Publishers of technology books, eBooks, and videos for creative people

Home > Articles > Web Design & Development > CSS

The Usual Suspects: Detecting and Preventing the Most Common Culprits Behind CSS Problems

📄 Contents

  1. Prepare Yourself with Structure and Interrogation Know-How
  2. Page Layout Misdemeanors: Bringing the Usual Suspects to Justice
  3. Book 'Em, Danno!
Denise R. Jacobs, author of The CSS Detective Guide: Tricks for Solving Tough CSS Mysteries, presents a lineup of the biggest CSS troublemakers. By arresting these problems in your code, you can create smooth layouts in which all the elements are good citizens.
Like this article? We recommend

No matter what your level of expertise is with coding CSS, you'll probably run up against some typical miscreants that cause layout issues. With a bit of foreknowledge, however, you can code proactively and prevent CSS crimes from being committed in your code. In case you don't catch the problems before they happen, I've provided some solid troubleshooting tips as well.

Prepare Yourself with Structure and Interrogation Know-How

The first step in preventing the usual culprits from page layout foul play is to create a structured environment in your code. Having standards-based, well-formed, and organized code goes a long way toward averting misdeeds. Following are five good tips for establishing a zero-tolerance policy for bugs and problems.

Get Everything in Order

Putting your CSS declarations into alphabetical order is a great way to set the stage for clean code and fewer problems. Why? Because your style declarations will be easier to locate. Don't believe me? Look for the width property in these two examples:

Example 1:

.login {
margin-top: 5px;
line-height: 1.5em;
padding-left: 5px;
float: right;
list-style-type: none;
width: 80px;
font-weight: bold;
border-left: 1px solid #69824d;

Example 2:

.login {
border-left: 1px solid #69824d;
float: right;
font-weight: bold;
line-height: 1.5em;
list-style-type: none;
margin-top: 5px;
padding-left: 5px;
width: 80px;

Of course you found the property in each example, but knowing that width was going to be at the bottom of one of the examples helped you to find it more easily, didn't it?

Clearly Indicate Hierarchy

Another way to maintain control of your coding environment (which acts as a preventive measure against later problems) is to indent style declarations. My preferred method is to match the style declarations to the hierarchy of the HTML document. Suppose you have an HTML document with this hierarchy and structure:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
<html xmlns="" xml:lang="en" lang="en">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Example Website Title</title>

<div id="pagewrap">
      <div id="header">
            <h1>Website Title</h1>

            <ul id="navigation">
                  <li><a href="#">Home</a></li>
                  <li><a href="#">About</a></li>
                  <li><a href="#">Contact</a></li>
      </div><!-- end #header -->

      <div id="contentwrap">
            <div id="maincontent">
                  <h2>Main Content Title</h2>
                  <p>Main content, which is so much more important than the secondary
                     content that it makes one teary with emotion.</p>
                  <p>More main content, which has you glued to the screen,
                     reading every new word with sweet anticipation.</p>
            </div><!-- end #maincontent -->

            <div id="secondarycontent">
                  <h3>Sidebar Title</h3>
                  <p>Sidebar content, which is not as important as the primary
                     content (which is why it is in the sidebar)</p>
            </div><!-- end #secondarycontent -->
      </div><!-- end #cotentwrap -->

      <div id="footer">
            <p>standard copyright and footer information</p>
      </div><!-- end #footer -->
</div><!-- end #container -->

You would structure the stylesheet style declarations like this:

body {...}

      #pagewrap {...}

            #header {...}

            #nav {...}

                  #nav li {...}

      #contentwrap {...}

            #maincontent {...}

            #secondcontent {...}

      #footer {...}

This kind of structure in the stylesheet not only reflects the document hierarchy, but helps you to find your styles more easily.

Make Comments

Comments are the unsung heroes of stylesheet organization and prospective bug management. Comments in stylesheets are used for many purposes, such as writing notating styles for yourself or anyone else who may be working in the document:

font-size: 1.2em;
/* font size change from original 1.25em */

Comments are also used to create sections in the stylesheet for better organization:

/* ---- Content Wrap Section Styles ---- */
      #contentwrap {...}

            #maincontent {...}

            #secondcontent {...}

Maintain Neutrality

You may have gotten to the point in your code where you've detected a de facto problem[md]or one that's waiting to happen. There are a couple of ways to take out potential code offenders.

Just as you can use comments to notate and organize your stylesheet, you can use them to remove pieces of code while troubleshooting:

#pagewrap {
/* background: transparent url(bg_design.png) top center no-repeat; */
border: 1px solid #eee;
margin: 0 auto;
padding: 0;
width: 990px;

Another good way to incapacitate styles for an element is to add x- in front of the selector:

x-#navigation {
border: 5px solid #aaa;
color: #456829;
margin: 10px 5px;
padding: 0;
width: 350px;

This is a quick way to disconnect the style from the element on the page, helping you get to the bottom of any issues in the document that much faster.

Establish a Perimeter

A final tool in your arsenal against delinquent styles and wayward elements is to box them in and show their boundaries. By adding either the border or outline property to the style declaration block, you can clearly delineate the periphery of the element. Here's an example using border:

#secondcontent {
border: 1px dotted blue;
font-size: .90em;
float: right;
margin: 0;
padding: 0;
width: 250px;

Or you can use outline:

#secondcontent {
outline: 1px dotted green;
font-size: .90em;
float: right;
margin: 0;
padding: 0;
width: 250px;

What's the difference between border and outline? A border is a component of the box model, so giving an element a border adds to the dimensions of the element. In contrast, outline is not part of the box model. Instead, an outline is drawn on top of the element's box. Thus, the outline property doesn't add to the dimension of the element.

Which technique is better? That depends on which browser you're using for testing. outline is great for modern browsers, but isn't supported by Internet Explorer 6 and 7. For delineating elements in these older browsers, border is a better bet.

Peachpit Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from Peachpit and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about Peachpit products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites; develop new products and services; conduct educational research; and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by Adobe Press. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive:

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020