diff --git a/apps/frontend/src/components/board/BoardView.tsx b/apps/frontend/src/components/board/BoardView.tsx
index 630d05e..bd8566e 100644
--- a/apps/frontend/src/components/board/BoardView.tsx
+++ b/apps/frontend/src/components/board/BoardView.tsx
@@ -14,12 +14,19 @@ const BoardView: FunctionComponent<{
   boardViewModel: BoardViewModel;
   revert: boolean;
   onPitSelect: (index: number, pit: Pit) => void;
-}> = ({ game, context, boardId, boardViewModel, revert, onPitSelect }) => {
+  // Width in px, e.g. for previews; by default the board is as wide as the viewport.
+  width?: number;
+}> = ({ game, context, boardId, boardViewModel, revert, onPitSelect, width }) => {
   const mancalaGame = game?.mancalaGame;
   const theme = context.themeManager.theme;
 
-  // Compute pit width based on viewport (each column is 11vw)
-  const pitWidth = typeof window !== "undefined" ? window.innerWidth * 0.11 : 100;
+  // The board is 92 units wide (8 columns of 11 plus padding); all board parts are sized in units.
+  const unit = width !== undefined ? width / 92 : (typeof window !== "undefined" ? window.innerWidth / 100 : 10);
+  const pitWidth = unit * 11;
+  const sizeVariables = {
+    "--board-unit": width !== undefined ? `${unit}px` : "1vw",
+    "--board-spacing": width !== undefined ? `${unit * 0.3}px` : "5px",
+  } as React.CSSProperties;
 
   const createPitView = (key: any, pit: Pit, pitViewModel: PitViewModel) => (
     <PitView
@@ -42,7 +49,7 @@ const BoardView: FunctionComponent<{
   const player2BankViewModel = boardViewModel.pits[player2BankIndex];
 
   return (
-    <div className="board" style={{ background: theme.boardColor }}>
+    <div className="board" style={{ background: theme.boardColor, ...sizeVariables }}>
       <StoreView
         context={context}
         pitViewModel={revert ? player2BankViewModel : player1BankViewModel}
@@ -61,11 +68,11 @@ const BoardView: FunctionComponent<{
       {revert ? player2Pits : player1Pits}
       <style jsx>{`
         .board {
-          padding: 2vw;
+          padding: calc(2 * var(--board-unit));
           display: grid;
-          grid-template-columns: repeat(8, 11vw);
-          grid-template-rows: repeat(2, 11vw);
-          border-radius: 3vw;
+          grid-template-columns: repeat(8, calc(11 * var(--board-unit)));
+          grid-template-rows: repeat(2, calc(11 * var(--board-unit)));
+          border-radius: calc(3 * var(--board-unit));
           transition: background-color 0.5s;
         }
       `}</style>
diff --git a/apps/frontend/src/components/board/PitView.tsx b/apps/frontend/src/components/board/PitView.tsx
index 052e9c4..1029084 100644
--- a/apps/frontend/src/components/board/PitView.tsx
+++ b/apps/frontend/src/components/board/PitView.tsx
@@ -53,9 +53,9 @@ const PitView: FunctionComponent<PitViewProps> = ({ pitViewModel, context, onCli
       )}
       <style jsx>{`
         .pit {
-          margin: 5px;
-          padding: 5px;
-          border-radius: 10vw;
+          margin: var(--board-spacing);
+          padding: var(--board-spacing);
+          border-radius: calc(10 * var(--board-unit));
           transition: background-color 0.5s;
           display: flex;
           align-items: center;
@@ -67,11 +67,11 @@ const PitView: FunctionComponent<PitViewProps> = ({ pitViewModel, context, onCli
         }
         .stone-count {
           position: absolute;
-          bottom: 1.0vw;
+          bottom: calc(1.0 * var(--board-unit));
           left: 50%;
           transform: translateX(-50%);
           font-family: monospace;
-          font-size: 1.5vw;
+          font-size: calc(1.5 * var(--board-unit));
           font-weight: bold;
           pointer-events: none;
         }
diff --git a/apps/frontend/src/components/board/StoneView.tsx b/apps/frontend/src/components/board/StoneView.tsx
index e795b33..790546c 100644
--- a/apps/frontend/src/components/board/StoneView.tsx
+++ b/apps/frontend/src/components/board/StoneView.tsx
@@ -7,9 +7,9 @@ const StoneView: FunctionComponent<{ color: string }> = ({ color }) => {
       <style jsx>{`
           .stone {
             margin: 1px;
-            width: 1vw;
-            height: 1vw;
-            border-radius: 10vw;
+            width: calc(1 * var(--board-unit));
+            height: calc(1 * var(--board-unit));
+            border-radius: calc(10 * var(--board-unit));
             transition: background-color 0.5s;
           }
         `}</style>
diff --git a/apps/frontend/src/components/board/StoreView.tsx b/apps/frontend/src/components/board/StoreView.tsx
index 850f3ef..358be1a 100644
--- a/apps/frontend/src/components/board/StoreView.tsx
+++ b/apps/frontend/src/components/board/StoreView.tsx
@@ -34,8 +34,8 @@ const StoreView: FunctionComponent<{
       </span>
       <style jsx>{`
           .store {
-            margin: 5px;
-            border-radius: 10vw;
+            margin: var(--board-spacing);
+            border-radius: calc(10 * var(--board-unit));
             display: flex;
             align-items: center;
             justify-content: center;
@@ -46,10 +46,10 @@ const StoreView: FunctionComponent<{
           }
           .store-stone-count-text {
             position: absolute;
-            bottom: 2vw;
+            bottom: calc(2 * var(--board-unit));
             font-family: monospace;
             font-weight: bold;
-            font-size: 2vw;
+            font-size: calc(2 * var(--board-unit));
           }
         `}</style>
     </div>
diff --git a/docs/specs/game-history/design.md b/docs/specs/game-history/design.md
index 3dc88b7..4c78fd1 100644
--- a/docs/specs/game-history/design.md
+++ b/docs/specs/game-history/design.md
@@ -166,7 +166,7 @@ not spectators (R4.5).
 
 ### Board size
 `BoardView` gets an optional `width` (px). All board components size themselves from a CSS variable
-`--board-unit` (default `1vw`, else `width / 100` px) instead of `vw`, so the same board renders at full width in a
+`--board-unit` (default `1vw`, else `width / 92` px, the board being 92 units wide) instead of `vw`, so the same board renders at full width in a
 game and small in previews.
 
 ### Home page (`routes/Home.tsx`)
diff --git a/docs/specs/game-history/tasks.md b/docs/specs/game-history/tasks.md
index 7ded402..8e4cff9 100644
--- a/docs/specs/game-history/tasks.md
+++ b/docs/specs/game-history/tasks.md
@@ -17,7 +17,7 @@ Work through the tasks in order; each ends with its tests passing and a commit.
       unit tests.
 - [x] 7. **API**: public ids, Bearer auth middleware, `/games/me/active`, `/games/me`, `/games/popular`,
       `/game/:id` for finished games, live games channel with throttled push; tests.
-- [ ] 8. **Board size**: `--board-unit` in `BoardView`, `PitView`, `StoreView`, `StoneView`; `width` prop.
+- [x] 8. **Board size**: `--board-unit` in `BoardView`, `PitView`, `StoreView`, `StoneView`; `width` prop.
 - [ ] 9. **Home page**: `ActiveGameBanner`, `LiveGamesSection` with live updates, `RecentGamesSection`; lobby
       rejection message.
 - [ ] 10. **Live game history**: `MoveList`, review mode with `ReviewBanner` and keyboard, timeout countdown.