docbrown/docs/design/theming.md
Jacob Herrington 7d0aeeefe5 Improve the clarity of the docs and fix Prettier config (#4899)
* Improve format and clarity of the docs [ci skip]

While this change produces a lot of git noise by enacting what seems
like an arbitrary linewrap on most of the files in the documentation it
will result in better version control and tracking of the changes in the
documentation.

For example, as it currently stands, if one was to make a
PR to move a comma in a sentence because each paragraph in most of the
files is on a single line, that small change would look in the git
history like the author had modified the entire paragraph. In reality,
this author just moved a comma.

This change also includes a significant number of modifications to the
more article-esque docs. Many of these docs were written in a sort of
stream-of-conciousness and aren't as easy to read as they could be.
Hopefully this is the first of several readability changes. If we could
get these docs to a more accessible reading level, we would probably see
an increase in contributions. :)

* Delegate markdown wrapping to Prettier

* Add linewrapping explanation in the docs [ci skip]
2019-11-26 08:40:53 -05:00

97 lines
3.4 KiB
Markdown

---
title: Theming Guidelines
---
# Theming Guidelines
DEV supports different themes, such as Default, Night, Pink.
You can switch the theme at <http://localhost:3000/settings/misc> in the "Style
Customization" section.
These themes are powered by [CSS custom
properties](https://developer.mozilla.org/en-US/docs/Web/CSS/Using_CSS_custom_properties),
loaded at runtime by Javascript via `layouts/_user_config.html.erb`.
An example of how it works:
```javascript
<script>
try {
var bodyClass = localStorage.getItem('config_body_class');
document.body.className = bodyClass;
if (bodyClass.includes('night-theme')) {
document.getElementById('body-styles').innerHTML = '<style>\
:root {\
--theme-background: #0d1219;\
--theme-color: #fff;\
--theme-logo-background: #0a0a0a;\
--theme-logo-color: #fff;\
--theme-anchor-color: #17a1f6;\
--theme-secondary-color: #cedae2;\
--theme-top-bar-background: #1c2938;\
--theme-top-bar-background-hover: #27384c;\
--theme-top-bar-color: #fff;\
--theme-top-bar-search-background: #424a54;\
--theme-top-bar-search-color: #fff;\
--theme-top-bar-write-background: #00af81;\
--theme-top-bar-write-color: #fff;\
--theme-container-background: #141f2d;\
--theme-container-accent-background: #202c3d;\
--theme-container-background-hover: #37475c;\
--theme-gradient-background: linear-gradient(to right, #293d56 8%, #282833 18%, #293d56 33%);\
--theme-container-color: #fff;\
--theme-container-box-shadow: none;\
--theme-container-border: 1px solid #141d26;\
--theme-social-icon-invert: invert(100)</style>'
```
Within SCSS files located at `app/assets/stylesheets` you can use `var()`
statements, which will call these CSS custom properties. If a CSS custom
property is not defined `var()` will fall back on the second parameter provided,
which can be a SCSS variable defined in `app/assets/stylesheets/variables.scss`.
An example of how to use `var()`:
```scss
div {
color: var(--theme-color, $black);
}
```
Note that fallback values aren't used to fix the browser compatibility. If the
browser doesn't support CSS custom Properties, the fallback value won't help. To
prevent this issue on older browsers, we need to write our styles like this:
```scss
div {
color: $black;
color: var(--theme-color, $black);
}
```
This can be too much work and browser fallback can be forgotten. For a better
developer experience, you should use the two mixins defined in
`app/assets/stylesheets/_mixins.scss` called `themeable` and
`themeable-important`. They take three arguments. The first argument is the CSS
property like `color` or `background`, the second argument is the CSS custom
property name (without `--`) like `theme-color`, and the third argument is the
CSS value, i.e., `$black` or `white`.
Make sure to import the mixin in your SCSS file and use it like this:
```scss
div {
@include themeable(color, theme-color, $black);
}
```
`themeable-important` is used when a CSS variable requires `!important` as a
postfix of the CSS property's value where the CSS variable is being used. You
can use it the same way you would use `themeable` mixin, but you should avoid
`!important` if possible.
# Other user config
In addition to themes, users can also directly configure their preferred fonts
and their nav bar preferences. The implementation of these is similar to themes.