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

Home > Articles > Web Design & Development > Usability

This chapter is from the book

Dealing with bugs and browser inconsistencies

Writing CSS that works consistently across browsers is often more difficult than it looks. Hacks—the "creative" syntax developers use to target or exclude a specific browser—should be used as a last resort, and applied selectively, because they're difficult to maintain and may cause rendering issues as newer, standards-compliant browser versions are released. Fortunately, hacks are usually avoidable if you approach CSS the right way. For the limited cases where it's unavoidable, we have some recommended techniques.

Conditional comments

Internet Explorer is infamous among web designers for its quirky handling of CSS, but given its share of the browser market, even minor rendering differences are hard to ignore. For situations where you simply can't make your layout render properly in versions of Internet Explorer, there are conditional comments—a proprietary feature of Internet Explorer that let you specify HTML markup that only IE will see. (Since they use standard HTML comment syntax, other browsers will disregard them.)

When CSS workarounds for IE are necessary, you can list those style rules in a separate style sheet and reference it on the page within conditional comments:

<!--[if IE]>
  <link rel="stylesheet" type="text/css" href="ie_fixes.css" />

Conditional comments can be targeted to a particular version of IE. We always recommend specifying a version, or all versions prior to a particular one, by using lt so later, more standards-compliant versions of IE won't see them. For example, the following conditional comment is read only by versions of IE released before version 7 (that is, earlier than IE 7):

<!--[if lt 7]>
  <link rel="stylesheet" type="text/css" href="ie_fixes.css" />

When writing CSS within IE-specific style sheets, we recommend the following:

  • Target exceptions only: An IE-specific style sheet should contain a minimal number of workarounds that cascade off styles that are served to all browsers.
  • Use filters sparingly: Many versions of Internet Explorer include proprietary CSS properties known as filters, which enable advanced effects such as shadows and blurs, and allow fixes for IE's rendering of semi-transparent PNGs (see sidebar). Unfortunately, IE filters are invalid CSS, and can also slow down page performance. Use with caution, if at all.

Common issues and workarounds

Through our experience in creating CSS layouts that work across a wide array of browsers, we've noticed a number of issues that seem to occur in almost every project. Here are some workarounds we commonly use to fix them.

Clearing and containing floats

When a CSS float is applied to an element, its height is no longer recognized by its parent element. This layout behavior sometimes conflicts with how the layout should render, so there's a need for a workaround to make the parent element wrap around its floated children. The simplest fix for the problem is to float the parent element, or to set its overflow property to auto, but this doesn't work in every situation.

As an alternate approach, we can apply a workaround known as "clearfix." The clearfix technique works by injecting an element just after the last floated child element, and using CSS to give it block and clear properties. Since this new element is not floated itself, it will cause the parent to recognize its location and wrap around it.

The CSS for clearfix is pretty clever. It uses the :after pseudo-element selector to create and style an element—in this case, a single character—without the need for JavaScript. Simply add the following style rule to your enhanced style sheet, and apply class="clearfix" to an element to force it to wrap around all floated child elements:

.clearfix:after {
  content: " ";
  display: block;
  height: 0;
  clear: both;
  visibility: hidden;

The :after selector is not supported in Internet Explorer versions 7 and earlier, so it's necessary to include a second selector to ensure the clearfix technique works. The proprietary zoom: 1 property triggers hasLayout (described later in this chapter) in Internet Explorer, which will cause it to wrap its floated child elements. Keep in mind that it's good practice to store IE-specific styles in a separate style sheet and reference that style sheet using a conditional comment:

/* for Internet Explorer */
.clearfix {
  zoom: 1;

There is an alternate, and less obtrusive, approach to assigning the clearfix class throughout the markup. The clearfix style rules can be scoped to all elements that need them by listing their selectors in the style sheet:

#footer:after {
  content: " ";
  display: block;
  height: 0;
  clear: both;
  visibility: hidden;
/* for Internet Explorer */
#footer {
  zoom: 1;

This change keeps the markup free of classes for visual workarounds, and can reduce page weight.

Addressing z-index issues

In modern websites, it's common for user interface components to not only be positioned next to each other, but also stacked in front of or behind other elements. In CSS, this stacking is handled through a property called z-index.

The z-index property can be applied to any element with relative, absolute, or fixed position (assigned with the position property), and accepts a number that represents its vertical stack position among other elements on the page; an element with a higher z-index value appears in front of elements with lower (or no) z-index values. The entire document has a stacking context—elements are stacked relative to sibling elements on the page—and every container element with a z-index applied creates a new stacking context for child elements, meaning that child z-index values are relative to one another, and not to the rest of the page.

Internet Explorer versions 7 and earlier interpret this stacking model incorrectly: they create a new stacking context for all positioned elements, even those without a specified z-index. This can make it difficult to layer stacked elements in a predictable way. For example, an absolutely positioned tooltip that sits inside a relatively positioned fieldset element may appear behind other positioned elements on the page, because IE treats them like stacked elements when they should just appear in the document flow.

To combat this issue for absolutely positioned elements, we use JavaScript to append the markup (in this case, the tooltip) just before the end of the body element. Doing this ensures that the tooltip will sit in the document's stack order (not a particular element's), and if we assign a high enough z-index value, it will appear in front of all other page elements. In general, we recommend taking this approach when dynamically appending any overlaid content, because it removes any guesswork about where an element should be inserted to layer correctly above all other page content.

Another Internet Explorer z-index issue is that "windowed" elements such as select, iframe, object (used for plugins like Adobe Flash), and anything with scrollbars, all tend to stack in front of everything else, regardless of source order or z-index value. Unfortunately, the workaround for this issue is not pretty: we use JavaScript and CSS to inject an empty, hidden iframe element directly behind any content that is intended to appear in front of the rest of the page, with dimensions large enough to act as a shield, blocking windowed content from leaking through.

Fixing hasLayout bugs in Internet Explorer

When you test CSS layouts in Internet Explorer, you're bound to run into seemingly random rendering bugs—elements that appear partially visible, act oblivious to style rules, blink while scrolling, or reveal fragments of text in unexpected places on the page.

These types of bugs are often the result of issues with IE's rendering engine, and are typically caused by an element lacking a quality Microsoft refers to as hasLayout. The details of what exactly hasLayout means are somewhat mysterious. In general, block-level elements are considered to have hasLayout in IE's rendering engine, but sometimes the engine forgets to apply hasLayout where it should.

There are a few CSS properties that can be applied to an element to trigger hasLayout:

  • position: relative; This property is often the safest hasLayout workaround; we generally try it first.
  • zoom: 1; An invalid and proprietary, yet somewhat harmless, CSS property that assigns a page-zoom level of 100% to an element, rendering it as it would by default.
  • height: 1%; or any height setting, for that matter, will usually trigger hasLayout.

To ensure that future browser versions with better standards support won't see these styles, consider placing hasLayout style fixes in an IE-specific style sheet that is targeted only to the specific versions of Internet Explorer that need them.

We've covered how to effectively write and organize your styles so they can be cleanly targeted to the basic and enhanced experiences. Next, we'll discuss how to transform the foundation markup by unobtrusively layering on JavaScript to enhance the page and add interactivity.

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