.btn 
{
   display: block;
   height: 17px;
   width: 17px;
   transition: 1s;
}

.btn-vlevo
{
  background-image: url('../pic/l_off.gif')
}
.btn-vlevo:hover
{
  background-image: url('../pic/l_on.gif')
}
.btn-vpravo
{
  background-image: url('../pic/p_off.gif')
}
.btn-vpravo:hover
{
  background-image: url('../pic/p_on.gif')
}
.btn-zacatek
{
  background-image: url('../pic/lk_off.gif')
}
.btn-zacatek:hover
{
  background-image: url('../pic/lk_on.gif')
}
.btn-konec
{
  background-image: url('../pic/pk_off.gif')
}
.btn-konec:hover
{
  background-image: url('../pic/pk_on.gif')
}
.btn-zpet
{
  background-image: url('../pic/end_off.gif')
}
.btn-zpet:hover
{
  background-image: url('../pic/end_on.gif')
}