Tweak welcome design

Co-Authored-By: Mikayla Maki <mikayla.c.maki@gmail.com>

crates/theme/src/theme.rs

@@ -855,6 +855,7 @@ pub struct FeedbackStyle {
 #[derive(Clone, Deserialize, Default)]
 pub struct WelcomeStyle {
     pub page_width: f32,
+    pub logo: IconStyle,
     pub logo_subheading: ContainedText,
     pub checkbox: CheckboxStyle,
     pub button: Interactive<ContainedText>,
@@ -863,6 +864,19 @@ pub struct WelcomeStyle {
     pub checkbox_group: ContainerStyle,
 }
 
+#[derive(Clone, Deserialize, Default)]
+pub struct IconStyle {
+    pub color: Color,
+    pub icon: String,
+    pub dimensions: Dimensions,
+}
+
+#[derive(Clone, Deserialize, Default)]
+pub struct Dimensions {
+    pub width: f32,
+    pub height: f32,
+}
+
 #[derive(Clone, Deserialize, Default)]
 pub struct CheckboxStyle {
     pub check_icon: String,