Current limitations

• In the Modern Form Designer, the Theme panel includes Themes, Styles, and CSS tabs, but the custom CSS entered there is still tied to an individual form rather than reusable across all forms that share a theme.
• The Modern Form Designer does make some layout changes easier, such as resizing fields by dragging in the layout, but many appearance adjustments still require custom CSS.
• Some styling needs in the Modern Form Designer are not covered by built-in style controls, especially for areas like sections, tables, collections, special labels, and detailed field presentation, so admins must rely on manual CSS.
• Because the CSS is not centralized at the theme level, teams must repeat the same customizations form by form, which becomes difficult to maintain across a large Modern Forms library.

Requested feature

• Add support in the Modern Form Designer for theme-level shared custom CSS, so a custom theme can include both standard style settings and reusable CSS rules.
• When a custom theme is applied in the Modern Form Designer, its associated CSS should automatically apply to the form without requiring admins to paste the same rules again.
• This would complement the existing Themes and Styles capabilities in the Modern Form Designer by covering advanced formatting scenarios that are not currently configurable through the visual interface.

Business impact

• Consistency across Modern Forms
  • Shared CSS in the Modern Form Designer would help organizations enforce a consistent look and feel across all forms, including branding, label formatting, help text, and advanced field styling.
  • It would reduce variation caused by manually copying styles from one Modern Form to another.
• Less maintenance
  • Today, if a design standard changes in the Modern Form Designer, admins may need to update each form individually, which is inefficient and easy to miss.
  • Theme-level CSS would allow one update to support many Modern Forms at once, reducing maintenance overhead and simplifying future redesigns.
• Faster form development
  • Admins could build new forms in the Modern Form Designer more quickly by selecting a theme that already includes both standard style settings and reusable CSS behavior.
  • That would reduce repetitive setup work and shorten the time required to publish new forms.
• Lower upgrade and support risk
  • Users have noted that moving styling between Classic and Modern experiences can require extra effort, and duplicated CSS increases the chance of inconsistency or breakage.
  • Centralizing CSS for the Modern Form Designer would make troubleshooting and future updates more controlled and predictable.