CSS Pseudo‑Class Playground - Online Test :is(), :where(), :not()
Write compound selectors and instantly see which elements they match on a test page. Master complex CSS logic.
UD5 Toolkit
Online test lab for the powerful :has() relational pseudo‑class. Write HTML & CSS, instantly see how child states can style their parent.
:has() is a relational pseudo‑class that represents an element if any of the relative selectors passed as argument match at least one element when anchored against this element. It lets you style a parent based on its children or descendants, e.g., div:has(> img).
:has() works by matching the parent if it contains a child that matches the inner selector. Example: .card:has(button:hover) { border-color: blue; }.
:has() is supported in all modern browsers including Chrome 105+, Edge 105+, Safari 15.4+, and Firefox 121+. As of 2024 it is safe to use in production for most projects.
:has() with class, attribute, or pseudo‑class selectors. For example, form:has(input:invalid) .error-message { display: block; }.
:has() is performant for most use cases, but overly broad selectors like *:has(*) can be expensive. Stick to reasonable, scoped selectors and test in DevTools.
.form-group:has(input:focus) { background: #f0f8ff; }. The container gets a highlight whenever the inner input is focused.
Write compound selectors and instantly see which elements they match on a test page. Master complex CSS logic.
Animated SVG steps showing how to fold a fitted sheet perfectly. Clean visual reference.
Enter ambient temperature, precipitation, and whether your horse is clipped to get a recommendation for blanket weight (sheet, medium, heavy).
Interactive checklist of the classic 10 essentials for safe hiking. Check items, see explanations, and never forget critical gear for the trail.
Practice positive/negative lookahead and lookbehind. See matches highlighted live. Master advanced regex.
Adjust a sleeping bag's EN rating based on sleeping pad R‑value, clothing, and personal warmth.
Enter expected low temperature and get minimum recommended pad R‑value. Visual conductivity guide for winter camping.
Visually configure scroll‑snap containers and items. Adjust alignment, stop behavior, and padding. Copy the clean CSS instantly.
Convert hex, RGB, or HSL into the modern OKLCH color space. See the preview and copy CSS oklch() value. Local.
Create complex linear gradients with any number of color stops, exact angles, and length units. Live preview and CSS code.
Design a light and dark theme by picking colors for backgrounds, text, and links. Get the CSS for both themes. Local.
Style underlines, overlines, and strike-throughs with colors, wavy styles, and thickness. Modern CSS text‑decoration.
Adjust opacity visually with a slider and see the different CSS representations (opacity property vs RGBA/HSLA). Copy best option.
Pick two images or colors and apply all 16 CSS mix‑blend‑mode values live. See and copy the right CSS for your design.
Design a fully styled scrollbar with colors, width, radius, and hover effects. Supports both ::-webkit‑scrollbar and Firefox scrollbar‑width.
Design a button or card that glows on hover. Adjust shadow color, spread, and transition. Copy the CSS. Rich UI.
Create CSS clamp() values for fluid typography. Enter min and max font sizes and viewport widths. Modern responsive design.
Create a realistic letterpress (debossed) text effect using CSS text‑shadow and background. Adjust depth and light direction. Copy code.
Create CSS mask‑image effects with custom shapes, gradients, and SVGs. Visually see the mask applied to an image. Copy the CSS.
Create a customizable checkerboard or grid background using pure CSS gradients. Adjust cell size and colors. Copy the code.
Paste HTML/CSS snippets or enter properties to test how z‑index and stacking contexts interact. Real‑time example.
Adjust margin, border, padding, and content sizes interactively and see the rendered box model. Get the exact CSS. Teach or learn layout.
Create a glowing or rotating border animation around an element. Copy the CSS keyframes. Pure CSS magic.
Design a pure CSS tooltip with custom text, position (top/bottom/left/right), and arrow. Copy the clean code.
Create a custom HTML/CSS progress bar with percentage, colors, and animation. Copy the code. Modern UI element.
Pick an emoji and get the exact CSS content property value with escaped Unicode. For inserting emojis via CSS.
Experiment with CSS Grid properties visually. Add rows, columns, and areas. See the grid in action and copy the code.
Fetch a website's CSS and extract :root custom properties (‑‑color) to reveal its design token palette. For learning and inspiration.
Recreate the target CSS linear gradient by adjusting stops and colors. A unique game for front‑end developers to master gradients.
Create text with a gradient fill using CSS background-clip. Configure colors and direction. Copy the code. Works in modern browsers.