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CSS: Core Concepts

The !important declaration


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CSS: Core Concepts

with James Williamson

Video: The !important declaration

In addition to the cascade, inheritance, and specificity, there is one more CSS technique that can be used to resolve conflicts, and that is the important declaration. I like to call the important declaration the WMD of CSS. It doesn't matter what else is going on in your styles, in the event of a conflict, the important declaration wins, end of story. In fact, the only thing that can override an important declaration is another more specific important declaration, or some type of user-controlled style sheet. Let's try it out.
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  1. 4m 57s
    1. Welcome
      55s
    2. Using the exercise files
      4m 2s
  2. 1h 7m
    1. Exploring default styling
      4m 56s
    2. CSS authoring tools
      2m 29s
    3. CSS syntax
      4m 45s
    4. Writing a selector
      4m 10s
    5. Setting properties
      8m 40s
    6. Common units of measurement
      7m 47s
    7. Inline styles
      5m 1s
    8. Embedded styles
      5m 19s
    9. Using external style sheets
      10m 34s
    10. Checking for browser support
      8m 48s
    11. Dealing with browser inconsistencies
      5m 30s
  3. 2h 15m
    1. Structuring HTML correctly
      2m 51s
    2. Element selectors
      4m 52s
    3. Class selectors
      6m 4s
    4. ID selectors
      3m 27s
    5. Using classes and IDs
      10m 7s
    6. Element-specific selectors
      4m 35s
    7. The universal selector
      5m 42s
    8. Grouping selectors
      4m 49s
    9. Descendent selectors
      7m 32s
    10. Child selectors
      5m 7s
    11. Adjacent selectors
      5m 30s
    12. Attribute selectors
      12m 43s
    13. Pseudo-class selectors
      3m 54s
    14. Dynamic pseudo-class selectors
      8m 29s
    15. Structural pseudo-class selectors
      6m 45s
    16. Nth-child selectors
      13m 10s
    17. Pseudo-element selectors
      12m 40s
    18. Targeting page content: Lab
      8m 56s
    19. Targeting page content: Solution
      7m 59s
  4. 42m 39s
    1. What happens when styles conflict?
      4m 0s
    2. Understanding the cascade
      5m 47s
    3. Using inheritance
      6m 11s
    4. Selector specificity
      6m 55s
    5. The !important declaration
      4m 5s
    6. Reducing conflicts through planning
      3m 33s
    7. Resolving conflicts: Lab
      6m 45s
    8. Resolving conflicts: Solution
      5m 23s
  5. 1h 47m
    1. Setting a font family
      7m 10s
    2. Using @font-face
      9m 18s
    3. Setting font size
      7m 35s
    4. Font style and font weight
      6m 52s
    5. Transforming text
      3m 58s
    6. Using text variants
      2m 49s
    7. Text decoration options
      4m 26s
    8. Setting text color
      3m 2s
    9. Writing font shorthand notation
      8m 49s
    10. Controlling text alignment
      6m 33s
    11. Letter and word spacing
      9m 11s
    12. Indenting text
      4m 30s
    13. Adjusting paragraph line height
      10m 30s
    14. Controlling the space between elements
      6m 41s
    15. Basic text formatting: Lab
      8m 45s
    16. Basic text formatting: Solution
      7m 14s
  6. 2h 1m
    1. Understanding the box model
      16m 53s
    2. Controlling element spacing
      14m 29s
    3. Controlling interior spacing
      10m 49s
    4. Margin and padding shorthand notation
      6m 27s
    5. Adding borders
      8m 57s
    6. Defining element size
      10m 7s
    7. Creating rounded corners
      6m 58s
    8. Background properties
      2m 51s
    9. Using background images
      5m 10s
    10. Controlling image positioning
      10m 25s
    11. Using multiple backgrounds
      7m 5s
    12. Background shorthand notation
      5m 25s
    13. Styling container elements: Lab
      7m 55s
    14. Styling container elements: Solution
      8m 17s
  7. 47m 51s
    1. Color keyword definitions
      5m 4s
    2. Understanding hexadecimal notation
      6m 5s
    3. Using RGB values
      4m 58s
    4. Using HSL values
      5m 17s
    5. Working with opacity
      2m 23s
    6. Using RGBa and HSLa
      3m 8s
    7. Styling drop shadows
      5m 38s
    8. CSS gradients
      6m 32s
    9. Working with color: Lab
      4m 26s
    10. Working with color: Solution
      4m 20s
  8. 1m 58s
    1. Additional resources
      1m 58s

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CSS: Core Concepts
8h 49m Beginner Nov 22, 2011

Viewers: in countries Watching now:

In this hands-on course, James Williamson demonstrates the concepts that form the foundation of Cascading Style Sheets (CSS), including styling text, adding margins and padding, and controlling how images display. The course also explores the tools needed to work with CSS, the differences between embedded and external styles, how to use selectors to target elements, and what to do when styles conflict.

Topics include:
  • Exploring default styling
  • Writing a selector
  • Setting properties
  • Working with common units of measurement, including ems and pixels
  • Structuring HTML correctly
  • Understanding the cascade and inheritance
  • Setting a font family, font size, text color, and more
  • Understanding the box model
  • Styling container elements
  • Working with RGB vs. HSL values
  • Styling drop shadows
Subject:
Web
Software:
CSS
Author:
James Williamson

The !important declaration

In addition to the cascade, inheritance, and specificity, there is one more CSS technique that can be used to resolve conflicts, and that is the important declaration. I like to call the important declaration the WMD of CSS. It doesn't matter what else is going on in your styles, in the event of a conflict, the important declaration wins, end of story. In fact, the only thing that can override an important declaration is another more specific important declaration, or some type of user-controlled style sheet. Let's try it out.

I have the important.htm file open here. You can find this in the 03_05 folder. Again, very simple. We have a section of an ID of main content, a paragraph with the strong tag inside of it, so really, you know basically the same thing we had in the previous movie. I want to go back up to our styles here and after the existing paragraph selector, I'm going to type in mainContent p, and here we're just going to get a new color, green. Obviously, the paragraph was going to be red, but we know since this paragraph is inside of an ID with main content and we know that the selector is much more specific plus its placed in the cascade, we know pretty what's going to happen here. If we preview this in a browser, yes, indeed we get green text.

Okay, so nothing new there. I want to go down, however, into the actual code itself, and I'm going to apply an inline style here, so style equals, and inside that I'm just going to new color purple. So again save this, preview this, and exactly what we expected to happen. So we have got inheritance, we have got the cascade, we have got the inline styles going on here, and all of them are behaving exactly the way we expected them to. But remember, there is one rule to rule them all, and that is the important declaration.

If I go back up to my very first paragraph selector and after the property value red-- now I'm going to do this inside of the semicolon, but leave a little bit to whitespace between the property value and this-- I'm going to type in an exclamation point and the word important. So the exclamation point means you're serious, so hey, this is important. And that's really what this is saying: this is saying hey, this is the most important thing in the world regarding this property. So you need to overwrite everybody else. So if I save this and once again preview it, it goes right back to being red.

So irregardless of the cascade, irregardless of specificity, irregardless of the inline style, the important declaration wins, and it will win every single time. Of course this is an extremely useful tool to have. I really want to caution you about using this. Too many times, designers that are new to CSS and when they run into a styling conflict that they just can't seem to solve with their complex site, they will just throw the important declaration out there, knowing that it's going to apply the desired styling and solve any of the other conflicts, so they just kind of start doing that as a regular thing.

Now the problem with this is that pretty soon you're styling becomes littered with important declarations that makes your styles an absolute nightmare to maintain, and it's almost impossible for anybody following you and editing your code to track down any of those styling conflict, because you have those things overwriting everything else. I would even almost go as far as to recommend that you not even use it or that if you do use it, you think of it as like kind of a last resort. Now I'll be honest, in all of the years that I've styled sites with CSS I have never used it, not one time.

I have always found that there's always another way to solve conflicts. Now, I'm not saying that you should never use it, just that I personally have never had to. In some cases, such as like a user- interface-widget styling that you want to make sure it never gets overwritten and those user interface widgets might travel from site to site, I would say it's very acceptable to use it. I'm just saying that make sure you have a valid reason for using it and that you have documented its use in your CSS, so that it doesn't come back to haunt you later on.

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