convert to CSS variables

frontend/src/app/lightning/channels-statistics/channels-statistics.component.html

@@ -1,7 +1,7 @@
 <div class="widget-toggler">
   <a href="" (click)="switchMode('avg')" class="toggler-option"
     [ngClass]="{'inactive': mode === 'avg'}"><small i18n="statistics.average-small">avg</small></a>
-  <span style="color: #ffffff66; font-size: 8px"> | </span>
+  <span style="color: var(--transparent-fg); font-size: 8px"> | </span>
   <a href="" (click)="switchMode('med')" class="toggler-option"
     [ngClass]="{'inactive': mode === 'med'}"><small i18n="statistics.median-small">med</small></a>
 </div>

frontend/src/app/lightning/channels-statistics/channels-statistics.component.scss

@@ -57,7 +57,7 @@
       margin-bottom: 0;
     }
     .card-text span {
-      color: #ffffff66;
+      color: var(--transparent-fg);
       font-size: 12px;
       top: 0px;
     }
@@ -110,5 +110,5 @@
 }
 
 .inactive {
-  color: #ffffff66;
+  color: var(--transparent-fg);
 }