CSS Mastery

Demos

CSS demos and decision tools

Each demo is static, inspectable, and focused on one production behavior.

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Layout decision helper

Choose between Grid, Flexbox, Subgrid, and container queries based on the behavior the component needs.

Changing either select updates the recommendation without changing the form layout.
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Specificity and cascade visualizer

Compare selectors and see why source order, layers, and specificity should be treated as separate levers.

Typing a selector updates a simple specificity score and gives a practical override hint.
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Responsive type scale playground

Tune reading measure, heading size, and line height without hiding the constraints from the page.