fixed some style issues

src/assets/css/barplot.css

@@ -19,6 +19,10 @@
     shape-rendering: crispEdges;
 }
 
+.ac-bar-axis {
+    font-size: 1em;
+}
+
 .ac-bar-left-axis path {
     stroke: none;
 }

src/charts/impl/Barplot.js

@@ -79,7 +79,7 @@ export default class extends Chart {
     const x = d3.scaleBand()
       .domain(categories)
       .range([0, width])
-      .paddingInner(0.1)
+      .paddingInner(0.15)
       .paddingOuter(0.05);
 
     const xSub = d3.scaleBand()