Tag: Simplified

Background Patterns, Simplified by Conic Gradients

For those who have missed the big news, Firefox now supports conic gradients!

Starting with Firefox 75, released on the April 7, we can go to about:config, look for the layout.css.conic-gradient.enabled flag and set its value to true (it’s false by default and all it takes to switch is double-clicking it).

Screenshot. Shows the Firefox URL bar at `about:config`, a search for 'conic' giving the `layout.css.conic-gradient.enabled` flag as the sole result and its value set to `true`.
Enabling conic gradients in Firefox 75+

With that enabled, now we can test our CSS including conic gradients in Firefox as well.

While some of the demos in this article work just fine when using a polyfill, some use CSS variables inside the conic gradient and therefore require native support for this feature.

One thing I particularly like about conic gradients is just how much they can simplify background patterns. So let’s take a few linear-gradient() patterns from the gallery created by Lea Verou about a decade ago and see how we can now simplify them with conic-gradient!

Pyramid

Screenshot. Shows the original pyramid pattern with the code that was used to create it.
The pyramid pattern

The pattern above uses four linear gradients:

background:   linear-gradient(315deg, transparent 75%, #d45d55 0) -10px 0,   linear-gradient(45deg, transparent 75%, #d45d55 0) -10px 0,   linear-gradient(135deg, #a7332b 50%, transparent 0) 0 0,   linear-gradient(45deg, #6a201b 50%, #561a16 0) 0 0 #561a16; background-size: 20px 20px;

That’s quite a bit of CSS and perhaps even a bit intimidating. It’s not easy to just look at this and understand how it all adds up to give us the pyramid pattern. I certainly couldn’t do it. It took me a while to get it, even though gradients are one of the CSS features I’m most comfortable with. So don’t worry if you don’t understand how those gradients manage to create the pyramid pattern because, one, it is complicated and, two, you don’t even need to understand that!

Using conic-gradient(), we can now get the same result in a much simpler manner, with a single background layer instead of four!

What I like to do when coding repeating patterns is draw equidistant vertical and horizontal lines delimiting the rectangular boxes defined by the background-size. In this case, it’s pretty obvious we have square boxes and where their limits are, but it’s a really useful technique for more complex patterns.

Annotated screenshot. Shows the rectangles (squares in this case) defined by the `background-size`.
Highlighting the pattern’s cells

By default, conic gradients start from 12 o’clock and go clockwise. However, in our case, we want to offset the start of the gradient by 45° in the clockwise direction and afterwards make every one of the four shades occupy a quarter (25%) of the available space around the midpoint of our square box.

SVG illustration. Shows how we place a conic gradient into a single pattern cell by rotating the gradient start point 45° in the clockwise (positive) direction.
A pattern cell with a conic gradient’s hard stops at every 25% starting from 45° w.r.t. the vertical axis (live).

This means our pyramid pattern can be reduced to:

$ s: 20px; background:   conic-gradient(from 45deg,      #561a16 25%,      #6a201b 0% 50%,      #a7332b 0% 75%,      #d45d55 0%)      50%/ #{$ s $ s};

Not only does the code look simpler, but we’ve also gone from 260 bytes to 103 bytes, reducing the code needed to get this pattern by more than half.

We’re using the double position syntax as that’s also well supported these days.

We can see it in action in the Pen below:

Checkerboard

Screenshot. Shows the original checkerboard pattern with the code that was used to create it.
The checkerboard pattern

This pattern above is created with two linear gradients:

background-color: #eee; background-image:   linear-gradient(45deg, black 25%, transparent 25%,      transparent 75%, black 75%, black),   linear-gradient(45deg, black 25%, transparent 25%,      transparent 75%, black 75%, black); background-size: 60px 60px; background-position: 0 0, 30px 30px;

Let’s see how we can simplify this CSS when replacing these linear gradients with a conic one!

Just like in the previous case, we draw vertical and horizontal lines in order to better see the rectangles defined by the background-size.

Annotated screenshot. Shows the rectangles (squares in this case) defined by the `background-size`.
Highlighting the pattern’s cells

Looking at the square highlighted in deeppink in the illustration above, we see that, in this case, our conic gradient starts from the default position at 12 o’clock. A quarter of it is black, the next quarter is dirty white and then we have repetition (the same black and then dirty white quarter slices once more).

SVG illustration. Shows how we place a conic gradient into a single pattern cell and then make it repeat after the 50% point.
A pattern cell with a conic gradient’s hard stops at every 25%, starting from the default at 12 o’clock and repeating after 50% (demo).

This repetition in the second half of the [0%, 100%] interval means we can use a repeating-conic-gradient(), which gives us the following code (bringing the compiled CSS from 263 bytes down to only 73 bytes – that’s reducing it by over 70%):

$ s: 60px; background:   repeating-conic-gradient(#000 0% 25%, #eee 0% 50%)      50%/ #{$ s $ s};

The Pen below shows it in action:

Diagonal checkerboard

Screenshot. Shows the original diagonal checkerboard pattern with the code that was used to create it.
The diagonal checkerboard pattern

Again, we have a pattern created with two linear gradients:

background-color: #eee; background-image:    linear-gradient(45deg, black 25%, transparent 25%,      transparent 75%, black 75%, black),   linear-gradient(-45deg, black 25%, transparent 25%,      transparent 75%, black 75%, black); background-size: 60px 60px;

We draw horizontal and vertical lines to split this pattern into identical rectangles:

Annotated screenshot. Shows the rectangles (squares in this case) defined by the `background-size`.
Highlighting the pattern’s cells

What we now have is pretty much the same checkerbox pattern as before, with the sole difference that we don’t start from the default position at 12 o’clock, but from 45° in the clockwise direction.

If you’re having trouble visualising how simply changing the start angle can make us go from the previous pattern to this one, you can play with it in the interactive demo below:

Note that this demo does not work in browsers that have no native support for conic gradients.

This means our code looks as follows:

$ s: 60px; background:   repeating-conic-gradient(from 45deg,      #000 0% 25%, #eee 0% 50%)    50%/ #{$ s $ s};

We can see it in action below:

Again, not only is the code simpler to understand, but we’ve also gone from 229 bytes to only 83 bytes in the compiled CSS, reducing it by almost two-thirds!

Half-Rombes

Screenshot. Shows the original Half-Rombes pattern with the code that was used to create it.
The half-rombes pattern

This pattern was created with four linear gradients:

background: #36c; background:   linear-gradient(115deg, transparent 75%, rgba(255,255,255,.8) 75%) 0 0,   linear-gradient(245deg, transparent 75%, rgba(255,255,255,.8) 75%) 0 0,   linear-gradient(115deg, transparent 75%, rgba(255,255,255,.8) 75%) 7px -15px,   linear-gradient(245deg, transparent 75%, rgba(255,255,255,.8) 75%) 7px -15px,   #36c; background-size: 15px 30px;

Just like in the previous cases, we draw equidistant vertical and horizontal lines in order to better see the repeating unit:

Annotated screenshot. Shows the rectangles (squares in this case) defined by the `background-size`.
Highlighting the pattern’s cells.

What we have here is a pattern that’s made up of congruent isosceles triangles (the angled edges are equal and the dark blue triangles are a reflection of the light blue ones) formed by the intersection of equidistant parallel lines that are either horizontal, angled clockwise, or the other way. Each of these three types of parallel lines is highlighted in the illustration below:

Illustration. Shows the equidistant parallel lines which create the pattern of isosceles triangles.
Parallel guides

Every pattern cell contains a full triangle and two adjacent triangle halves in the upper part, then a reflection of this upper part in the lower part. This means we can identify a bunch of congruent right triangles that will help us get the angles we need for our conic-gradient():

SVG illustration. Shows how we place a conic gradient into a single pattern cell by rotating the gradient start point by an angle β in the clockwise (positive) direction such that the 0% line goes through the top right corner and then all the other hard stops are either horizontal or going through the cell corners.
A pattern cell with a conic gradient’s hard stops such that they’re either horizontal or go through the cell corners, all starting from β w.r.t. the vertical axis (demo)

This illustration shows us that the gradient starts from an angle, β, away from the default conic gradient start point at 12 o’clock. The first conic slice (the top right half triangle) goes up to α, the second one (the bottom right dark triangle) up to 2·α, and the third one (the bottom light triangle) goes halfway around the circle from the start (that’s 180°, or 50%). The fourth one (the bottom left dark triangle) goes to 180° + α and the fifth one (the top left light triangle) goes to 180° + 2·α, while the sixth one covers the rest.

SVG illustration. Highlights the right triangle from where we can get α knowing the catheti and shows how we can then compute β.
Getting α and β (demo)

From the highlighted right triangle we get that:

tan(α) = (.5·h)/(.5·w) = h/w

Knowing the width (w) and height (h) of a pattern cell, we can get the angles α and β:

α = atan(h/w) β = 90° - α

It results in the pattern that’s generated by the following code:

$ w: 15px; $ h: 30px; $ a: atan($ h/$ w)*180deg/pi(); $ b: 90deg - $ a; $ c0: #36c; $ c1: #d6e0f5;  html {   background:      conic-gradient(from $ b,        $ c1 0% $ a,        $ c0 0% 2*$ a,        $ c1 0% 50%,        $ c0 0% 180deg + $ a,        $ c1 0% 180deg + 2*$ a,        $ c0 0%)      0 0/ #{$ w $ h}; }

This means going from 343 bytes to only 157 bytes in the compiled CSS. The result can be seen below:

You can tweak the pattern width ($ w) and height ($ h) in the Sass code in order to see how the pattern gets squished and stretched for different aspect ratios.

In the particular case where the angle between 2*$ a and 50% (or 180deg) is also $ a, it results that $ a is 60deg, our isosceles triangles are equilateral, and our gradient can be reduced to a repeating one (and under 100 bytes in the compiled CSS):

$ a: 60deg; $ b: 90deg - $ a; $ w: 15px; $ h: $ w*tan($ a); $ c0: #36c; $ c1: #d6e0f5;  html {   background:      repeating-conic-gradient(from $ b,        $ c1 0% $ a, $ c0 0% 2*$ a)      0 0/ #{$ w $ h} }

The live result can be seen below:

Bonus: Intersecting line backgrounds!

Screenshot. Shows the original intersecting lines pattern with the code that was used to create it.
Intersecting line background examples

While these are not repeating patterns, they’re examples of a situation where a single conic gradient achieves an effect that would have previously needed a bunch of linear ones.

What we have here is a conic-gradient() created starting from two straight lines intersecting within the rectangular box where we set the background.

SVG illustration. Shows a rectangular box and two random lines intersecting inside it. This intersection point (x,y) is the point the conic gradient goes around, while the gradient's start is from the angle β formed by the line segment closest to the top right corner with the vertical. The hard stops are at α, the angle between the start segment and the next one in clockwise order, at 50% and at 180° + α.
Bonus pattern structure (ldemo)

The gradient goes around the point of coordinates, x,y, where the two straight lines intersect. It starts from an angle, β, which is the angle of the line segment that’s closest to the top-right corner, then has hard stops at α, 50% (or 180°) and 180° + α.

If we want to have multiple elements with similar such patterns created with the help of different intersecting lines and different palettes, we have the perfect use case for CSS variables:

.panel {   background:      conic-gradient(from var(--b) at var(--xy),        var(--c0) var(--a), var(--c1) 0% 50%,        var(--c2) 0% calc(180deg + var(--a)), var(--c3) 0%); }

All we have to do is set the position (--xy), the start angle (--b), the first angle (--a) and the palette (--c0 through --c3).

.panel {   /* same as before */      &:nth-child(1) {     --xy: 80% 65%;      --b: 31deg;     --a: 121deg;      --c0: #be5128;     --c1: #ce9248;     --c2: #e4c060;     --c3: #db9c4e   }      /* similarly for the other panels */ }

Instead of hardcoding, we could also generate these values randomly or extract them from a data object with the help of a CSS or HTML preprocessor. In this second case, we’d set these custom properties inline, which is precisely what I did in the Pen below:

Since we’re using custom properties inside the conic gradients, this demo does not work in browsers that don’t support them natively.

Well, that’s it! I hope you’ve enjoyed this article and that it gives you some ideas about how conic gradients can make your life easier.

The post Background Patterns, Simplified by Conic Gradients appeared first on CSS-Tricks.

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Simplified Fluid Typography

Fluid typography is the idea that font-size (and perhaps other attributes of type, like line-height) change depending on the screen size (or perhaps container queries if we had them).

The core trickery comes from viewport units. You can literally set type in viewport units (e.g. font-size: 4vw), but the fluctuations in size are so extreme that it’s usually undesirable. That’s tampered by doing something like font-size: calc(16px + 1vw). But while we’re getting fancy with calculations anyway, the most common implementation ended up being an equation to calculate plain English:

I want the type to go between being 16px on a 320px screen to 22px on a 1000px screen.

Which ended up like this:

html {   font-size: 16px; } @media screen and (min-width: 320px) {   html {     font-size: calc(16px + 6 * ((100vw - 320px) / 680));   } } @media screen and (min-width: 1000px) {   html {     font-size: 22px;   } } 

That’s essentially setting a minimum and maximum font size so the type won’t shrink or grow to anything too extreme. “CSS locks” was a term coined by Tim Brown.

Minimum and maximum you say?! Well it so happens that functions for these have made their way into the CSS spec in the form of min() and max().

So we can simplify our fancy setup above with a one-liner and maintain the locks:

html {   font-size: min(max(16px, 4vw), 22px); }

We actually might want to stop there because even though both Safari (11.1+) and Chrome (79+) support this at the current moment, that’s as wide as support will get today. Speaking of which, you’d probably want to slip a font-size declaration before this to set an acceptable fallback value with no fancy functions.

But as long as we’re pushing the limits, there is another function to simplify things even more: clamp()! Clamp takes three values, a min, max, and a flexible unit (or calculation or whatever) in the middle that it will use in case the value is between the min and max. So, our one-liner gets even smaller:

body {   font-size: clamp(16px, 4vw, 22px); } 

That’ll be Chrome 79+ (which doesn’t hasn’t even dropped to stable but will very soon).

Uncle Dave is very happy that FitText is now a few bytes instead of all-of-jQuery plus 40 more lines. Here is us chucking CSS custom properties at it:

See the Pen
FitText in CSS with clamp()
by Dave Rupert (@davatron5000)
on CodePen.

The post Simplified Fluid Typography appeared first on CSS-Tricks.

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