The answer is the Salesforce Lightning Design System (SLDS), a collection of design guidelines, resources, and code samples that help you create consistent and beautiful user experiences across the Salesforce platform.
But what if we could customize the appearance of screen flows without having to write or install any custom components? Many developer and third party hours have been spent building custom components or packages to help fill this styling gap instead of helping tackle more complex problems. However, when it comes to look and feel, the default styling for displaying things has limited options and may not match user expectations. Screen Flows have become an indispensable tool for Salesforce admins and developers to quickly construct guided wizards, prompts, input forms, and more without writing code.