How to change DIV `background linear-gradient` on hover with fade effect using CSS only? [duplicate]

Answer 1

For this, you can use transition but transition does not work for linear-gradient so I'm changing here opacity of ::after pseudo element. button name will not show that why i used z-index for stack order.

#div-text {
    display: flex;
    flex-direction: row;
    width: 80%;
    height: 80%;
    border-radius: 20px;
    background: #2d2e31;
    position: relative;
    z-index: 1;
    overflow: hidden;
  }
  
  #div-text::after {
    content: "";
    position: absolute;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    transition: opacity 1s ease;
    background: linear-gradient(45deg, #36D8FF, #00acee, #66757f);
    opacity: 0;
  }

  .cl-button {
    font-family: 'Merienda One', monospace;
    order: 2;
    align-self: center;
    height: 80%;
    width: 60%;
    border: 0;
    background-color: transparent;
    color: aliceblue;
    font-size: 16px;
    margin-left: 10px;
    text-align: left;
    position: relative;
    z-index: 3;
  }


    #div-text:hover::after{
      opacity: 1;
  }

  Text Here

I think, it will be helpful for you.