p5.js-web-editor/styles/layout/_ide.scss

.app {
	display: flex;
	flex-direction: row;
	height: 100%;
	flex-wrap: wrap;
}

.editor-holder {
	width: 50%;
	height: 100%;
}

.preview-frame {
	width: 50%;
}

.toolbar {
	width: 100%;
}