Fix navbar transparency in light mode and some scss linter issues (#1827)

## Description

Fix navbar transparency in light mode and some scss linter issues

See separate commits for transparency and linter issues

## Does this PR need a docs update or release note?

- [ ] ✅ Yes, it's included
- [ ] 🕐 Yes, but in a later PR
- [x] ⛔ No 

## Type of change

<!--- Please check the type of change your PR introduces: --->
- [ ] 🌻 Feature
- [x] 🐛 Bugfix
- [ ] 🗺️ Documentation
- [ ] 🤖 Test
- [ ] 💻 CI/Deployment
- [x] 🐹 Trivial/Minor

## Issue(s)

## Test Plan

<!-- How will this be tested prior to merging.-->
- [x] 💪 Manual
- [ ] ⚡ Unit test
- [ ] 💚 E2E

website/src/css/custom.scss

@@ -35,6 +35,7 @@ html{
   background-image: url("../../static/assets/download_blue.svg");
   transform: rotate(-180deg);
 }
+
 .accordion-button-custom:not(.collapsed) {
   color: #2563eb;
   background-color: #fff;
@@ -105,13 +106,10 @@ html{
 
 html[data-theme='dark'] {
   --ifm-background-color: #111629;
+  --ifm-navbar-background-color: #111629;
   --ifm-link-color: #087EA4;
 }
 
-.navbar {
-  background-color: var(--ifm-background-color);
-}
-
 .footer {
   --ifm-footer-background-color: #1b2131;
 }
@@ -177,8 +175,6 @@ html[data-theme='dark'] {
         width: 55%;
       }
 
-
-
     }
 
     tr th {
@@ -241,6 +237,7 @@ html[data-theme='dark'] {
     }
 
     div[class*="codeBlockContainer"] {
+
       &,
       & pre {
         margin-bottom: 0;