Accordion elements are UI components that allow users to expand and collapse sections of content. They are useful for organizing information in a limited space, such as on mobile devices. However, they also have some usability challenges, such as discoverability, accessibility, and navigation. To improve the usability of accordion elements in a mobile environment, two possible ways are:

Include persistent headings. Persistent headings are the labels that indicate the content of each section and allow users to tap on them to expand or collapse the content. Persistent headings should be visible at all times, even when the content is expanded, so that users can easily see the context and switch between sections. Persistent headings should also be clear, concise, and descriptive, so that users can understand what each section contains and decide whether to explore it or not. [UX Designer Certification Prep: User Interface Design Principles], [UX Designer Certification Prep: Mobile Design]

Only allow users to open one selection at a time. This means that when a user taps on a heading to expand a section, any other previously expanded section should automatically collapse. This prevents the content from becoming too long and overwhelming for the user, and also helps to maintain the focus and hierarchy of the information. It also reduces the need for scrolling and the risk of losing the position of the headings. [UX Designer Certification Prep: User Interface Design Principles], [UX Designer Certification Prep: Mobile Design]

Nesting an accordion inside of another is not a good way to improve the usability of accordion elements in a mobile environment, because it creates a complex and confusing structure that is hard to navigate and understand. It also increases the cognitive load and the number of taps required for the user to access the information. Using the ‘back’ browser button to collapse content is also not a good way to improve the usability of accordion elements in a mobile environment, because it breaks the user’s expectation and the consistency of the UI. The ‘back’ browser button should be used to go back to the previous page or screen, not to collapse the content within the same page or screen. It also makes it difficult for the user to return to the expanded content if they want to. [UX Designer Certification Prep: User Interface Design Principles], [UX Designer Certification Prep: Mobile Design] References: [UX Designer Certification Prep: User Interface Design Principles], [UX Designer Certification Prep: Mobile Design]