diff --git a/src/config.zig b/src/config.zig
index 46cbfe1..eef7cb8 100644
--- a/src/config.zig
+++ b/src/config.zig
@@ -1 +1,2 @@
 theme: []const u8 = "default",
+include_files: []const u8 = "",
diff --git a/src/config_loader.zig b/src/config_loader.zig
index 040e39b..cb47ede 100644
--- a/src/config_loader.zig
+++ b/src/config_loader.zig
@@ -1,54 +1,158 @@
 const std = @import("std");
 const cbor = @import("cbor");
+const Theme = @import("theme");
+const themes = @import("themes");
 const builtin = @import("builtin");
 
 const application_name = "flow";
 
-const config = struct {
-    theme: []const u8 = "default",
-};
-
-pub fn read_config(a: std.mem.Allocator, buf: *?[]const u8) config {
-    const file_name = get_app_config_file_name(application_name) catch return .{};
-    return read_json_config_file(a, file_name, buf) catch .{};
+pub fn read_config(T: type, allocator: std.mem.Allocator) struct { T, [][]const u8 } {
+    var bufs: [][]const u8 = &[_][]const u8{};
+    const json_file_name = get_app_config_file_name(application_name, @typeName(T)) catch return .{ .{}, bufs };
+    const text_file_name = json_file_name[0 .. json_file_name.len - ".json".len];
+    var conf: T = .{};
+    if (!read_config_file(T, allocator, &conf, &bufs, text_file_name)) {
+        _ = read_config_file(T, allocator, &conf, &bufs, json_file_name);
+    }
+    read_nested_include_files(T, allocator, &conf, &bufs);
+    return .{ conf, bufs };
 }
 
-fn read_json_config_file(a: std.mem.Allocator, file_name: []const u8, buf: *?[]const u8) !config {
-    var file = std.fs.openFileAbsolute(file_name, .{ .mode = .read_only }) catch |e| switch (e) {
-        error.FileNotFound => return .{},
-        else => return e,
+pub fn free_config(allocator: std.mem.Allocator, bufs: [][]const u8) void {
+    for (bufs) |buf| allocator.free(buf);
+}
+
+// returns true if the file was found
+fn read_config_file(T: type, allocator: std.mem.Allocator, conf: *T, bufs: *[][]const u8, file_name: []const u8) bool {
+    std.log.info("loading {s}", .{file_name});
+    const err: anyerror = blk: {
+        if (std.mem.endsWith(u8, file_name, ".json")) if (read_json_config_file(T, allocator, conf, bufs, file_name)) return true else |e| break :blk e;
+        if (read_text_config_file(T, allocator, conf, bufs, file_name)) return true else |e| break :blk e;
     };
+    switch (err) {
+        error.FileNotFound => return false,
+        else => |e| std.log.err("error reading config file '{s}': {s}", .{ file_name, @errorName(e) }),
+    }
+    return true;
+}
+
+fn read_text_config_file(T: type, allocator: std.mem.Allocator, conf: *T, bufs_: *[][]const u8, file_name: []const u8) !void {
+    var file = try std.fs.openFileAbsolute(file_name, .{ .mode = .read_only });
     defer file.close();
-    const json = try file.readToEndAlloc(a, 64 * 1024);
-    defer a.free(json);
-    const cbor_buf: []u8 = try a.alloc(u8, json.len);
-    buf.* = cbor_buf;
+    const text = try file.readToEndAlloc(allocator, 64 * 1024);
+    defer allocator.free(text);
+    var cbor_buf = std.ArrayList(u8).init(allocator);
+    defer cbor_buf.deinit();
+    const writer = cbor_buf.writer();
+    var it = std.mem.splitScalar(u8, text, '\n');
+    var lineno: u32 = 0;
+    while (it.next()) |line| {
+        lineno += 1;
+        if (line.len == 0 or line[0] == '#')
+            continue;
+        const sep = std.mem.indexOfScalar(u8, line, ' ') orelse {
+            std.log.err("{s}:{}: {s} missing value", .{ file_name, lineno, line });
+            continue;
+        };
+        const name = line[0..sep];
+        const value_str = line[sep + 1 ..];
+        const cb = cbor.fromJsonAlloc(allocator, value_str) catch {
+            std.log.err("{s}:{}: {s} has bad value: {s}", .{ file_name, lineno, name, value_str });
+            continue;
+        };
+        defer allocator.free(cb);
+        try cbor.writeValue(writer, name);
+        try cbor_buf.appendSlice(cb);
+    }
+    const cb = try cbor_buf.toOwnedSlice();
+    var bufs = std.ArrayListUnmanaged([]const u8).fromOwnedSlice(bufs_.*);
+    bufs.append(allocator, cb) catch @panic("OOM:read_text_config_file");
+    bufs_.* = bufs.toOwnedSlice(allocator) catch @panic("OOM:read_text_config_file");
+    return read_cbor_config(T, conf, file_name, cb);
+}
+
+fn read_json_config_file(T: type, allocator: std.mem.Allocator, conf: *T, bufs_: *[][]const u8, file_name: []const u8) !void {
+    var file = try std.fs.openFileAbsolute(file_name, .{ .mode = .read_only });
+    defer file.close();
+    const json = try file.readToEndAlloc(allocator, 64 * 1024);
+    defer allocator.free(json);
+    const cbor_buf: []u8 = try allocator.alloc(u8, json.len);
+    var bufs = std.ArrayListUnmanaged([]const u8).fromOwnedSlice(bufs_.*);
+    bufs.append(allocator, cbor_buf) catch @panic("OOM:read_json_config_file");
+    bufs_.* = bufs.toOwnedSlice(allocator) catch @panic("OOM:read_json_config_file");
     const cb = try cbor.fromJson(json, cbor_buf);
     var iter = cb;
-    var len = try cbor.decodeMapHeader(&iter);
-    var data: config = .{};
-    while (len > 0) : (len -= 1) {
-        var found = false;
-        var field_name: []const u8 = undefined;
-        if (!(try cbor.matchString(&iter, &field_name))) return error.InvalidConfig;
-        inline for (@typeInfo(config).@"struct".fields) |field_info| {
-            if (std.mem.eql(u8, field_name, field_info.name)) {
+    _ = try cbor.decodeMapHeader(&iter);
+    return read_cbor_config(T, conf, file_name, iter);
+}
+
+fn read_cbor_config(
+    T: type,
+    conf: *T,
+    file_name: []const u8,
+    cb: []const u8,
+) !void {
+    var iter = cb;
+    var field_name: []const u8 = undefined;
+    while (cbor.matchString(&iter, &field_name) catch |e| switch (e) {
+        error.TooShort => return,
+        else => return e,
+    }) {
+        var known = false;
+        inline for (@typeInfo(T).@"struct".fields) |field_info|
+            if (comptime std.mem.eql(u8, "include_files", field_info.name)) {
+                if (std.mem.eql(u8, field_name, field_info.name)) {
+                    known = true;
+                    var value: field_info.type = undefined;
+                    if (try cbor.matchValue(&iter, cbor.extract(&value))) {
+                        if (conf.include_files.len > 0) {
+                            std.log.warn("{s}: ignoring nested 'include_files' value '{s}'", .{ file_name, value });
+                        } else {
+                            @field(conf, field_info.name) = value;
+                        }
+                    } else {
+                        try cbor.skipValue(&iter);
+                        std.log.err("invalid value for key '{s}'", .{field_name});
+                    }
+                }
+            } else if (std.mem.eql(u8, field_name, field_info.name)) {
+                known = true;
                 var value: field_info.type = undefined;
-                if (!(try cbor.matchValue(&iter, cbor.extract(&value)))) return error.InvalidConfig;
-                @field(data, field_info.name) = value;
-                found = true;
-            }
+                if (try cbor.matchValue(&iter, cbor.extract(&value))) {
+                    @field(conf, field_info.name) = value;
+                } else {
+                    try cbor.skipValue(&iter);
+                    std.log.err("invalid value for key '{s}'", .{field_name});
+                }
+            };
+        if (!known) {
+            try cbor.skipValue(&iter);
+            std.log.warn("unknown config value '{s}' ignored", .{field_name});
         }
-        if (!found) try cbor.skipValue(&iter);
     }
-    return data;
+}
+
+fn read_nested_include_files(T: type, allocator: std.mem.Allocator, conf: *T, bufs: *[][]const u8) void {
+    if (conf.include_files.len == 0) return;
+    var it = std.mem.splitScalar(u8, conf.include_files, std.fs.path.delimiter);
+    while (it.next()) |path| if (!read_config_file(T, allocator, conf, bufs, path)) {
+        std.log.warn("config include file '{s}' is not found", .{path});
+    };
 }
 
 pub fn get_config_dir() ![]const u8 {
     return get_app_config_dir(application_name);
 }
 
-fn get_app_config_dir(appname: []const u8) ![]const u8 {
+pub const ConfigDirError = error{
+    NoSpaceLeft,
+    MakeConfigDirFailed,
+    MakeHomeConfigDirFailed,
+    MakeAppConfigDirFailed,
+    AppConfigDirUnavailable,
+};
+
+fn get_app_config_dir(appname: []const u8) ConfigDirError![]const u8 {
     const a = std.heap.c_allocator;
     const local = struct {
         var config_dir_buffer: [std.posix.PATH_MAX]u8 = undefined;
@@ -64,7 +168,7 @@ fn get_app_config_dir(appname: []const u8) ![]const u8 {
         const dir = try std.fmt.bufPrint(&local.config_dir_buffer, "{s}/.config", .{home});
         std.fs.makeDirAbsolute(dir) catch |e| switch (e) {
             error.PathAlreadyExists => {},
-            else => return e,
+            else => return error.MakeHomeConfigDirFailed,
         };
         break :ret try std.fmt.bufPrint(&local.config_dir_buffer, "{s}/.config/{s}", .{ home, appname });
     } else if (builtin.os.tag == .windows) ret: {
@@ -73,7 +177,7 @@ fn get_app_config_dir(appname: []const u8) ![]const u8 {
             const dir = try std.fmt.bufPrint(&local.config_dir_buffer, "{s}/{s}", .{ appdata, appname });
             std.fs.makeDirAbsolute(dir) catch |e| switch (e) {
                 error.PathAlreadyExists => {},
-                else => return e,
+                else => return error.MakeAppConfigDirFailed,
             };
             break :ret dir;
         } else return error.AppConfigDirUnavailable;
@@ -82,21 +186,79 @@ fn get_app_config_dir(appname: []const u8) ![]const u8 {
     local.config_dir = config_dir;
     std.fs.makeDirAbsolute(config_dir) catch |e| switch (e) {
         error.PathAlreadyExists => {},
-        else => return e,
+        else => return error.MakeConfigDirFailed,
     };
+
+    var theme_dir_buffer: [std.posix.PATH_MAX]u8 = undefined;
+    std.fs.makeDirAbsolute(try std.fmt.bufPrint(&theme_dir_buffer, "{s}/{s}", .{ config_dir, theme_dir })) catch {};
+
     return config_dir;
 }
 
-fn get_app_config_file_name(appname: []const u8) ![]const u8 {
+fn get_app_config_file_name(appname: []const u8, comptime base_name: []const u8) ConfigDirError![]const u8 {
+    return get_app_config_dir_file_name(appname, base_name ++ ".json");
+}
+
+fn get_app_config_dir_file_name(appname: []const u8, comptime config_file_name: []const u8) ConfigDirError![]const u8 {
     const local = struct {
         var config_file_buffer: [std.posix.PATH_MAX]u8 = undefined;
-        var config_file: ?[]const u8 = null;
     };
-    const config_file_name = "config.json";
-    const config_file = if (local.config_file) |file|
-        file
-    else
-        try std.fmt.bufPrint(&local.config_file_buffer, "{s}/{s}", .{ try get_app_config_dir(appname), config_file_name });
-    local.config_file = config_file;
-    return config_file;
+    return std.fmt.bufPrint(&local.config_file_buffer, "{s}/{s}", .{ try get_app_config_dir(appname), config_file_name });
+}
+
+const theme_dir = "themes";
+
+fn get_theme_directory() ![]const u8 {
+    const local = struct {
+        var dir_buffer: [std.posix.PATH_MAX]u8 = undefined;
+    };
+    const a = std.heap.c_allocator;
+    if (std.process.getEnvVarOwned(a, "FLOW_THEMES_DIR") catch null) |dir| {
+        defer a.free(dir);
+        return try std.fmt.bufPrint(&local.dir_buffer, "{s}", .{dir});
+    }
+    return try std.fmt.bufPrint(&local.dir_buffer, "{s}/{s}", .{ try get_app_config_dir(application_name), theme_dir });
+}
+
+pub fn get_theme_file_name(theme_name: []const u8) ![]const u8 {
+    const dir = try get_theme_directory();
+    const local = struct {
+        var file_buffer: [std.posix.PATH_MAX]u8 = undefined;
+    };
+    return try std.fmt.bufPrint(&local.file_buffer, "{s}/{s}.json", .{ dir, theme_name });
+}
+
+fn read_theme(allocator: std.mem.Allocator, theme_name: []const u8) ?[]const u8 {
+    const file_name = get_theme_file_name(theme_name) catch return null;
+    var file = std.fs.openFileAbsolute(file_name, .{ .mode = .read_only }) catch return null;
+    defer file.close();
+    return file.readToEndAlloc(allocator, 64 * 1024) catch null;
+}
+
+fn load_theme_file(allocator: std.mem.Allocator, theme_name: []const u8) !?std.json.Parsed(Theme) {
+    return load_theme_file_internal(allocator, theme_name) catch |e| {
+        std.log.err("loaded theme from file failed: {}", .{e});
+        return e;
+    };
+}
+
+fn load_theme_file_internal(allocator: std.mem.Allocator, theme_name: []const u8) !?std.json.Parsed(Theme) {
+    _ = std.json.Scanner;
+    const json_str = read_theme(allocator, theme_name) orelse return null;
+    defer allocator.free(json_str);
+    return try std.json.parseFromSlice(Theme, allocator, json_str, .{ .allocate = .alloc_always });
+}
+
+pub fn get_theme_by_name(allocator: std.mem.Allocator, name: []const u8) ?struct { Theme, ?std.json.Parsed(Theme) } {
+    if (load_theme_file(allocator, name) catch null) |parsed_theme| {
+        std.log.info("loaded theme from file: {s}", .{name});
+        return .{ parsed_theme.value, parsed_theme };
+    }
+
+    std.log.info("loading theme: {s}", .{name});
+    for (themes.themes) |theme_| {
+        if (std.mem.eql(u8, theme_.name, name))
+            return .{ theme_, null };
+    }
+    return null;
 }
diff --git a/src/main.zig b/src/main.zig
index 9d4668a..72bca06 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -13,6 +13,11 @@ var lang_override: ?[]const u8 = null;
 var lang_default: []const u8 = "conf";
 const no_highlight = std.math.maxInt(usize);
 
+const builtin = @import("builtin");
+pub const std_options: std.Options = .{
+    .log_level = if (builtin.mode == .Debug) .info else .err,
+};
+
 pub fn main() !void {
     const params = comptime clap.parseParamsComptime(
         \\-h, --help               Display this help and exit.
@@ -20,6 +25,7 @@ pub fn main() !void {
         \\-t, --theme <name>       Select theme to use.
         \\-d, --default <name>     Set the language to use if guessing failed (default: conf).
         \\-s, --show-language      Show detected language in output.
+        \\-T, --show-theme         Show selected theme in output.
         \\-C, --color              Always produce color output, even if stdout is not a tty.
         \\--html                   Output HTML instead of ansi escape codes.
         \\--list-themes            Show available themes.
@@ -72,8 +78,8 @@ pub fn main() !void {
     if (res.args.color == 0 and !stdout_file.supportsAnsiEscapeCodes())
         return plain_cat(res.positionals[0]);
 
-    var conf_buf: ?[]const u8 = null;
-    const conf = config_loader.read_config(a, &conf_buf);
+    const conf, const conf_bufs = config_loader.read_config(@import("config.zig"), a);
+    defer config_loader.free_config(a, conf_bufs);
     const theme_name = if (res.args.theme) |theme| theme else conf.theme;
     const limit_lines = res.args.limit;
 
@@ -88,14 +94,15 @@ pub fn main() !void {
     }
 
     if (highlight_line_end < highlight_line_start) {
-        try std.io.getStdErr().writer().print("invalid range\n", .{});
+        std.log.err("invalid range", .{});
         std.process.exit(1);
     }
 
-    const theme = get_theme_by_name(theme_name) orelse {
-        try std.io.getStdErr().writer().print("theme \"{s}\" not found\n", .{theme_name});
+    const theme, const parsed_theme = config_loader.get_theme_by_name(a, theme_name) orelse {
+        std.log.err("theme \"{s}\" not found", .{theme_name});
         std.process.exit(1);
     };
+    _ = parsed_theme;
 
     const set_style: StyleFn = if (res.args.html != 0) set_html_style else set_ansi_style;
     const unset_style: StyleFn = if (res.args.html != 0) unset_html_style else unset_ansi_style;
@@ -122,6 +129,7 @@ pub fn main() !void {
                 arg,
                 &theme,
                 res.args.@"show-language" != 0,
+                res.args.@"show-theme" != 0,
                 set_style,
                 unset_style,
                 highlight_line_start,
@@ -143,6 +151,7 @@ pub fn main() !void {
             "-",
             &theme,
             res.args.@"show-language" != 0,
+            res.args.@"show-theme" != 0,
             set_style,
             unset_style,
             highlight_line_start,
@@ -166,7 +175,7 @@ fn get_parser(a: std.mem.Allocator, content: []const u8, file_path: []const u8,
 }
 
 fn unknown_file_type(name: []const u8) noreturn {
-    std.io.getStdErr().writer().print("unknown file type \'{s}\'\n", .{name}) catch {};
+    std.log.err("unknown file type \'{s}\'\n", .{name});
     std.process.exit(1);
 }
 
@@ -178,7 +187,8 @@ fn render_file(
     content: []const u8,
     file_path: []const u8,
     theme: *const Theme,
-    show: bool,
+    show_file_type: bool,
+    show_theme: bool,
     set_style: StyleFn,
     unset_style: StyleFn,
     highlight_line_start: usize,
@@ -203,10 +213,14 @@ fn render_file(
     const query_cache = try syntax.QueryCache.create(a, .{});
     const parser = get_parser(a, content, file_path, query_cache);
     try parser.refresh_full(content);
-    if (show) {
+    if (show_file_type) {
         try render_file_type(writer, parser.file_type, theme);
         end_line -= 1;
     }
+    if (show_theme) {
+        try render_theme_indicator(writer, theme);
+        end_line -= 1;
+    }
 
     const Ctx = struct {
         writer: @TypeOf(writer),
@@ -378,14 +392,6 @@ pub const fallbacks: []const FallBack = &[_]FallBack{
     .{ .ts = "field", .tm = "variable" },
 };
 
-fn get_theme_by_name(name: []const u8) ?Theme {
-    for (themes.themes) |theme| {
-        if (std.mem.eql(u8, theme.name, name))
-            return theme;
-    }
-    return null;
-}
-
 fn list_themes(writer: Writer) !void {
     var max_name_len: usize = 0;
     for (themes.themes) |theme|
@@ -488,6 +494,20 @@ fn render_file_type(writer: Writer, file_type: *const syntax.FileType, theme: *c
     try writer.writeAll("\n");
 }
 
+fn render_theme_indicator(writer: Writer, theme: *const Theme) !void {
+    const style = Theme.Style{ .bg = theme.editor_selection.bg, .fg = theme.editor.fg };
+    const reversed = Theme.Style{ .fg = theme.editor_selection.bg };
+    const plain: Theme.Style = Theme.Style{ .fg = theme.editor.fg };
+    try set_ansi_style(writer, reversed);
+    try writer.writeAll("");
+    try set_ansi_style(writer, style);
+    try writer.writeAll(theme.name);
+    try set_ansi_style(writer, reversed);
+    try writer.writeAll("");
+    try set_ansi_style(writer, plain);
+    try writer.writeAll("\n");
+}
+
 fn plain_cat(files: []const []const u8) !void {
     const stdout = std.io.getStdOut();
     if (files.len == 0) {