--- /dev/null
+# property-no-unknown
+
+Disallow unknown properties.
+
+```css
+a { heigth: 100%; }
+/** ↑
+ * These properties */
+```
+
+This rule considers properties defined in the [CSS Specifications and browser specific properties](https://github.com/betit/known-css-properties#source) to be known.
+
+This rule ignores variables (`$sass`, `@less`, `--custom-property`).
+
+This rule ignores vendor-prefixed properties (e.g., `-moz-align-self`, `-webkit-align-self`).
+Use option `checkPrefixed` described below to turn on checking of vendor-prefixed properties.
+
+## Options
+
+### `true`
+
+The following patterns are considered violations:
+
+```css
+a {
+ colr: blue;
+}
+```
+
+```css
+a {
+ my-property: 1;
+}
+```
+
+The following patterns are *not* considered violations:
+
+```css
+a {
+ color: green;
+}
+```
+
+```css
+a {
+ fill: black;
+}
+```
+
+```css
+a {
+ -moz-align-self: center;
+}
+```
+
+```css
+a {
+ -webkit-align-self: center;
+}
+```
+
+```css
+a {
+ align-self: center;
+}
+```
+
+## Optional secondary options
+
+### `ignoreProperties: ["/regex/", "string"]`
+
+Given:
+
+```js
+["/^my-/", "custom"]
+```
+
+The following patterns are *not* considered violations:
+
+```css
+a {
+ my-property: 10px;
+}
+```
+
+```css
+a {
+ my-other-property: 10px;
+}
+```
+
+```css
+a {
+ custom: 10px;
+}
+```
+
+### `checkPrefixed: true | false` (default: `false`)
+
+If `true`, this rule will check vendor-prefixed properties.
+
+For example with `true`:
+
+The following patterns are *not* considered violations:
+
+```css
+a {
+ -webkit-overflow-scrolling: auto;
+}
+```
+
+```css
+a {
+ -moz-box-flex: 0;
+}
+```
+
+The following patterns are considered violations:
+
+```css
+a {
+ -moz-align-self: center;
+}
+```
+
+```css
+a {
+ -moz-overflow-scrolling: center;
+}
+```