* {
  padding: 0;
  margin: 0;
}

/* https://stackoverflow.com/questions/29147806/
  how-can-i-set-the-image-opacity-for-body-background/29147887 */

body:after {
  content: '';
  background: url('https://universoretro.com.br/wp-content/uploads/2020/09/super-mario-world.jpg');
  background-repeat: no-repeat;
  background-size: cover;
  opacity: 0.5;
  top: 0;
  left: 0;
  bottom: 0;
  right: 0;
  position: absolute;
  z-index: -1;
}

h1 {
  text-align: center;
}

p {
  margin-top: 15px;
  font-size: smaller;
  text-align: center;
}

main {
  width: 70%;
  margin: 10px auto;
}

.container-list {
  background-color: rgba(4 , 156 , 216 , 0.7);
  border: 1px solid black;
  border-radius: 2%;
  padding: 25px;
  margin-bottom: 15px;
}

#texto-tarefa {
  margin-bottom: 10px;
  width: 70%;
  height: 20px;
}

li {
  background-image: url('https://i.gifer.com/ZNec.gif');
  background-repeat: no-repeat;
  background-position: left center;
  background-size: 20px;
  font-size: 20px;
  list-style: none;
  padding: 8px 0 8px 25px;
}

.selected {
  background-color: gray;
}

.completed {
  text-decoration: line-through;
}

#criar-tarefa {
  background-color: rgb(251 , 208 , 0);
  color: black;
  display: inline-block;
  height: 30px;
  margin: 5px 10px;
  text-decoration: none;
  text-align: center;
  width: 100px;
}

.save , .up-down , .remove {
  text-align: center;
  margin: 10px 0;
}

.btn {
  background-color: rgb(102 , 102 , 102);
  background-repeat: no-repeat;
  background-position: left center;
  background-size: 20px;
  color: rgb(204 , 204 , 204);
  display: inline-block;
  height: 30px;
  margin: 5px 10px;
  text-decoration: none;
  text-align: center;
  width: 150px;
}

#mover-cima {
  background-image: url('https://i.gifer.com/Xysh.gif');
  background-position: left bottom;
  padding-left: 15px;
}

#mover-baixo {
  background-image: url('https://i.gifer.com/5UKF.gif');
  padding-left: 15px;
}

#salvar-tarefas {
  background-image: url('https://i.gifer.com/5RTB.gif');
}

.remove button {
  background-image: url('https://i.gifer.com/WiCH.gif');
  background-size: 30px;
  width: 175px;
}

.btn:hover {
  color: rgb(153 , 153 , 153);
}

#mover-cima:hover {
  background-position: left top;
}