fix: dim connection lines for unavailable quests

(used to work this way, but stopped recently due to themability commit)

FTBTeam/FTB-Mods-Issues#1183

common/src/main/java/dev/ftb/mods/ftbquests/client/gui/quests/QuestPanel.java

@@ -195,6 +195,10 @@ public void drawOffsetBackground(GuiGraphics graphics, Theme theme, int x, int y
 				Color4I c = complete ?
 						ThemeProperties.DEPENDENCY_LINE_COMPLETED_COLOR.get(questScreen.selectedChapter) :
 						ThemeProperties.DEPENDENCY_LINE_UNCOMPLETED_COLOR.get(questScreen.selectedChapter);
+				if (unavailable || qb.quest.getProgressionMode() == ProgressionMode.FLEXIBLE && !questScreen.file.selfTeamData.areDependenciesComplete(qb.quest)) {
+					// dim connection lines for unavailable quests
+					c = c.withAlpha(Math.max(30, c.alphai() / 2));
+				}
 
 				for (QuestButton button : qb.getDependencies()) {
 					if (button.shouldDraw() && button.quest != selectedQuest && qb.quest != selectedQuest && !button.quest.shouldHideDependentLines()) {