Modern userform design in Excel has evolved significantly to incorporate user-friendly, visually appealing, and highly functional elements. Here are some key characteristics and best practices of modern userform design in Excel:

1. Sleek and Intuitive User Interface (UI)

• Minimalistic Design: Focus on a clean, uncluttered interface. Use sufficient white space, simple color schemes, and intuitive layout to ensure the form is not overwhelming.
• Consistent Styling: Use consistent fonts, colors, and button styles throughout the form. This creates a professional look and feel.

2. Responsive Layout

• Adaptive Sizing: Ensure the userform adapts well to different screen sizes and resolutions. Controls should resize and reposition appropriately to maintain usability.
• Scalable Fonts and Controls: Use scalable fonts and controls to ensure readability and accessibility across different devices and resolutions.

3. Enhanced User Experience (UX)

• Guidance and Feedback: Provide tooltips, placeholders, and labels that guide the user. Use visual or textual feedback for user actions like clicking buttons or submitting forms.
• Error Handling: Implement clear and helpful error messages. Highlight fields with incorrect inputs and provide guidance on how to correct them.
• Navigation: Include easy navigation options, such as next/previous buttons, tabs, and breadcrumbs for multi-step forms.

4. Data Validation and Security

• Input Constraints: Implement input masks, dropdown lists, and other validation controls to ensure data integrity. For example, use date pickers for date fields, numeric inputs for numbers, etc. 

5. Interactive Elements

• Dynamic Controls: Use dynamic controls like dependent dropdowns, sliders, and checkboxes to enhance interactivity. Show or hide sections of the form based on user inputs.
• Macros and VBA: Leverage VBA (Visual Basic for Applications) to add functionality such as auto-filling fields, performing calculations, and interacting with other Excel features.