diff --git a/crates/color/src/palette_io.rs b/crates/color/src/palette_io.rs
index 065e06eed..80f740321 100644
--- a/crates/color/src/palette_io.rs
+++ b/crates/color/src/palette_io.rs
@@ -181,7 +181,9 @@ fn css_comment(s: &str) -> String {
 
 fn write_css(lib: &SwatchLibrary, keep: impl Fn(&&Swatch) -> bool) -> String {
     let mut out = format!("/* {} */\n:root {{\n", css_comment(&lib.name));
-    let mut taken: Vec<String> = vec![];
+    let mut taken: HashSet<String> = HashSet::new();
+    // The next number to try for each base, so repeated names don't search the ones used before.
+    let mut next: HashMap<String, usize> = HashMap::new();
     let mut props = |out: &mut String, list: &[Swatch]| {
         for w in list.iter().filter(&keep) {
             let value = match &w.paint {
@@ -198,8 +200,18 @@ fn write_css(lib: &SwatchLibrary, keep: impl Fn(&&Swatch) -> bool) -> String {
             };
             // Names differing only in case or punctuation map to one property: number the others.
             let base = css_property(&w.name);
-            let name = (1..).map(|i| if i == 1 { base.clone() } else { format!("{base}-{i}") }).find(|n| !taken.contains(n)).unwrap_or(base);
-            taken.push(name.clone());
+            let name = if taken.insert(base.clone()) {
+                base
+            } else {
+                let n = next.entry(base.clone()).or_insert(1);
+                loop {
+                    *n += 1;
+                    let name = format!("{base}-{n}");
+                    if taken.insert(name.clone()) {
+                        break name;
+                    }
+                }
+            };
             let note = if w.spot { " /* spot */" } else { "" };
             out.push_str(&format!("  {name}: {value};{note}\n"));
         }
diff --git a/crates/effects/src/pixel/mod.rs b/crates/effects/src/pixel/mod.rs
index 87335670c..8885c9def 100644
--- a/crates/effects/src/pixel/mod.rs
+++ b/crates/effects/src/pixel/mod.rs
@@ -932,22 +932,41 @@ pub fn dilate_plane(a: &mut Vec<f32>, w: usize, h: usize, radius: f64) {
 /// One horizontal pass of [`dilate_plane`] over the rows of `w` values of a plane: the largest
 /// value within `whole`, blended by `frac` towards the largest within `whole + 1`.
 fn max_plane(src: &[f32], dst: &mut [f32], w: usize, whole: usize, frac: f32) {
+    let (mut inner, mut ring) = (vec![0.0f32; w], vec![0.0f32; w]);
     for (row, out) in src.chunks_exact(w).zip(dst.chunks_exact_mut(w)) {
-        for (x, o) in out.iter_mut().enumerate() {
-            let lo = x.saturating_sub(whole + 1);
-            let hi = (x + whole + 1).min(w - 1);
-            let (mut inner, mut ring) = (row[x], row[x]);
-            for (j, v) in row[lo..=hi].iter().enumerate() {
-                if (lo + j).abs_diff(x) <= whole {
-                    inner = inner.max(*v);
-                }
-                ring = ring.max(*v);
-            }
-            *o = inner + (ring - inner) * frac;
+        window_max(row, whole, &mut inner);
+        window_max(row, whole + 1, &mut ring);
+        for ((o, i), r) in out.iter_mut().zip(&inner).zip(&ring) {
+            *o = i + (r - i) * frac;
         }
     }
 }
 
+/// For each `x`, the largest of `row[x - radius..=x + radius]` (cut at the row's ends) into `out`,
+/// in time linear in the row (a sliding window, not a scan of the window for each `x`).
+fn window_max(row: &[f32], radius: usize, out: &mut [f32]) {
+    use std::collections::VecDeque;
+    // Indices of the window's values that can still be its largest, falling in value.
+    let mut keep: VecDeque<usize> = VecDeque::new();
+    let mut next = 0;
+    for (x, o) in out.iter_mut().enumerate().take(row.len()) {
+        let hi = x.saturating_add(radius).min(row.len().saturating_sub(1));
+        while next <= hi {
+            let v = row[next];
+            while keep.back().is_some_and(|&b| row[b] <= v) {
+                keep.pop_back();
+            }
+            keep.push_back(next);
+            next += 1;
+        }
+        let lo = x.saturating_sub(radius);
+        while keep.front().is_some_and(|&f| f < lo) {
+            keep.pop_front();
+        }
+        *o = keep.front().map_or(row[x], |&f| row[f]);
+    }
+}
+
 /// Premultiplied RGBA at 16 bits (×257): blurs and averages that keep their tones.
 pub(super) type Px16 = [u16; 4];
 
@@ -1061,3 +1080,22 @@ mod tests;
 mod tests_paint;
 #[cfg(test)]
 mod tests_sketch;
+
+#[cfg(test)]
+mod window_max_tests {
+    use super::window_max;
+
+    #[test]
+    fn the_sliding_maximum_matches_a_scan_of_each_window() {
+        let row: Vec<f32> = (0..40u32).map(|i| ((i * 7919) % 31) as f32).collect();
+        for radius in [0, 1, 2, 5, 39, 100] {
+            let mut out = vec![0.0; row.len()];
+            window_max(&row, radius, &mut out);
+            for (x, got) in out.iter().enumerate() {
+                let (lo, hi) = (x.saturating_sub(radius), (x + radius).min(row.len() - 1));
+                let want = row[lo..=hi].iter().copied().fold(f32::MIN, f32::max);
+                assert_eq!(*got, want, "radius {radius} at {x}");
+            }
+        }
+    }
+}
diff --git a/crates/effects/src/stylize.rs b/crates/effects/src/stylize.rs
index 2db14d10f..bdb5f8623 100644
--- a/crates/effects/src/stylize.rs
+++ b/crates/effects/src/stylize.rs
@@ -184,9 +184,14 @@ pub fn scribble(path: &PathData, b: Rect, p: &Value) -> PathData {
         row: u64,
     }
     let mut chains: Vec<Chain> = vec![];
-    let mut y = y0 + step / 2.0;
     let mut row = 0u64;
-    while y < y1 {
+    // Rows are counted, not summed: adding a step that is below the spacing of the numbers at `y`
+    // would never move it.
+    while row <= 2001 {
+        let y = y0 + step / 2.0 + row as f64 * step;
+        if y.partial_cmp(&y1) != Some(std::cmp::Ordering::Less) {
+            break;
+        }
         let mut xs: Vec<f64> = vec![];
         for pl in &polys {
             for w in pl.windows(2) {
@@ -225,7 +230,6 @@ pub fn scribble(path: &PathData, b: Rect, p: &Value) -> PathData {
             }
         }
         row += 1;
-        y += step;
     }
     let lines: Vec<SubPath> = chains
         .into_iter()