diff --git a/runtime/syntax/cpp.vim b/runtime/syntax/cpp.vim
index ed38913..3ad79d5 100644
--- a/runtime/syntax/cpp.vim
+++ b/runtime/syntax/cpp.vim
@@ -2,7 +2,7 @@
 " Language:	C++
 " Current Maintainer:	vim-jp (https://github.com/vim-jp/vim-cpp)
 " Previous Maintainer:	Ken Shan <ccshan@post.harvard.edu>
-" Last Change:	2021 Jan 12
+" Last Change:	2021 May 04
 
 " quit when a syntax file was already loaded
 if exists("b:current_syntax")
@@ -44,33 +44,45 @@
   syn keyword cppConstant	ATOMIC_WCHAR_T_LOCK_FREE ATOMIC_SHORT_LOCK_FREE
   syn keyword cppConstant	ATOMIC_INT_LOCK_FREE ATOMIC_LONG_LOCK_FREE
   syn keyword cppConstant	ATOMIC_LLONG_LOCK_FREE ATOMIC_POINTER_LOCK_FREE
-  syn region cppRawString	matchgroup=cppRawStringDelimiter start=+\%(u8\|[uLU]\)\=R"\z([[:alnum:]_{}[\]#<>%:;.?*\+\-/\^&|~!=,"']\{,16}\)(+ end=+)\z1"+ contains=@Spell
+  syn region cppRawString	matchgroup=cppRawStringDelimiter start=+\%(u8\|[uLU]\)\=R"\z([[:alnum:]_{}[\]#<>%:;.?*\+\-/\^&|~!=,"']\{,16}\)(+ end=+)\z1"\(sv\|s\|_[_a-zA-Z][_a-zA-Z0-9]*\)\=+ contains=@Spell
   syn match cppCast		"\<\(const\|static\|dynamic\)_pointer_cast\s*<"me=e-1
   syn match cppCast		"\<\(const\|static\|dynamic\)_pointer_cast\s*$"
 endif
 
 " C++ 14 extensions
 if !exists("cpp_no_cpp14")
-  syn case ignore
-  syn match cppNumber		display "\<0b[01]\('\=[01]\+\)*\(u\=l\{0,2}\|ll\=u\)\>"
-  syn match cppNumber		display "\<[1-9]\('\=\d\+\)*\(u\=l\{0,2}\|ll\=u\)\>" contains=cFloat
-  syn match cppNumber		display "\<0x\x\('\=\x\+\)*\(u\=l\{0,2}\|ll\=u\)\>"
-  syn case match
-endif
-
-" C++ 20 extensions
-if !exists("cpp_no_cpp20")
-  syn keyword cppStatement	co_await co_return co_yield requires
-  syn keyword cppStorageClass	consteval constinit
-  syn keyword cppStructure	concept
-  syn keyword cppType		char8_t
-  syn keyword cppModule		import module export
+  syn match cppNumbers		display transparent "\<\d\|\.\d" contains=cppNumber,cppFloat
+  syn match cppNumber		display contained "\<0\([Uu]\=\([Ll]\|LL\|ll\)\|\([Ll]\|LL\|ll\)\=[Uu]\|i[fl]\=\|h\|min\|s\|ms\|us\|ns\|_\i*\)\=\>"
+  syn match cppNumber		display contained "\<[1-9]\('\=\d\+\)*\([Uu]\=\([Ll]\|LL\|ll\)\|\([Ll]\|LL\|ll\)\=[Uu]\|i[fl]\=\|h\|min\|s\|ms\|us\|ns\|_\i*\)\=\>"
+  syn match cppNumber		display contained "\<0\o\+\([Uu]\=\([Ll]\|LL\|ll\)\|\([Ll]\|LL\|ll\)\=[Uu]\|i[fl]\=\|h\|min\|s\|ms\|us\|ns\|_\i*\)\=\>"
+  syn match cppNumber		display contained "\<0b[01]\('\=[01]\+\)*\([Uu]\=\([Ll]\|LL\|ll\)\|\([Ll]\|LL\|ll\)\=[Uu]\|i[fl]\=\|h\|min\|s\|ms\|us\|ns\|_\i*\)\=\>"
+  syn match cppNumber		display contained "\<0x\x\('\=\x\+\)*\([Uu]\=\([Ll]\|LL\|ll\)\|\([Ll]\|LL\|ll\)\=[Uu]\|i[fl]\=\|h\|min\|s\|ms\|us\|ns\|_\i*\)\=\>"
+  syn match cppFloat		display contained "\<\d\+\.\d*\(e[-+]\=\d\+\)\=\([FfLl]\|i[fl]\=\|h\|min\|s\|ms\|us\|ns\|_\i*\)\=\>"
+  syn match cppFloat		display contained "\<\.\d\+\(e[-+]\=\d\+\)\=\([FfLl]\|i[fl]\=\|h\|min\|s\|ms\|us\|ns\|_\i*\)\=\>"
+  syn match cppFloat		display contained "\<\d\+e[-+]\=\d\+\([FfLl]\|i[fl]\=\|h\|min\|s\|ms\|us\|ns\|_\i*\)\=\>"
+  syn region cppString		start=+\(L\|u\|u8\|U\|R\|LR\|u8R\|uR\|UR\)\="+ skip=+\\\\\|\\"\|\\$+ excludenl end=+"\(sv\|s\|_\i*\)\=+ end='$' contains=cSpecial,cFormat,@Spell
 endif
 
 " C++ 17 extensions
 if !exists("cpp_no_cpp17")
   syn match cppCast		"\<reinterpret_pointer_cast\s*<"me=e-1
   syn match cppCast		"\<reinterpret_pointer_cast\s*$"
+  syn match cppFloat		display contained "\<0x\x*\.\x\+p[-+]\=\d\+\([FfLl]\|i[fl]\=\|h\|min\|s\|ms\|us\|ns\|_\i*\)\=\>"
+  syn match cppFloat		display contained "\<0x\x\+\.\=p[-+]\=\d\+\([FfLl]\|i[fl]\=\|h\|min\|s\|ms\|us\|ns\|_\i*\)\=\>"
+endif
+
+" C++ 20 extensions
+if !exists("cpp_no_cpp20")
+  syn match cppNumber		display contained "\<0\(y\|d\)\>"
+  syn match cppNumber		display contained "\<[1-9]\('\=\d\+\)*\(y\|d\)\>"
+  syn match cppNumber		display contained "\<0\o\+\(y\|d\)\>"
+  syn match cppNumber		display contained "\<0b[01]\('\=[01]\+\)*\(y\|d\)\>"
+  syn match cppNumber		display contained "\<0x\x\('\=\x\+\)*\(y\|d\)\>"
+  syn keyword cppStatement	co_await co_return co_yield requires
+  syn keyword cppStorageClass	consteval constinit
+  syn keyword cppStructure	concept
+  syn keyword cppType		char8_t
+  syn keyword cppModule		import module export
 endif
 
 " The minimum and maximum operators in GNU C++
@@ -90,7 +102,9 @@
 hi def link cppConstant		Constant
 hi def link cppRawStringDelimiter	Delimiter
 hi def link cppRawString		String
+hi def link cppString		String
 hi def link cppNumber		Number
+hi def link cppFloat		Number
 hi def link cppModule		Include
 
 let b:current_syntax = "cpp"