my page has three background colors that change depending on what a div displays (just a word actually).

The colors do change right now, but the transition is not smooth as expected. Colors just change brutally, without a transition operating.

Here is my CSS :

```
.gradient-low{
background: #ddd6f3;
background: -webkit-linear-gradient(to left, #faaca8 , #ddd6f3);
background: linear-gradient(to left, #faaca8 , #ddd6f3);
transition-duration: 0.4s;
}

.gradient-moderate{
background: #ff6e7f;
background: -webkit-linear-gradient(to left, #ff6e7f , #bfe9ff);
background: linear-gradient(to left, #ff6e7f , #bfe9ff);
transition-duration: 0.4s;
}

.gradient-high{

background: #EECDA3;
background: -webkit-linear-gradient(to left, #EF629F , #EECDA3);
background: linear-gradient(to left, #EF629F , #EECDA3);
transition-duration: 0.4s;
}

```

Do you have any suggestions so the change of colour is operated gradually and smoothly ?