zotero/scss/components/_createParent.scss

#zotero-create-parent-container {
	.title {
		font-size: 1.4em;
		font-weight: 700;
		// Let the dialog get a little wider if the title is long
		max-width: 550px;
	}
	
	.intro {
		margin-bottom: .5em;
		max-width: 550px; // Avoid expanding the dialog too wide; instead, in some languages, the intro text will wrap.
	}
	
	.body {
		align-items: center;
		display: flex;
		margin-bottom: 1em;

		input {
			flex: 1;
			margin-left: 0;
		}
	}
}