font: don't fallback styles when searching for a codepoint

see comment

src/Surface.zig

@@ -296,6 +296,9 @@ pub fn init(
                 }
             }
         } else {
+            // We don't support auto-italics. If we don't have an italic font
+            // face let the user know so they aren't surprised (if they look
+            // at logs).
             if (group.getFace(.italic) == null) {
                 log.warn("no italic font face available, italics will not render", .{});
             }

src/font/Group.zig

@@ -198,8 +198,15 @@ pub fn indexForCodepoint(
     // If we can find the exact value, then return that.
     if (self.indexForCodepointExact(cp, style, p)) |value| return value;
 
-    // Try looking for another font that will satisfy this request.
-    if (font.Discover != void) {
+    // If we're not a regular font style, try looking for a regular font
+    // that will satisfy this request. Blindly looking for unmatched styled
+    // fonts to satisfy one codepoint results in some ugly rendering.
+    if (style != .regular) {
+        if (self.indexForCodepoint(cp, .regular, p)) |value| return value;
+    }
+
+    // If we are regular, try looking for a fallback using discovery.
+    if (style == .regular and font.Discover != void) {
         if (self.discover) |*disco| discover: {
             var disco_it = disco.discover(.{
                 .codepoint = cp,