diff --git a/CLAUDE.md b/CLAUDE.md
index 541da27..14a4ebe 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -43,11 +43,16 @@ Navigation is a simple `useState<Page>` state machine in `App.tsx` — no router
 |------|-----|-------------|
 | Title screen | `'title'` | Shown on first load (no saved game). "New Game" button navigates to setup. |
 | Player setup | `'setup'` | Enter 3–6 player names, then "Start" saves the game and goes to scoresheet. |
-| Score sheet | `'scoresheet'` | Shows current scores. "Score Round" → enter scores; "New Game" → clears state, back to title. |
+| Score sheet | `'scoresheet'` | Shows per-round scores and running totals. Small red "New Game" button (top-right) opens a confirmation dialog before clearing state and going to setup. "Score Round" (footer) → enter scores. |
 | Enter scores | `'enterscores'` | Form to enter each player's score for the round. "Submit" → back to scoresheet. |
 
 On mount, `App.tsx` checks `localStorage` for a saved game and jumps straight to `'scoresheet'` if found.
 
+## Game rules
+
+- Each round every player scores some points; all players' scores in a round must sum to **-110**
+- Each player starts at 0; the game ends when any player reaches **-200**
+
 ## Data model
 
 ```ts
@@ -61,6 +66,13 @@ interface GameState {
 
 Persisted to `localStorage` under the key `currentGame`. No game history yet — only one game at a time.
 
+## Scoring logic
+
+Pure functions live in `src/game/scoring.ts` (no React imports):
+
+- `computeRunningTotals(rounds)` — returns `totals[i][j]`, the cumulative score for player `j` after round `i`
+- `isGameOver(totals)` — true if any player's total in the last round is ≤ -200
+
 ## Design system
 
 ### Layout
@@ -72,8 +84,10 @@ Persisted to `localStorage` under the key `currentGame`. No game history yet —
 
 ### PageFrame component
 
-Shared layout for non-title pages. Props: `title`, `children`, `footer?`. Renders:
+Shared layout for non-title pages. Props: `title`, `children`, `footer?`, `headerAction?`, `overlay?`. Renders:
 - Fixed-position card with header (h1 + diamond rule divider), scrollable content area, optional sticky footer
+- `headerAction` — rendered absolutely in the top-right of the header (used for the scoresheet's "New Game" button)
+- `overlay` — rendered `position: fixed; inset: 0` over the full viewport with a dim backdrop; the caller provides the dialog box content centered inside it
 
 Diamond rule: CSS `::before` pseudo-element with `content: '◆'` centered on a thin border line. Color `#c8b99a`.
 
@@ -91,10 +105,10 @@ Diamond rule: CSS `::before` pseudo-element with `content: '◆'` centered on a
 
 ### Buttons
 
-All buttons share the same press animation: `translateY(2px)` + shadow reduction, 80ms ease transition.
+Shadow and press animation are on the global `button` selector in `src/index.css` — every `<button>` gets them automatically.
 
 - **Resting shadow**: `0 4px 12px rgba(0,0,0,0.25)`
-- **Pressed shadow**: `0 2px 6px rgba(0,0,0,0.2)`
+- **Pressed shadow**: `0 2px 6px rgba(0,0,0,0.2)` via `button:active:not(:disabled)`
 - **`PrimaryButton`**: full-width, blue, `border-radius: 1rem`, `font-size: 1.25rem`, `font-weight: 600`. Accepts `disabled` prop — disabled state: `opacity: 0.45`, no shadow, `cursor: not-allowed`, no press animation.
 - **Round buttons**: circular, `border: none`. Add button: `3rem`, blue. Remove button: `2.5rem`, red.
 
diff --git a/src/App.tsx b/src/App.tsx
index 8a37b54..cae4216 100644
--- a/src/App.tsx
+++ b/src/App.tsx
@@ -43,6 +43,6 @@ export default function App() {
 
   if (page === 'title') return <TitleScreen onNewGame={handleNewGame} />
   if (page === 'setup') return <PlayerSetup onStart={handleStart} />
-  if (page === 'scoresheet') return <ScoreSheet onScoreRound={() => setPage('enterscores')} onNewGame={handleNewGame} />
+  if (page === 'scoresheet') return <ScoreSheet game={game!} onScoreRound={() => setPage('enterscores')} onNewGame={handleNewGame} />
   if (page === 'enterscores') return <EnterScores onSubmit={handleSubmitScores} />
 }
diff --git a/src/components/PageFrame.module.css b/src/components/PageFrame.module.css
index e94aaf7..415ddf8 100644
--- a/src/components/PageFrame.module.css
+++ b/src/components/PageFrame.module.css
@@ -4,10 +4,17 @@
 }
 
 .header {
+  position: relative;
   padding: 1.25rem 1.5rem 0;
   text-align: center;
 }
 
+.headerAction {
+  position: absolute;
+  top: 0.75rem;
+  right: 1rem;
+}
+
 .title {
   margin: 0;
   font-size: 1.5rem;
@@ -43,3 +50,13 @@
 .footer {
   padding: 1rem 1.5rem 1.5rem;
 }
+
+.overlay {
+  position: fixed;
+  inset: 0;
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  justify-content: center;
+  background: rgba(0, 0, 0, 0.45);
+}
diff --git a/src/components/PageFrame.tsx b/src/components/PageFrame.tsx
index fe24c01..2c6cfc2 100644
--- a/src/components/PageFrame.tsx
+++ b/src/components/PageFrame.tsx
@@ -4,19 +4,23 @@ interface Props {
   title: string
   children: React.ReactNode
   footer?: React.ReactNode
+  headerAction?: React.ReactNode
+  overlay?: React.ReactNode
 }
 
-export default function PageFrame({ title, children, footer }: Props) {
+export default function PageFrame({ title, children, footer, headerAction, overlay }: Props) {
   return (
     <div className={styles.frame}>
       <header className={styles.header}>
         <h1 className={styles.title}>{title}</h1>
         <div className={styles.rule} role="separator" />
+        {headerAction && <div className={styles.headerAction}>{headerAction}</div>}
       </header>
       <div className={styles.content}>
         {children}
       </div>
       {footer && <div className={styles.footer}>{footer}</div>}
+      {overlay && <div className={styles.overlay}>{overlay}</div>}
     </div>
   )
 }
diff --git a/src/components/PrimaryButton.module.css b/src/components/PrimaryButton.module.css
index bd5f899..a93d77e 100644
--- a/src/components/PrimaryButton.module.css
+++ b/src/components/PrimaryButton.module.css
@@ -1,5 +1,4 @@
 .button {
-  composes: pressable from '../styles/shared.module.css';
   width: 100%;
   padding: 1rem;
   background: var(--color-blue);
diff --git a/src/game/scoring.ts b/src/game/scoring.ts
new file mode 100644
index 0000000..4bba1c9
--- /dev/null
+++ b/src/game/scoring.ts
@@ -0,0 +1,18 @@
+// Returns totals[i][j] = cumulative score for player j after round i.
+export function computeRunningTotals(rounds: number[][]): number[][] {
+  const totals: number[][] = []
+  for (let i = 0; i < rounds.length; i++) {
+    if (i === 0) {
+      totals.push([...rounds[0]])
+    } else {
+      totals.push(rounds[i].map((score, j) => totals[i - 1][j] + score))
+    }
+  }
+  return totals
+}
+
+// Game ends when any player reaches -200 (checked against the most recent round's totals).
+export function isGameOver(totals: number[][]): boolean {
+  const last = totals[totals.length - 1]
+  return last?.some((t: number) => t <= -200) ?? false
+}
diff --git a/src/index.css b/src/index.css
index 7fad4e9..1249c18 100644
--- a/src/index.css
+++ b/src/index.css
@@ -5,7 +5,8 @@
 }
 
 *, *::before, *::after { box-sizing: border-box; }
-button { min-height: 2.75rem; font-size: 1rem; font-family: inherit; cursor: pointer; }
+button { min-height: 2.75rem; font-size: 1rem; font-family: inherit; cursor: pointer; box-shadow: 0 4px 12px rgba(0,0,0,0.25); transition: transform 80ms ease, box-shadow 80ms ease; }
+button:active:not(:disabled) { transform: translateY(2px); box-shadow: 0 2px 6px rgba(0,0,0,0.2); }
 html, body, #root { margin: 0; height: 100%; }
 body {
   font-family: sans-serif;
diff --git a/src/pages/PlayerSetup.module.css b/src/pages/PlayerSetup.module.css
index ebdb925..869e7c3 100644
--- a/src/pages/PlayerSetup.module.css
+++ b/src/pages/PlayerSetup.module.css
@@ -21,7 +21,6 @@
 }
 
 .circleBtn {
-  composes: pressable from '../styles/shared.module.css';
   border-radius: 50%;
   border: none;
   line-height: 1;
diff --git a/src/pages/ScoreSheet.module.css b/src/pages/ScoreSheet.module.css
new file mode 100644
index 0000000..575a6ac
--- /dev/null
+++ b/src/pages/ScoreSheet.module.css
@@ -0,0 +1,108 @@
+.tableWrapper {
+  overflow-x: auto;
+  -webkit-overflow-scrolling: touch;
+  margin: 0 -1.5rem;
+  padding: 0 1.5rem;
+}
+
+.grid {
+  display: grid;
+  grid-template-columns: 5rem repeat(var(--player-count), 1fr);
+  width: max-content;
+  min-width: 100%;
+}
+
+.headerCell {
+  padding: 0.5rem 0.4rem;
+  font-weight: 600;
+  font-size: 0.8rem;
+  text-align: center;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+  border-bottom: 1px solid var(--color-parchment-border);
+}
+
+.labelCell {
+  padding: 0.35rem 0.4rem;
+  font-size: 0.75rem;
+  color: #666;
+  white-space: nowrap;
+}
+
+.scoreCell {
+  padding: 0.35rem 0.4rem;
+  text-align: right;
+  font-size: 0.95rem;
+  font-variant-numeric: tabular-nums;
+}
+
+.totalCell {
+  padding: 0.35rem 0.4rem;
+  text-align: right;
+  font-size: 0.9rem;
+  font-weight: 600;
+  font-variant-numeric: tabular-nums;
+}
+
+.divider {
+  border-top: 1px solid var(--color-parchment-border);
+}
+
+/* Small red "New Game" button in header top-right */
+.newGameBtn {
+  background: #d94f4f;
+  color: white;
+  border: none;
+  border-radius: 0.5rem;
+  font-size: 0.7rem;
+  font-weight: 600;
+  min-height: unset;
+  padding: 0.25rem 0.5rem;
+  line-height: 1.3;
+}
+
+/* Confirmation overlay content */
+.confirmContent {
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  gap: 1.5rem;
+  padding: 2rem;
+  background: var(--color-parchment);
+  border: 2px solid black;
+  border-radius: 1.5rem;
+  width: calc(100% - 4rem);
+  max-width: 20rem;
+}
+
+.confirmText {
+  margin: 0;
+  font-size: 1.25rem;
+  font-weight: 600;
+}
+
+.confirmButtons {
+  display: flex;
+  gap: 1rem;
+  width: 100%;
+  max-width: 16rem;
+}
+
+.cancelBtn {
+  flex: 1;
+  background: white;
+  border: 2px solid var(--color-parchment-border);
+  border-radius: 0.75rem;
+  font-size: 1rem;
+}
+
+.endGameBtn {
+  flex: 1;
+  background: #d94f4f;
+  color: white;
+  border: none;
+  border-radius: 0.75rem;
+  font-size: 1rem;
+  font-weight: 600;
+}
\ No newline at end of file
diff --git a/src/pages/ScoreSheet.tsx b/src/pages/ScoreSheet.tsx
index 03ba921..b6fda34 100644
--- a/src/pages/ScoreSheet.tsx
+++ b/src/pages/ScoreSheet.tsx
@@ -1,15 +1,78 @@
+import { Fragment, useState, type CSSProperties } from 'react'
+import { type GameState } from '../types'
+import { computeRunningTotals, isGameOver } from '../game/scoring'
 import PageFrame from '../components/PageFrame'
+import PrimaryButton from '../components/PrimaryButton'
+import styles from './ScoreSheet.module.css'
 
 interface Props {
+  game: GameState
   onScoreRound: () => void
   onNewGame: () => void
 }
 
-export default function ScoreSheet({ onScoreRound, onNewGame }: Props) {
+export default function ScoreSheet({ game, onScoreRound, onNewGame }: Props) {
+  const [confirmingNewGame, setConfirmingNewGame] = useState(false)
+
+  const totals = computeRunningTotals(game.rounds)
+  const gameOver = isGameOver(totals)
+
+  const newGameButton = (
+    <button className={styles.newGameBtn} onClick={() => setConfirmingNewGame(true)}>
+      New Game
+    </button>
+  )
+
+  const confirmOverlay = (
+    <div className={styles.confirmContent}>
+      <p className={styles.confirmText}>End this game?</p>
+      <div className={styles.confirmButtons}>
+        <button className={styles.cancelBtn} onClick={() => setConfirmingNewGame(false)}>
+          Cancel
+        </button>
+        <button className={styles.endGameBtn} onClick={onNewGame}>
+          End Game
+        </button>
+      </div>
+    </div>
+  )
+
   return (
-    <PageFrame title="Score Sheet">
-      <button onClick={onScoreRound}>Score Round</button>
-      <button onClick={onNewGame} style={{ fontSize: '0.75em' }}>New Game</button>
+    <PageFrame
+      title="Score Sheet"
+      headerAction={newGameButton}
+      overlay={confirmingNewGame ? confirmOverlay : undefined}
+      footer={<PrimaryButton onClick={onScoreRound} disabled={gameOver}>Score Round</PrimaryButton>}
+    >
+      <div className={styles.tableWrapper}>
+        <div
+          className={styles.grid}
+          style={{ '--player-count': game.players.length } as CSSProperties}
+        >
+          <div className={styles.labelCell} />
+          {game.players.map((name, j) => (
+            <div key={j} className={styles.headerCell}>{name}</div>
+          ))}
+
+          {game.rounds.map((roundScores, i) => (
+            <Fragment key={i}>
+              <div className={styles.labelCell}>Round {i + 1}</div>
+              {roundScores.map((score, j) => (
+                <div key={j} className={styles.scoreCell}>{score}</div>
+              ))}
+
+              {i > 0 && (
+                <>
+                  <div className={`${styles.labelCell} ${styles.divider}`} />
+                  {totals[i].map((total, j) => (
+                    <div key={j} className={`${styles.totalCell} ${styles.divider}`}>{total}</div>
+                  ))}
+                </>
+              )}
+            </Fragment>
+          ))}
+        </div>
+      </div>
     </PageFrame>
   )
-}
+}
\ No newline at end of file
diff --git a/src/styles/shared.module.css b/src/styles/shared.module.css
index 9b3319f..62b5c6b 100644
--- a/src/styles/shared.module.css
+++ b/src/styles/shared.module.css
@@ -7,13 +7,3 @@
   flex-direction: column;
   overflow: hidden;
 }
-
-.pressable {
-  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.25);
-  transition: transform 80ms ease, box-shadow 80ms ease;
-}
-
-.pressable:active:not(:disabled) {
-  transform: translateY(2px);
-  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.2);
-}