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Let's write more semantic CSS
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<h1>Let's write more semantic CSS</h1>
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<div id="article-date">2024-05-18</div>
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<p class="tags">
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<a href="/index/web.html" class="tag">web</a>
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<a href="/index/css.html" class="tag">css</a>
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<a href="/index/html.html" class="tag">html</a>
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</p>
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<article class="content-area">
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<p>You probably wrote something like this at least once in your life:
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</p><pre data-language="html"><div class="card card--rounded card--primary">
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<div class="card__image-container">
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<img src="image.jpg" alt="A nice image" class="card__image">
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<span class="card__image-caption">A nice image</span>
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</div>
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<div class="card__content">
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<div class="card__header">
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<div class="card__title">Hello, world!</div>
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</div>
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<p class="card__text">
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Lorem ipsum dolor sit amet, consectetur adipiscing elit.
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</p>
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</div>
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<div class="card__footer">
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<button class="btn btn--primary btn--raised btn--accent card__button card__button--primary">Click me!</button>
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<button class="btn btn--secondary btn--raised btn--accent card__button card__button--secondary">Click me!</button>
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</div>
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</div>
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</pre><p>Or this:
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</p><pre data-language="html"><div class="max-w-sm rounded overflow-hidden shadow-lg">
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<div>
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<img class="w-full" src="image.jpg" alt="A nice image">
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<span class="text-gray-500 text-base">A nice image</span>
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</div>
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<div class="px-6 py-4">
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<div>
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<div class="font-bold text-xl mb-2">Hello, world!</div>
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</div>
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<p class="text-gray-700 text-base">
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Lorem ipsum dolor sit amet, consectetur adipiscing elit.
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</p>
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</div>
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<div class="px-6 py-4">
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<button class="bg-blue-500 hover:bg-blue-700 text-white font-bold py-2 px-4 rounded">Click me!</button>
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<button class="bg-transparent hover:bg-blue-500 text-blue-700 font-semibold hover:text-white py-2 px-4 border border-blue-500 hover:border-transparent rounded">Click me!</button>
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</div>
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</div>
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</pre><p>The second one is an adapted example from the <strong class="emphasis-2">Tailwind</strong> CSS docs. The first one is a variant that
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uses <strong class="emphasis-2">BEM</strong> instead. Both of them have <em class="emphasis-1">many</em> problems.
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</p><p>HTML has got over 100 elements you could use to structure your content. These examples use only
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5: <code>div</code>, <code>span</code>, <code>p</code>, <code>img</code>, and <code>button</code>. This is not a problem in itself for small components,
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but it can indicate one. Using <code>div</code> and <code>span</code> for everything means you're misusing HTML. This
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is wrong: don't overlook HTML. JS or CSS may be more interesting, but the document language of
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the WWW is HTML.
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</p><p>The first example uses classes in place of elements. This creates extra work for both the HTML
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and CSS author. The CSS still mirrors the HTML structure, and the HTML is much more verbose than
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it needs to be. The word "button" or "btn" appears 8 times for each button. Ideally, it should
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appear two times: once in the opening tag and once in the closing tag.
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</p><p>The second example intentionally has the same markup tree as the first one. However, the classes
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changed a lot. Tailwind uses classes instead of CSS rules. It leads to repetition. If you don't
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want to repeat, you use components. But what if you don't do components? Then use <code>@apply</code> in
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CSS. Yes, CSS. So you're basically writing CSS only with a different syntax and less flexibility.
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</p><h2>A Simpler Way</h2><p>Let's strip the classes and focus on the markup tree for now. The two examples are identical in
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this regard.
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</p><pre data-language="html"><div>
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<div>
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<img src="image.jpg" alt="A nice image">
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<span>A nice image</span>
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</div>
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<div>
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<div>
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<div>Hello, world!</div>
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</div>
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<p>
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Lorem ipsum dolor sit amet, consectetur adipiscing elit.
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</p>
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</div>
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<div>
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<button>Click me!</button>
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<button>Click me!</button>
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</div>
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</div>
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</pre><p>Now you see what I said? This tree is not semantic at all. Let's find the appropriate elements for
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each generic one.
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</p><pre data-language="html"><article>
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<figure>
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<img src="image.jpg" alt="A nice image">
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<figcaption>A nice image</figcaption>
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</figure>
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<section>
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<header>
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<h2>Hello, world!</h2>
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</header>
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<p>
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Lorem ipsum dolor sit amet, consectetur adipiscing elit.
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</p>
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</section>
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<menu>
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<button>Click me!</button>
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<button>Click me!</button>
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</menu>
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</article>
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</pre><p>In case you're not familiar with the new elements, the quick meaning is:
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</p><ul><li><p><a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/article">article</a> - a self-contained
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piece of content that makes sense independently from the rest of the page
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</p></li><li><p><a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/figure">figure</a> - a piece of content
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that is referenced from the main content, but can stand alone
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</p></li><li><p><a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/figcaption">figcaption</a> - a caption
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for a <code>figure</code>'s other content (optional)
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</p></li><li><p><a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/section">section</a> - a thematic grouping
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of content, typically with a heading
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</p></li><li><p><a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/header">header</a> - header for the
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document or a smaller part of it, can include context, navigation or information about the
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content
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</p></li><li><p><a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/h2">h2</a> - a second-level section
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heading (you probably knew this one already)
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</p></li><li><p><a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/menu">menu</a> - a list of commands
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available to take on a specific part of the content
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</p></li></ul><p>Please read the MDN articles I linked if you want to know more about these elements.
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</p><p>Depending on the other needs of your website or application, you will probably need to add a few
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classes. However, unlike the other examples, classes should be used as little as possible. Let's
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remember some things from the examples:
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</p><ul><li><p>The article is supposed to be a card and styled as such.
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</p></li><li><p>The first button is the primary action, and the second one is the secondary action.
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</p></li></ul><p>In this site, let's say not all articles are cards, but since this one <em class="emphasis-1">is</em> a card, we'll
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classify it as such. Let's also say that the secondary buttons are more common, this means we'll
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add a class to the primary button and style that later.
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</p><pre data-language="html"><article class="card">
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<figure>
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<img src="image.jpg" alt="A nice image">
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<figcaption>A nice image</figcaption>
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</figure>
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<section>
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<header>
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<h2>Hello, world!</h2>
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</header>
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<p>
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Lorem ipsum dolor sit amet, consectetur adipiscing elit.
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</p>
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</section>
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<menu>
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<button class="button-primary">Click me!</button>
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<button>Click me!</button>
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</menu>
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</article>
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</pre><p>Now, let's write a basic stylesheet for this. It won't look exactly like the second example for
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the sake of simplicity, but it could easily be made to look like that. We're going to use a CSS
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selector you've probably only seen in resets and to set the font on the <code>html</code> element, the
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tag selector. We're also going to use some new CSS smarts to make the styles more maintainable.
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</p><pre data-language="css">html, button, input, select, textarea {
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font-family: system-ui, sans-serif;
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}
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article.card {
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background-color: whitesmoke;
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border-radius: 12px;
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box-shadow: 0 0 4px #00000040;
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display: flex;
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flex-direction: column;
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gap: 1rem;
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overflow: hidden;
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}
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figure {
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display: flex;
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flex-direction: column;
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gap: 0.25rem;
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}
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figure > img {
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width: 100%;
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height: auto;
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}
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figcaption {
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font-style: italic;
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opacity: 0.875;
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}
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article.card > section {
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padding-left: 1rem;
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padding-right: 1rem;
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}
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article.card > menu, menu.buttonbox {
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display: flex;
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gap: 1rem;
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justify-content: flex-end;
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}
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button, .button, /* provide alternative where it makes sense, since we may want to make something else look like a button */
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input:is([type="button"], [type="submit"], [type="reset"]) {
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background-color: white;
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color: orange;
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border: 4px solid currentColor;
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padding: 0.5rem 1rem;
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display: inline-flex;
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align-items: center;
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gap: 0.5rem;
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border: none;
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border-radius: 4px; /* Border radii are a decoration so pixels are fine */
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}
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:is(button, .button, input:is([type="button"], [type="submit"], [type="reset"])).button-primary {
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background-color: orange;
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color: white;
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}
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</pre><p>Observations:
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</p><ul><li><p>We provide alternatives for some tag selectors where it makes sense, in case we want to make
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something else look like a button. However, we don't force using both when it's already clear:
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<code><button></code> will produce a styled button, same as <code><a class="button"></code>. <code><button class="button"></code>
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is redundant.
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</p></li><li><p>The <code>></code> child selector is used to avoid leaking styles in more complex nested layouts.
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</p></li><li><p>We use the <code>:is()</code> pseudo-class to group selectors that have the same styles. This is a new
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feature in CSS and it saves us from writing an enormous amount of combinations.
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</p></li></ul><h2>Conclusion</h2><p>Now, writing HTML is much easier: the CSS will adapt to what you intended to describe. The CSS
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is also much easier to maintain: the style can be changed easily without changing the HTML. The
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elements are always styled automatically, and you can copy-paste a snippet of plain HTML
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and have it magically match the rest of your site.
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</p><p>A more complete framework for this could add some layout container utilities. For example, a
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<code>grid</code> class that makes the element a grid container and uses <code>--width</code> and <code>--gap</code> custom
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properties to position the children. There could also be layout <em class="emphasis-1">elements</em> to use in place of
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divs like <code>x-hbox</code> and <code>x-vbox</code> that are flex containers. This would indicate the default style,
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and an additional class or ID would be used to make them responsive as well. Utility classes
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aren't bad, but they should be used for the things that can't cause repetition - which side a
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dialogue should emerge from, or whether to add padding in a generic row container.
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</p><h2>Frameworks Using Semantic CSS</h2><ul><li><p><a href="https://picocss.com/">Pico CSS</a> - does it very well, I should take some inspiration from it
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</p></li><li><p><a href="https://watercss.kognise.dev/">Water.css</a> - a very minimalistic CSS framework, primarily intended
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for publishing, but also includes interactive elements
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</p></li><li><p><a href="https://andybrewer.github.io/mvp/">MVP.css</a> - a basic stylesheet for plain HTML made for any
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site to look acceptable
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</p></li><li><p>The roundabout also uses semantic CSS. Once the API is stabilised a little the CSS will be
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released as a framework.
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</p></li><li><p>You might not even need a framework.
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</p></li></ul>
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</article>
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