Fetch doxygen css files directly from GH repo

Author: Hind-M

docs/CMakeLists.txt

@@ -1,5 +1,31 @@
 find_package(Doxygen REQUIRED)
 
+set(DOXYGEN_AWESOME_DIR ${CMAKE_CURRENT_BINARY_DIR}/doxygen-awesome-css)
+file(MAKE_DIRECTORY ${DOXYGEN_AWESOME_DIR})
+
+set(BASE_URL "https://raw.githubusercontent.com/jothepro/doxygen-awesome-css/v2.3.4")
+
+set(FILES_TO_DOWNLOAD
+    LICENSE
+    doxygen-awesome-darkmode-toggle.js
+    doxygen-awesome-fragment-copy-button.js
+    doxygen-awesome-interactive-toc.js
+    doxygen-awesome-paragraph-link.js
+    doxygen-awesome-sidebar-only-darkmode-toggle.css
+    doxygen-awesome-sidebar-only.css
+    doxygen-awesome-tabs.js
+    doxygen-awesome.css
+)
+
+foreach(FILE ${FILES_TO_DOWNLOAD})
+    if(NOT EXISTS ${DOXYGEN_AWESOME_DIR}/${FILE})
+        message(STATUS "Downloading ${FILE}")
+        file(DOWNLOAD ${BASE_URL}/${FILE} ${DOXYGEN_AWESOME_DIR}/${FILE} STATUS status)
+    endif()
+endforeach()
+
+set(DOXYGEN_AWESOME_CSS_PATH "${DOXYGEN_AWESOME_DIR}/doxygen-awesome.css")
+
 # Configure the doxygen.in file
 configure_file(${CMAKE_CURRENT_SOURCE_DIR}/Doxyfile.in ${CMAKE_CURRENT_BINARY_DIR}/Doxyfile @ONLY)
 

docs/Doxyfile.in

@@ -1365,7 +1365,7 @@ HTML_STYLESHEET        =
 # documentation.
 # This tag requires that the tag GENERATE_HTML is set to YES.
 
-HTML_EXTRA_STYLESHEET  = @CMAKE_SOURCE_DIR@/docs/doxygen-awesome-css/doxygen-awesome.css
+HTML_EXTRA_STYLESHEET  = @DOXYGEN_AWESOME_CSS_PATH@
 
 # The HTML_EXTRA_FILES tag can be used to specify one or more extra images or
 # other source files which should be copied to the HTML output directory. Note