.flex-container {
  display: flex;
  flex-direction: row;
  flex-wrap: nowrap;
  justify-content: normal;
  align-items: baseline;
  align-content: stretch;
}

.flex-items:nth-child(1) {
  display: block;
  flex-grow: 0;
  flex-shrink: 1;
  flex-basis: auto;
  align-self: auto;
  order: 0;
}

.flex-items:nth-child(2) {
  display: block;
  flex-grow: 0;
  flex-shrink: 1;
  flex-basis: auto;
  align-self: auto;
  order: 0;
}

@media (max-width: 600px){
.flex-container {
    flex-direction: column; /* En colonne */
    }
.flex-items {
    min-width: 100%;
    }