Selectors, cascade, and inheritance

What this means

Selectors choose elements. The cascade considers origin, importance, specificity, and source order. Some properties, such as text color, inherit from a parent.

In beginner terms, this topic answers one practical question: "What should I write, and why does React care about it?" Do not try to memorize the syntax first. First understand the idea, then connect the syntax to that idea.

Why it matters

Most CSS confusion comes from not knowing which rule is active. Understanding the cascade reduces overrides and fragile selectors.

When you build real React screens, this idea helps you decide where data should live, what the user should see, and what should happen after an interaction. That is why this lesson is part of the main path instead of being an optional detail.

Step by step

1. Notice the UI problem this topic solves. 2. Look at the smallest possible example. 3. Change one value and predict what should appear. 4. Run the example and compare the result with your prediction. 5. Use the practice task before moving on.

Small example

main { color: #0f172a; }
.note { color: #2563eb; }

Common mistake

Do not solve every conflict with !important. Find the competing rule and improve the selector structure.

Practice task

Style headings, paragraphs, and one highlighted note with simple class selectors.

Remember this

The cascade decides which matching declaration applies.