Organise your styles with component-based CSS approach

Slides to my talk at the FrontConf Munich 2019.
You can find the examples and further reading links here: https://github.com/programmiri/component-based-functional-css-examples

Transcript

1. My approach to a Component-based CSS
2. Frontend Engineer Special ! for JavaScript, Unit-Testing and full aboard the Game of Thrones Hype train Twitter: @mirjam_diala
3. DAE?
4. It's just about making things look pretty. Right?
5. How we handle CSS
6. 1. Methology ... BEM & OOSCSS & SMACSS & DRY CSS & ACSS & ...
7. 2. Pre Processors ... SASS & SCSS & Stylus & ...
8. 3. Just don't write CSS CSS-in-JS: ... JSS & Styled Components & Emotion & Radium & ...
9. The C in CSS stands for "Calm down" ¯\_(ϑ)_/¯
10. Component-based CSS
11. Component-based what now? official definition my current approach
12. Better description • Functional Component-based CSS • Component-based functional CSS !
13. We’re not designing pages, we’re designing systems of components.1 — Stephen Hay 1 From his book "Responsive Design Workflow". Read more: http://bradfrost.com/blog/post/bdconf-stephen-hay-presents- responsive-design-workflow/
14. Components let you split the UI into independent, reusable pieces, and think about each piece in isolation.2 2 https://reactjs.org/docs/components-and-props.html
15. Style every component separately • components are easily reusable • easy to delete components • no side-effects when adding or removing styles
16. but...
17. .component-one { position: relative; font-family: 'Fancy Font'; font-weight: 500; font-size: 20px; color: var(--color-blue); margin-bottom: 2rem; padding: 1rem 1.5rem; background-color: var(--color-black); } .component-two { position: relative; font-family: 'Fancy Font'; font-weight: 700; font-size: 15px; color: var(--color-blue); margin-top: 2rem; padding: 1rem 1.5rem; background-color: var(--color-black); }
18. What about repetition?
19. Style every component separately
20. Functional CSS to the rescue!
21. .arial { font-family: Arial; } .font-1rem { font-size: 1rem; } .font-1.5rem { font-size: 1.5rem; } .font-color-primary { color: var(--color-primary) } .font-color-highlight { color: yellow; } <h2 class="font-1.5-rem font-color-primary arial">Headline</h2>
22. but...
23. What about redesigns?
24. Style everything with functional classes
25. We need a compromise
26. Separation of concerns does not really work with CSS anyways.
27. First try: content-specific classes Component based approach <p class="profil-lead"> I'm Mirjam and I'm a cat AND dog person! </p> .profil-lead { font-size: 150%; color: yellow; }
28. Second try: style-specific classes Functional CSS approach <p class="text-highlight text-big"> I'm Mirjam and I'm a cat AND dog person! </p> .text-big { font-size: 150%; } .text-highlight { color: yellow; }
29. So, what to do?
30. My current approach for separation Basic general styles like: font styles, colors Utility (functional) classes repeating styles that can be used universally CSS Component Counterpart to our website component
31. Basic - Characteristics • They are like a styleguide. • They tell you how your brand looks and behaves.
32. Basic - Example
33. :root { --font-headline: 'Domine', serif; --font-standard: 'Roboto', sans-serif; } html { font-size: 16px; } body { font-family: var(--font-standard); font-weight: 200; } h1,h2,h3,h4,h5,h6 { font-family: var(--font-headline); } .h1 { font-size: 3.5rem; }
34. Utility - Characteristics • They help you with all styles you would write over and over again. • They support you - and your team! - with a consistent style.
35. Utility - Example
36. .display-flex { display: flex; } .display-inline-flex { display: inline-flex; } .flex-direction-row { flex-direction: row; } .flex-direction-column { flex-direction: column; } .text-center { text-align: center; } .text-left { text-align: left; }
37. .margin-0 { margin: var(--spacer-0); } .margin-1 { margin: var(--spacer-1); } .margin-2 { margin: var(--spacer-2); } .padding-bottom-0 { padding-bottom: var(--spacer-0); } .padding-bottom-1 { padding-bottom: var(--spacer-1); } .padding-bottom-2 { padding-bottom: var(--spacer-2); }
38. CSS Component - Characteristics • They determine the rules how a specific website component has to look like. • This component style will work in every place of the markup.
39. CSS Component - Example
40. .Button { display: inline-block; font-weight: 500; text-align: center; vertical-align: middle; border: 1px solid transparent; padding: 0.375rem 0.75rem; font-size: 1rem; line-height: 1.5; border-radius: 0.25rem; transition: color 0.15s ease-in-out, background-color 0.15s ease-in-out, border-color 0.15s ease-in-out, box-shadow 0.15s ease-in-out; } .Button:hover { border: 1px solid var(--color-black); } .Button.Button-primary { background-color: var(--color-primary); } .Button.Button-secondary { color: var(--color-white); background-color: var(--color-secondary); }
41. General Rules
42. 1. Use classes • use classes to define styles • use styles on elements very carefully • don't use IDs to style
43. 2. Naming: consistent and clear • use speaking, semantic class names in basic and utility classes .text-lg { font-size: 150%; } .d-flex { display-flex; } .background-warning { background-color: var(--color-warning) } // ( ᐛ )و
44. Keep in mind: don't generate unexpected results (side effects)! .background-red { background-color: var(--color-warning); // var(--color-warning)= orange; font-weight: bold; } // <(ҹ^´)>
45. 2. Naming: consistent and clear Naming approach for the CSS Components • mirror the website component name <blockquote class="Quote">Text</blockquote> .Quote { width: 75%; margin-left: auto; margin-right: auto; }
46. • add classes with a prefix to style nested elements <blockquote class="Quote"> <div class="Quote-text"> <p> Imagine a inspirational quotes about dogs here. It's a really nice one and gives you a warm and fuzzy feeling, I promise! </p> <cite class="Quote-cite">Mirjam</cite> </div> </blockquote> .Quote .Quote-text { margin-top: 2rem; margin-bottom: 2rem; border-left: 10px solid var(--color-primary); padding-top: 1rem; padding-bottom: 1rem; padding-left: 2rem; font-size: 1.25rem; }
47. How to use it
48. That's how it looks • A lot of compositions to define appearance. • CSS Components whenever it makes sense. <div class="col-2 borderd border-dark padding-2 text-center margin-right-2"> <p> Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. </p> <button class="Button Button-primary" role="button">Get the Thing!</button> </div>
49. "display-flex align-items-center justify-content-center padding-3 background-primary" Embrace compositions! ❤
50. Build CSS components when it's useful • its style can't be accomplished easily with utility and basic classes • it's is a piece of content • it will be used in the same manner at least thrice
51. Build independent components Style components should only contain styles that define their unique appearance. They're independent from their environment. You should be able to put them anywhere in the markup.
52. Example <button class="Button Button-primary margin-2" role="button"> Get the Thing! </button>
53. How to use it - summary • Use compositions • Duplication cheaper than wrong abstraction • Discipline!
54. There is a big No-Go
55. Nest components, not styles Components can be nested in other components, but never nest CSS components to overwrite styles. <div class="Card Card-primary"> <p> Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. </p> <p>Lorem ipsum some more.</p> <button class="Button Button-primary" role="button">Get the Thing!</button> </div> <!-- (*^-^) -->
56. .Card-primary { .Button-primary { font-size: 0.8rem; } } // ( ಠ ಠ )
58. And that's it! Examples: github.com/programmiri/ component-based-functional-css-examples See, that's kinda too long for a good name. Twitter: @mirjam_diala Github: programmiri