diff --git a/README.md b/README.md
index d3e0116..83c2221 100644
--- a/README.md
+++ b/README.md
@@ -82,13 +82,14 @@ Private repositories work too. GitHub Free gives 2,000 Actions minutes/month (th
 
 ## Themes
 
-Three built-in themes, each with light/dark mode and responsive design.
+Four built-in themes, each with light/dark mode and responsive design.
 
 | Theme | Screenshot | Description |
 |---|---|---|
 | **brutalist** (default) | <img src="scripts/screenshots/brutalist-dark.png" width="400" /> | Bold, high-contrast dark theme with monospace typography. [Example](https://deariary.github.io/github-weekly-reporter/brutalist/en/2026/W14/) |
 | **minimal** | <img src="scripts/screenshots/minimal-light.png" width="400" /> | Clean lines, generous whitespace, understated elegance. [Example](https://deariary.github.io/github-weekly-reporter/minimal/en/2026/W14/) |
 | **editorial** | <img src="scripts/screenshots/editorial-light.png" width="400" /> | Horizontal-scroll magazine with serif typography and column layout. [Example](https://deariary.github.io/github-weekly-reporter/editorial/en/2026/W14/) |
+| **swiss** | <img src="scripts/screenshots/swiss-light.png" width="400" /> | International Typographic Style with asymmetric grid, Space Grotesk, and geometric motifs. [Example](https://deariary.github.io/github-weekly-reporter/swiss/en/2026/W14/) |
 
 Set the theme in your workflow or during `setup`:
 
diff --git a/action.yml b/action.yml
index 5276891..ed30d06 100644
--- a/action.yml
+++ b/action.yml
@@ -59,7 +59,7 @@ inputs:
     required: false
     default: ''
   theme:
-    description: 'Report theme: brutalist, minimal, editorial'
+    description: 'Report theme: brutalist, minimal, editorial, swiss'
     required: false
     default: 'brutalist'
   date:
diff --git a/docs/customization.md b/docs/customization.md
index e787f0f..52c9e0e 100644
--- a/docs/customization.md
+++ b/docs/customization.md
@@ -135,13 +135,14 @@ Pin the action to a commit SHA and the CLI to a specific version for better secu
 
 ## Theme
 
-Three built-in themes are available, each with light/dark mode:
+Four built-in themes are available, each with light/dark mode:
 
 | Theme | Description |
 |---|---|
 | `brutalist` | Bold, high-contrast dark theme with monospace typography (default) |
 | `minimal` | Clean lines, generous whitespace, understated elegance |
 | `editorial` | Horizontal-scroll magazine with serif typography and column layout |
+| `swiss` | International Typographic Style with asymmetric grid, Space Grotesk, and geometric motifs |
 
 Edit `weekly-report.yml`:
 
diff --git a/scripts/generate-preview-index.js b/scripts/generate-preview-index.js
index 4353ba8..6d76b09 100644
--- a/scripts/generate-preview-index.js
+++ b/scripts/generate-preview-index.js
@@ -20,6 +20,9 @@ const themeData = {
   editorial: {
     desc: "Horizontal-scroll magazine layout inspired by print editorial design. Serif typography (Playfair Display + Newsreader), column-based content flow, and data visualizations woven into the narrative.",
   },
+  swiss: {
+    desc: "International Typographic Style (Swiss Design) with asymmetric grid, Space Grotesk neo-grotesque typography, numbered sections, and geometric motifs inspired by Max Bill and Muller-Brockmann.",
+  },
 };
 
 const html = `<!DOCTYPE html>
@@ -272,7 +275,7 @@ const html = `<!DOCTYPE html>
 
 <section class="fade-in">
   <h2>Themes</h2>
-  <p class="lead">Three built-in themes, each with light/dark mode and responsive layout.</p>
+  <p class="lead">Four built-in themes, each with light/dark mode and responsive layout.</p>
   <ul class="theme-list">
 ${themes
   .map(
diff --git a/scripts/generate-preview.sh b/scripts/generate-preview.sh
index 377f9ff..926a7d4 100755
--- a/scripts/generate-preview.sh
+++ b/scripts/generate-preview.sh
@@ -2,7 +2,7 @@
 # Generate preview site: theme x lang combinations from example/ data
 set -euo pipefail
 
-THEMES="brutalist minimal editorial"
+THEMES="brutalist minimal editorial swiss"
 LANGS="en ja"
 BASE_URL="${BASE_URL:-https://deariary.github.io/github-weekly-reporter}"
 OUT_DIR="${OUT_DIR:-preview-site}"
diff --git a/scripts/screenshots/swiss-dark.png b/scripts/screenshots/swiss-dark.png
new file mode 100644
index 0000000..6c30522
Binary files /dev/null and b/scripts/screenshots/swiss-dark.png differ
diff --git a/scripts/screenshots/swiss-light.png b/scripts/screenshots/swiss-light.png
new file mode 100644
index 0000000..d11913f
Binary files /dev/null and b/scripts/screenshots/swiss-light.png differ
diff --git a/src/cli/commands/setup/workflows.ts b/src/cli/commands/setup/workflows.ts
index afa629f..19ad7c7 100644
--- a/src/cli/commands/setup/workflows.ts
+++ b/src/cli/commands/setup/workflows.ts
@@ -231,7 +231,7 @@ Edit \`.github/workflows/weekly-report.yml\` to change:
 | \`username\` | \`${opts.username}\` | GitHub user to report on |
 | \`language\` | \`${opts.language}\` | Report language (en, ja, zh-CN, zh-TW, ko, es, fr, de, pt, ru) |
 | \`timezone\` | \`${opts.timezone}\` | IANA timezone for date calculations |
-| \`theme\` | \`${opts.theme}\` | Report theme (brutalist, minimal, editorial) |
+| \`theme\` | \`${opts.theme}\` | Report theme (brutalist, minimal, editorial, swiss) |
 | \`SITE_TITLE\` | \`${displayTitle}\` | Site title in the header and hero |
 ${opts.llmProvider ? `| \`llm-provider\` | \`${opts.llmProvider}\` | LLM provider for AI narrative |\n| \`llm-model\` | \`${opts.llmModel}\` | Model name |\n` : ""}
 ## Base URL
diff --git a/src/renderer/themes/index.ts b/src/renderer/themes/index.ts
index 7c910b5..36ba66c 100644
--- a/src/renderer/themes/index.ts
+++ b/src/renderer/themes/index.ts
@@ -25,6 +25,13 @@ import {
   THEME_INIT_SCRIPT as editorialInitScript,
   THEME_TOGGLE_SCRIPT as editorialToggleScript,
 } from "./editorial/index.js";
+import {
+  buildCSS as swissBuildCSS,
+  buildIndexCSS as swissBuildIndexCSS,
+  colors as swissColors,
+  THEME_INIT_SCRIPT as swissInitScript,
+  THEME_TOGGLE_SCRIPT as swissToggleScript,
+} from "./swiss/index.js";
 
 export type ThemeColors = {
   bg: string;
@@ -72,6 +79,13 @@ const themeModules: Record<Theme, Omit<ThemeModule, "templatesDir">> = {
     themeInitScript: editorialInitScript,
     themeToggleScript: editorialToggleScript,
   },
+  swiss: {
+    buildCSS: swissBuildCSS,
+    buildIndexCSS: swissBuildIndexCSS,
+    colors: swissColors,
+    themeInitScript: swissInitScript,
+    themeToggleScript: swissToggleScript,
+  },
 };
 
 export const AVAILABLE_THEMES: Theme[] = Object.keys(themeModules) as Theme[];
diff --git a/src/renderer/themes/swiss/index.ts b/src/renderer/themes/swiss/index.ts
new file mode 100644
index 0000000..a144b46
--- /dev/null
+++ b/src/renderer/themes/swiss/index.ts
@@ -0,0 +1,3 @@
+// Swiss theme: International Typographic Style, mathematical precision, pure grid
+
+export { buildCSS, buildIndexCSS, colors, THEME_INIT_SCRIPT, THEME_TOGGLE_SCRIPT } from "./styles.js";
diff --git a/src/renderer/themes/swiss/styles.ts b/src/renderer/themes/swiss/styles.ts
new file mode 100644
index 0000000..247c336
--- /dev/null
+++ b/src/renderer/themes/swiss/styles.ts
@@ -0,0 +1,695 @@
+// Swiss theme: International Typographic Style (Swiss Design)
+// Clean white, strict grid, neo-grotesque sans-serif, single accent color
+// Zero animation, zero shadows, zero gradients. Pure structure.
+
+import type { Language } from "../../../types.js";
+import { getFontConfig } from "../../../i18n/index.js";
+
+const c = {
+  bg: "#ffffff",
+  text: "#000000",
+  textSecondary: "#444444",
+  textTertiary: "#999999",
+  border: "#000000",
+  accent: "#ff0000",
+  green: "#1a7f37",
+  red: "#cf222e",
+  badgePr: "#8250df",
+  badgeRelease: "#1a7f37",
+  badgeIssue: "#9a6700",
+  badgeDiscussion: "#0969da",
+};
+
+export const colors = c;
+
+const LIGHT_VARS = `
+    --s-bg: #ffffff;
+    --s-text: #000000;
+    --s-text-secondary: #444444;
+    --s-text-tertiary: #999999;
+    --s-border: #999999;
+    --s-border-subtle: #e0e0e0;
+    --s-accent: #ff0000;
+    --s-code-bg: #f5f5f5;
+    --s-green: #1a7f37;
+    --s-red: #cf222e;
+    --s-badge-pr: #8250df;
+    --s-badge-release: #1a7f37;
+    --s-badge-issue: #9a6700;
+    --s-badge-discussion: #0969da;
+    --s-heatmap-0: #f0f0f0;
+    --s-heatmap-1: #d0e8d0;
+    --s-heatmap-2: #a0d0a0;
+    --s-heatmap-3: #60b060;
+    --s-heatmap-4: #1a7f37;
+    --s-heatmap-text: #fff;
+    --s-section-num: #e8e8e8;
+`;
+
+const DARK_VARS = `
+    --s-bg: #0a0a0a;
+    --s-text: #f0f0f0;
+    --s-text-secondary: #b0b0b0;
+    --s-text-tertiary: #666666;
+    --s-border: #666666;
+    --s-border-subtle: #2a2a2a;
+    --s-accent: #ff3333;
+    --s-code-bg: #1a1a1a;
+    --s-green: #3fb950;
+    --s-red: #f85149;
+    --s-badge-pr: #a371f7;
+    --s-badge-release: #3fb950;
+    --s-badge-issue: #d29922;
+    --s-badge-discussion: #58a6ff;
+    --s-heatmap-0: #1a1a1a;
+    --s-heatmap-1: #0e4429;
+    --s-heatmap-2: #006d32;
+    --s-heatmap-3: #26a641;
+    --s-heatmap-4: #39d353;
+    --s-heatmap-text: #000;
+    --s-section-num: #1a1a1a;
+`;
+
+const COLOR_VARS = `
+  :root { ${LIGHT_VARS} }
+  @media (prefers-color-scheme: dark) { :root { ${DARK_VARS} } }
+  html[data-theme="light"] { ${LIGHT_VARS} }
+  html[data-theme="dark"] { ${DARK_VARS} }
+`;
+
+const THEME_TOGGLE_CSS = `
+  .theme-toggle {
+    background: none; border: none;
+    color: var(--s-text-tertiary); cursor: pointer;
+    font-family: inherit; font-size: 0.75rem; line-height: 1;
+    padding: 0; letter-spacing: 0.05em;
+    text-transform: uppercase;
+  }
+  .theme-toggle:hover { color: var(--s-accent); }
+`;
+
+export const THEME_INIT_SCRIPT = `<script>
+(function(){
+  var s=localStorage.getItem("theme");
+  if(s)document.documentElement.setAttribute("data-theme",s);
+})();
+</script>`;
+
+export const THEME_TOGGLE_SCRIPT = `<script>
+(function(){
+  var btn=document.querySelector(".theme-toggle");
+  if(!btn)return;
+  function current(){
+    return document.documentElement.getAttribute("data-theme")
+      || (matchMedia("(prefers-color-scheme:dark)").matches?"dark":"light");
+  }
+  function update(){btn.textContent=current()==="dark"?"\\u2600\\uFE0E Light":"\\u263D\\uFE0E Dark";}
+  update();
+  btn.addEventListener("click",function(){
+    var next=current()==="dark"?"light":"dark";
+    document.documentElement.setAttribute("data-theme",next);
+    localStorage.setItem("theme",next);
+    update();
+  });
+})();
+</script>`;
+
+export const buildCSS = (language: Language = "en"): string => {
+  const f = getFontConfig(language);
+  const heading = `'Space Grotesk', ${f.bodyFamily}`;
+  const body = `'Space Grotesk', ${f.bodyFamily}`;
+  const mono = f.monoFamily;
+
+  return `
+    @import url('https://fonts.googleapis.com/css2?family=Space+Grotesk:wght@300;400;700&display=swap');
+    @import url('${f.importUrl}');
+
+    ${COLOR_VARS}
+    ${THEME_TOGGLE_CSS}
+
+    * { margin: 0; padding: 0; box-sizing: border-box; }
+
+    body {
+      font-family: ${body};
+      font-weight: 400;
+      background: var(--s-bg);
+      color: var(--s-text);
+      line-height: ${f.lineHeight};
+      -webkit-font-smoothing: antialiased;
+    }
+
+    a { color: var(--s-text); }
+    a:hover { color: var(--s-accent); }
+
+    code {
+      font-family: ${mono};
+      font-size: 0.85em;
+      padding: 0.1em 0.3em;
+      background: var(--s-code-bg);
+    }
+
+    /* ==================== LAYOUT: asymmetric grid ==================== */
+    .swiss-layout {
+      display: grid;
+      grid-template-columns: 80px 1fr;
+      max-width: 880px;
+      margin: 0 auto;
+      padding: 3rem 2rem;
+      gap: 0 2rem;
+    }
+
+    main { grid-column: 1 / -1; }
+
+    /* ==================== NAV ==================== */
+    nav {
+      grid-column: 1 / -1;
+      display: flex;
+      justify-content: space-between;
+      align-items: center;
+      padding-bottom: 1.5rem;
+      margin-bottom: 2rem;
+      border-bottom: 2px solid var(--s-border);
+    }
+    nav a {
+      text-decoration: none;
+      font-size: 0.75rem;
+      text-transform: uppercase;
+      letter-spacing: 0.1em;
+    }
+    .nav-site-title {
+      font-size: 0.75rem;
+      font-weight: 700;
+      text-transform: uppercase;
+      letter-spacing: 0.1em;
+      color: var(--s-text);
+    }
+
+    /* ==================== SECTION NUMBERS ==================== */
+    .section-num {
+      font-size: 5rem;
+      font-weight: 300;
+      line-height: 1;
+      vertical-align: top;
+      color: var(--s-section-num);
+      text-align: right;
+      margin-top: 9px;
+      position: sticky;
+      top: 3rem;
+    }
+    .section-num-overview {
+      margin-top: -7px;
+    }
+
+    /* ==================== HEADER ==================== */
+    .header {
+      grid-column: 1 / -1;
+      margin-bottom: 3rem;
+      position: relative;
+    }
+    .header::before {
+      content: '';
+      position: absolute;
+      inset: 0;
+      background: repeating-linear-gradient(
+        45deg,
+        transparent,
+        transparent 18px,
+        var(--s-border-subtle) 18px,
+        var(--s-border-subtle) 19px
+      );
+      opacity: 0.5;
+      pointer-events: none;
+      z-index: 0;
+    }
+    .header > * { position: relative; z-index: 1; }
+    .header-meta {
+      font-size: 0.6875rem;
+      text-transform: uppercase;
+      letter-spacing: 0.12em;
+      color: var(--s-text-tertiary);
+      margin-bottom: 1.5rem;
+      display: flex;
+      align-items: center;
+      gap: 0.5rem;
+    }
+    .header-meta a {
+      color: var(--s-text-tertiary);
+      text-decoration: none;
+      display: inline-flex;
+      align-items: center;
+      gap: 0.35rem;
+    }
+    .header-meta a:hover { color: var(--s-accent); }
+    .header-meta img {
+      width: 18px; height: 18px; border-radius: 50%;
+    }
+    h1 {
+      font-family: ${heading};
+      font-size: clamp(2.5rem, 5vw, 4rem);
+      font-weight: 700;
+      line-height: 1.05;
+      letter-spacing: -0.03em;
+      margin-bottom: 0.75rem;
+    }
+    .header-sub {
+      font-size: 1rem;
+      font-weight: 400;
+      color: var(--s-text-secondary);
+    }
+    .header-rule {
+      border: none;
+      height: 2px;
+      background: var(--s-border);
+      margin-top: 2rem;
+    }
+
+    /* ==================== OVERVIEW ==================== */
+    .overview-row {
+      grid-column: 1 / -1;
+      display: grid;
+      grid-template-columns: 80px 1fr;
+      gap: 0 2rem;
+      margin-bottom: 3rem;
+      position: relative;
+    }
+    .overview-row::before {
+      content: '';
+      position: absolute;
+      right: -20px;
+      top: 0;
+      width: 200px;
+      height: 200px;
+      background:
+        linear-gradient(var(--s-border-subtle) 1px, transparent 1px) 0 0 / 40px 40px,
+        linear-gradient(90deg, var(--s-border-subtle) 1px, transparent 1px) 0 0 / 40px 40px;
+      opacity: 0.5;
+      pointer-events: none;
+      mask-image: radial-gradient(circle at center, black 30%, transparent 70%);
+      -webkit-mask-image: radial-gradient(circle at center, black 30%, transparent 70%);
+    }
+    .overview-row::after {
+      content: '';
+      position: absolute;
+      right: 20px;
+      top: 40px;
+      width: 72px;
+      height: 72px;
+      border: 2px solid var(--s-accent);
+      opacity: 0.25;
+      transform: rotate(45deg);
+      pointer-events: none;
+    }
+    .overview-geo {
+      position: absolute;
+      right: 56px;
+      top: 16px;
+      width: 48px;
+      height: 48px;
+      border: 2px solid var(--s-border-subtle);
+      border-radius: 50%;
+      pointer-events: none;
+    }
+    .overview-geo::before {
+      content: '';
+      position: absolute;
+      right: -40px;
+      top: 80px;
+      width: 100px;
+      height: 100px;
+      border: 2px solid var(--s-border-subtle);
+      transform: rotate(20deg);
+      pointer-events: none;
+    }
+    .overview {
+      max-width: 600px;
+      position: relative;
+      z-index: 1;
+    }
+    .overview p {
+      font-size: 0.9375rem;
+      color: var(--s-text-secondary);
+      margin-bottom: 1rem;
+    }
+    .overview p:last-child { margin-bottom: 0; }
+
+    /* ==================== SECTIONS ==================== */
+    .section-row {
+      grid-column: 1 / -1;
+      display: grid;
+      grid-template-columns: 80px 1fr;
+      gap: 0 2rem;
+      margin-bottom: 3rem;
+    }
+    .section-content {
+      border-top: 2px solid var(--s-border);
+      padding-top: 1rem;
+    }
+    .section-group-header {
+      display: flex;
+      justify-content: space-between;
+      align-items: baseline;
+      margin-bottom: 1.5rem;
+    }
+    .section-group-title {
+      font-size: 0.6875rem;
+      font-weight: 700;
+      text-transform: uppercase;
+      letter-spacing: 0.15em;
+    }
+    .section-group-count {
+      font-size: 0.6875rem;
+      color: var(--s-text-tertiary);
+      text-transform: uppercase;
+      letter-spacing: 0.1em;
+    }
+
+    /* ==================== SUMMARY ==================== */
+    .section-summary {
+      margin-bottom: 2rem;
+      padding-bottom: 2rem;
+      border-bottom: 1px solid var(--s-border-subtle);
+    }
+    .section-summary:last-child { border-bottom: none; padding-bottom: 0; }
+    .section-type {
+      font-size: 0.625rem;
+      font-weight: 700;
+      text-transform: uppercase;
+      letter-spacing: 0.15em;
+      color: var(--s-accent);
+      margin-bottom: 0.5rem;
+    }
+    .section-heading {
+      font-family: ${heading};
+      font-size: 1.125rem;
+      font-weight: 700;
+      line-height: 1.2;
+      margin-bottom: 0.35rem;
+    }
+    .section-body {
+      font-size: 0.875rem;
+      color: var(--s-text-secondary);
+      max-width: 540px;
+    }
+
+    /* ==================== CHIPS ==================== */
+    .data-chips {
+      display: flex; flex-wrap: wrap; gap: 0.5rem;
+      margin-top: 0.75rem;
+    }
+    .chip {
+      font-family: ${mono};
+      font-size: 0.6875rem;
+      color: var(--s-text-secondary);
+    }
+    .chip-label::after { content: ": "; }
+    .chip-green { color: var(--s-green); }
+    .chip-red { color: var(--s-red); }
+
+    /* ==================== DIFF BAR ==================== */
+    .diff-bar {
+      display: flex; height: 3px; overflow: hidden;
+      margin-top: 0.75rem; margin-bottom: 0.25rem;
+      background: var(--s-border-subtle);
+    }
+    .diff-add { background: var(--s-green); height: 100%; }
+    .diff-del { background: var(--s-red); height: 100%; }
+    .diff-labels {
+      display: flex; justify-content: space-between;
+      font-family: ${mono}; font-size: 0.6875rem;
+    }
+    .diff-label-add { color: var(--s-green); }
+    .diff-label-del { color: var(--s-red); }
+
+    /* ==================== HEATMAP ==================== */
+    .mini-heatmap { display: flex; gap: 4px; margin-top: 0.75rem; }
+    .mh-day { display: flex; flex-direction: column; align-items: center; gap: 2px; }
+    .mh-block {
+      width: 32px; height: 32px;
+      display: flex; align-items: center; justify-content: center;
+      font-family: ${mono}; font-size: 0.6875rem;
+    }
+    .mh-label {
+      font-size: 0.5625rem;
+      text-transform: uppercase;
+      letter-spacing: 0.05em;
+      color: var(--s-text-tertiary);
+    }
+    .mh-level-0 { background: var(--s-heatmap-0); color: var(--s-text-tertiary); }
+    .mh-level-1 { background: var(--s-heatmap-1); }
+    .mh-level-2 { background: var(--s-heatmap-2); }
+    .mh-level-3 { background: var(--s-heatmap-3); color: var(--s-heatmap-text); }
+    .mh-level-4 { background: var(--s-heatmap-4); color: var(--s-heatmap-text); }
+
+    /* ==================== REPO BARS ==================== */
+    .repo-bars { margin-top: 0.75rem; display: flex; flex-direction: column; gap: 0.5rem; }
+    .repo-bar-header { display: flex; justify-content: space-between; font-size: 0.6875rem; }
+    .repo-bar-label { font-family: ${mono}; color: var(--s-text-secondary); }
+    .repo-bar-value { font-family: ${mono}; color: var(--s-text-tertiary); }
+    .repo-bar-track { width: 100%; height: 3px; background: var(--s-border-subtle); overflow: hidden; }
+    .repo-bar-fill { height: 100%; background: var(--s-accent); }
+
+    /* ==================== HIGHLIGHTS ==================== */
+    .highlight-grid {
+      display: grid;
+      grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
+      gap: 1.5rem;
+    }
+    .highlight-card {
+      padding-top: 1rem;
+      border-top: 2px solid var(--s-border);
+    }
+    .highlight-badge {
+      font-size: 0.5625rem;
+      font-weight: 700;
+      text-transform: uppercase;
+      letter-spacing: 0.12em;
+      display: inline-block;
+      margin-bottom: 0.4rem;
+    }
+    .highlight-pr { color: var(--s-badge-pr); }
+    .highlight-release { color: var(--s-badge-release); }
+    .highlight-issue { color: var(--s-badge-issue); }
+    .highlight-discussion { color: var(--s-badge-discussion); }
+    .highlight-title {
+      font-size: 1rem;
+      font-weight: 700;
+      line-height: 1.25;
+      margin-bottom: 0.25rem;
+    }
+    .highlight-title a { color: var(--s-text); text-decoration: none; }
+    .highlight-title a:hover { color: var(--s-accent); }
+    .highlight-meta {
+      font-family: ${mono};
+      font-size: 0.625rem;
+      color: var(--s-text-tertiary);
+      margin-bottom: 0.35rem;
+      text-transform: uppercase;
+      letter-spacing: 0.05em;
+    }
+    .highlight-body {
+      font-size: 0.8125rem;
+      color: var(--s-text-secondary);
+    }
+
+    /* ==================== SHARE ==================== */
+    .share-bar {
+      grid-column: 1 / -1;
+      margin-top: 2rem;
+      padding-top: 1rem;
+      border-top: 1px solid var(--s-border-subtle);
+      font-size: 0.75rem;
+      display: flex; gap: 1rem; align-items: center;
+    }
+    .share-label {
+      color: var(--s-text-tertiary);
+      text-transform: uppercase;
+      letter-spacing: 0.1em;
+      font-size: 0.625rem;
+    }
+    .share-btn {
+      color: var(--s-text);
+      text-decoration: none;
+      text-transform: uppercase;
+      letter-spacing: 0.05em;
+      font-size: 0.6875rem;
+    }
+    .share-btn:hover { color: var(--s-accent); }
+
+    /* ==================== WEEK NAV ==================== */
+    .week-nav {
+      grid-column: 1 / -1;
+      margin-top: 1.5rem;
+      padding-top: 1rem;
+      border-top: 1px solid var(--s-border-subtle);
+      display: flex;
+      justify-content: space-between;
+      font-size: 0.75rem;
+      text-transform: uppercase;
+      letter-spacing: 0.05em;
+    }
+    .week-nav a { color: var(--s-text); text-decoration: none; }
+    .week-nav a:hover { color: var(--s-accent); }
+
+    /* ==================== FOOTER ==================== */
+    .footer {
+      grid-column: 1 / -1;
+      margin-top: 4rem;
+      padding-top: 1.5rem;
+      border-top: 2px solid var(--s-border);
+      text-align: left;
+      font-size: 0.6875rem;
+      color: var(--s-text-tertiary);
+      text-transform: uppercase;
+      letter-spacing: 0.08em;
+    }
+    .footer a { color: var(--s-text-secondary); text-decoration: none; }
+    .footer a:hover { color: var(--s-accent); }
+    .theme-toggle-row { margin-bottom: 0.5rem; }
+
+    /* ==================== RESPONSIVE ==================== */
+    @media (max-width: 640px) {
+      .swiss-layout {
+        grid-template-columns: 1fr;
+        padding: 2rem 1.25rem;
+        gap: 0;
+      }
+      .section-num { display: none; }
+      .overview-row,
+      .section-row {
+        grid-template-columns: 1fr;
+      }
+      h1 { font-size: 2rem; }
+      .highlight-grid { grid-template-columns: 1fr; }
+    }
+
+    @media print {
+      body { background: #fff; color: #000; }
+      nav, .share-bar, .week-nav { display: none; }
+      .section-num { color: #ddd; }
+    }
+  `;
+};
+
+export const buildIndexCSS = (language: Language = "en"): string => {
+  const f = getFontConfig(language);
+  const heading = `'Space Grotesk', ${f.bodyFamily}`;
+  const mono = f.monoFamily;
+
+  return `
+    .index-layout {
+      max-width: 880px;
+      margin: 0 auto;
+      padding: 4rem 2rem;
+    }
+
+    /* ==================== INDEX HEADER ==================== */
+    .index-header {
+      margin-bottom: 4rem;
+    }
+    .index-header h1 {
+      font-family: ${heading};
+      font-size: clamp(3rem, 10vw, 6rem);
+      font-weight: 300;
+      line-height: 1;
+      letter-spacing: -0.04em;
+      color: var(--s-text);
+      margin-bottom: 2rem;
+    }
+    .index-profile {
+      display: flex; align-items: center; gap: 0.75rem;
+      text-decoration: none; color: inherit;
+    }
+    .index-profile:hover { color: var(--s-accent); }
+    .index-profile img { width: 40px; height: 40px; border-radius: 50%; }
+    .index-profile-name {
+      font-weight: 700;
+      font-size: 0.875rem;
+      text-transform: uppercase;
+      letter-spacing: 0.08em;
+    }
+    .index-profile-handle {
+      font-size: 0.75rem;
+      color: var(--s-text-tertiary);
+      letter-spacing: 0.05em;
+    }
+    .index-stats {
+      font-size: 0.6875rem;
+      color: var(--s-text-tertiary);
+      margin-top: 0.75rem;
+      text-transform: uppercase;
+      letter-spacing: 0.1em;
+    }
+
+    /* ==================== YEAR GROUPS ==================== */
+    .year-group {
+      display: grid;
+      grid-template-columns: 80px 1fr;
+      gap: 0 2rem;
+      margin-bottom: 3rem;
+    }
+    .year-label {
+      font-size: 1.25rem;
+      font-weight: 700;
+      line-height: 1;
+      color: var(--s-text-tertiary);
+      text-align: right;
+      padding-top: 0.75rem;
+    }
+
+    .week-list { list-style: none; padding: 0; border-top: 2px solid var(--s-border); }
+    .week-item {
+      display: block;
+      padding: 1rem 0;
+      border-bottom: 1px solid var(--s-border-subtle);
+      text-decoration: none;
+      color: inherit;
+    }
+    .week-item:hover .week-item-title { color: var(--s-accent); }
+    .week-item-header {
+      display: flex; justify-content: space-between; align-items: baseline;
+    }
+    .week-item-title {
+      font-weight: 700;
+      font-size: 0.9375rem;
+    }
+    .week-item-week {
+      font-family: ${mono};
+      font-size: 0.625rem;
+      color: var(--s-text-tertiary);
+      text-transform: uppercase;
+      letter-spacing: 0.1em;
+    }
+    .week-item-subtitle {
+      font-size: 0.8125rem;
+      color: var(--s-text-secondary);
+      margin-top: 0.125rem;
+    }
+
+    /* ==================== FOOTER ==================== */
+    .footer {
+      margin-top: 4rem;
+      padding-top: 1.5rem;
+      border-top: 2px solid var(--s-border);
+      font-size: 0.6875rem;
+      color: var(--s-text-tertiary);
+      text-transform: uppercase;
+      letter-spacing: 0.08em;
+    }
+    .footer a { color: var(--s-text-secondary); text-decoration: none; }
+    .footer a:hover { color: var(--s-accent); }
+
+    @media (max-width: 640px) {
+      .index-layout { padding: 2rem 1.25rem; }
+      .year-group { grid-template-columns: 1fr; }
+      .year-label {
+        text-align: left;
+        font-size: 2rem;
+        margin-bottom: 0.5rem;
+      }
+    }
+
+    @media print {
+      body { background: #fff; }
+    }
+  `;
+};
diff --git a/src/renderer/themes/swiss/templates/index-page.hbs b/src/renderer/themes/swiss/templates/index-page.hbs
new file mode 100644
index 0000000..9b4fae4
--- /dev/null
+++ b/src/renderer/themes/swiss/templates/index-page.hbs
@@ -0,0 +1,79 @@
+<!DOCTYPE html>
+<html lang="{{lang}}">
+<head>
+  <title>{{siteTitleInline}}</title>
+  <meta charset="utf-8" />
+  <meta name="viewport" content="width=device-width, initial-scale=1" />
+  <meta name="description" content="{{description}}" />
+  <meta name="view-transition" content="same-origin" />
+  <meta property="og:title" content="{{siteTitleInline}}" />
+  <meta property="og:description" content="{{description}}" />
+  <meta property="og:type" content="website" />
+  {{#if ogImageUrl}}<meta property="og:image" content="{{ogImageUrl}}" />
+  <meta property="og:image:width" content="1200" />
+  <meta property="og:image:height" content="630" />{{/if}}
+  {{#if baseUrl}}<meta property="og:url" content="{{baseUrl}}/" />{{/if}}
+  <meta name="twitter:card" content="summary_large_image" />
+  <meta name="twitter:title" content="{{siteTitleInline}}" />
+  <meta name="twitter:description" content="{{description}}" />
+  {{#if ogImageUrl}}<meta name="twitter:image" content="{{ogImageUrl}}" />{{/if}}
+  {{#if baseUrl}}<link rel="alternate" type="application/rss+xml" title="RSS Feed" href="{{baseUrl}}/feed.xml" />{{/if}}
+  <style>{{{css}}}</style>
+  <style>{{{indexCss}}}</style>
+  {{{themeInitScript}}}
+</head>
+<body>
+
+<div class="index-layout">
+
+  <div class="index-header">
+    <h1>{{siteTitle}}</h1>
+
+    {{#if username}}
+    <a href="https://github.com/{{username}}" class="index-profile" target="_blank" rel="noopener nofollow">
+      {{#if avatarUrl}}<img src="{{avatarUrl}}" alt="{{username}}" width="40" height="40" />{{/if}}
+      <div>
+        <div class="index-profile-name">{{#if profile.name}}{{profile.name}}{{else}}{{username}}{{/if}}</div>
+        <div class="index-profile-handle">@{{username}}</div>
+      </div>
+    </a>
+    {{#if profile}}
+    <div class="index-stats">
+      {{#if profile.followers}}{{profile.followers}} followers{{/if}}
+      {{#if profile.publicRepos}} &middot; {{profile.publicRepos}} repos{{/if}}
+    </div>
+    {{/if}}
+    {{/if}}
+  </div>
+
+  {{#each yearGroups}}
+  <div class="year-group">
+    <div class="year-label">{{this.year}}</div>
+    <div class="week-list">
+      {{#each this.reports}}
+      <a href="{{this.path}}/" class="week-item">
+        <div class="week-item-header">
+          <span class="week-item-title">{{#if this.title}}{{this.title}}{{else}}Week {{this.week}}{{/if}}</span>
+          <span class="week-item-week">{{this.week}}</span>
+        </div>
+        {{#if this.subtitle}}<div class="week-item-subtitle">{{this.subtitle}}</div>{{/if}}
+      </a>
+      {{/each}}
+    </div>
+  </div>
+  {{/each}}
+
+  <footer class="footer">
+    <div class="theme-toggle-row">
+      <button class="theme-toggle" type="button" aria-label="Toggle theme">&#9790;&#65038; Dark</button>
+    </div>
+    {{poweredBy}} <a href="https://deariary.com?utm_source=github-weekly-reporter&utm_medium=footer" target="_blank" rel="noopener">deariary</a>
+    &middot;
+    {{generatedWith}} <a href="https://github.com/deariary/github-weekly-reporter" target="_blank" rel="noopener">github-weekly-reporter</a>
+  </footer>
+
+</div>
+
+{{{themeToggleScript}}}
+</body>
+</html>
diff --git a/src/renderer/themes/swiss/templates/partials/footer.hbs b/src/renderer/themes/swiss/templates/partials/footer.hbs
new file mode 100644
index 0000000..45040d6
--- /dev/null
+++ b/src/renderer/themes/swiss/templates/partials/footer.hbs
@@ -0,0 +1,8 @@
+<footer class="footer">
+  <div class="theme-toggle-row">
+    <button class="theme-toggle" type="button" aria-label="Toggle theme">&#9790;&#65038; Dark</button>
+  </div>
+  {{i18n.poweredBy}} <a href="https://deariary.com?utm_source=github-weekly-reporter&utm_medium=footer" target="_blank" rel="noopener">deariary</a>
+  &middot;
+  {{i18n.generatedWith}} <a href="https://github.com/deariary/github-weekly-reporter" target="_blank" rel="noopener">github-weekly-reporter</a>
+</footer>
diff --git a/src/renderer/themes/swiss/templates/partials/header.hbs b/src/renderer/themes/swiss/templates/partials/header.hbs
new file mode 100644
index 0000000..79f9fd1
--- /dev/null
+++ b/src/renderer/themes/swiss/templates/partials/header.hbs
@@ -0,0 +1,11 @@
+<div class="header-meta">
+  <a href="https://github.com/{{username}}" target="_blank" rel="noopener nofollow">
+    <img src="{{avatarUrl}}" alt="{{username}}" width="18" height="18" loading="lazy" />
+    {{username}}
+  </a>
+  &middot;
+  {{weekLabel dateRange.from dateRange.to}}
+</div>
+<h1>{{aiContent.title}}</h1>
+<p class="header-sub">{{aiContent.subtitle}}</p>
+<hr class="header-rule" />
diff --git a/src/renderer/themes/swiss/templates/partials/highlights.hbs b/src/renderer/themes/swiss/templates/partials/highlights.hbs
new file mode 100644
index 0000000..18bce61
--- /dev/null
+++ b/src/renderer/themes/swiss/templates/partials/highlights.hbs
@@ -0,0 +1,26 @@
+{{#if aiContent.highlights.length}}
+<div class="section-row">
+  <div class="section-num">02</div>
+  <div class="section-content">
+    <div class="section-group-header">
+      <span class="section-group-title">{{i18n.sectionHighlights}}</span>
+      <span class="section-group-count">{{itemsCount aiContent.highlights.length}}</span>
+    </div>
+
+    <div class="highlight-grid">
+    {{#each aiContent.highlights}}
+    <div class="highlight-card">
+      <span class="highlight-badge highlight-{{this.type}}">{{this.type}}</span>
+      {{#if this.url}}
+      <div class="highlight-title"><a href="{{this.url}}" target="_blank" rel="noopener nofollow">{{this.title}}</a></div>
+      {{else}}
+      <div class="highlight-title">{{this.title}}</div>
+      {{/if}}
+      <div class="highlight-meta">{{this.repo}} &middot; {{this.meta}}</div>
+      <div class="highlight-body">{{{mdInline this.body}}}</div>
+    </div>
+    {{/each}}
+    </div>
+  </div>
+</div>
+{{/if}}
diff --git a/src/renderer/themes/swiss/templates/partials/overview.hbs b/src/renderer/themes/swiss/templates/partials/overview.hbs
new file mode 100644
index 0000000..80c1a94
--- /dev/null
+++ b/src/renderer/themes/swiss/templates/partials/overview.hbs
@@ -0,0 +1,7 @@
+<div class="overview-row">
+  <div class="section-num section-num-overview">00</div>
+  <div class="overview">
+    {{{md aiContent.overview}}}
+  </div>
+  <div class="overview-geo" aria-hidden="true"></div>
+</div>
diff --git a/src/renderer/themes/swiss/templates/partials/summaries.hbs b/src/renderer/themes/swiss/templates/partials/summaries.hbs
new file mode 100644
index 0000000..69da4a6
--- /dev/null
+++ b/src/renderer/themes/swiss/templates/partials/summaries.hbs
@@ -0,0 +1,71 @@
+{{#if aiContent.summaries.length}}
+<div class="section-row">
+  <div class="section-num">01</div>
+  <div class="section-content">
+    <div class="section-group-header">
+      <span class="section-group-title">{{i18n.sectionSummary}}</span>
+      <span class="section-group-count">{{sectionsCount aiContent.summaries.length}}</span>
+    </div>
+
+    {{#each aiContent.summaries}}
+    <div class="section-summary">
+      <div class="section-type">{{this.type}}</div>
+      <div class="section-heading">{{{mdInline this.heading}}}</div>
+      <div class="section-body">{{{mdInline this.body}}}</div>
+
+      {{#eq this.type "activity-pattern"}}
+      {{#if @root.dailyCommits.length}}
+      <div class="mini-heatmap">
+        {{#each @root.dailyCommits}}
+        <div class="mh-day">
+          <div class="mh-block mh-level-{{this.level}}">{{this.count}}</div>
+          <div class="mh-label">{{weekday this.date}}</div>
+        </div>
+        {{/each}}
+      </div>
+      {{/if}}
+      {{/eq}}
+
+      {{#eq this.type "commit-summary"}}
+      {{#if @root.stats.totalAdditions}}
+      <div class="diff-bar">
+        <div class="diff-add" style="flex:{{@root.stats.totalAdditions}}"></div>
+        <div class="diff-del" style="flex:{{@root.stats.totalDeletions}}"></div>
+      </div>
+      <div class="diff-labels">
+        <span class="diff-label-add">+{{formatNumber @root.stats.totalAdditions}}</span>
+        <span class="diff-label-del">-{{formatNumber @root.stats.totalDeletions}}</span>
+      </div>
+      {{/if}}
+      {{/eq}}
+
+      {{#eq this.type "repo-summary"}}
+      {{#if @root.repositories.length}}
+      <div class="repo-bars">
+        {{#each (sortReposDesc @root.repositories)}}
+        <div class="repo-bar-item">
+          <div class="repo-bar-header">
+            <span class="repo-bar-label">{{this.name}}</span>
+            <span class="repo-bar-value">{{this.prsOpened}} PRs</span>
+          </div>
+          <div class="repo-bar-track">
+            <div class="repo-bar-fill" style="width:{{repoBarWidth this.prsOpened @root.repositories}}%"></div>
+          </div>
+        </div>
+        {{/each}}
+      </div>
+      {{/if}}
+      {{/eq}}
+
+      {{#if this.chips}}
+      <div class="data-chips">
+        {{#each this.chips}}
+        <span class="chip"><span class="chip-label">{{this.label}}</span><span class="chip-value chip-{{this.color}}">{{this.value}}</span></span>
+        {{/each}}
+      </div>
+      {{/if}}
+    </div>
+    {{/each}}
+  </div>
+</div>
+{{/if}}
diff --git a/src/renderer/themes/swiss/templates/report.hbs b/src/renderer/themes/swiss/templates/report.hbs
new file mode 100644
index 0000000..f693b17
--- /dev/null
+++ b/src/renderer/themes/swiss/templates/report.hbs
@@ -0,0 +1,110 @@
+<!DOCTYPE html>
+<html lang="{{lang}}">
+<head>
+  <title>{{aiContent.title}} - {{dateRange.from}} - {{dateRange.to}}</title>
+  <meta charset="utf-8" />
+  <meta name="viewport" content="width=device-width, initial-scale=1" />
+  <meta name="description" content="{{aiContent.subtitle}}" />
+  <meta property="og:title" content="{{aiContent.title}}" />
+  <meta property="og:description" content="{{aiContent.subtitle}}" />
+  <meta property="og:image" content="{{{ogImageUrl}}}" />
+  <meta property="og:image:width" content="1200" />
+  <meta property="og:image:height" content="630" />
+  <meta property="og:type" content="article" />
+  {{#if canonicalUrl}}<meta property="og:url" content="{{{canonicalUrl}}}" />
+  {{/if}}<meta property="og:site_name" content="{{username}} Weekly Reports" />
+  <meta name="twitter:card" content="summary_large_image" />
+  <meta name="twitter:title" content="{{aiContent.title}}" />
+  <meta name="twitter:description" content="{{aiContent.subtitle}}" />
+  <meta name="twitter:image" content="{{{ogImageUrl}}}" />
+  <meta name="author" content="{{username}}" />
+  <meta name="theme-color" content="{{themeColor}}" />
+  <meta property="article:published_time" content="{{dateRange.to}}" />
+  <meta property="article:author" content="https://github.com/{{username}}" />
+  <link rel="icon" href="{{avatarUrl}}" />
+  {{#if canonicalUrl}}<link rel="canonical" href="{{{canonicalUrl}}}" />
+  {{/if}}{{#if baseUrl}}<link rel="alternate" type="application/rss+xml" title="RSS Feed" href="{{{baseUrl}}}/feed.xml" />
+  {{/if}}<meta name="view-transition" content="same-origin" />
+  <script type="application/ld+json">
+  {
+    "@context": "https://schema.org",
+    "@type": "Article",
+    "headline": "{{jsonLdEscape aiContent.title}}",
+    "description": "{{jsonLdEscape aiContent.subtitle}}",
+    "author": {
+      "@type": "Person",
+      "name": "{{jsonLdEscape username}}",
+      "url": "https://github.com/{{jsonLdEscape username}}"
+    },
+    "image": "{{jsonLdEscape ogImageUrl}}",
+    "datePublished": "{{jsonLdEscape dateRange.to}}"
+  }
+  </script>
+  {{#if canonicalUrl}}
+  <script type="application/ld+json">
+  {
+    "@context": "https://schema.org",
+    "@type": "BreadcrumbList",
+    "itemListElement": [
+      { "@type": "ListItem", "position": 1, "name": "Home", "item": "{{jsonLdEscape baseUrl}}/" },
+      { "@type": "ListItem", "position": 2, "name": "{{jsonLdEscape dateRange.from}} - {{jsonLdEscape dateRange.to}}", "item": "{{jsonLdEscape canonicalUrl}}" }
+    ]
+  }
+  </script>
+  {{/if}}
+  <style>{{{css}}}</style>
+  {{{themeInitScript}}}
+</head>
+<body>
+
+<div class="swiss-layout">
+
+  <nav>
+    <a href="../../" class="nav-site-title">{{siteTitleInline}}</a>
+    <a href="../../">&larr; {{i18n.allWeeks}}</a>
+  </nav>
+
+  <div class="header">
+    {{> header}}
+  </div>
+
+  {{> overview}}
+
+  <main>
+    {{> summaries}}
+    {{> highlights}}
+  </main>
+
+  {{#if canonicalUrl}}
+  <div class="share-bar">
+    <span class="share-label">{{i18n.share}}</span>
+    <a href="https://x.com/intent/tweet?url={{{canonicalUrl}}}&text={{urlEncode aiContent.title}}" target="_blank" rel="noopener nofollow" class="share-btn">X</a>
+    <a href="https://www.linkedin.com/sharing/share-offsite/?url={{{canonicalUrl}}}" target="_blank" rel="noopener nofollow" class="share-btn">LinkedIn</a>
+    <a href="https://bsky.app/intent/compose?text={{urlEncode aiContent.title}}%20{{{canonicalUrl}}}" target="_blank" rel="noopener nofollow" class="share-btn">Bluesky</a>
+  </div>
+  {{/if}}
+
+  {{#if prevWeek}}{{#if nextWeek}}
+  <div class="week-nav">
+    <a href="{{prevWeek}}">&larr; {{i18n.prevWeek}}</a>
+    <a href="{{nextWeek}}">{{i18n.nextWeek}} &rarr;</a>
+  </div>
+  {{else}}
+  <div class="week-nav">
+    <a href="{{prevWeek}}">&larr; {{i18n.prevWeek}}</a>
+    <span></span>
+  </div>
+  {{/if}}{{else}}{{#if nextWeek}}
+  <div class="week-nav">
+    <span></span>
+    <a href="{{nextWeek}}">{{i18n.nextWeek}} &rarr;</a>
+  </div>
+  {{/if}}{{/if}}
+
+  {{> footer}}
+
+</div>
+
+{{{themeToggleScript}}}
+</body>
+</html>
diff --git a/src/renderer/themes/themes.test.ts b/src/renderer/themes/themes.test.ts
index f7ed5e4..5ffc788 100644
--- a/src/renderer/themes/themes.test.ts
+++ b/src/renderer/themes/themes.test.ts
@@ -61,6 +61,10 @@ describe("AVAILABLE_THEMES", () => {
   it("includes editorial", () => {
     expect(AVAILABLE_THEMES).toContain("editorial");
   });
+
+  it("includes swiss", () => {
+    expect(AVAILABLE_THEMES).toContain("swiss");
+  });
 });
 
 describe("loadTheme", () => {
@@ -350,3 +354,75 @@ describe("editorial theme", () => {
     expect(html).toContain("fixed-footer");
   });
 });
+
+describe("swiss theme", () => {
+  it("loads swiss theme", () => {
+    const theme = loadTheme("swiss");
+    expect(theme.buildCSS).toBeTypeOf("function");
+    expect(theme.colors.bg).toBe("#ffffff");
+    expect(theme.colors.accent).toBe("#ff0000");
+    expect(theme.templatesDir).toContain("themes/swiss/templates");
+  });
+
+  it("buildCSS includes Space Grotesk", () => {
+    const theme = loadTheme("swiss");
+    const css = theme.buildCSS("en");
+    expect(css).toContain("Space Grotesk");
+  });
+
+  it("buildCSS uses CSS custom properties", () => {
+    const theme = loadTheme("swiss");
+    const css = theme.buildCSS("en");
+    expect(css).toContain("var(--s-bg)");
+    expect(css).toContain("var(--s-accent)");
+    expect(css).toContain("var(--s-border)");
+  });
+
+  it("buildCSS includes asymmetric grid layout", () => {
+    const theme = loadTheme("swiss");
+    const css = theme.buildCSS("en");
+    expect(css).toContain("swiss-layout");
+    expect(css).toContain("grid-template-columns: 80px 1fr");
+  });
+
+  it("buildCSS includes dark mode", () => {
+    const theme = loadTheme("swiss");
+    const css = theme.buildCSS("en");
+    expect(css).toContain("prefers-color-scheme: dark");
+    expect(css).toContain("--s-bg: #0a0a0a");
+  });
+
+  it("buildCSS supports data-theme override", () => {
+    const theme = loadTheme("swiss");
+    const css = theme.buildCSS("en");
+    expect(css).toContain('html[data-theme="light"]');
+    expect(css).toContain('html[data-theme="dark"]');
+  });
+
+  it("has theme toggle scripts", () => {
+    const theme = loadTheme("swiss");
+    expect(theme.themeInitScript).toContain("localStorage");
+    expect(theme.themeToggleScript).toContain("theme-toggle");
+  });
+
+  it("renders report with swiss theme", () => {
+    const html = renderReport(MOCK_DATA, { theme: "swiss" });
+    expect(html).toMatch(/^<!DOCTYPE html>/);
+    expect(html).toContain("Auth refactor completed");
+    expect(html).toContain("Space Grotesk");
+    expect(html).toContain("swiss-layout");
+  });
+
+  it("renders section numbers and geometric motifs", () => {
+    const html = renderReport(MOCK_DATA, { theme: "swiss" });
+    expect(html).toContain("section-num");
+    expect(html).toContain("overview-geo");
+  });
+
+  it("renders highlights in grid layout", () => {
+    const html = renderReport(MOCK_DATA, { theme: "swiss" });
+    expect(html).toContain("highlight-grid");
+    expect(html).toContain("highlight-card");
+    expect(html).toContain("feat: add OAuth flow");
+  });
+});
diff --git a/src/types.ts b/src/types.ts
index 6a9b5f4..4e10e16 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -201,7 +201,7 @@ export type AIContent = {
 
 // Configuration types
 
-export type Theme = "brutalist" | "minimal" | "editorial";
+export type Theme = "brutalist" | "minimal" | "editorial" | "swiss";
 
 export type LLMProvider = "openai" | "anthropic" | "gemini" | "openrouter" | "groq" | "grok";
 
