diff --git a/public/css/global.css b/public/css/global.css
index 48ab81a..30c5620 100644
--- a/public/css/global.css
+++ b/public/css/global.css
@@ -51,6 +51,7 @@
         --c-primary: rgb(255, 180, 180);
         --c-pink: #374259;
         --c-link: #0284c7;
+        --c-border-1: #909090;
 
         --c-nav-bg: rgb(255, 247, 255, 0.5);
         --c-secondary: rgba(255, 255, 240, 0.5);
diff --git a/public/css/pages.css b/public/css/pages.css
index b52cfd5..881321e 100644
--- a/public/css/pages.css
+++ b/public/css/pages.css
@@ -60,6 +60,10 @@
     padding: 0.5rem 0;
 }
 
+.markdown > p > code {
+    border: solid 1px var(--c-border-1);
+}
+
 .markdown > pre {
     margin: 0.5em 0;
     padding: 0.75em 0.75em;
diff --git a/src/lexer/highlighter.ts b/src/lexer/highlighter.ts
index 88cdb67..8f5f91d 100644
--- a/src/lexer/highlighter.ts
+++ b/src/lexer/highlighter.ts
@@ -1,7 +1,7 @@
 import { spawn } from "node:child_process";
 import { leftTrimDedent } from "../components/utils";
 import { HighlightLevel } from "./types";
-import type { LexError, SyntaxError, SemanticError, Token, TokenizeResult, TokenType } from "./types";
+import type { LexError, SyntaxError, Token, TokenizeResult, TokenType } from "./types";
 
 const error_classes = "underline underline-offset-4 decoration-wavy decoration-red-500";
 
diff --git a/src/pages/spec/tokens/numbers.mdx b/src/pages/spec/tokens/numbers.mdx
index 6b20cb9..cb17f6c 100644
--- a/src/pages/spec/tokens/numbers.mdx
+++ b/src/pages/spec/tokens/numbers.mdx
@@ -10,23 +10,30 @@ import Code from "../../../components/Code.astro"
 
 ```ebnf
 Int = hexadecimal_number
+    | octal_number
+    | binary_number
     | decimal_number
 
 hexadecimal_number = "0", ("x" | "X"), hexadecimal_digit+
 decimal_number     = decimal_digit+
+octal_number       = "0", ("o" | "O"), octal_digit+
+binary_number      = "0", "b", binary_digit +
 ```
 
 <Code thpcode={`
 12345
 01234   // This is a decimal number, not an octal number
+0o755   // This is octal
+0b0110
 0xff25
 0XFfaA
 `} />
 
-`TODO`: Implement octal `0o777` and binary `0b0110`.
-
 `TODO`: Allow underscores `_` between any number: `1_000_000`.
 
+`TODO`: Make it an error to have a number start with a leading zero,
+to eliminate confusion with proper octal and legacy PHP octal.
+
 
 ## Float