[O] Make the full grade color gray

src/pages/overall/graph-average/graph-average.ts

@@ -1,6 +1,7 @@
 import {Component, Prop, Vue} from 'vue-property-decorator';
 import {Course} from '@/components/app/app';
 import {GPAUtils} from '@/utils/gpa-utils';
+import Constants from '@/constants';
 
 @Component({
 })
@@ -42,7 +43,11 @@ export default class GraphAverage extends Vue
                 {
                     type: 'bar',
                     barGap: '-100%',
-                    data: this.courses.map(course => [course.name, GPAUtils.getGP(course, 'A+')]),
+                    data: this.courses.map(course =>
+                    {
+                        return {value: [course.name, GPAUtils.getGP(course, 'A+')],
+                            itemStyle: {color: '#d8d8d8'}}
+                    }),
                 },
                 {
                     type: 'bar',