diff --git a/HellionChat/Ui/StyleEngine/TypeScale.cs b/HellionChat/Ui/StyleEngine/TypeScale.cs
new file mode 100644
index 0000000..ca8f3a5
--- /dev/null
+++ b/HellionChat/Ui/StyleEngine/TypeScale.cs
@@ -0,0 +1,42 @@
+namespace HellionChat.Ui.StyleEngine;
+
+internal enum TypeRole
+{
+    Body,
+    Sender,
+    Header,
+    Meta,
+}
+
+// Named sizes derived from one base, so a role means the same thing wherever it
+// is drawn.
+//
+// Three of the four share the base size. That is deliberate: what sets the
+// sender apart is weight and what sets the header apart is small caps with wide
+// tracking, and neither is a size. Solving those with size instead would make
+// the log look like a ransom note. Only the meta role -- timestamps and the
+// header's trailing detail -- steps down, because it is meant to be skipped over
+// rather than read.
+//
+// The factors are defaults, not constants. The master spec puts typography under
+// theme control rather than user control, and ThemeTypography already exists as
+// the extension point for exactly that. A const would wall it off. What is
+// deliberately absent either way is a user-facing slider per role.
+internal static class TypeScale
+{
+    // Below this a timestamp stops being readable at any display scale.
+    internal const float MinPt = 7f;
+
+    private static readonly float[] Factors =
+    [
+        1.00f, // Body   -- the reference every other role is stated against
+        1.00f, // Sender -- set apart by weight, see FontManager.SenderWeight
+        1.00f, // Header -- set apart by small caps and tracking
+        0.82f, // Meta   -- timestamps, and the world and clock in the header
+    ];
+
+    internal static float FactorOf(TypeRole role) => Factors[(int)role];
+
+    internal static float SizePtOf(TypeRole role, float basePt) =>
+        TypeScaleMath.Resolve(basePt, FactorOf(role), MinPt);
+}