use a valid sans-serif font (#4160)

* ensure our css is always more specific than vendor

* set dc axis text to valid sans-serif value

frontend/src/metabase/css/dashboard.css

@@ -299,6 +299,12 @@
 .dc-chart .axis {
   z-index: -1;
 }
+
+/* TODO (@kdoh) remove this if dc-js/dc.js#1260 is merged */
+.dc-chart .axis text {
+  font-family: sans-serif;
+}
+
 .dc-chart .axis .domain,
 .dc-chart .axis .tick line {
   stroke: #EDEDED;

frontend/src/metabase/css/index.css

+@import './vendor.css';
+
 @import './core/index.css';
 
 @import './components/buttons.css';
@@ -21,4 +23,3 @@
 @import './setup.css';
 @import './tutorial.css';
 
-@import './vendor.css';