diff --git a/src/formatitko/context.py b/src/formatitko/context.py
index 9eac008..adaa9da 100644
--- a/src/formatitko/context.py
+++ b/src/formatitko/context.py
@@ -1,4 +1,4 @@
-from panflute import Doc, Element, Div
+from panflute import Doc, Element, Div, Span
 
 from typing import Union, Callable
 from types import ModuleType
@@ -79,8 +79,6 @@ class Context:
 			return None
 
 	def set_metadata(self, key: str, value):
-		if key == "language":
-			warnings.warn("Setting language this way doesn't propagate to TeX. Either use the Front Matter or specify it additionally using the \\languagexx macro.", UserWarning)
 		meta = self.doc.metadata
 		keys = key.split(".")
 		for k in keys[:-1]:
@@ -99,9 +97,14 @@ class Context:
 # and also causes KaTeX math blocks to be isolated in a similar way.
 #
 # Whenever a new context is created, its content should be eclosed in a group and vice-versa.
-class Group(Div):
+class Group(Element):
 	def __init__(self, *args, context:Context, metadata={}, **kwargs):
-		self.metadata = metadata
+		self.metadata = metadata # This is only here for backwards compatibility with old html.py, tex.py and transform.py. FIXME: Remove this when the time comes.
 		self.context = context
 		super().__init__(*args, **kwargs)
 
+class BlockGroup(Group, Div):
+	pass
+
+class InlineGroup(Group, Span):
+	pass
diff --git a/src/formatitko/elements.py b/src/formatitko/elements.py
index 25aea17..9915f15 100644
--- a/src/formatitko/elements.py
+++ b/src/formatitko/elements.py
@@ -2,7 +2,7 @@ from panflute import Quoted
 
 
 from .command import Command, InlineCommand, BlockCommand
-from .context import Group
+from .context import Group, BlockGroup, InlineGroup
 from .whitespace import Whitespace, NBSP
 
 # This is a small extension to the Quoted panflute elements which allows to
diff --git a/src/formatitko/formatitko.py b/src/formatitko/formatitko.py
index a31931a..770984a 100755
--- a/src/formatitko/formatitko.py
+++ b/src/formatitko/formatitko.py
@@ -6,7 +6,7 @@ import sys
 # Import local files
 from .transform import transform
 from .util import import_md
-from .context import Context, Group
+from .context import Context, BlockGroup
 from .katex import KatexClient
 from .html import html
 from .tex import tex
@@ -41,7 +41,7 @@ def main():
 
 	# The language metadatum is important, so it's read before transformation and
 	# then attached to a group inside the Doc
-	language = doc1.get_metadata("language", None, True)
+	language = doc1.get_metadata("lang", None, True)
 	context = Context(doc1, args.input_filename)
 
 	# Transform the document. This includes all the fancy formatting this software does.
@@ -49,7 +49,7 @@ def main():
 
 	# Now wrap the document contents in a group, which is able to pop its language
 	# setting out to TeX
-	doc1.content = [Group(*doc1.content, context=context, metadata={"language":language})]
+	doc1.content = [BlockGroup(*doc1.content, context=context, metadata={"lang":language})]
 
 	doc2 = TransformProcessor(args.input_filename).transform(doc2)
 
diff --git a/src/formatitko/html_generator.py b/src/formatitko/html_generator.py
index f366998..a579d3f 100644
--- a/src/formatitko/html_generator.py
+++ b/src/formatitko/html_generator.py
@@ -14,7 +14,7 @@ from pygments.formatters import HtmlFormatter
 from pygments.util import ClassNotFound
 
 from .whitespace import NBSP
-from .context import Group
+from .context import Group, BlockGroup, InlineGroup
 from .output_generator import OutputGenerator
 from .katex import KatexClient
 from .images import ImageProcessor
@@ -78,6 +78,8 @@ class HTMLGenerator(OutputGenerator):
 				TableFoot: "tfoot",
 				TableRow: "tr",
 				TableCell: "td",
+				InlineGroup: "span",
+				BlockGroup: "div"
 			}[type(e)]
 		except KeyError:
 			return type(e).__name__.lower()
@@ -193,9 +195,15 @@ class HTMLGenerator(OutputGenerator):
 
 		self.generate(link)
 
+	def generate_InlineGroup(self, e: InlineGroup):
+		self.generate_Group(e)
+
+	def generate_BlockGroup(self, e: BlockGroup):
+		self.generate_Group(e)
+
 	def generate_Group(self, e: Group):
 		self.katexClient.begingroup()
-		self.generate(e.content)
+		self.generate_simple_tag(e, attributes=self.common_attributes(e) | {"lang":self.context.get_metadata("lang")})
 		self.katexClient.endgroup()
 
 	def generate_Plain(self, e: Plain):
diff --git a/src/formatitko/output_generator.py b/src/formatitko/output_generator.py
index b898365..0fc973c 100644
--- a/src/formatitko/output_generator.py
+++ b/src/formatitko/output_generator.py
@@ -6,7 +6,7 @@ from typing import Union
 
 from .whitespace import NBSP
 from .elements import FQuoted
-from .context import Group
+from .context import Group, InlineGroup, BlockGroup
 
 import re
 
@@ -59,7 +59,7 @@ class OutputGenerator:
 			TableBody: self.generate_TableBody,
 			TableFoot: self.generate_TableFoot,
 			TableHead: self.generate_TableHead,
-			Group: self.generate_Group
+			BlockGroup: self.generate_BlockGroup
 		}
 
 		self.TYPE_DICT_INLINE = {
@@ -84,7 +84,8 @@ class OutputGenerator:
 			Superscript: self.generate_Superscript,
 			Underline: self.generate_Underline,
 			NBSP: self.generate_NBSP,
-			FQuoted: self.generate_FQuoted
+			FQuoted: self.generate_FQuoted,
+			InlineGroup: self.generate_InlineGroup
 		}
 
 	def generate(self, e: Union[Element, ListContainer, list[Union[Element, ListContainer]]]):
@@ -408,9 +409,12 @@ class OutputGenerator:
 	def generate_Doc(self, e: Doc):
 		self.generate_simple_tag(e)
 	
-	def generate_Group(self, e: Group):
+	def generate_BlockGroup(self, e: BlockGroup):
 		self.generate_simple_tag(e)
-	
+
+	def generate_InlineGroup(self, e: InlineGroup):
+		self.generate_simple_tag(e)
+
 	# Special elements with more contents
 	def generate_Table(self, e: Table):
 		self.generate_simple_tag(e, content=[e.head, e.content, e.foot])
diff --git a/src/formatitko/tex.py b/src/formatitko/tex.py
index 23a2d62..74b6e6f 100644
--- a/src/formatitko/tex.py
+++ b/src/formatitko/tex.py
@@ -247,8 +247,8 @@ def tex(e: Union[Element, ListContainer], i: ImageProcessor, indent_level: int=0
 	elif isinstance(e, Group):
 		tag = "begingroup"
 		open = ""
-		if "language" in e.metadata and e.metadata["language"] is not None:
-			open = "\\language"+e.metadata["language"]
+		if "lang" in e.metadata and e.metadata["lang"] is not None:
+			open = "\\language"+e.metadata["lang"]
 		close = "\\endgroup"
 	
 	# The default which all non-overriding elements get generated by. This
diff --git a/src/formatitko/transform.py b/src/formatitko/transform.py
index 83601de..92c820e 100644
--- a/src/formatitko/transform.py
+++ b/src/formatitko/transform.py
@@ -5,7 +5,7 @@ import os
 # Import local files
 from .whitespace import Whitespace, NBSP, bavlna
 from .util import nullify, import_md
-from .context import Context, Group
+from .context import Context, BlockGroup
 from .command import Command, BlockCommand, InlineCommand
 from .command_util import handle_command_define, parse_command
 from .elements import FQuoted
@@ -70,9 +70,9 @@ def transform(e: Element, c: Context) -> Element:
 				if not c.trusted:
 					trusted = False
 				nContext = Context(includedDoc, path, c, trusted=trusted)
-				language = includedDoc.get_metadata("language")
+				language = includedDoc.get_metadata("lang")
 				includedDoc = includedDoc.walk(transform, nContext)
-				e = Group(*includedDoc.content, context=nContext, metadata={"language": language})
+				e = BlockGroup(*includedDoc.content, context=nContext, metadata={"lang": language})
 
 	# Transform panflute's Quoted to custom FQuoted, see above.
 	if isinstance(e, Quoted):
@@ -82,7 +82,7 @@ def transform(e: Element, c: Context) -> Element:
 			"sk": "cs",
 			None: None
 		}
-		e = FQuoted(*e.content, quote_type=e.quote_type, style=quote_styles[c.get_metadata("language")])
+		e = FQuoted(*e.content, quote_type=e.quote_type, style=quote_styles[c.get_metadata("lang")])
 	
 	if isinstance(e, Image):
 		# Pass down the directory of the current source file for finding image
diff --git a/src/formatitko/transform_processor.py b/src/formatitko/transform_processor.py
index b0032cf..998e6a9 100644
--- a/src/formatitko/transform_processor.py
+++ b/src/formatitko/transform_processor.py
@@ -6,10 +6,11 @@ from typing import Union, Callable
 
 import os
 import re
+import warnings
 
 from .whitespace import NBSP
 from .elements import FQuoted
-from .context import Group
+from .context import Group, InlineGroup, BlockGroup
 from .util import nullify, import_md
 from .context import Context
 from .whitespace import Whitespace, bavlna
@@ -69,6 +70,8 @@ class TransformProcessor:
 			TableFoot: self.transform_TableFoot,
 			TableHead: self.transform_TableHead,
 			Group: self.transform_Group,
+			InlineGroup: self.transform_InlineGroup,
+			BlockGroup: self.transform_BlockGroup,
 
 			Cite: self.transform_Cite,
 			Code: self.transform_Code,
@@ -253,6 +256,14 @@ class TransformProcessor:
 		e.content = self.transform(e.content)
 		return e
 
+	def transform_InlineGroup(self, e: InlineGroup) -> InlineGroup:
+		e.content = self.transform(e.content)
+		return e
+
+	def transform_BlockGroup(self, e: BlockGroup) -> BlockGroup:
+		e.content = self.transform(e.content)
+		return e
+
 	def transform_Cite(self, e: Cite) -> Cite:
 		e.content = self.transform(e.content)
 		return e
@@ -314,7 +325,7 @@ class TransformProcessor:
 			raise DoubleDocError()
 		self.context = Context(e, self.root_file_path)
 		e.content = self.transform(e.content)
-		e.content = [Group(*e.content, context=self.context)]
+		e.content = [BlockGroup(*e.content, context=self.context)]
 		return e
 
 
@@ -326,7 +337,7 @@ class TransformProcessor:
 			"sk": "cs",
 			None: None
 		}
-		return FQuoted(*e.content, quote_type=e.quote_type, style=quote_styles[self.context.get_metadata("language")])
+		return FQuoted(*e.content, quote_type=e.quote_type, style=quote_styles[self.context.get_metadata("lang")])
 
 	def transform_Image(self, e: Image) -> Image:
 		e.content = self.transform(e.content)
@@ -340,12 +351,15 @@ class TransformProcessor:
 			e.attributes["no-srcset"] = self.context.get_metadata("no-srcset") if self.context.get_metadata("no-srcset") is not None else False
 		return e
 
-	def create_Group(self, *content, new_context: Context) -> Group:
+	def create_Group(self, *content, new_context: Context, inline: bool=False) -> Group:
 		old_context = self.context
 		self.context = new_context
 		content = self.transform([*content])
 		self.context = old_context
-		return Group(*content, context=new_context)
+		if inline:
+			return InlineGroup(*content, context=new_context)
+		else:
+			return BlockGroup(*content, context=new_context)
 
 	def transform_Div(self, e: Div) -> Union[Div, Group, Null]:
 		e.content = self.transform(e.content)
@@ -355,7 +369,7 @@ class TransformProcessor:
 			# Content of Div is enclosed in a separate context, all attributes are passed as metadata
 			new_context = Context(Doc(), self.context.path, self.context, trusted=self.context.trusted)
 			for attribute, value in e.attributes.items():
-				new_context.set_metadata(attribute, value) # FIXME: This raises a warning when done with `language`. Since context is available to OG, we should trash the warning and rework the OG to use the Context.
+				new_context.set_metadata(attribute, value)
 			return self.create_Group(*e.content, new_context=new_context)
 
 		if "c" in e.attributes:
@@ -383,19 +397,22 @@ class TransformProcessor:
 				trusted = False
 			return self.create_Group(*includedDoc.content, new_context=Context(includedDoc, path, self.context, trusted=trusted))
 
+		if "lang" in e.attributes:
+			warnings.warn("To set language in a way formátítko will understand, this Div has to have the `.group` class and be a Group.", UserWarning)
+
 		return e
 
 	def transform_Span(self, e: Span) -> Span:
 		e.content = self.transform(e.content)
 
 		# TODO: This sadly doesn't work. We would need to create a separate class InlineGroup, that would be Inline.
-		#if "group" in e.classes:
-		#	# `.group` class for Spans
-		#	# Content of Span is enclosed in a separate context, all attributes are passed as metadata
-		#	new_context = Context(Doc(), self.context.path, self.context, trusted=self.context.trusted)
-		#	for attribute, value in e.attributes.items():
-		#		new_context.set_metadata(attribute, value)
-		#	return self.create_Group(*e.content, new_context=new_context)
+		if "group" in e.classes:
+			# `.group` class for Spans
+			# Content of Span is enclosed in a separate context, all attributes are passed as metadata
+			new_context = Context(Doc(), self.context.path, self.context, trusted=self.context.trusted)
+			for attribute, value in e.attributes.items():
+				new_context.set_metadata(attribute, value)
+			return self.create_Group(*e.content, new_context=new_context, inline=True)
 
 		if "c" in e.attributes:
 			# Commands can be called multiple ways, this handles the following syntax:
diff --git a/test/test-files/test-partial.md b/test/test-files/test-partial.md
index 9e63376..db8ae8e 100644
--- a/test/test-files/test-partial.md
+++ b/test/test-files/test-partial.md
@@ -30,14 +30,14 @@ return [
 
 ```markdown {.group}
 ---
-language: "cs"
+lang: "cs"
 ---
 Tak toto je "v prádelně" pánové!
 ```
 
 ```markdown {.group}
 ---
-language: "en"
+lang: "en"
 ---
 This is "in a laundry room" gentlemen!
 ```
diff --git a/test/test.md b/test/test.md
index 90eb111..8cafab2 100644
--- a/test/test.md
+++ b/test/test.md
@@ -2,7 +2,6 @@
 title: 'Wooooo a title'
 subtitle: 'A subtitle'
 are_we_there_yet: False
-language: "en"
 lang: "en"
 ---
 [#test-files/test-import.md]{}
@@ -56,7 +55,7 @@ This should only be shown to cats the second time
 
 ```markdown {.group}
 ---
-language: cs
+lang: cs
 ---
 V​ pravém jízdním bruhu.
 V pravém jízdním bruhu.
@@ -115,10 +114,10 @@ $$
 
 ---
 
-In this text, there might be some phrases [v češtině]{.group language=cs} and <!-- Tohle nefunguje :( -->
+In this text, there might be some phrases [v češtině]{.group lang=cs} and
 maybe even
 
-:::{.group language=cs}
+:::{.group lang=cs}
 celé pasáže textu v češtině.
 
 Růžový bagr bez zeleného bagru se žlutým bagrem.