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How to: expand an element's cover area beyond its container

Occasionally, your designer will hand you designs where elements break the layout's horizontal container width, like navigation buttons of a slider that should be at the left/right of the browser window, or simply by applying a background color that reaches until the left and right of the browser window.

In the past, we've done some horrible things to achieve that. Like margin: 0 -10000px plus overflow-x: hidden.
There is a much saner approach.

Consider the following markup:

```html

<div class="sec...
Linked contentRepeats

CSS: Matching against attributes and their values (or parts of them)

You probably know that you can use CSS selectors to match against elements and their attributes, such as:

a[title] { /* any <a> that has a "title" */ }
a[data-fancy="true"] { /* any <a> that has their "data-fancy" attribute set to "true" */ }

But there is more: You do not need to match against "full" attribute values but can match against parts of them.

They work in all somewhat modern browsers, and IE9 or later.

Exact match (CSS2)
[foo="bar"] (matches <div foo="bar" />, but not `<div…

Minify Font Awesome fonts with webpack

Font Awesome 5 is a comprehensive solution for vector icons on your website.

Originally, Font Awesome came as an icon font (plus stylesheets), but recently it can also be used as a pure JavaScript solution (which will render icons as inline <svg> tags), or even as SVG sprites.

All solutions have their pros and cons:

Icon font:

  • little CPU load (no JavaScript)
  • fonts are relatively large
  • 1 extra HTTP request

Javascript + inline SVG:

  • higher CPU load (needs to watch the DOM via mutation observers to ad…
Repeats

Raising JavaScript errors in Cucumber scenarios and how to silence them for particular scenarios

Raising JavaScript errors in Cucumber

With selenium JavaScript errors do not cause any failture in your cucumber scenarios. To archive a failture we can use the the Ruby bindings to Selenium Webdriver expose the Webdriver logging API introduced in version 2.38 .

The following step can be used:

```
Then /^there should be no JavaScript errors$/ do
if alert_present?
# Chrome 54 and/or Chromedriver 2.24 introduced a breaking change on how
# accessing browser logs work.
#
# Apparently, while an alert/confirm is open, Chro…

Repeats

Capybara: Find an element that contains a string

There is no CSS selector for matching elements that contains a given string ¹. Luckily, Capybara offers the :text option to go along with your selector:

page.find('div', text: 'Expected content')

You can also pass a regular expression!

page.find('div', text: /Expected contents?/i)

Note that if your CSS selector is as generic as div, you might get a lot more results than you expect. E.g. a <div class="container"> that surrounds your entire layout will probably also contain that text (in a descendant) and Capybara wil…

Repeats

CSS: Combining different length units with calc()

calc() lets you mix CSS units. Ever wanted to give an element "the container's width minus 20px on each side"? Here you go:

width: calc(100% - (20px * 2));

When using Sass, you need to interpolate Sass expressions:

width: calc(100% - #{$margin})

Supported by all modern browsers and IE9+.

Linked contentRepeats

Do not use "flex: 1" or "flex-basis: 0" inside "flex-direction: column" when you need to support IE11

Flexbox is awesome. Most of it even works in IE11, but flex: 1 won't work reliably in Internet Explorer.
This it because implicitly sets flex-basis: 0 which IE fails to support properly.

Example

Consider the following HTML and CSS.

<div class="container">
  <div class="child">
    foo
  </div>
  <div class="bar">
    bar
  </div>
</div>
.container {
  display: flex;
  flex-direction: column;
}

.child {
  flex: 1;
}

See it in action at Plunker.

Background

Chrome bug: Wrong stacking order when transitioning composited elements

Google Chrome has a subtle rendering bug that hits me once in a while. It usually occurs in sliders with HTML content.

The issue

When a slider contains a composited[1] element, the element will overlap any other element when sliding, being rendered as frontmost element. After the slider has settled, stacking order jumps back to normal.

It seems like Chrome is doing its compositing wrong. This doesn't happen in Firefox.

The cause

The issue only occurs if:

  • two elements A and B are nested inside an element C
  • A overlaps B (part…

Introduction to Google Tag Manager (for web developers who know Google Analytics)

As a web developer, you know Google Analytics (GA). Probably you've dropped the GA snippet into more than one website, maybe you've even used its Javascript API to implement tracking at the event level.

Google Tag Manager (GTM) is a related tool, but on a higher level and thus with much more power. GTM is not a replacement for GA. Rather, it can make GA configurable without changing anything in the application's code base (and much more beyond, see below).

Only prefer GTM if the customer requests it, or if he is updating his tracking r…

Linked contentRepeats

Designing HTML emails

The 90s are calling: they want their tables back. Unfortunately, you need them all for laying out your HTML emails.

Email client HTML rendering is way more scattered than browser HTML. While you might have a pretty good understanding of what features and patterns you can use to support all major browsers, I doubt anyone masters this craft for HTML email clients.

The only way to ensure your email looks good (acceptable, at least) in all mail clients, is to check it. Litmus is your go-to solution for this (see below). W…

Linked content

CSS: Using interaction media detection to disable hover styles for devices that have no hover

Since late 2015, all major browsers (still excluding Firefox) support pointing device media queries. These can be used to distinguish e.g. coarse from fine pointers (e.g. finger vs mouse), or a device with hover support from one without (e.g. desktop with mouse vs tablet).

Motivation

When hover styles modify the DOM, most mobile devices activate the hover styles on first tap. A second tap is required to trigger a click. While this can be handy, at times it makes the UX worse.

Another issue with hover styles is that they tend to st…

Linked content

Logic in media queries

Here is how to model basic logic in media queries.

AND

With keyword and.

# Target viewport widths between 500 and 800px
@media (min-width: 500px) and (max-width: 800px)

OR

Comma-separated.

# Target viewport widths below 500 or above 800px
@media (max-width: 500px), (min-width: 800px)

NOT

Needs a little overhead with not all and.

# Target devices that can't hover
@media not all and (hover)

See CSS: Using interaction media detection on why you'd need this.

Repeats

How to make your application assets cachable in Rails

Note: Modern Rails has two build pipelines, the asset pipeline (or "Sprockets") and Webpacker. The principles below apply for both, but the examples shown are for Sprockets.


Every page in your application uses many assets, such as images, javascripts and stylesheets. Without your intervention, the browser will request these assets again and again on every request. There is no magic in Rails that gives you automatic caching for assets. In fact, if you haven't been paying attention to this, your application is probabl…

Linked contentRepeats

Printing background color of elements

Browsers' printing methods usually don't print background colors. In most cases this is the desired behavior, because you don't want to spent tons of ink printing the background of a web page. But in some cases you want to print the background color of elements, e.g. bars of a chart. For those elements you need to set the following css styles:

Chrome and Safari:

-webkit-print-color-adjust: exact;

Firefox:

color-adjust: exact;
Repeats

Stretching an HTML page to full height

This card existed before, but was outdated due to browser implementation changes. The information below is validated for the current list of browsers we support.


By default your html and body elements are only as high as the actual page content. If you only have two lines of text in your page, your html and body elements will only be around 40 pixels high, regardless of the size of your browser window.

You might be surprised by this, since setting a background on either html and body does cover the enti…

Linked content

CSS: Using the current text color for other color properties

There is a kinda secret, yet well supported CSS feature called currentColor. It's like a special CSS variable that has been supported in almost all browsers for almost all time (see linked Caniuse).

Usage

The currentColor value can be used in CSS to indicate the current value of color should be used. A common use case is setting a border color:

a.ghost
  color: white
  border: 1px solid currentColor
  &:hover
    color: red // Border color will change as well 

Note that in many cases, you can simply omit the color to ac…

Linked contentRepeats

Lazy-loading images

Since images are magnitudes larger in file size than text (HTML, CSS, Javascript) is, loading the images of a large web page takes a significant amount of the total load time. When your internet connection is good, this is usually not an issue. However, users with limited bandwidth (i.e. on mobile) need to mine their data budget better.

One popular strategy to improve the website performance is to not load images until they enter the viewport – aka "lazy-loading images".

General Issues

  • Crawlers do not execute JavaScript (generally sp…
Repeats

Rails asset pipeline: Why things break in production and what precompilation does to your assets

When you work with a Rails 3.1+ application, you will be working with the asset pipeline. The asset pipeline is awesome until you deploy. Then it will be less so if you haven't done everything as the pipeline expected it from you.

The problem

When using the asset pipeline your assets (images, javascripts, stylesheets, fonts) live in folders inside app:

app/assets/fonts
app/assets/images
app/assets/javascripts
app/assets/stylesheets

With the asset p…

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