Installer: Use dropdown for network selection

Change-Id: If50b8a585c55831cf3eee1172571d4dd5a098f4d
diff --git a/core/installer/welcome/static/appmanager.css b/core/installer/welcome/static/appmanager.css
index 2e9787b..cde49ab 100644
--- a/core/installer/welcome/static/appmanager.css
+++ b/core/installer/welcome/static/appmanager.css
@@ -11,6 +11,7 @@
   --pico-form-element-background-color: #d6d6d6;
   --pico-form-element-active-background-color: #d6d6d6;
   --pico-form-element-selected-background-color: #d6d6d6;
+  --pico-dropdown-color: #3a3a3a;
   --pico-dropdown-background-color: #d6d6d6;
   --pico-dropdown-border-color: #7f9f7f;
   --pico-dropdown-hover-background-color: #7f9f7f;