CSS / CONTROL FLOW
Media queries and feature queries
Learn how media queries and feature queries works in CSS, why the underlying model matters, and how to apply it in a small program without hiding important trade-offs.
What you will learn
- Explain media queries in CSS using the correct mental model
- Trace a focused CSS example and predict its result before execution
- Recognize a boundary case involving feature queries and handle it deliberately
Understanding Media queries and feature queries
Media queries and feature queries belongs to the practical core of CSS. Start by identifying the values or state involved and the rule that connects the input to the result.
Trace the example one operation at a time. Keep media queries visible in the code rather than hiding it behind an abstraction before the behavior is understood.
Test a normal case and a boundary case. The difference between the prediction and the observed result is the most useful signal for deciding what to review next.
Media queries and feature queries is a defining part of practical CSS work. Start by identifying the data or state involved, then trace the operation that changes or interprets it. Pay attention to the rules CSS applies at this boundary, because those rules explain both the useful behavior and the common failure modes. This lesson keeps the example deliberately small, then connects it to flexbox and grid layout systems so the ideas form a coherent progression rather than a list of isolated syntax facts.
Worked examples
Media queries and feature queries example
A focused CSS example for media queries.
body {
font-family: system-ui;
color: #17352b;
}
/* Lesson 6: media queries. Change one value and predict the result before running it. */Example explained
Line 1Identify where media queries appears in the CSS example and name the data it operates on.
Line 2Trace the relevant CSS rule one operation at a time, recording any state, type, or control-flow change.
Line 3Change one input or boundary condition, predict the result, and compare that prediction with the documented outcome.
Important notes
Keep the first media queries example small enough to trace completely.
Use the normal CSS toolchain or browser workspace to compare the actual result with your prediction.
Common mistakes
Treating media queries as punctuation to memorize instead of a CSS behavior to reason about.
Ignoring feature queries until it appears in production data or a larger program.
Try it yourself
Change, predict, then run
Create a small CSS example that demonstrates media queries. Add a normal case and a boundary case, write down the expected result for each, then explain which CSS rule produces that result. Lesson 6 should remain small enough to trace without guessing.
Open CSS workspaceCheck your understanding
What is the best first step when working with media queries?
- Identify the data and predict the result
- Add more abstraction immediately
- Ignore boundary cases
- Memorize punctuation only
Show answer
A clear input, operation, and predicted result create a testable mental model.