diff --git a/crates/gpui_widgets/Cargo.toml b/crates/gpui_widgets/Cargo.toml
index e484b42884..11f6a3633d 100644
--- a/crates/gpui_widgets/Cargo.toml
+++ b/crates/gpui_widgets/Cargo.toml
@@ -42,3 +42,7 @@ path = "examples/project_explorer.rs"
 [[example]]
 name = "scopes"
 path = "examples/scopes.rs"
+
+[[example]]
+name = "themes"
+path = "examples/themes.rs"
diff --git a/crates/gpui_widgets/examples/themes.rs b/crates/gpui_widgets/examples/themes.rs
new file mode 100644
index 0000000000..c001f29fc8
--- /dev/null
+++ b/crates/gpui_widgets/examples/themes.rs
@@ -0,0 +1,124 @@
+//! A theme demo: toggle between Olive Dark and Olive Light at runtime. Every
+//! widget that reads `cx.default_colors()` re-themes immediately.
+
+use gpui::{
+    App, Bounds, ClickEvent, Context, Entity, Render, Window, WindowBounds, WindowOptions,
+    colors::DefaultColors, div, prelude::*, px, size,
+};
+use gpui_widgets::checkbox::{CheckBox, CheckBoxEvent, CheckState};
+use gpui_widgets::slider::{Slider, SliderEvent, SliderModel};
+use gpui_widgets::theme::{OakTheme, apply_theme};
+use gpui_widgets::value::ValueKind;
+
+struct Example {
+    slider: Entity<Slider>,
+    checkbox: Entity<CheckBox>,
+    dark: bool,
+}
+
+impl Example {
+    fn new(window: &mut Window, cx: &mut Context<Self>) -> Self {
+        let slider = cx.new(|cx| {
+            Slider::new(
+                1,
+                SliderModel::new(ValueKind::Float, 0.0, 1.0, 0.05, 0.5),
+                window,
+                cx,
+            )
+        });
+        cx.subscribe(
+            &slider,
+            |_this: &mut Self, _s: Entity<Slider>, event: &SliderEvent, _cx| {
+                println!("slider: {event:?}");
+            },
+        )
+        .detach();
+
+        let checkbox = cx.new(|cx| {
+            CheckBox::new(2, CheckState::Checked, window, cx).with_label("Track enabled")
+        });
+        cx.subscribe(
+            &checkbox,
+            |_this: &mut Self, _c: Entity<CheckBox>, event: &CheckBoxEvent, _cx| {
+                println!("checkbox: {event:?}");
+            },
+        )
+        .detach();
+
+        Self {
+            slider,
+            checkbox,
+            dark: true,
+        }
+    }
+}
+
+impl Render for Example {
+    fn render(&mut self, _window: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
+        let colors = cx.default_colors().clone();
+        let theme = if self.dark {
+            OakTheme::olive_dark()
+        } else {
+            OakTheme::olive_light()
+        };
+
+        div()
+            .size_full()
+            .bg(theme.base)
+            .flex()
+            .flex_col()
+            .gap_3()
+            .p_6()
+            .child(
+                div()
+                    .text_color(colors.text)
+                    .child(format!("Current theme: {}", theme.name)),
+            )
+            .child(div().flex().items_center().gap_2().child(self.slider.clone()))
+            .child(self.checkbox.clone())
+            .child(
+                div()
+                    .id("theme-toggle")
+                    .px_3()
+                    .py_1()
+                    .rounded_md()
+                    .bg(colors.selected)
+                    .text_color(colors.selected_text)
+                    .cursor_pointer()
+                    .on_click(cx.listener(|this, _event: &ClickEvent, _window, cx| {
+                        this.dark = !this.dark;
+                        let theme = if this.dark {
+                            OakTheme::olive_dark()
+                        } else {
+                            OakTheme::olive_light()
+                        };
+                        apply_theme(cx, &theme);
+                        cx.notify();
+                    }))
+                    .child("Toggle theme"),
+            )
+    }
+}
+
+fn main() {
+    gpui_platform::application().run(|cx: &mut App| {
+        apply_theme(cx, &OakTheme::olive_dark());
+        let bounds = Bounds::centered(None, size(px(480.0), px(320.0)), cx);
+        cx.open_window(
+            WindowOptions {
+                window_bounds: Some(WindowBounds::Windowed(bounds)),
+                ..Default::default()
+            },
+            |window, cx| cx.new(|cx| Example::new(window, cx)),
+        )
+        .expect("Failed to open window");
+
+        cx.activate(true);
+        cx.on_window_closed(|cx, _| {
+            if cx.windows().is_empty() {
+                cx.quit();
+            }
+        })
+        .detach();
+    });
+}
diff --git a/crates/gpui_widgets/src/lib.rs b/crates/gpui_widgets/src/lib.rs
index d90ec0cea1..ff3b993f67 100644
--- a/crates/gpui_widgets/src/lib.rs
+++ b/crates/gpui_widgets/src/lib.rs
@@ -30,5 +30,6 @@ pub mod radio_group;
 pub mod scopes;
 pub mod slider;
 pub mod spinbox;
+pub mod theme;
 pub mod value;
 pub mod viewer;
diff --git a/crates/gpui_widgets/src/theme.rs b/crates/gpui_widgets/src/theme.rs
new file mode 100644
index 0000000000..bf4dca065b
--- /dev/null
+++ b/crates/gpui_widgets/src/theme.rs
@@ -0,0 +1,193 @@
+//! Oak's olive themes: the QSS palettes translated to gpui colors, with
+//! runtime switching.
+//!
+//! [`OakTheme::olive_dark`] / [`OakTheme::olive_light`] mirror
+//! `oak/app/ui/style/olive-{dark,light}/palette.ini`. Applying a theme via
+//! [`apply_theme`] swaps the global [`Colors`](gpui::colors::Colors) — so
+//! every widget that reads `cx.default_colors()` re-themes immediately — and
+//! stores the full theme in a [`ThemeGlobal`] for widgets that want the
+//! extended fields (accent, link, alternate base).
+
+use gpui::{App, Global, Rgba, colors::GlobalColors, rgb};
+use std::sync::Arc;
+
+/// Oak's olive theme palette.
+#[derive(Debug, Clone, PartialEq)]
+pub struct OakTheme {
+    /// The theme's display name.
+    pub name: gpui::SharedString,
+    /// Window background (panels, bars).
+    pub window: Rgba,
+    /// Base background (content areas, inputs).
+    pub base: Rgba,
+    /// Alternate base (stripes, separators).
+    pub alternate_base: Rgba,
+    /// Primary text.
+    pub text: Rgba,
+    /// Accent (selection, highlight).
+    pub accent: Rgba,
+    /// Text on the accent.
+    pub accent_text: Rgba,
+    /// Link color.
+    pub link: Rgba,
+    /// Disabled text.
+    pub disabled_text: Rgba,
+    /// Disabled button text.
+    pub disabled_button_text: Rgba,
+}
+
+fn rgba(hex: u32) -> Rgba {
+    let r = ((hex >> 16) & 0xff) as f32 / 255.0;
+    let g = ((hex >> 8) & 0xff) as f32 / 255.0;
+    let b = (hex & 0xff) as f32 / 255.0;
+    Rgba { r, g, b, a: 1.0 }
+}
+
+impl OakTheme {
+    /// The olive-dark palette (oak's default).
+    pub fn olive_dark() -> Self {
+        Self {
+            name: "Olive Dark".into(),
+            window: rgba(0x353535),
+            base: rgba(0x191919),
+            alternate_base: rgba(0x353535),
+            text: rgb(0xffffff),
+            accent: rgba(0x2A82DA),
+            accent_text: rgb(0xffffff),
+            link: rgba(0xE0B040),
+            disabled_text: rgba(0xA0A0A0),
+            disabled_button_text: rgba(0x808080),
+        }
+    }
+
+    /// The olive-light palette.
+    pub fn olive_light() -> Self {
+        Self {
+            name: "Olive Light".into(),
+            window: rgba(0xD0D0D0),
+            base: rgba(0xF0F0F0),
+            alternate_base: rgba(0xD0D0D0),
+            text: rgb(0x000000),
+            accent: rgba(0x2A82DA),
+            accent_text: rgb(0xffffff),
+            link: rgba(0x2A82DA),
+            disabled_text: rgba(0x808080),
+            disabled_button_text: rgba(0x808080),
+        }
+    }
+
+    /// The border color derived from this theme (alternate base darkened for
+    /// dark themes, lightened for light themes).
+    pub fn border(&self) -> Rgba {
+        let factor = if relative_luminance(self.text) > relative_luminance(self.base) {
+            0.7
+        } else {
+            1.25
+        };
+        scale_luma(self.alternate_base, factor)
+    }
+
+    /// Map this theme onto gpui's [`Colors`](gpui::colors::Colors) struct so
+    /// `cx.default_colors()` picks it up.
+    pub fn colors(&self) -> gpui::colors::Colors {
+        gpui::colors::Colors {
+            text: self.text,
+            selected_text: self.accent_text,
+            background: self.base,
+            disabled: self.disabled_text,
+            selected: self.accent,
+            border: self.border(),
+            separator: self.alternate_base,
+            container: self.window,
+        }
+    }
+}
+
+/// The current full theme, set by [`apply_theme`].
+pub struct ThemeGlobal(pub Arc<OakTheme>);
+
+impl Global for ThemeGlobal {}
+
+/// Apply a theme: swaps the global [`Colors`](gpui::colors::Colors) (re-theming
+/// every widget that reads `cx.default_colors()`) and stores the full theme.
+pub fn apply_theme(cx: &mut App, theme: &OakTheme) {
+    cx.set_global(GlobalColors(Arc::new(theme.colors())));
+    cx.set_global(ThemeGlobal(Arc::new(theme.clone())));
+}
+
+/// The current theme, or olive-dark if none was applied.
+pub fn current_theme(cx: &App) -> Arc<OakTheme> {
+    cx.try_global::<ThemeGlobal>()
+        .map(|global| global.0.clone())
+        .unwrap_or_else(|| Arc::new(OakTheme::olive_dark()))
+}
+
+fn relative_luminance(color: Rgba) -> f32 {
+    // Simple perceptual approximation (sRGB -> luma).
+    0.2126 * color.r + 0.7152 * color.g + 0.0722 * color.b
+}
+
+fn scale_luma(color: Rgba, factor: f32) -> Rgba {
+    let scale = |channel: f32| (channel * factor).clamp(0.0, 1.0);
+    Rgba {
+        r: scale(color.r),
+        g: scale(color.g),
+        b: scale(color.b),
+        a: color.a,
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use gpui::{TestAppContext, colors::DefaultColors};
+
+    #[test]
+    fn dark_theme_text_contrasts_with_base() {
+        let theme = OakTheme::olive_dark();
+        let text_luma = relative_luminance(theme.text);
+        let base_luma = relative_luminance(theme.base);
+        // Text must be clearly brighter than the base.
+        assert!(text_luma - base_luma > 0.4, "dark theme lacks contrast");
+        // The accent must be visible against both.
+        let accent_luma = relative_luminance(theme.accent);
+        assert!((accent_luma - base_luma).abs() > 0.1);
+    }
+
+    #[test]
+    fn light_theme_text_contrasts_with_base() {
+        let theme = OakTheme::olive_light();
+        let text_luma = relative_luminance(theme.text);
+        let base_luma = relative_luminance(theme.base);
+        assert!(base_luma - text_luma > 0.5, "light theme lacks contrast");
+    }
+
+    #[test]
+    fn colors_map_keeps_text_and_selected() {
+        let colors = OakTheme::olive_dark().colors();
+        assert_eq!(colors.selected, rgb(0x2A82DA));
+        assert_eq!(colors.selected_text, rgb(0xffffff));
+    }
+
+    #[test]
+    fn border_derives_from_alternate_base() {
+        let dark = OakTheme::olive_dark();
+        let border = dark.border();
+        // Dark theme: border is darker than the alternate base.
+        assert!(relative_luminance(border) < relative_luminance(dark.alternate_base));
+        let light = OakTheme::olive_light();
+        assert!(relative_luminance(light.border()) > relative_luminance(light.alternate_base));
+    }
+
+    #[gpui::test]
+    async fn apply_theme_switches_default_colors(cx: &mut TestAppContext) {
+        cx.update(|app| {
+            apply_theme(app, &OakTheme::olive_light());
+            let colors = app.default_colors().clone();
+            assert_eq!(colors.background, rgb(0xF0F0F0));
+            assert_eq!(colors.text, rgb(0x000000));
+            // And the extended theme is queryable.
+            assert_eq!(current_theme(app).name, "Olive Light");
+        });
+    }
+}
diff --git a/docs/zh/oak-app-rewrite.md b/docs/zh/oak-app-rewrite.md
index 74110246fe..b6cb536725 100644
--- a/docs/zh/oak-app-rewrite.md
+++ b/docs/zh/oak-app-rewrite.md
@@ -126,8 +126,14 @@
 
 ## W7. 主题系统
 
-- [ ] 设计系统：把 oak 的 olive-dark/olive-light QSS 翻译成 gpui
+- [x] 设计系统：把 oak 的 olive-dark/olive-light QSS 翻译成 gpui
   的 `Colors`/样式结构，支持运行期切换。
+  > `gpui_widgets::theme`：`OakTheme::olive_dark()/olive_light()`
+  > 从 `oak/app/ui/style/olive-*/palette.ini` 提取（window/base/
+  > accent/link/disabled 等 + 派生 border）；`apply_theme` 同时设置
+  > gpui 的 `GlobalColors`（所有读 `cx.default_colors()` 的控件立即
+  > 换肤）与扩展的 `ThemeGlobal`。调色板对比度/映射单测 +
+  > `#[gpui::test]` 运行期切换验证。`examples/themes.rs`。
 
 ## 顺序与验收