Make UI colors theme-safe by default and configurable via [theme]

De-emphasized text now uses the faint attribute instead of DarkGray, and
status colors move to the bright ANSI range, so the UI stays legible on
terminal themes with mid-toned backgrounds like macOS Terminal's "Ocean"
(#25). Past-TTL becomes orange to stay distinct from the brighter error
red.

Every color role (accent, agree, differ, error, pending, stale, upstream,
muted, coastline, grid) can be overridden from a [theme] table in the
config file, accepting ANSI names, 256-color indexes, or hex. The muted
role also accepts "faint" (the default) as an escape hatch works the other
way: terminals that render faint poorly can set a fixed color instead.

Fixes #25

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: callicles

CHANGELOG.md

@@ -26,6 +26,23 @@ adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
   releases can be pinned via git tag (`github:514-labs/dnsglobe/v0.3.0`).
   A `devbox.json` is included for reproducible development environments.
   ([#10](https://github.com/514-labs/dnsglobe/issues/10))
+- Custom color themes: a `[theme]` table in the config file recolors any UI
+  role (`accent`, `agree`, `differ`, `error`, `pending`, `stale`,
+  `upstream`, `muted`, `coastline`, `grid`) using ANSI color names,
+  256-color indexes, or hex values.
+  ([#27](https://github.com/514-labs/dnsglobe/pull/27))
+
+### Changed
+
+- The default palette now stays legible on terminal themes with mid-toned
+  backgrounds, like macOS Terminal's "Ocean": de-emphasized text uses the
+  faint attribute instead of dark gray (dimming your theme's own foreground
+  color, which is always readable), and status colors moved to the bright
+  ANSI range. Past-TTL is now orange to stay distinct from the brighter
+  error red. Set `muted = "darkgray"` in `[theme]` to restore the old
+  de-emphasis on terminals that render faint poorly.
+  ([#25](https://github.com/514-labs/dnsglobe/issues/25),
+  [#27](https://github.com/514-labs/dnsglobe/pull/27))
 
 ## [0.3.1] - 2026-07-06
 

README.md

@@ -97,10 +97,28 @@ lon = -74.0              #            omit both to leave it off the map
 [[resolvers]]
 name = "NS1 (public)"
 ip = "198.51.100.53"
+
+# Optionally recolor the UI. Every key is optional; unset roles keep their
+# defaults. Colors are ANSI names ("lightcyan"), 256-color indexes ("208"),
+# or hex ("#ff8700" — needs truecolor support).
+[theme]
+accent   = "lightcyan"    # borders, titles, cursor, anycast sites
+agree    = "lightgreen"   # answers matching the majority; fast latency
+differ   = "lightmagenta" # answers disagreeing with the majority
+error    = "lightred"     # ERR / SERVFAIL / NONE; slow latency
+pending  = "lightyellow"  # queries in flight; middling latency
+stale    = "208"          # caches serving an answer past its own TTL
+upstream = "lightblue"    # refetched but upstream still has the old data
+muted    = "faint"        # labels, hints, countdowns, quiet borders —
+                          # "faint" dims your terminal's default foreground;
+                          # set a color if your terminal renders faint poorly
+coastline = "gray"        # map/globe land outline
+grid      = "244"         # globe graticule and limb
 ```
 
-Invalid config (bad IP, unknown key, `lat` without `lon`, `replace = true`
-with no resolvers) is reported at startup with the offending entry named.
+Invalid config (bad IP, unknown key, unrecognized color, `lat` without
+`lon`, `replace = true` with no resolvers) is reported at startup with the
+offending entry named.
 
 ## Notes
 

demo/demo.gif

@@ -1,6 +1,7 @@
 //! Optional TOML config file that adds resolvers to the built-in list, or
 //! replaces the list entirely (e.g. to check propagation across your own
-//! infrastructure, or an internal split-horizon zone).
+//! infrastructure, or an internal split-horizon zone), and recolors the UI
+//! via a `[theme]` table.
 //!
 //! Looked up at `$DNSGLOBE_CONFIG`, else `$XDG_CONFIG_HOME/dnsglobe/config.toml`,
 //! else `~/.config/dnsglobe/config.toml`. A missing default file just means
@@ -14,6 +15,7 @@ use serde::Deserialize;
 
 use crate::app::ViewMode;
 use crate::resolvers::{self, Resolver};
+use crate::theme::{self, Theme};
 
 #[derive(Debug, Default, Deserialize)]
 #[serde(deny_unknown_fields)]
@@ -25,9 +27,29 @@ pub struct Config {
     /// Preferred map panel style; the --view flag overrides it.
     view: Option<ViewMode>,
     #[serde(default)]
+    theme: ThemeTable,
+    #[serde(default)]
     resolvers: Vec<Entry>,
 }
 
+/// Raw `[theme]` colors as written in the file; validated into a
+/// `theme::Theme` by `build_theme`. Every key is optional — unset roles keep
+/// their defaults, so a theme can adjust a single color.
+#[derive(Debug, Default, Deserialize)]
+#[serde(deny_unknown_fields)]
+struct ThemeTable {
+    accent: Option<String>,
+    agree: Option<String>,
+    differ: Option<String>,
+    error: Option<String>,
+    pending: Option<String>,
+    stale: Option<String>,
+    upstream: Option<String>,
+    muted: Option<String>,
+    coastline: Option<String>,
+    grid: Option<String>,
+}
+
 #[derive(Debug, Deserialize)]
 #[serde(deny_unknown_fields)]
 struct Entry {
@@ -46,13 +68,15 @@ struct Entry {
 pub struct Settings {
     pub resolvers: Vec<Resolver>,
     pub view: Option<ViewMode>,
+    pub theme: Theme,
 }
 
 impl Settings {
     fn defaults() -> Self {
         Self {
             resolvers: resolvers::defaults(),
             view: None,
+            theme: Theme::default(),
         }
     }
 }
@@ -76,12 +100,18 @@ pub fn load() -> Result<Settings> {
             return Err(err).with_context(|| format!("reading config file {}", path.display()));
         }
     };
-    let config: Config =
+    let mut config: Config =
         toml::from_str(&text).with_context(|| format!("parsing {}", path.display()))?;
     let view = config.view;
+    let theme = build_theme(std::mem::take(&mut config.theme))
+        .with_context(|| format!("invalid config {}", path.display()))?;
     let resolvers =
         resolver_list(config).with_context(|| format!("invalid config {}", path.display()))?;
-    Ok(Settings { resolvers, view })
+    Ok(Settings {
+        resolvers,
+        view,
+        theme,
+    })
 }
 
 fn default_path() -> Option<PathBuf> {
@@ -92,6 +122,31 @@ fn default_path() -> Option<PathBuf> {
     Some(base.join("dnsglobe").join("config.toml"))
 }
 
+/// Overlay the config's `[theme]` colors on the defaults, erroring with the
+/// offending key so a typo'd color is easy to find in the file.
+fn build_theme(table: ThemeTable) -> Result<Theme> {
+    let mut out = Theme::default();
+    for (key, value, slot) in [
+        ("accent", table.accent, &mut out.accent),
+        ("agree", table.agree, &mut out.agree),
+        ("differ", table.differ, &mut out.differ),
+        ("error", table.error, &mut out.error),
+        ("pending", table.pending, &mut out.pending),
+        ("stale", table.stale, &mut out.stale),
+        ("upstream", table.upstream, &mut out.upstream),
+        ("coastline", table.coastline, &mut out.coastline),
+        ("grid", table.grid, &mut out.grid),
+    ] {
+        if let Some(value) = value {
+            *slot = theme::parse_color(&value).with_context(|| format!("theme.{key}"))?;
+        }
+    }
+    if let Some(value) = table.muted {
+        out.muted = theme::parse_muted(&value).context("theme.muted")?;
+    }
+    Ok(out)
+}
+
 /// Validate the config and merge it with the built-in list.
 fn resolver_list(config: Config) -> Result<Vec<Resolver>> {
     let mut list = if config.replace {
@@ -259,6 +314,48 @@ mod tests {
         assert!(toml::from_str::<Config>("view = \"sphere\"").is_err());
     }
 
+    fn theme(toml_text: &str) -> Result<Theme> {
+        let config: Config = toml::from_str(toml_text)?;
+        build_theme(config.theme)
+    }
+
+    #[test]
+    fn missing_or_empty_theme_keeps_the_defaults() {
+        assert_eq!(theme("").unwrap(), Theme::default());
+        assert_eq!(theme("[theme]").unwrap(), Theme::default());
+    }
+
+    #[test]
+    fn theme_overrides_only_the_given_roles() {
+        let theme = theme(
+            r##"
+            [theme]
+            accent = "#ff8700"
+            muted = "darkgray"
+            "##,
+        )
+        .unwrap();
+        assert_eq!(theme.accent, ratatui::style::Color::Rgb(0xff, 0x87, 0x00));
+        assert_eq!(
+            theme.muted,
+            crate::theme::Muted::Color(ratatui::style::Color::DarkGray)
+        );
+        assert_eq!(theme.agree, Theme::default().agree);
+    }
+
+    #[test]
+    fn bad_theme_color_errors_with_the_key_name() {
+        let err = theme("[theme]\nstale = \"ornage\"").unwrap_err();
+        let chain = format!("{err:#}");
+        assert!(chain.contains("theme.stale"), "{chain}");
+        assert!(chain.contains("\"ornage\""), "{chain}");
+    }
+
+    #[test]
+    fn unknown_theme_keys_are_rejected_to_catch_typos() {
+        assert!(toml::from_str::<Config>("[theme]\naccnt = \"red\"").is_err());
+    }
+
     #[test]
     fn unknown_keys_are_rejected_to_catch_typos() {
         assert!(toml::from_str::<Config>("replase = true").is_err());

src/config.rs

@@ -4,6 +4,7 @@ mod dns;
 mod globe;
 mod resolvers;
 mod sites;
+mod theme;
 mod ui;
 mod world_data;
 
@@ -35,7 +36,14 @@ Configuration:
   ip = \"10.0.0.53\"       # required, IPv4 or IPv6
   location = \"HQ\"        # optional; shown in the Loc column
   lat = 40.7             # optional map position;
-  lon = -74.0            # give both or neither";
+  lon = -74.0            # give both or neither
+
+  [theme]                # optional; override any UI color role
+  # accent = \"lightcyan\" # roles: accent, agree, differ, error, pending,
+  # stale = \"208\"        #   stale, upstream, muted, coastline, grid
+  # muted = \"faint\"      # colors: ANSI names (\"lightred\"), 256-color
+  #                      #   indexes (\"208\"), or hex (\"#ff8700\"); `muted`
+  #                      #   also takes \"faint\" (dim the default foreground)";
 
 /// Global DNS propagation checker TUI — watch a DNS record propagate across
 /// public resolvers worldwide, on a world map in your terminal.
@@ -86,6 +94,7 @@ async fn main() -> Result<()> {
     let settings = config::load()?;
     let view = cli.view.or(settings.view).unwrap_or_default();
     resolvers::init(settings.resolvers);
+    theme::init(settings.theme);
 
     // `--once` runs a single check and prints plain text — handy for scripts
     // and for testing without a TTY.