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Comments in CSS

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Introduction
Comments help you write notes inside your CSS code. They make it easier to understand and remember what your styles do.
To explain why a style is used for a certain element.
To leave reminders for yourself or others working on the code.
To temporarily disable a style without deleting it.
To organize your CSS by sections with headings.
To clarify complex or unusual style rules.
Syntax
CSS
/* This is a comment in CSS */
Comments start with /* and end with */.
Anything between these symbols is ignored by the browser.
Examples
A comment before a CSS rule to explain what it does.
CSS
/* This comment explains the body styles */
body {
  background-color: lightblue;
}
A comment placed after a style on the same line.
CSS
p {
  color: red; /* This makes text red */
}
A comment that covers multiple lines for longer explanations.
CSS
/*
  This is a multi-line comment.
  It can span several lines.
*/
h1 {
  font-size: 2rem;
}
Sample Program
This example shows comments before CSS rules and inside a rule to explain styles. The comments do not affect how the page looks.
CSS
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8" />
  <meta name="viewport" content="width=device-width, initial-scale=1" />
  <title>CSS Comments Example</title>
  <style>
    /* Set background color for the whole page */
    body {
      background-color: #f0f8ff;
    }

    /* Style for main heading */
    h1 {
      color: #333;
      /* Use a friendly font */
      font-family: Arial, sans-serif;
    }

    /* Paragraph text color */
    p {
      color: #666;
    }
  </style>
</head>
<body>
  <h1>Welcome to CSS Comments</h1>
  <p>This page shows how comments work in CSS.</p>
</body>
</html>
OutputSuccess
Important Notes
Never nest comments inside each other; CSS does not support nested comments.
Use comments to keep your code clean and easy to understand.
Comments do not appear on the webpage; they are only visible in the code.
Summary
Comments in CSS start with /* and end with */.
They help explain and organize your styles without affecting the page.
Use comments to make your CSS easier to read and maintain.

Practice

(1/5)
1. What is the correct way to write a comment in CSS?
easy
A. // This is a comment
B. # This is a comment
C.
D. /* This is a comment */

Solution

  1. Step 1: Identify CSS comment syntax

    CSS comments always start with /* and end with */.

  2. Step 2: Compare options with CSS syntax

    Only /* This is a comment */ uses /* and */ correctly; others are for different languages.

  3. Final Answer:

    /* This is a comment */ -> Option D

  4. Quick Check:

    CSS comments = /* comment */ [OK]
Hint: CSS comments always use /* and */ symbols [OK]
Common Mistakes:
  • Using // which is for JavaScript
  • Using which is for HTML
  • Using # which is for some scripting languages
2. Which of the following is a valid CSS comment placement?
easy
A. /* color: red; color: blue;
B. color: red; /* This sets text color */
C. color: green; // This is green
D. color: yellow; # This is yellow

Solution

  1. Step 1: Check comment syntax in each option

    Only color: red; /* This sets text color */ uses correct /* ... */ syntax. /* color: red; color: blue; starts /* but lacks closing */ making it invalid. C uses // invalid in CSS. D uses # invalid.

  2. Step 2: Verify comment placement

    color: red; /* This sets text color */ correctly places the comment after the property value and semicolon, a valid inline position.

  3. Final Answer:

    color: red; /* This sets text color */ -> Option B

  4. Quick Check:

    Valid comment placement = after property with /* */ [OK]
Hint: Use /* comment */ after or around CSS code [OK]
Common Mistakes:
  • Using // or # for comments
  • Placing comments inside property values
  • Commenting out code unintentionally
3. What will be the color of the text rendered by this CSS?
p {
  color: blue; /* This is blue text */
  /* color: red; */
}
medium
A. Blue
B. Black (default)
C. No color applied
D. Red

Solution

  1. Step 1: Understand comment effect on CSS

    Comments do not apply styles; they are ignored by the browser.

  2. Step 2: Analyze which color property is active

    The line setting color to red is commented out, so only color: blue; applies.

  3. Final Answer:

    Blue -> Option A

  4. Quick Check:

    Commented code ignored = blue color applied [OK]
Hint: Commented CSS lines do not affect styles [OK]
Common Mistakes:
  • Thinking commented lines still apply styles
  • Confusing comment syntax with disabling code
  • Assuming last property always wins
4. Identify the error in this CSS snippet:
body {
  color: green; /* Set text color
  background: white;
}
medium
A. Missing closing */ for the comment
B. Missing semicolon after color property
C. background property is invalid
D. No error, code is correct

Solution

  1. Step 1: Check comment syntax

    The comment starts with /* but does not have a closing */.

  2. Step 2: Understand impact of missing comment end

    Without closing */, the rest of the CSS is treated as comment, causing errors.

  3. Final Answer:

    Missing closing */ for the comment -> Option A

  4. Quick Check:

    Every /* must have matching */ [OK]
Hint: Always close comments with */ to avoid errors [OK]
Common Mistakes:
  • Forgetting to close comments
  • Assuming semicolon fixes comment errors
  • Ignoring that unclosed comments break CSS
5. You want to temporarily disable a CSS rule without deleting it. Which is the best way to do this?
hard
A. Change the property values to empty strings
B. Delete the rule and save a backup elsewhere
C. Wrap the rule inside /* and */ comment markers
D. Use // before the rule to comment it out

Solution

  1. Step 1: Understand how to disable CSS rules temporarily

    Using comments /* */ around a rule disables it without deleting.

  2. Step 2: Evaluate other options

    Deleting loses the rule, empty strings may cause invalid CSS, and // is not valid in CSS.

  3. Final Answer:

    Wrap the rule inside /* and */ comment markers -> Option C

  4. Quick Check:

    Use /* */ to disable CSS rules temporarily [OK]
Hint: Comment out rules with /* */ to disable temporarily [OK]
Common Mistakes:
  • Using // which is invalid in CSS
  • Deleting instead of commenting
  • Setting properties to empty strings causing errors