header {
  background-color: cadetblue;
  padding: 25px;
}

.header--theme-week {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
}

.header__back {
  display: block;
  border-radius: 5px;
  background-color: blueviolet;
  padding: 10px;
  min-width: 80px;
  text-align: center;
}

/*text*/
.header__title {
  margin: 0;
  text-align: center;
  margin-bottom: 10px;
}

.header__title--theme-week {
  margin: auto;
}

.header__title--sub {
  text-align: left;
}

/*responsive*/

@media (max-width: 650px) {
  .header__back {
    margin-bottom: 20px;
  }
}

@media (min-width: 1000px) {
  
}