chore: Update macOS mozconfig and Zen theme CSS

Author: mauro-balades

configs/macos/mozconfig

@@ -14,13 +14,13 @@ if test "$SURFER_COMPAT" = "true"; then
     ac_add_options --target=x86_64-apple-darwin
 
     ac_add_options --enable-wasm-avx
-    ac_add_options --enable-optimize="-march=nehalem -mtune=haswell -O3 -w"
+    ac_add_options --enable-optimize="-mtune=haswell -O3 -w -march=armv8.3-a+simd"
 
-    export CFLAGS="-O3 -march=nehalem"
-    export CPPFLAGS="-O3 -march=nehalem"
-    export CXXFLAGS="-O3 -march=nehalem"
-    export LDFLAGS="-Wl,-O3 -march=nehalem"
-    export RUSTFLAGS="-Ctarget-cpu=nehalem -C codegen-units=1"
+    export CFLAGS="-O3 -march=armv8.3-a+simd"
+    export CPPFLAGS="-O3 -march=armv8.3-a+simd"
+    export CXXFLAGS="-O3 -march=armv8.3-a+simd"
+    export LDFLAGS="-Wl,-O3 -march=armv8.3-a+simd"
+    export RUSTFLAGS="-C target-feature=+v8.3a -C codegen-units=1"
 else
     ac_add_options --target=aarch64-apple-darwin
 

src/browser/base/content/zen-styles/zen-tabs.css

@@ -2,3 +2,7 @@
 /* Styles for both vertical and horizontal tabs */
 /*@import url("chrome://browser/content/zen-styles/zen-tabs/horizontal-tabs.css");*/
 @import url("chrome://browser/content/zen-styles/zen-tabs/vertical-tabs.css");
+
+#zen-tabbox-wrapper {
+  position: relative;
+}