Style symptom row

components/chart/day-column.js

@@ -108,7 +108,7 @@ export default class DayColumn extends Component {
 
     return (
       <View>
-        <View style={{ height: symptomHeight }}>
+        <View style={[styles.symptomRow, {height: symptomHeight}]}>
           {typeof mucus === 'number' &&
             <View
               {...styles.mucusIcon}

components/chart/styles.js

@@ -87,6 +87,10 @@ const styles = {
     borderColor: '#00b159',
     borderWidth: 2,
     borderStyle: 'solid'
+  },
+  symptomRow: {
+    alignItems: 'center',
+    justifyContent: 'center'
   }
 }