flow like the river

VISUALIZACION/node_modules/postcss-calc/README.md

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+# postcss-calc [![Build Status](https://travis-ci.org/postcss/postcss-calc.png)](https://travis-ci.org/postcss/postcss-calc)
+
+> [PostCSS](https://github.com/postcss/postcss) plugin to reduce `calc()`.
+
+This plugin reduce `calc()` references whenever it's possible.
+This can be particularly useful with the [postcss-custom-properties](https://github.com/postcss/postcss-custom-properties) plugin.
+
+**Note:** When multiple units are mixed together in the same expression, the `calc()` statement is left as is, to fallback to the [w3c calc() feature](http://www.w3.org/TR/css3-values/#calc).
+
+## Installation
+
+```console
+$ npm install postcss-calc
+```
+
+## Usage
+
+```js
+// dependencies
+var fs = require("fs")
+var postcss = require("postcss")
+var calc = require("postcss-calc")
+
+// css to be processed
+var css = fs.readFileSync("input.css", "utf8")
+
+// process css
+var output = postcss()
+  .use(calc())
+  .process(css)
+  .css
+```
+
+**Example** (with [postcss-custom-properties](https://github.com/postcss/postcss-custom-properties) enabled as well):
+
+```js
+// dependencies
+var fs = require("fs")
+var postcss = require("postcss")
+var customProperties = require("postcss-custom-properties")
+var calc = require("postcss-calc")
+
+// css to be processed
+var css = fs.readFileSync("input.css", "utf8")
+
+// process css
+var output = postcss()
+  .use(customProperties())
+  .use(calc())
+  .process(css)
+  .css
+```
+
+Using this `input.css`:
+
+```css
+:root {
+  --main-font-size: 16px;
+}
+
+body {
+  font-size: var(--main-font-size);
+}
+
+h1 {
+  font-size: calc(var(--main-font-size) * 2);
+  height: calc(100px - 2em);
+  margin-bottom: calc(
+      var(--main-font-size)
+      * 1.5
+    )
+}
+```
+
+you will get:
+
+```css
+body {
+  font-size: 16px
+}
+
+h1 {
+  font-size: 32px;
+  height: calc(100px - 2em);
+  margin-bottom: 24px
+}
+```
+
+Checkout [tests](test) for more examples.
+
+### Options
+
+#### `precision` (default: `5`)
+
+Allow you to definine the precision for decimal numbers.
+
+```js
+var out = postcss()
+  .use(calc({precision: 10}))
+  .process(css)
+  .css
+```
+
+#### `preserve` (default: `false`)
+
+Allow you to preserve calc() usage in output so browsers will handle decimal precision themselves.
+
+```js
+var out = postcss()
+  .use(calc({preserve: true}))
+  .process(css)
+  .css
+```
+
+#### `warnWhenCannotResolve` (default: `false`)
+
+Adds warnings when calc() are not reduced to a single value.
+
+```js
+var out = postcss()
+  .use(calc({warnWhenCannotResolve: true}))
+  .process(css)
+  .css
+```
+
+#### `mediaQueries` (default: `false`)
+
+Allows calc() usage as part of media query declarations.
+
+```js
+var out = postcss()
+  .use(calc({mediaQueries: true}))
+  .process(css)
+  .css
+```
+
+#### `selectors` (default: `false`)
+
+Allows calc() usage as part of selectors.
+
+```js
+var out = postcss()
+  .use(calc({selectors: true}))
+  .process(css)
+  .css
+```
+
+Example:
+
+```css
+div[data-size="calc(3*3)"] {
+  width: 100px;
+}
+```
+
+---
+
+## Contributing
+
+Work on a branch, install dev-dependencies, respect coding style & run tests before submitting a bug fix or a feature.
+
+```console
+$ git clone https://github.com/postcss/postcss-calc.git
+$ git checkout -b patch-1
+$ npm install
+$ npm test
+```
+
+## [Changelog](CHANGELOG.md)
+
+## [License](LICENSE)