Add colors to --help (#253)

Thank you!

CHANGELOG.md

@@ -6,6 +6,7 @@
 - Add `--color-scheme` option, see #247 (@aticu)
 - Add `braille` character table, see #247 (@aticu)
 - Add command line argument to generate shell completion, see #155 (@friedz)
+- Add colors to `--help`/`-h`, see #253 (@starsep)
 
 ## Bugfixes
 

src/main.rs

@@ -3,7 +3,9 @@ use std::io::{self, prelude::*, BufWriter, SeekFrom};
 use std::num::{NonZeroI64, NonZeroU64};
 use std::path::PathBuf;
 
+use clap::builder::styling::{AnsiColor, Effects};
 use clap::builder::ArgPredicate;
+use clap::builder::Styles;
 use clap::{ArgAction, CommandFactory, Parser, ValueEnum};
 use clap_complete::aot::{generate, Shell};
 
@@ -54,8 +56,14 @@ Since the terminal width may not be an evenly divisible by the width per hex dat
                                         the right.
 Cannot be used with other width-setting options.";
 
+const STYLES: Styles = Styles::styled()
+    .header(AnsiColor::Green.on_default().effects(Effects::BOLD))
+    .usage(AnsiColor::Green.on_default().effects(Effects::BOLD))
+    .literal(AnsiColor::Cyan.on_default().effects(Effects::BOLD))
+    .placeholder(AnsiColor::Cyan.on_default());
+
 #[derive(Debug, Parser)]
-#[command(version, about, max_term_width(90))]
+#[command(version, about, max_term_width(90), styles = STYLES)]
 struct Opt {
     /// The file to display. If no FILE argument is given, read from STDIN.
     #[arg(value_name("FILE"))]