What are common issues when switching PHP forum designs?

Common issues when switching PHP forum designs include compatibility issues with existing plugins, themes, or customizations, as well as potential layout or styling discrepancies. To solve these issues, it is important to thoroughly test the new design before fully implementing it, make necessary adjustments to ensure compatibility, and update any custom code or stylesheets accordingly.

// Example code snippet for updating custom code or stylesheets
if (is_plugin_active('my-custom-plugin')) {
    // Update custom code to work with new forum design
}

// Example code snippet for adjusting layout or styling
if (is_page('forum')) {
    // Add new CSS styles for the forum layout
}