body {
background-color: grey;
}

#lyrics {
  font-size: 4vw; 
  font-family: sans-serif; 
  white-space: pre-line; 
}

#lyrics > div { 
    position: absolute; top: 10px; left: 10px; right: 10px; bottom: 10px; 
    display: flex; align-items: center; justify-content:  center;
    text-align: center;
}

.slide {display: none;}
.slide:first-line { line-height: 0 !important; }
.slide:nth-of-type(1) {display: inherit; }
.slide:nth-of-type(3) {//background-color: blue; //opacity: 0.5;}

/* btn - vsechna ovladani */
.btn { border: 1px dashed black;
 position: fixed; 
 background-color: ;
z-index: 99; 
display: block;
}
.next {
bottom: 0px; 
right: 0px;
width: 10%; 
height: 80%; 
}
.prev {
bottom: 0px; 
left: 0px;
width: 10%; 
height: 80%; 
}
.back {
top: 0px; 
left: 0px; 
width: 10%; 
height: 10%; 
}