diff --git a/RtfPipe/Html/CssString.cs b/RtfPipe/Html/CssString.cs
index 6f24dcb..fe963aa 100644
--- a/RtfPipe/Html/CssString.cs
+++ b/RtfPipe/Html/CssString.cs
@@ -1,6 +1,7 @@
 using RtfPipe.Tokens;
 using System;
 using System.Collections.Generic;
+using System.Globalization;
 using System.Linq;
 using System.Text;
 
@@ -33,7 +34,7 @@ public CssString(IEnumerable<IToken> tokens, ElementType elementType, IEnumerabl
         if (token is Font font)
           Append(font);
         else if (token is FontSize fontSize)
-          Append("font-size", fontSize.Value.ToPt().ToString("0.#") + "pt");
+          Append("font-size", fontSize.Value.ToPt().ToString("0.#", CultureInfo.InvariantCulture) + "pt");
         else if (token is BackgroundColor background)
           Append("background", "#" + background.Value);
         else if (token is ParagraphBackgroundColor backgroundPara)
@@ -104,8 +105,8 @@ public CssString(IEnumerable<IToken> tokens, ElementType elementType, IEnumerabl
         {
           if (tokens.OfType<LineSpacingMultiple>().Any(m => m.Value == 1))
           {
-            if ((Math.Abs(lineSpace.Value) / 240.0).ToString("0.#") != "1")
-              Append("line-height", (Math.Abs(lineSpace.Value) * DefaultBrowserLineHeight / 240.0).ToString("0.#"));
+            if ((Math.Abs(lineSpace.Value) / 240.0).ToString("0.#", CultureInfo.InvariantCulture) != "1")
+              Append("line-height", (Math.Abs(lineSpace.Value) * DefaultBrowserLineHeight / 240.0).ToString("0.#", CultureInfo.InvariantCulture));
           }
           else if (lineSpace.Value < 0)
           {
@@ -389,7 +390,7 @@ public CssString Append(string property, BorderToken border)
       }
       else
       {
-        _builder.Append(width.ToString("0")).Append("px ");
+        _builder.Append(width.ToString("0", CultureInfo.InvariantCulture)).Append("px ");
         
         switch (border.Style)
         {
@@ -496,7 +497,7 @@ public CssString Append(string property, params UnitValue[] values)
       {
         if (i > 0)
           _builder.Append(' ');
-        var px = values[i].ToPx().ToString("0.#");
+        var px = values[i].ToPx().ToString("0.#", CultureInfo.InvariantCulture);
         _builder.Append(px);
         if (px != "0")
           _builder.Append("px");