Currently the font size is entered in px and there is no way to change this to pt or em.

Using em instead of px for font sizes in website development offers several advantages:

Scalability and responsiveness:

Em units are relative to the parent element's font size, allowing for better scalability across different devices and screen sizes. This makes em units particularly useful for responsive design, as they adapt to the user's preferred font size settings.

Accessibility: Em units respect the user's browser settings and preferences for font size, which is crucial for users with visual impairments or those who need larger text. Pixel-based font sizes, on the other hand, override user preferences and can make text impossible to resize.

Proportional scaling: When using em units, all related elements (like headings, paragraphs, and margins) scale proportionally when the base font size changes. This maintains the design's visual hierarchy and overall layout consistency across different screen sizes and user preferences.

Easier maintenance: By using em units, designers can change the entire site's typography by adjusting the base font size, rather than updating individual pixel values throughout the CSS.

Compatibility with zoom functionality: Em units work better with browser zoom functionality, ensuring that text remains readable and properly scaled when users zoom in or out.

Flexibility for different contexts:

Em units allow for more flexible designs that can adapt to various contexts, such as different sections of a website or different devices, without requiring separate pixel-based definitions for each scenario.