CSS Error automatic zoom in background image when transition flex-grow

With this code in CSS:

.image-accordion{    background-size: contain;    flex-grow: 1;    background-position: center center;    margin-bottom: 2px;    transition: flex-grow 0.7s ease-in-out;    @include respond-to(large){        height: 600px;        margin-right: 4px;    }&:last-child{        margin-bottom: 0px;        @include respond-to(large){            margin-right: 0px;        }    }&.clicked{        flex-grow: 2.8;        @include respond-to(large){            flex-grow: 4.57;        }    }  }

When click in DIV apply automatic zoom in background image. I need to delete the zoom. Thanks.

I tried to change background-size and position. But not working.