Fix bug in font family ordering. Regenerate some css.

Author: mrmrs

css/tachyons.css

@@ -1,4 +1,4 @@
-/*! TACHYONS v4.6.0 | http://tachyons.io */
+/*! TACHYONS v4.6.1 | http://tachyons.io */
 /*
  *
  *      ________            ______
@@ -756,7 +756,7 @@ img { max-width: 100%; }
    Docs: http://tachyons.io/docs/typography/font-family/
 
 */
-.sans-serif { font-family: -apple-system, BlinkMacSystemFont, 'avenir next', avenir, helvetica, 'helvetica neue', ubuntu, roboto, noto, 'segoe ui', arial, sans-serif; }
+.sans-serif { font-family: -apple-system, BlinkMacSystemFont, 'avenir next', avenir, 'helvetica neue', helvetica, ubuntu, roboto, noto, 'segoe ui', arial, sans-serif; }
 .serif { font-family: georgia, times, serif; }
 .system-sans-serif { font-family: sans-serif; }
 .system-serif { font-family: serif; }

css/tachyons.min.css

@@ -45,9 +45,9 @@ You can always grab the latest version with
 ```html
 <link rel="stylesheet" href="https://unpkg.com/tachyons/css/tachyons.min.css">
 ```
-You can also specify a specific version. The latest version is 4.6.0
+You can also specify a specific version. The latest version is 4.6.1
 ```html
-<link rel="stylesheet" href="https://unpkg.com/tachyons@4.6.0/css/tachyons.min.css">
+<link rel="stylesheet" href="https://unpkg.com/tachyons@4.6.1/css/tachyons.min.css">
 ```
 
 ### Local Setup

readme.md

@@ -9,7 +9,7 @@
 .sans-serif {
   font-family: -apple-system, BlinkMacSystemFont,
                'avenir next', avenir,
-               helvetica, 'helvetica neue',
+               'helvetica neue', helvetica,
                ubuntu,
                roboto, noto,
                'segoe ui', arial,

src/_font-family.css

@@ -1,4 +1,4 @@
-/*! TACHYONS v4.6.0 | http://tachyons.io */
+/*! TACHYONS v4.6.1 | http://tachyons.io */
 
 /*
  *