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Two CSS layouting techniques compared: Flexbox vs. Grid

CSS Flexbox has become extremely popular amongst front-end developers the last couple of years. This isn’t surprising, as it has made it a lot easier for us to create dynamic layouts and align content within containers.
However, there’s a new kid in town called CSS Grid, and it’s got a lot of the same capabilities as Flexbox. In come cases it’s better than Flexbox, while in other cases it’s not.

If you are to take one lesson from this article, let it be this one:

Flexbox is made for one-dimensional layouts and Grid is made for tw…

Repeats

Sass partial names must always begin with an underscore

Be careful to name any file @imported by SASS with a leading underscore.

SASS files not beginning with an underscore will be rendered on their own, which will fail if they are using variables or mixins defined elsewhere. (For me it broke only in production, which may be due to some settings in SASS-GEM/lib/sass/plugin/rails.rb.)

From the SASS docs:

The underscore lets Sass know that the file is only a partial file and that it should not be generated into a CSS file.

Repeats

Detect the current Rails environment from JavaScript or CSS

Detecting if a Javascript is running under Selenium WebDriver is super-painful. It's much easier to detect the current Rails environment instead.

You might be better of checking against the name of the current Rails environment. To do this, store the environment name in a data-environment of your <body>. E.g., in your application layout:

%body{'data-environment' => Rails.env}

Now you can say in a piece of Jav…

Repeats

Grep through the DOM using the Capybara API

When your Cucumber feature needs to browse the page HTML, and you are not sure how to express your query as a clever CSS or XPath expression, there is another way: You can use all and find to grep through the DOM and then perform your search in plain Ruby.

Here is an example for this technique:

Then /^I should see an image with the filename...
Linked content

Nested Spreewald patiently blocks are now patient

In Spreewald 1.10.4+, nested patiently blocks are now patient.

Here is an example:

patiently do
  outer_code
  patiently do
    inner_code
  end
end

On spreewald 1.11.2+ the inner block will wait for the full configured wait time (by default 5 seconds). The outer patiently block would now be out of time, but it will always be retried at least a second time. This behavior allows with_scope to be patient, and it must be patient, as explained below.

In versions 1.10.4 - 1.11.1, inner blocks would keep giving the ou…

Linked contentRepeats

CSS: Opacity is not inherited in Internet Explorer

Elements will not inherit their parent's opacity in IE for no good reason. This can lead to unexpected behaviour when you want to fade/hide an element and all its children.

To fix it, give the element defining the opacity a non-static positioning. For example:

.foo {
  opacity: 0.2;
  position: relative; /* for IE */
}

While the linked article describes this problem for IE9 and below, I have encountered the same issue in IE10 and IE11.

Just go away, Internet Explorer!

Deprecated

Centering with CSS vertically and horizontally (all options overview)

There are a million ways to center <div>s or text in CSS, horizontally or vertically. All the ways are unsatisfying in their own unique way, or have restrictions regarding browser support, element sizes, etc.

Here are two great resources for finding the best way of aligning something given your use case and browser support requirements:

How to center in CSS
A long form that lets you define your use case and browser support requirements, then shows you the preferred way of aligning.

[Centering CSS: A com…

Capybara: A step for finding images with filename and extension

This cucumber step is useful for testing an image (looking at the src of the image).

Then(/^I should see the image "([^"]*)"$/) do |filename_with_extension|
  expect(page).to have_css("img[src*='#{filename_with_extension}']")
end
Then I should see the image "placeholder.png"

Outline: Read more about how to test a uploaded file here, e.g. file downloads.

Sprites with Compass

Using CSS sprites for background images is a technique for optimizing page load time by combining smaller images into a larger image sprite.

There are ongoing arguments on how useful this still is, as modern browsers become more comfortable to load images in parallel. However, many major websites still use them, for example amazon, [facebook](…

Repeats

Check that an element is hidden via CSS with Spreewald

If you have content inside a page that is hidden by CSS, the following will work with Selenium, but not when using the Rack::Test driver:

Then I should not see "foobear"

This is because the Rack::Test driver does not know if an element is visible, and only looks at the DOM.

Spreewald offers steps to check that an element is hidden by CSS:

Then "foo" should be hidden # "should not be visible" in Spreewald < 1.2.3

You can also check that an element is visible:

Then "foo" shou...
Linked content

CSS: Giving text lines a background-color (with configurable line padding and margin)

The gist is:

  • wrap the text with a span
  • use line-height for the spacing between lines ("margin")
  • use box-shadow to control the line background size ("padding")

Example

text_lines_with_background_color.png

span
  box-shadow: 0 0 0 10px #fff
  background-color: #fff
  box-decoration-break: clone # Fix Firefox
  line-height: 2.2

→ [jsfiddle](https://jsfiddle.net/2fmqgbh…

How to fix HTML elements being cut off when printing

When you print (or print preview) and elements are cut off (e.g. after 1st page, or "randomly") you should check your CSS rules for these:

  • Is there an element with "display: inline-block" that surrounds your content? Make sure it has "display: block" for printing.
    This primarily affects Firefox and Internet Explorer. Chrome seems to be able to handle inline-block elements in most cases.

  • Does the element itself, or a container, define "overflow: hidden"? Use "overflow: auto" (or maybe "overflow: visible") instead.

  • Is th…

Linked content

Limitations you should be aware of when Internet Explorer 9 parses CSS files

Internet Explorer until version 9 has some limitations when parsing CSS files

Summarized, these are:

  • Up to 31 CSS files or
  • Up to 4095 selectors per CSS file.
  • Up to 3 nested @import rules

To test the selector limit for a specific browser, check this CSS selector limitation test website.

When you run into this issue, the following links might be helpful to fix the problem. The Idea is to split up the css fi…

Repeats

HTML: Making browsers wrap long words

By default, browsers will not wrap text at syllable boundaries. Text is wrapped at word boundaries only.

This card explains some options to make browsers wrap inside a long word like "Donaudampfschifffahrt".

Option 1: Soft hyphens

Unicode has a soft hyphen character you can use to mark optional word division opportunities. The soft hyphen is an invisible character with zero width. Only when the browser decides to wrap at a soft hyphen, it is turned in…

Repeats

Jasmine: Testing AJAX calls that manipulate the DOM

Here is a Javascript function reloadUsers() that fetches a HTML snippet from the server using AJAX and replaces the current .users container in the DOM:

window.reloadUsers = ->
  $.get('/users').then (html) ->
    $('.users').html(html)

Testing this simple function poses a number of challenges:

  • It only works if there is a <div class="users">...</div> container in the current DOM. Obviously the Jasmine spec runner has no such container.
  • The code requests /users and we want to prevent network interaction in our unit test…
Linked contentRepeats

CSS has a well-supported :empty selector

All browsers + IE9 know the CSS :empty selector. It lets you hide an element when it has no content, i.e. not even white space.

For instance, you have a badge displaying the number of unread messages in a red bubble with white text:

.unread-messages-bubble {
  background-color: red;
  border-radius: 10px;
  padding: 10px;
  color: white;
}

To hide that bubble entirely when there are no new messages:

.unread-messages-bubble:empty {
  display: none;
}

Note that the element must be…

How to fix broken font collisions in wkhtmltopdf

If you are using PDFKit / wkhtmltopdf, you might as well want to use custom fonts in your stylesheets. Usually this should not be a problem, but at times they include misleading Meta-information that leads to a strange error in the PDF.

The setup

  • The designer gave you two fonts named something like BrandonText-Regular and BrandonText-Bold. (With flawed Meta-information)
  • You have a HTML string to be rendered by PDFKit
  • For demonstration purposes, this strin…
Linked content

How to exploit websites that include user input in their CSS

The linked article shows how to exploit websites that include unsanitized user input in their CSS.

Although the article often mentions React and CSS-in-JS libraries, the methods are applicable to any web app that injects user input into style tags or properties.

Also, sanitizing user input for CSS injection is much harder than sanitizing HTML.

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