diff --git a/modules/hex_wave.frag b/modules/hex_wave.frag
index 55f7d96..6c0e4c2 100644
--- a/modules/hex_wave.frag
+++ b/modules/hex_wave.frag
@@ -22,9 +22,11 @@ float sdHexagon(vec2 p, float r) {
     return length(p) * sign(p.y);
 }
 
-// Rainbow from angle — color picker style
-vec3 hsv2rgb(float h) {
-    return clamp(abs(mod(h * 6.0 + vec3(0.0, 4.0, 2.0), 6.0) - 3.0) - 1.0, 0.0, 1.0);
+// Interpolate between three theme stops (t in [0,1])
+vec3 themeGradient(float t) {
+    return t < 0.5
+        ? mix(uC0.rgb, uC1.rgb, t * 2.0)
+        : mix(uC1.rgb, uC2.rgb, (t - 0.5) * 2.0);
 }
 
 void main() {
@@ -73,15 +75,13 @@ void main() {
     float edgeWidth = 5.0;
     float edgeFactor = smoothstep(-edgeWidth, 0.0, d);  // 0 at interior, 1 at edge
     if (wf > 0.01 && edgeFactor > 0.0) {
-        // Angle around hex center → hue
+        // Vary shimmer color across theme gradient using angle + position
         float angle = atan(p.y, p.x);
-        float hue = (angle + 3.14159) / 6.28318;
-        // Shift hue by position so neighboring hexes have different phase
-        hue = fract(hue + center.x * 0.003 + center.y * 0.005);
-        vec3 rainbow = hsv2rgb(hue);
+        float t = fract((angle + 3.14159) / 6.28318 + center.x * 0.003 + center.y * 0.005);
+        vec3 shimmerColor = themeGradient(t);
 
         float shimmer = edgeFactor * wf;
-        rgb = mix(rgb, rainbow, shimmer * 0.8);
+        rgb = mix(rgb, shimmerColor, shimmer * 0.8);
         a = mix(a, 0.5, shimmer * 0.6);
     }