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CSS: Selectors

We've seen tag and class selectors in tutorials before. A selector is a description of what a particular CSS style should be applied to. They can be quite complex, indicating not just the specific element, but where it's located or which tag it's in. Remember the class selector. It applies to any element whose class we have specified.

<p class="text-bold">Bold text inside a paragraph</p>

<div class="text-bold">Another text inside a simple block element. Since it too has the text-bold class, it will be bold</div>
.text-bold {
  font-weight: bold;

The font-weight property with a value of bold will set the text to bold. You'll learn more about this property when you study text formatting. The most important thing now is that this style will be applied to both the paragraph and the block element <div>, since they have the same class.

Another familiar selector is the tag selector. Its purpose is to set styles for all the tags on the page. This is very useful if you want to set initial styles for tags throughout your project. For example, to set the font, its size, and its thickness.

p {
  color: #333;
  font: 18px/1.5 sans-serif;

Use the tag selector only to set global rules within the entire project. This is important because styles will be applied to all the tags at once, and you could accidentally overwrite existing styles

Another way to specify styles is to use the Identity Selector. By using the id attribute, you can specify a unique name for any element on the page. If this name is specified, then the element can be referred to using the identifying selector. For this purpose, the form selector #identifier_name is used

<p id="red">Red paragraph</p>
#red {
  color: red;

It is important to remember that the ID value is unique. There can only be one element on a page with one specific value. For example, in the example above, the identifier red has already been used on the paragraph. There cannot be a second version of this element on the page. For this reason, identifiers are generally specified for large wrappers, such as the main site header, but this is not a prerequisite


In the editor, create a paragraph with the ID as red and class set to bold. Set the following properties:

  • For the identifier red, set the text color to red
  • Set the bold class to have bold text
The exercise doesn't pass checking. What to do? 😶

If you've reached a deadlock it's time to ask your question in the «Discussions». How ask a question correctly:

  • Be sure to attach the test output, without it it's almost impossible to figure out what went wrong, even if you show your code. It's complicated for developers to execute code in their heads, but having a mistake before their eyes most probably will be helpful.
In my environment the code works, but not here 🤨

Tests are designed so that they test the solution in different ways and against different data. Often the solution works with one kind of input data but doesn't work with others. Check the «Tests» tab to figure this out, you can find hints at the error output.

My code is different from the teacher's one 🤔

It's fine. 🙆 One task in programming can be solved in many different ways. If your code passed all tests, it complies with the task conditions.

In some rare cases, the solution may be adjusted to the tests, but this can be seen immediately.

I've read the lessons but nothing is clear 🙄

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