diff --git a/crates/ui-egui/src/panels/typography/spacing.rs b/crates/ui-egui/src/panels/typography/spacing.rs
index 54c327dd0..5ffaf22a2 100644
--- a/crates/ui-egui/src/panels/typography/spacing.rs
+++ b/crates/ui-egui/src/panels/typography/spacing.rs
@@ -164,7 +164,11 @@ pub(crate) fn parse_line_height(s: &str, cur: Option<LineHeight>) -> Option<Valu
         return widgets::eval(p.trim(), cur_pct).filter(|v| v.is_finite()).map(|v| json!(format!("{}%", trim_num(v.max(0.0)))));
     }
     if let Some(px) = s.strip_suffix("px") {
-        return widgets::eval(px.trim(), None).filter(|v| v.is_finite()).map(|v| json!(v.max(0.0)));
+        let cur_px = match cur {
+            Some(LineHeight::Pixels(p)) => Some(p),
+            _ => None,
+        };
+        return widgets::eval(px.trim(), cur_px).filter(|v| v.is_finite()).map(|v| json!(v.max(0.0)));
     }
     match cur {
         Some(LineHeight::Percent(p)) => widgets::eval(s, Some(p)).filter(|v| v.is_finite()).map(|v| json!(format!("{}%", trim_num(v.max(0.0))))),
@@ -178,10 +182,18 @@ pub(crate) fn parse_line_height(s: &str, cur: Option<LineHeight>) -> Option<Valu
 pub(crate) fn parse_letter_spacing(s: &str, cur: Option<LetterSpacing>) -> Option<Value> {
     let s = s.trim();
     if let Some(p) = s.strip_suffix('%') {
-        return widgets::eval(p.trim(), None).filter(|v| v.is_finite()).map(|v| json!(format!("{}%", trim_num(v))));
+        let cur_pct = match cur {
+            Some(LetterSpacing::Percent(p)) => Some(p),
+            _ => None,
+        };
+        return widgets::eval(p.trim(), cur_pct).filter(|v| v.is_finite()).map(|v| json!(format!("{}%", trim_num(v))));
     }
     if let Some(p) = s.strip_suffix("px") {
-        return widgets::eval(p.trim(), None).filter(|v| v.is_finite()).map(|v| json!(v));
+        let cur_px = match cur {
+            Some(LetterSpacing::Pixels(p)) => Some(p),
+            _ => None,
+        };
+        return widgets::eval(p.trim(), cur_px).filter(|v| v.is_finite()).map(|v| json!(v));
     }
     match cur {
         Some(LetterSpacing::Pixels(px)) => widgets::eval(s, Some(px)).filter(|v| v.is_finite()).map(|v| json!(v)),
@@ -206,3 +218,21 @@ pub(crate) fn letter_spacing_of(v: &Value) -> Option<LetterSpacing> {
         other => other.as_f64().filter(|v| v.is_finite()).map(LetterSpacing::Pixels),
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn relative_edit_with_unit_suffix_adds_to_current() {
+        let lh = Some(LineHeight::Pixels(10.0));
+        assert_eq!(parse_line_height("+2", lh), Some(json!(12.0)));
+        assert_eq!(parse_line_height("+2px", lh), Some(json!(12.0)));
+        let ls = Some(LetterSpacing::Pixels(10.0));
+        assert_eq!(parse_letter_spacing("+1", ls), Some(json!(11.0)));
+        assert_eq!(parse_letter_spacing("+1px", ls), Some(json!(11.0)));
+        let pct = Some(LetterSpacing::Percent(10.0));
+        assert_eq!(parse_letter_spacing("+1%", pct), parse_letter_spacing("+1", pct));
+        assert_eq!(parse_letter_spacing("+1%", pct), Some(json!("11%")));
+    }
+}