diff --git a/Cargo.lock b/Cargo.lock
index cab7774..37a34b8 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -62,7 +62,9 @@ version = "0.1.0"
 dependencies = [
  "arg",
  "crossterm",
+ "once_cell",
  "ropey",
+ "toml",
  "yacexits",
 ]
 
@@ -129,6 +131,22 @@ version = "0.3.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d2fabcfbdc87f4758337ca535fb41a6d701b65693ce38287d856d1674551ec9b"
 
+[[package]]
+name = "hashbrown"
+version = "0.12.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8a9ee70c43aaf417c914396645a0fa852624801b24ebb7ae78fe8272889ac888"
+
+[[package]]
+name = "indexmap"
+version = "1.9.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bd070e393353796e801d209ad339e89596eb4c8d430d18ede6a1cced8fafbd99"
+dependencies = [
+ "autocfg",
+ "hashbrown",
+]
+
 [[package]]
 name = "lazy_static"
 version = "1.4.0"
@@ -309,6 +327,21 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d29ab0c6d3fc0ee92fe66e2d99f700eab17a8d57d1c1d3b748380fb20baa78cd"
 
+[[package]]
+name = "serde"
+version = "1.0.160"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bb2f3770c8bce3bcda7e149193a069a0f4365bda1fa5cd88e03bca26afc1216c"
+
+[[package]]
+name = "serde_spanned"
+version = "0.6.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0efd8caf556a6cebd3b285caf480045fcc1ac04f6bd786b09a6f11af30c4fcf4"
+dependencies = [
+ "serde",
+]
+
 [[package]]
 name = "shlex"
 version = "1.1.0"
@@ -377,6 +410,40 @@ dependencies = [
  "unicode-width",
 ]
 
+[[package]]
+name = "toml"
+version = "0.7.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b403acf6f2bb0859c93c7f0d967cb4a75a7ac552100f9322faf64dc047669b21"
+dependencies = [
+ "serde",
+ "serde_spanned",
+ "toml_datetime",
+ "toml_edit",
+]
+
+[[package]]
+name = "toml_datetime"
+version = "0.6.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3ab8ed2edee10b50132aed5f331333428b011c99402b5a534154ed15746f9622"
+dependencies = [
+ "serde",
+]
+
+[[package]]
+name = "toml_edit"
+version = "0.19.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "239410c8609e8125456927e6707163a3b1fdb40561e4b803bc041f466ccfdc13"
+dependencies = [
+ "indexmap",
+ "serde",
+ "serde_spanned",
+ "toml_datetime",
+ "winnow",
+]
+
 [[package]]
 name = "unicode-ident"
 version = "1.0.8"
@@ -494,6 +561,15 @@ version = "0.42.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9aec5da331524158c6d1a4ac0ab1541149c0b9505fde06423b02f5ef0106b9f0"
 
+[[package]]
+name = "winnow"
+version = "0.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ae8970b36c66498d8ff1d66685dc86b91b29db0c7739899012f63a63814b4b28"
+dependencies = [
+ "memchr",
+]
+
 [[package]]
 name = "yacexits"
 version = "0.1.5"
diff --git a/Cargo.toml b/Cargo.toml
index 9dc3429..45438d7 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -7,5 +7,7 @@ license = "AGPL-3.0-or-later"
 [dependencies]
 arg = "0.4.1"
 crossterm = "0.26"
+once_cell = "1.17"
 ropey = "1.6"
+toml = "0.7"
 yacexits = "0.1.5"
diff --git a/default_theme.toml b/default_theme.toml
new file mode 100644
index 0000000..be3ce26
--- /dev/null
+++ b/default_theme.toml
@@ -0,0 +1,3 @@
+"ui.linenr" = "gray"
+
+"error" = "red"
diff --git a/src/main.rs b/src/main.rs
index ea9a540..c814eaa 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -20,12 +20,7 @@
 use std::{
     env::args,
     fs::File,
-    io::{
-        Read,
-        stdout,
-        Stdout,
-        Write,
-    },
+    io::{stdout, Read, Stdout, Write},
     os::fd::FromRawFd,
 };
 
@@ -35,7 +30,11 @@ use crossterm::{
     terminal, ExecutableCommand, Result,
 };
 use ropey::Rope;
-use yacexits::{ exit, EX_DATAERR, EX_UNAVAILABLE };
+use yacexits::{exit, EX_DATAERR, EX_UNAVAILABLE};
+
+mod theme;
+
+use theme::StyleStore;
 
 struct Buffer {
     pub text: Rope,
@@ -50,13 +49,15 @@ impl Buffer {
 
     pub fn draw(
         &self,
+        styles: &mut StyleStore,
         cols: u16,
         rows: u16,
         scroll: Cursor,
         out: &mut (impl ExecutableCommand + Write),
     ) -> Result<u32> {
-        let lr_width = self.text.len_lines().ilog10() + 1;
-        let gutter_width = lr_width + 1;
+        let linenr_style = styles.get_scope("ui.linenr");
+        let linenr_width = self.text.len_lines().ilog10() + 1;
+        let gutter_width = linenr_width + 1;
         let text_width = cols as usize - gutter_width as usize;
 
         out.execute(cursor::MoveTo(0, 0))?;
@@ -68,7 +69,8 @@ impl Buffer {
             }
 
             let row = row as usize + scroll.line;
-            write!(out, "{:width$} ", row, width = lr_width as usize)?;
+            let linenr = format!("{:width$} ", row, width = linenr_width as usize);
+            linenr_style.print_styled(out, &linenr)?;
 
             let lhs = scroll.column;
             let width = line.len_chars().saturating_sub(1); // lop off whitespace
@@ -192,6 +194,7 @@ enum Direction {
 }
 
 struct State {
+    pub style_store: StyleStore,
     pub buffer: Buffer,
     pub cursor: Cursor,
     pub scroll: Cursor,
@@ -205,6 +208,7 @@ impl State {
         let (cols, rows) = terminal::size()?;
 
         Ok(Self {
+            style_store: StyleStore::default(),
             buffer: Buffer::from_str(text),
             cursor: Cursor::default(),
             scroll: Cursor::default(),
@@ -214,7 +218,7 @@ impl State {
         })
     }
 
-    pub fn draw(&self, out: &mut impl Write) -> Result<()> {
+    pub fn draw(&mut self, out: &mut impl Write) -> Result<()> {
         // begin update
         let (cols, rows) = terminal::size()?;
         out.execute(terminal::BeginSynchronizedUpdate)?;
@@ -234,8 +238,9 @@ impl State {
                 show_status_bar = true;
             }
             Mode::Normal(NormalState { error: Some(error) }) => {
+                let error_style = self.style_store.get_scope("error");
                 out.execute(cursor::MoveTo(0, rows - 1))?;
-                write!(out, "{}", error)?;
+                error_style.print_styled(out, error)?;
                 show_status_bar = true;
             }
             _ => {}
@@ -243,7 +248,9 @@ impl State {
 
         // draw buffer
         let buffer_rows = if show_status_bar { rows - 1 } else { rows };
-        let lr_width = self.buffer.draw(cols, buffer_rows, self.scroll, out)?;
+        let lr_width =
+            self.buffer
+                .draw(&mut self.style_store, cols, buffer_rows, self.scroll, out)?;
 
         // draw cursor
         let cursor_pos = set_cursor_pos.unwrap_or_else(|| {
@@ -452,21 +459,18 @@ fn main() -> Result<()> {
 
     match argv.get(1).map(|s| s.as_str()) {
         Some("-") | None => unsafe { File::from_raw_fd(0) }, // stdin as a file
-        Some(path) => {
-            std::fs::File::open(path).unwrap_or_else(|_| {
-                eprintln!(
-                    "{}: {}: No such file or directory.",
-                    argv[0],
-                    argv[1]
-                );
-                exit(EX_UNAVAILABLE);
-            })
-        },
-    }.read_to_end(&mut buf).unwrap();
+        Some(path) => std::fs::File::open(path).unwrap_or_else(|_| {
+            eprintln!("{}: {}: No such file or directory.", argv[0], argv[1]);
+            exit(EX_UNAVAILABLE);
+        }),
+    }
+    .read_to_end(&mut buf)
+    .unwrap();
 
     let text = String::from_utf8(buf).unwrap_or_else(|_| {
         eprintln!(
-            "{}: {}: File contents are not valid UTF-8.", argv[0], argv[1]
+            "{}: {}: File contents are not valid UTF-8.",
+            argv[0], argv[1]
         );
         exit(EX_DATAERR);
     });
diff --git a/src/theme.rs b/src/theme.rs
new file mode 100644
index 0000000..5235321
--- /dev/null
+++ b/src/theme.rs
@@ -0,0 +1,311 @@
+/*
+ * Copyright (c) 2023 Marceline Cramer
+ * Copyright (c) 2023 Emma Tebibyte <emma@tebibyte.media>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU Affero General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option) any
+ * later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see https://www.gnu.org/licenses/.
+ */
+
+use std::collections::HashMap;
+use std::io::Write;
+
+use crossterm::{style::Color, ExecutableCommand};
+use once_cell::sync::Lazy;
+use toml::{map::Map, Value};
+
+pub static DEFAULT_THEME: Lazy<Theme> = Lazy::new(|| {
+    let text = include_str!("../default_theme.toml");
+    let value = toml::from_str(text).expect("Failed to parse default theme");
+    Theme::from_value("default", value).expect("Failed to load default theme")
+});
+
+#[derive(Debug)]
+pub struct StyleStore {
+    /// The current theme.
+    theme: Theme,
+
+    /// The current generation of the store. Increments every update.
+    generation: usize,
+
+    /// Maps named scopes to indices.
+    scopes: HashMap<String, usize>,
+
+    /// The style data store.
+    styles: Vec<Style>,
+}
+
+impl Default for StyleStore {
+    fn default() -> Self {
+        let theme = Lazy::force(&DEFAULT_THEME).to_owned();
+        Self::new(theme)
+    }
+}
+
+impl StyleStore {
+    /// Creates a new style store with a given theme.
+    pub fn new(theme: Theme) -> Self {
+        Self {
+            theme,
+            generation: 0,
+            scopes: HashMap::new(),
+            styles: Vec::new(),
+        }
+    }
+
+    /// Adds a scope to this store and returns its index. Reuses indices for existing scopes.
+    pub fn add_scope(&mut self, scope: &str) -> usize {
+        let style = self.theme.get_scope_style(scope);
+
+        if let Some(style_idx) = self.scopes.get(scope).copied() {
+            let old_style = self
+                .styles
+                .get_mut(style_idx)
+                .expect("StyleStore index is out-of-bounds");
+            let _ = std::mem::replace(old_style, style);
+            style_idx
+        } else {
+            let style_idx = self.styles.len();
+            self.styles.push(style);
+            self.scopes.insert(scope.to_string(), style_idx);
+            style_idx
+        }
+    }
+
+    /// Gets the style for a scope by name.
+    pub fn get_scope(&mut self, scope: &str) -> Style {
+        let idx = self.add_scope(scope);
+        self.get_style(idx)
+    }
+
+    /// Gets the style for a scope index. Panics if out-of-bounds.
+    pub fn get_style(&self, index: usize) -> Style {
+        self.styles
+            .get(index)
+            .expect("StyleStore is out-of-bounds")
+            .to_owned()
+    }
+
+    /// The current generation of the store. Increments every update.
+    pub fn generation(&self) -> usize {
+        self.generation
+    }
+
+    /// Applies a theme to this store and updates the generation.
+    pub fn apply(&mut self, theme: Theme) {
+        self.generation += 1;
+        self.theme = theme;
+
+        for (scope, style_idx) in self.scopes.iter() {
+            let new_style = self.theme.get_scope_style(scope);
+            let old_style = self.styles.get_mut(*style_idx).unwrap();
+            let _ = std::mem::replace(old_style, new_style);
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, Default, PartialEq, Eq)]
+pub struct Style {
+    pub fg: Option<Color>,
+    pub bg: Option<Color>,
+}
+
+impl Style {
+    pub fn print_styled(
+        &self,
+        out: &mut (impl ExecutableCommand + Write),
+        content: &str,
+    ) -> crossterm::Result<()> {
+        use crossterm::style::{ResetColor, SetBackgroundColor, SetForegroundColor};
+
+        if let Some(fg) = self.fg {
+            out.execute(SetForegroundColor(fg))?;
+        }
+
+        if let Some(bg) = self.bg {
+            out.execute(SetBackgroundColor(bg))?;
+        }
+
+        write!(out, "{}", content)?;
+
+        out.execute(ResetColor)?;
+
+        Ok(())
+    }
+}
+
+#[derive(Clone, Debug, Default)]
+pub struct Theme {
+    pub name: String,
+    pub styles: HashMap<String, Style>,
+}
+
+impl Theme {
+    pub fn from_value(name: &str, value: Value) -> Result<Self, String> {
+        if let Value::Table(table) = value {
+            Self::from_map(name, table)
+        } else {
+            panic!("Expected theme TOML value to be a table, found {:?}", value);
+        }
+    }
+
+    pub fn from_map(name: &str, mut values: Map<String, Value>) -> Result<Self, String> {
+        let palette = values
+            .remove("palette")
+            .map(Palette::try_from)
+            .unwrap_or_else(|| Ok(Palette::default()))?;
+
+        let mut styles = HashMap::with_capacity(values.len());
+
+        for (name, style) in values {
+            let style = palette.parse_style(style)?;
+            styles.insert(name.to_string(), style);
+        }
+
+        Ok(Self {
+            name: name.to_string(),
+            styles,
+        })
+    }
+
+    /// Gets a style for a scope, matching the longest available scope.
+    ///
+    /// If no match is found, defaults to the default [Style].
+    pub fn get_scope_style(&self, scope: &str) -> Style {
+        let mut longest = Style::default();
+        let mut longest_len = 0;
+
+        for (target, style) in self.styles.iter() {
+            if target.len() > longest_len && scope.starts_with(target) {
+                longest = *style;
+                longest_len = target.len();
+            }
+        }
+
+        longest
+    }
+}
+
+pub struct Palette {
+    pub palette: HashMap<String, Color>,
+}
+
+impl Default for Palette {
+    fn default() -> Self {
+        use Color::*;
+        let pairs = &[
+            ("black", Black),
+            ("red", DarkRed),
+            ("green", DarkGreen),
+            ("yellow", DarkYellow),
+            ("blue", DarkBlue),
+            ("magenta", DarkMagenta),
+            ("cyan", DarkCyan),
+            ("gray", DarkGrey),
+            ("grey", DarkGrey),
+            ("light-red", Red),
+            ("light-green", Green),
+            ("light-yellow", Yellow),
+            ("light-blue", Blue),
+            ("light-magenta", Magenta),
+            ("light-cyan", Cyan),
+            ("light-gray", Grey),
+            ("light-grey", Grey),
+            ("white", White),
+        ];
+
+        Self {
+            palette: HashMap::from_iter(
+                pairs
+                    .into_iter()
+                    .map(|(name, color)| (name.to_string(), *color)),
+            ),
+        }
+    }
+}
+
+impl TryFrom<Value> for Palette {
+    type Error = String;
+
+    fn try_from(value: Value) -> Result<Self, String> {
+        let values = value.as_table().ok_or(format!(
+            "Theme: expected table for palette but got: {:?}",
+            value
+        ))?;
+
+        let default = Self::default();
+        let mut palette = HashMap::with_capacity(values.len());
+
+        for (name, value) in values {
+            let color = default.parse_color(value)?;
+            palette.insert(name.to_string(), color);
+        }
+
+        Ok(Self { palette })
+    }
+}
+
+impl Palette {
+    pub fn hex_string_to_rgb(s: &str) -> Result<Color, String> {
+        if s.starts_with('#') && s.len() == 7 {
+            if let (Ok(r), Ok(g), Ok(b)) = (
+                u8::from_str_radix(&s[1..3], 16),
+                u8::from_str_radix(&s[3..5], 16),
+                u8::from_str_radix(&s[5..7], 16),
+            ) {
+                return Ok(Color::Rgb { r, g, b });
+            }
+        }
+
+        Err(format!("Theme: malformed hexcode: {}", s))
+    }
+
+    pub fn parse_value_as_str(value: &Value) -> Result<&str, String> {
+        value
+            .as_str()
+            .ok_or(format!("Theme: expected string but got: {:?}", value))
+    }
+
+    pub fn parse_color(&self, value: &Value) -> Result<Color, String> {
+        let str = Self::parse_value_as_str(&value)?;
+
+        self.palette
+            .get(str)
+            .copied()
+            .ok_or("")
+            .or_else(|_| Self::hex_string_to_rgb(&str))
+    }
+
+    pub fn parse_style_map(&self, entries: Map<String, Value>) -> Result<Style, String> {
+        let mut style = Style::default();
+        for (name, value) in entries {
+            match name.as_str() {
+                "fg" => style.fg = Some(self.parse_color(&value)?),
+                "bg" => style.bg = Some(self.parse_color(&value)?),
+                _ => return Err(format!("Theme: invalid style attribute: {}", name)),
+            }
+        }
+
+        Ok(style)
+    }
+
+    pub fn parse_style(&self, value: Value) -> Result<Style, String> {
+        if let Value::Table(entries) = value {
+            self.parse_style_map(entries)
+        } else {
+            let mut style = Style::default();
+            style.fg = Some(self.parse_color(&value)?);
+            Ok(style)
+        }
+    }
+}