National Library of Medicine Web Application/Site Development Guidelines

This Style Guide for the National Library of Medicine (NLM) explains the markup and design requirements for all NLM Web projects, along with various standards and best practices. NLM Web pages must be authored in valid HTML styled with valid Cascading Style Sheets and be coded in order to ensure accessibility.

Accessibility

NLM is committed to serving the entire public, and that means striving to ensure that all pages of our site are accessible to the greatest possible number of people and Assistive Technology devices.

Browsers

The NLM web site supports the current release of Chrome, Firefox and Safari, and the previous two versions. It also supports IE11 and above, and the current release of Microsoft Edge. "Supports" means that NLM will actively work to identify and fix bugs.

The use of HTML markup aimed at a specific browser (e.g., Microsoft Internet Explorer) should be avoided.

Scripts

NLM uses JavaScript in a selective manner. Pages should degrade gracefully when JavaScript is disabled. Any use of JavaScript should be cleared with your NLM project coordinator to assure it works well with existing site-wide implementations.

Charset

NLM recommends the use of the UTF-8 character set for Web pages so that non-English languages and diacritics are more effectively displayed. The coding to be placed in the HEAD tag of all Web pages is:

<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />

Design Policies

NLM's Web design policies.

Header and Footer

Guidelines for appropriately branding a Web site or application in development for NLM, and when to use the official NLM header and footer.

NLM Main Web Site - Coding Instructions

Includes NLM's official Cascading Style Sheets. If you wish to create your own style sheets, please discuss your requirements with your NLM project coordinator.

NLM Main Web Site - Coding Examples

Web page examples showing how markup will display the NLM css.

HTML and CSS

NLM Web pages must be authored in HTML5. All HTML must validate.

Web pages must use valid Cascading Style Sheets (CSS) to control typography, color, and other layout elements. Style sheets must be linked in a way that accommodates the capabilities of new and old browsers.

HTML: Guidelines

National Library of Medicine (NLM) Web pages must be authored in structural HTML5. Page authors should follow accessibility guidelines in compliance with Section 508 and the WAI so that our site’s content will be made available to the widest possible number of people, browsers, and Internet devices. In addition, all HTML must validate.

What is HTML5? (www.w3schools.com)
- A introduction to HTML5
HTML Accessibility (National Library of Medicine Accessibility)
- Making sure your pages can be read by all visitors, browsers, and devices.
HTML Validation (W3C's Unified Validator)
- Ensure interoperability by avoiding errors and sticking to coding standards.

CSS: Style Sheets & Tips

Web sites and web-based applications must use valid Cascading Style Sheets (CSS) to control typography, color, and other layout elements. Style sheets must be linked in a way that accommodates the capabilities of new and old browsers.

Cascading Style Sheets (W3C Cascading Style Sheets home page)
- What is CSS?
NLM Style Sheets
- NLM's official Cascading Style Sheets.
CSS Validation (W3C CSS Validation Service)
- Ensure style sheets are error-free.

If you wish to create your own style sheets, please discuss your requirements with your NLM project coordinator.

Last Reviewed: March 15, 2023