JSFiddle - React, Tailwind, and code Playground

HTML

<header>
    <img src="http://www.clker.com/cliparts/3/w/P/g/w/m/white-apple-logo-on-black-background.svg"/>
</header>

CSS

header{
   background: black;
    height: 50px;
}

img{
   opacity: 1; 
    height: 30px;
    padding-top: 10px;
    padding-left: 30px; 
    transition: opacity 0.2s cubic-bezier(0.645, 0.045, 0.355, 1) 0s;
}

img:hover{
    opacity: .5;
}