Tips from GPT

Popovers without JavaScript

<details> and <summary> Tags: The `<details>` and `<summary>` elements provide a built-in way to create toggleable content.
Checkbox Hack: This technique involves using a hidden checkbox input and a label. The label, when clicked, toggles the checkbox. Using the `:checked` pseudo-class in CSS, you can control the display of content based on whether the checkbox is checked.
Hover Effects: For purely mouse-based interactions, the `:hover` pseudo-class can be used to display content when an element is moused over.

Sliders/Carousels: With radio buttons and labels, you can create simple content sliders or carousels.
Lightbox Image Gallery: Using the `:checked` pseudo-class along with radio buttons or checkboxes, you can build a lightbox image viewer.
Collapsible Accordions: Besides `<details>` and `<summary>`, the checkbox hack or focus can be used to create collapsible content sections.
CSS Transitions and Animations: Achieve visual effects using CSS transitions and animations.
Form Validations: Use `:invalid` and `:valid` pseudo-classes for basic form validations.
Dropdown Menus: Using the `:hover` pseudo-class, create nested dropdown menus.
Modals: Use the checkbox hack to trigger modals.
Tabs: Use radio buttons and labels to create a tabbed interface.
Tooltips with Attribute Selectors: Use the `data-` attribute and the `::before` or `::after` pseudo-elements to create tooltips based on attribute content.
Toggle Dark Mode: With a checkbox, toggle between light and dark themes using the `:checked` pseudo-class.

Considerations:

Fallbacks: Test methods in various browsers and provide fallbacks.
Semantics and Accessibility: Some techniques might not be semantically correct or accessible.
Limitations: These techniques won't replace complex JavaScript functionality.