.button-plus {
  /*
    --dim 
    la valeur 1 est pourri!
    bien à partir de 1.5rem
   */
  --dim: 4rem; 
  --font-size: calc(var(--dim));
  background-image: url("./button-green.png");
  background-repeat: no-repeat;
  background-size: contain;
  font-size: var(--font-size);
  width: calc(var(--dim));
  height: calc(var(--dim));
  color: white;
  display: flex;
  flex-flow: column;
  justify-content: center;
  align-items: center;
  border-radius: 50%;
  padding: 0;
  padding-bottom: calc(var(--font-size)/5);
  cursor: pointer;
}

.button-plus:enabled:active  {
  color: black;
}

.button-plus:disabled {
  background-image: url("./button-gray.png");
  cursor: default;
}