'BebaBold';
  font-weight:normal;
  font-size:16px;
  font-style:italic;
  color:#fff;
  text-align:left;
  margin-left:30px;
text-shadow: auto;
    clear: right;
}

/* Switch */
.switch{
  width:120px;
  height:10px;
  position:absolute;
  bottom:50px;
  z-index:99;
  left:30px;
}
.switch > ul{
  list-style:none;
}
.switch > ul > li{
  width:10px;
  height:10px;
  border-radius:50%;
  background:#333;
  float:left;
  margin-right:5px;
  cursor:pointer;
}
.switch ul{
  overflow:hidden;
}
.on{
  width:100%;
  height:100%;
  border-radius:50%;
  background:#f39c12;
  position:relative;
  -webkit-animation:on 30s infinite;
  -moz-animation:on 30s infinite;
  animation:on 30s infinite;
}



@-webkit-keyframes slide{
  0%,100%{
    margin-left:0%;
  }
  21%{
    margin-left:0%;
  }
  25%{
    margin-left:-100%;
  }
  46%{
    margin-left:-100%;
  }
  50%{
    margin-left:-200%;
  }
  71%{
    margin-left:-200%;
  }
  75%{
    margin-left:-300%;
  }
  96%{
    margin-left:-300%;
  }
}
@-moz-keyframes slide{
  0%,100%{
    margin-left:0%;
  }
  21%{
    margin-left:0%;
  }
  25%{
    margin-left:-100%;
  }
  46%{
    margin-left:-100%;
  }
  50%{
    margin-left:-200%;
  }
  71%{
    margin-left:-200%;
  }
  75%{
    margin-left:-300%;
  }
  96%{
    margin-left:-300%;
  }
}
@keyframes slide{
  0%,100%{
    margin-left:0%;
  }
  21%{
    margin-left:0%;
  }
  25%{
    margin-left:-100%;
  }
  46%{
    margin-left:-100%;
  }
  50%{
    margin-left:-200%;
  }
  71%{
    margin-left:-200%;
  }
  75%{
    margin-left:-300%;
  }
  96%{
    margin-left:-300%;
  }
}