CSS

css create sidebar

<style>
	#app {
    	width:100vw;
        height:100vh; // u can set it as auto if you want
        display:flex;
    }
    
    
    
    #sidebar {
    	width:30%; // u can adjust it
        height:100%;
    }
    
    #main-content {
    	width:100%;
        height:100%;
    }
</style>


<div id="app">
	<div id="sidebar">
    	
    </div>
    <div id="main-content">
    
    </div>
</div>