diff --git a/Text/Cassius.hs b/Text/Cassius.hs
--- a/Text/Cassius.hs
+++ b/Text/Cassius.hs
@@ -20,6 +20,16 @@
     , Color (..)
     , colorRed
     , colorBlack
+      -- ** Size
+    , mkSize
+    , AbsoluteUnit (..)
+    , AbsoluteSize (..)
+    , absoluteSize
+    , EmSize (..)
+    , ExSize (..)
+    , PercentageSize (..)
+    , percentageSize
+    , PixelSize (..)
 #if HAMLET6TO7
     , parseBlocks
     , Content (..)
@@ -27,8 +37,10 @@
 #endif
     ) where
 
+import Text.MkSizeType
 import Text.Shakespeare
 import Text.ParserCombinators.Parsec hiding (Line)
+import Text.Printf (printf)
 import Language.Haskell.TH.Quote (QuasiQuoter (..))
 import Language.Haskell.TH.Syntax
 import Language.Haskell.TH
@@ -295,3 +307,114 @@
                 fromText $ TS.pack $ render' u p
             _ -> error $ show d ++ ": expected CDUrlParam"
     go'' (k, v) = (toLazyText $ mconcat $ map go' k, mconcat $ map go' v)
+
+
+-- CSS size wrappers
+
+-- | Create a CSS size, e.g. $(mkSize "100px").
+mkSize :: String -> ExpQ
+mkSize s = appE nameE valueE
+  where [(value, unit)] = reads s :: [(Double, String)]
+        absoluteSizeE = varE $ mkName "absoluteSize"
+        nameE = case unit of
+          "cm" -> appE absoluteSizeE (conE $ mkName "Centimeter")
+          "em" -> conE $ mkName "EmSize"
+          "ex" -> conE $ mkName "ExSize"
+          "in" -> appE absoluteSizeE (conE $ mkName "Inch")
+          "mm" -> appE absoluteSizeE (conE $ mkName "Millimeter")
+          "pc" -> appE absoluteSizeE (conE $ mkName "Pica")
+          "pt" -> appE absoluteSizeE (conE $ mkName "Point")
+          "px" -> conE $ mkName "PixelSize"
+          "%" -> varE $ mkName "percentageSize"
+        valueE = litE $ rationalL (toRational value)
+
+-- | Absolute size units.
+data AbsoluteUnit = Centimeter
+                  | Inch
+                  | Millimeter
+                  | Pica
+                  | Point
+                  deriving (Eq, Show)
+
+data AbsoluteSize = AbsoluteSize -- | Not intended for direct use, see 'mkSize'.
+                      AbsoluteUnit -- | Units used for text formatting.
+                      Rational -- | Normalized value in centimeters.
+
+-- | Absolute size unit convertion rate to centimeters.
+absoluteUnitRate :: AbsoluteUnit -> Rational
+absoluteUnitRate Centimeter = 1
+absoluteUnitRate Inch = 2.54
+absoluteUnitRate Millimeter = 0.1
+absoluteUnitRate Pica = 12 * absoluteUnitRate Point
+absoluteUnitRate Point = 1 / 72 * absoluteUnitRate Inch
+
+-- | Constructs 'AbsoluteSize'. Not intended for direct use, see 'mkSize'.
+absoluteSize :: AbsoluteUnit -> Rational -> AbsoluteSize
+absoluteSize unit value = AbsoluteSize unit (value * absoluteUnitRate unit)
+
+instance Show AbsoluteSize where
+  show (AbsoluteSize unit value') = printf "%f" value ++ suffix
+    where value = fromRational (value' / absoluteUnitRate unit) :: Double
+          suffix = case unit of
+            Centimeter -> "cm"
+            Inch -> "in"
+            Millimeter -> "mm"
+            Pica -> "pc"
+            Point -> "pt"
+
+instance Eq AbsoluteSize where
+  (AbsoluteSize _ v1) == (AbsoluteSize _ v2) = v1 == v2
+
+instance Ord AbsoluteSize where
+  compare (AbsoluteSize _ v1) (AbsoluteSize _ v2) = compare v1 v2
+
+instance Num AbsoluteSize where
+  (AbsoluteSize u1 v1) + (AbsoluteSize _ v2) = AbsoluteSize u1 (v1 + v2)
+  (AbsoluteSize u1 v1) * (AbsoluteSize _ v2) = AbsoluteSize u1 (v1 * v2)
+  (AbsoluteSize u1 v1) - (AbsoluteSize _ v2) = AbsoluteSize u1 (v1 - v2)
+  abs (AbsoluteSize u v) = AbsoluteSize u (abs v)
+  signum (AbsoluteSize u v) = AbsoluteSize u (abs v)
+  fromInteger x = AbsoluteSize Centimeter (fromInteger x)
+
+instance Fractional AbsoluteSize where
+  (AbsoluteSize u1 v1) / (AbsoluteSize _ v2) = AbsoluteSize u1 (v1 / v2)
+  fromRational x = AbsoluteSize Centimeter (fromRational x)
+
+instance ToCss AbsoluteSize where
+  toCss = TL.pack . show
+
+data PercentageSize = PercentageSize -- | Not intended for direct use, see 'mkSize'.
+                        Rational -- | Normalized value, 1 == 100%.
+                    deriving (Eq, Ord)
+
+-- | Constructs 'PercentageSize'. Not intended for direct use, see 'mkSize'.
+percentageSize :: Rational -> PercentageSize
+percentageSize value = PercentageSize (value / 100)
+
+instance Show PercentageSize where
+  show (PercentageSize value') = printf "%f" value ++ "%"
+    where value = fromRational (value' * 100) :: Double
+
+instance Num PercentageSize where
+  (PercentageSize v1) + (PercentageSize v2) = PercentageSize (v1 + v2)
+  (PercentageSize v1) * (PercentageSize v2) = PercentageSize (v1 * v2)
+  (PercentageSize v1) - (PercentageSize v2) = PercentageSize (v1 - v2)
+  abs (PercentageSize v) = PercentageSize (abs v)
+  signum (PercentageSize v) = PercentageSize (abs v)
+  fromInteger x = PercentageSize (fromInteger x)
+
+instance Fractional PercentageSize where
+  (PercentageSize v1) / (PercentageSize v2) = PercentageSize (v1 / v2)
+  fromRational x = PercentageSize (fromRational x)
+
+instance ToCss PercentageSize where
+  toCss = TL.pack . show
+
+-- | Converts number and unit suffix to CSS format.
+showSize :: Rational -> String -> String
+showSize value' unit = printf "%f" value ++ unit
+  where value = fromRational value' :: Double
+
+mkSizeType "EmSize" "em"
+mkSizeType "ExSize" "ex"
+mkSizeType "PixelSize" "px"
diff --git a/Text/Hamlet/Parse.hs b/Text/Hamlet/Parse.hs
--- a/Text/Hamlet/Parse.hs
+++ b/Text/Hamlet/Parse.hs
@@ -73,6 +73,7 @@
                            (char '\t' >> return 4))
     x <- doctype <|>
          comment <|>
+         htmlComment <|>
          backslash <|>
          controlIf <|>
          controlElseIf <|>
@@ -97,6 +98,11 @@
         return $ LineContent [ContentRaw $ hamletDoctype set ++ "\n"]
     comment = do
         _ <- try $ string "$#"
+        _ <- many $ noneOf "\r\n"
+        eol
+        return $ LineContent []
+    htmlComment = do
+        _ <- try $ string "<!--"
         _ <- many $ noneOf "\r\n"
         eol
         return $ LineContent []
diff --git a/Text/MkSizeType.hs b/Text/MkSizeType.hs
new file mode 100644
--- /dev/null
+++ b/Text/MkSizeType.hs
@@ -0,0 +1,71 @@
+-- | Internal functions to generate CSS size wrapper types.
+module Text.MkSizeType (mkSizeType) where
+
+import Language.Haskell.TH.Syntax
+
+mkSizeType :: String -> String -> Q [Dec]
+mkSizeType name' unit = return [ dataDec name
+                               , showInstanceDec name unit
+                               , numInstanceDec name
+                               , fractionalInstanceDec name
+                               , toCssInstanceDec name ]
+  where name = mkName $ name'
+
+dataDec :: Name -> Dec
+dataDec name = DataD [] name [] [constructor] derives
+  where constructor = NormalC name [(NotStrict, ConT $ mkName "Rational")]
+        derives = map mkName ["Eq", "Ord"]
+
+showInstanceDec :: Name -> String -> Dec
+showInstanceDec name unit' = InstanceD [] (instanceType "Show" name) [showDec]
+  where showSize = VarE $ mkName "showSize"
+        x = mkName "x"
+        unit = LitE $ StringL unit'
+        showDec = FunD (mkName "show") [Clause [showPat] showBody []]
+        showPat = ConP name [VarP x]
+        showBody = NormalB $ AppE (AppE showSize $ VarE x) unit
+
+numInstanceDec :: Name -> Dec
+numInstanceDec name = InstanceD [] (instanceType "Num" name) decs
+  where decs = map (binaryFunDec name) ["+", "*", "-"] ++
+               map (unariFunDec1 name) ["abs", "signum"] ++
+               [unariFunDec2 name "fromInteger"]
+
+fractionalInstanceDec :: Name -> Dec
+fractionalInstanceDec name = InstanceD [] (instanceType "Fractional" name) decs
+  where decs = [binaryFunDec name "/", unariFunDec2 name "fromRational"]
+
+toCssInstanceDec :: Name -> Dec
+toCssInstanceDec name = InstanceD [] (instanceType "ToCss" name) [toCssDec]
+  where toCssDec = FunD (mkName "toCss") [Clause [] showBody []]
+        showBody = NormalB $ AppE (AppE dot pack) show
+        pack = VarE (mkName "TL.pack")
+        dot = VarE (mkName ".")
+        show = VarE (mkName "show")
+
+instanceType :: String -> Name -> Type
+instanceType className name = AppT (ConT $ mkName className) (ConT name)
+
+binaryFunDec :: Name -> String -> Dec
+binaryFunDec name fun' = FunD fun [Clause [pat1, pat2] body []]
+  where pat1 = ConP name [VarP v1]
+        pat2 = ConP name [VarP v2]
+        body = NormalB $ AppE (ConE name) result
+        result = AppE (AppE (VarE fun) (VarE v1)) (VarE v2)
+        fun = mkName fun'
+        v1 = mkName "v1"
+        v2 = mkName "v2"
+
+unariFunDec1 :: Name -> String -> Dec
+unariFunDec1 name fun' = FunD fun [Clause [pat] body []]
+  where pat = ConP name [VarP v]
+        body = NormalB $ AppE (ConE name) (AppE (VarE fun) (VarE v))
+        fun = mkName fun'
+        v = mkName "v"
+
+unariFunDec2 :: Name -> String -> Dec
+unariFunDec2 name fun' = FunD fun [Clause [pat] body []]
+  where pat = VarP x
+        body = NormalB $ AppE (ConE name) (AppE (VarE fun) (VarE x))
+        fun = mkName fun'
+        x = mkName "x"
diff --git a/hamlet.cabal b/hamlet.cabal
--- a/hamlet.cabal
+++ b/hamlet.cabal
@@ -1,5 +1,5 @@
 name:            hamlet
-version:         0.7.1
+version:         0.7.2
 license:         BSD3
 license-file:    LICENSE
 author:          Michael Snoyman <michael@snoyman.com>
@@ -57,6 +57,7 @@
     other-modules:   Text.Hamlet.Parse
                      Text.Hamlet.Quasi
                      Text.Hamlet.Debug
+                     Text.MkSizeType
                      Text.Shakespeare
     ghc-options:     -Wall
 
diff --git a/runtests.hs b/runtests.hs
--- a/runtests.hs
+++ b/runtests.hs
@@ -98,6 +98,7 @@
     , testCase "string literals" caseStringLiterals
     , testCase "embed json" caseEmbedJson
     , testCase "interpolated operators" caseOperators
+    , testCase "HTML comments" caseHtmlComments
     ]
 
 data Url = Home | Sub SubUrl
@@ -905,3 +906,11 @@
 caseOperators = do
     helper "3" [$hamlet|#{show $ (+) 1 2}|]
     helper "6" [$hamlet|#{show $ sum $ (:) 1 ((:) 2 $ return 3)}|]
+
+caseHtmlComments = do
+    helper "<p>1</p><p>2</p>" [$hamlet|
+<p>1
+<!-- ignored comment -->
+<p
+    2
+|]