Here a curated collection of css snippets that you can use for determinate situations or just for fun. Let's start.

Image rendering

img.QRcode {
  image-rendering: pixelated;
}

This property is useful to render QR codes and image thumbnails to increase their quality.

Check empty nodes

element:empty {
  display: none;
}

Hide your element when have no content inside. Returns and white spaces are considered as content.

Shape your text

p {
  shape-outside: polygon(0 0, 0 200px, 300px 600px);
}

Change the way how content will wrap around your floated elements.

Plain SVG as background

element {
  background-image: url('data:image/svg+xml;utf8,<svg>...</svg>');
}

Use <svg> as css background without convert it to base64.

Disable all user interactions

[data-untouchable] {
  pointer-events: none;
}

Disable all user interactions, even js events, with just one property.

Cleaned and self-contained component

element {
  all: initial;
  contain: content;
}

Create a style-cleaned and self-contained component with two properties. With contain: content will be created a new stacking-context and position fixed coordinates will reference to this property.

Overflow snapping

element {
  scroll-snap-type: mandatory;
  scroll-snap-align: center;
}

Control scroll snapping for elements with overflow.

System Font Stack

element {
  font-family:
    -apple-system,
    BlinkMacSystemFont,
    'Segoe UI',
    Helvetica,
    Arial,
    Ubuntu,
    sans-serif,
    'Apple Color Emoji',
    'Segoe UI Emoji',
    'Segoe UI Symbol';
}

Use the system font to provide a consistent typography experience.

Check if input has value

.Note {
  opacity: 0;
  transition: opacity 200ms ease-out;
}

input:not(:placeholder-shown) + .Note {
  opacity: 1;
}

This pseudo class allows you to check if the input have a value. Live demo.

Repeat Gradients

.RepeatLinear {
  background:
    repeating-linear-gradient(
      45deg,
      lime,
      lime 10px,
      pink 10px,
      pink 20px
    );
}

.RepeatRadial {
  background:
    repeating-conic-gradient(
      circle at 0 0,
      tomato,
      limegreen 50px
    );
}

You can repeat gradients instead of going mess with mixins.

Vector icons as mask

button {
  background: linear-gradient(to right, #d2ff52 0%, #30a85a 100%);
  height: 40px;
  width: 100px;
  mask: url('https://cdn.onlinewebfonts.com/svg/img_529012.svg');
  mask-repeat: no-repeat;
  mask-position: center;
  mask-size: 24px;
}

Use svg icons as mask and keep color manipilation. Live demo.

Float based on document direction

img {
  float: inline-start; /* ...or inline-end */
}

Float an element based on the text direction (rtl or ltr). More about logical properties

Target default form element

input:default {
  opacity: 0.2;
}

Target the default selected input in a gruop. Live demo.

Import your css when you need it

@import url('portrait.css') screen and (orientation: portrait);

You can conditionally import your css like you can do inline with the <link>. Please consider that vanilla css imports are a bad thing in terms of performance because they start an potentially infinite calls chain.

Target devices by pointer precision

@media (any-pointer: fine) { /* I'm default */ }
@media (any-pointer: coarse) { /* I'm a bit larger. I have a less precise pointer method */ }

Improve your touchable elements if the main pointer input is precise (mouse) or less precise (touch).

Prevent over-scroll

.ScollingContent {
  overscroll-behavior: contain;
}

Prevent over-scroll when the scroll reach the end of the element

Environment variables for edge screens

my-component {
  padding-bottom: env(safe-area-inset-bottom, 24px); /* 24px as fallback */
}

You need to enable env variables with:

<meta name='viewport' content='initial-scale=1, viewport-fit=cover'>

Prevent outline overlapping

button:focus {
  transform: rotate(0); /* rotate(0) is just an example */
}

By creating a new stacking context with the transform property you can fix the outline overlapping. Live demo.

Anchor scroll padding and margins

body {
  scroll-padding: 100px;
  scroll-margin-top: 10em;
}

Set the offset for in-page anchors links. Live demo.. More info about scroll-padding and scroll-margin.