cssta

🌞 CSSTA

Docs

CSSTA is a way to co-locate your CSS with your React components, and lets you define components using isolated units of style.

It is available both for React for web 🌍 and React Native 📱. For web, it generates real CSS files with <1kb JS overhead.

It is almost identical in concept to styled-components, but makes different trade-offs.

import cssta from 'cssta';

const Button = cssta.button`
  background: blue;
  color: white;
`;

<Button>I am a blue button with white text</Button>

This returns a regular React component, which when used, will have the styling applied.

You can install Cssta with,

npm install --save cssta
npm install --save-dev babel-plugin-cssta

Note that while we are using template strings, interpolation (${value}) is not supported on web, but is supported for React Native. There are also other platform differences documented in the individual guides.

📝 CSS

The CSS input is mostly regular CSS—but you should look at the platform guides for more information.

However, selectors are changed on all platforms: only the following selector parts are permitted:

• & to refer to the current component
• :hover, ::before, :not(...), :nth-child(...) etc. pseudo selectors (platform dependent)
• [attribute] and [attribute="value'] (these refer to React Props—see below)

Combinators (a b, a > b etc.) are not permitted.

🎛 Props

Attribute selectors have their meaning redefined to refer to React props. Defined as [stringAttribute="stringValue"] for string props, and [booleanAttribute] for boolean props, these apply conditional styling.

const Button = cssta.button`
  padding: 0.5em 1em;

  [large] {
    font-size: 2em;
  }

  :not([noOutline]) {
    border: 1px solid currentColor;
  }

  [priority="critical"] {
    color: red;
  }
  [priority="important"] {
    color: orange;
  }
`;

<Button large>Large Button with an Outline</Button>,
<Button noOutline>Button with no Outline</Button>,
<Button priority="critical">Red Button with an Outline</Button>,
<Button priority="important">Orange Button with an Outline</Button>,

<Button large noOutline priority="critical">
  Large, Red Button with no Outline
</Button>

Note that only the attribute formats shown are valid: [value~="invalid" i] is invalid.

The properties you defined in the CSS determine the style applied, and are not passed down to the base component. All other props get passed down.

const button = `
  [large] { font-size: 12pt; }
`;

<Button large onClick={() => alert('clicked')}>
  onClick Prop Passed Down
</Button>;

The properties defined in your CSS are type checked with propTypes to check for typos.

💗 Composition

It is possible React components only when the component accepts the prop className for web, and style for React Native.

import { Link }  from 'react-router';

const StyledLink = cssta(Link)`
  color: rebeccapurple;
  text-decoration: none;
`;

It is also possible to compose your own components.

const OutlineButton = cssta.button`
  padding: 0.5rem 1rem;
  border: 2px solid currentColor;
  border-radius: 1000px;
`;

const RedButton = cssta(OutlineButton)`
  color: red;
`;

const BlueButton = cssta(OutlineButton)`
  color: blue;
`;

Note that for the moment, this only works when the components get defined in the same file!

🏳️‍🌈 Theming

The best way to do theming in Cssta is by using CSS custom properties. We provide polyfills for React Native, so these will just work. On the web, you can either rely on native browser support, or a postCSS plugin.

const LightBox = cssta.div`
  background-color: black;
  --primary: white;
`;

const Button = cssta.button`
  color: var(--primary);
  border: 1px solid var(--primary);
  padding: 0.5rem 1rem;
`;

const Example = (
  <LightBox>
    <Button>I am white on black!</Button>
  </LightBox>
);

There's a few extra examples in theming.

🖌 Overriding Styles

The properties className on web, and style on React Native have special behavior. They append styles to those already defined by the component.

// Web only
;<Button className="margin-right-1">
  Composing Classes
</Button>

// Web and React Native
<Button style={{ marginRight: 0 }}>
  Composing Styles
</Button>

Note that you cannot remove the classes otherwise set by the component.

For class names, it is your responsibility to resolve the specificity. I recommend you only add util classes, and each declaration in those util classes uses !important for everything.

✂️ Overriding the Component

You can define component property on any Cssta elements to override the base component.

const Div = cssta.div`
  background: red;
`;

<Div component="span">I am a span now</Div>

Docs