diff --git a/CHANGES.rst b/CHANGES.rst
index 83155e42..b7f5cc5a 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -1,6 +1,12 @@
 Release Notes
 -------------
 
+**3.1.1 (unreleased)**
+
+* Fix issue with reporting of missing CSS files. (`#388 <https://github.com/pytest-dev/pytest-html/issues/388>`_)
+
+  * Thanks to `@prakhargurunani <https://github.com/prakhargurunani>`_ for reporting and fixing!
+
 **3.1.0 (2020-12-2)**
 
 * Stop attaching test reruns to final test report entries (`#374 <https://github.com/pytest-dev/pytest-html/issues/374>`_)
diff --git a/src/pytest_html/plugin.py b/src/pytest_html/plugin.py
index bec01a74..c01cc7d5 100644
--- a/src/pytest_html/plugin.py
+++ b/src/pytest_html/plugin.py
@@ -86,9 +86,18 @@ def pytest_addoption(parser):
 def pytest_configure(config):
     htmlpath = config.getoption("htmlpath")
     if htmlpath:
+        missing_css_files = []
         for csspath in config.getoption("css"):
             if not os.path.exists(csspath):
-                raise OSError(f"No such file or directory: '{csspath}'")
+                missing_css_files.append(csspath)
+
+        if missing_css_files:
+            oserror = (
+                f"Missing CSS file{'s' if len(missing_css_files) > 1 else ''}:"
+                f" {', '.join(missing_css_files)}"
+            )
+            raise OSError(oserror)
+
         if not hasattr(config, "workerinput"):
             # prevent opening htmlpath on worker nodes (xdist)
             config._html = HTMLReport(htmlpath, config)
diff --git a/testing/test_pytest_html.py b/testing/test_pytest_html.py
index 75a8922a..2bab9a19 100644
--- a/testing/test_pytest_html.py
+++ b/testing/test_pytest_html.py
@@ -1005,12 +1005,31 @@ def test_css(self, testdir, recwarn, colors):
             assert str(v["path"]) in html
             assert v["style"] in html
 
-    def test_css_invalid(self, testdir, recwarn):
+    @pytest.mark.parametrize(
+        "files",
+        [
+            "style.css",
+            ["abc.css", "xyz.css"],
+            "testdir.makefile('.css', * {color: 'white'}",
+        ],
+    )
+    def test_css_invalid(self, testdir, recwarn, files):
         testdir.makepyfile("def test_pass(): pass")
-        result = testdir.runpytest("--html", "report.html", "--css", "style.css")
+        path = files
+        if isinstance(files, list):
+            file1 = files[0]
+            file2 = files[1]
+            result = testdir.runpytest(
+                "--html", "report.html", "--css", file1, "--css", file2
+            )
+        else:
+            result = testdir.runpytest("--html", "report.html", "--css", path)
         assert result.ret
         assert len(recwarn) == 0
-        assert "No such file or directory: 'style.css'" in result.stderr.str()
+        if isinstance(files, list):
+            assert files[0] in result.stderr.str() and files[1] in result.stderr.str()
+        else:
+            assert path in result.stderr.str()
 
     def test_css_invalid_no_html(self, testdir):
         testdir.makepyfile("def test_pass(): pass")