Reasonable theme defaults for URL highlighting

src/posting/posting.scss

@@ -301,11 +301,11 @@ Tree {
 Input {
   padding: 0 1;
   height: 1;
-  background: $surface;
+  background: $surface 80%;
   border: none;
 
   &:focus {
-    background: $surface-lighten-1;
+    background: $surface;
     padding-left: 0;
     border-left: outer $surface-lighten-2;
 

src/posting/themes.py

@@ -73,6 +73,14 @@ class VariableStyles(BaseModel):
     unresolved: str | None = Field(default="dim")
     """The style to apply to unresolved variables."""
 
+    def fill_with_defaults(self, theme: "Theme") -> "VariableStyles":
+        """Return a new VariableStyles object with `None` values filled
+        with reasonable defaults from the given theme."""
+        return VariableStyles(
+            resolved=self.resolved or theme.success,
+            unresolved=self.unresolved or theme.secondary,
+        )
+
 
 class UrlStyles(BaseModel):
     """The style to apply to URL input fields."""
@@ -83,9 +91,18 @@ class UrlStyles(BaseModel):
     protocol: str | None = Field(default=None)
     """The style to apply to the URL protocol."""
 
-    separator: str | None = Field(default="dim b")
+    separator: str | None = Field(default="dim")
     """The style to apply to URL separators e.g. `/`."""
 
+    def fill_with_defaults(self, theme: "Theme") -> "UrlStyles":
+        """Return a new UrlStyles object with `None` values filled
+        with reasonable defaults from the given theme."""
+        return UrlStyles(
+            base=self.base or theme.secondary,
+            protocol=self.protocol or theme.accent,
+            separator=self.separator or "dim",
+        )
+
 
 class Theme(BaseModel):
     name: str = Field(exclude=True)

src/posting/widgets/request/url_bar.py

@@ -100,9 +100,9 @@ def watch_cursor_position(self, cursor_position: int) -> None:
     def on_theme_change(self, theme: Theme) -> None:
         super().on_theme_change(theme)
         if theme.variable:
-            self.highlighter.variable_styles = theme.variable
+            self.highlighter.variable_styles = theme.variable.fill_with_defaults(theme)
         if theme.url:
-            self.highlighter.url_styles = theme.url
+            self.highlighter.url_styles = theme.url.fill_with_defaults(theme)
 
 
 class SendRequestButton(Button, can_focus=False):

src/posting/widgets/variable_input.py

@@ -36,5 +36,6 @@ def on_theme_change(self, theme: Theme) -> None:
             theme: The new app theme.
         """
         super().on_theme_change(theme)
-        self.highlighter.variable_styles = theme.variable
-        self.refresh()
+        if theme.variable:
+            self.highlighter.variable_styles = theme.variable.fill_with_defaults(theme)
+            self.refresh()