diff --git a/README.md b/README.md
index ff821f0..881eabd 100644
--- a/README.md
+++ b/README.md
@@ -9,7 +9,8 @@
 - 每次固定產生 3 組完整配對結果
 - 每一隊都由 `1 位 A 區 + 1 位 B 區` 組成
 - 每一組都會把 A 區與 B 區名單完整分配完成
-- 若某一區人數不足，系統會自動補入「那個」
+- 兩區人數差 2 以上時，每輪會輪流讓人多的一區成員跨區支援
+- 跨區平衡後仍有缺口（總人數為奇數）時，才補入「那個」
 - 產生配對後可用按鈕手動上傳資料到資料庫
 - 若指定日期已經有資料，上傳前會先詢問是否覆蓋
 - 可讀取指定日期的資料庫內容並回填到畫面
diff --git a/src/App.css b/src/App.css
index 6b20956..b6663d8 100644
--- a/src/App.css
+++ b/src/App.css
@@ -287,18 +287,16 @@
   color: #8d2d22;
 }
 
-.round-list,
 .team-list {
   display: grid;
   gap: 14px;
 }
 
-.share-row {
-  margin-bottom: 18px;
-}
-
-.share-button {
-  min-width: 160px;
+.round-list {
+  display: grid;
+  grid-template-columns: repeat(3, minmax(0, 1fr));
+  gap: 18px;
+  align-items: start;
 }
 
 .round-card,
@@ -368,6 +366,10 @@
     grid-template-columns: 1fr;
   }
 
+  .round-list {
+    grid-template-columns: 1fr;
+  }
+
   .hero-copy h1 {
     max-width: 10ch;
   }
diff --git a/src/App.tsx b/src/App.tsx
index 6a0dfec..7424037 100644
--- a/src/App.tsx
+++ b/src/App.tsx
@@ -72,9 +72,10 @@ function App() {
 
   const parsedAreaA = parseRoster(areaAInput)
   const parsedAreaB = parseRoster(areaBInput)
-  const teamCount = Math.max(parsedAreaA.length, parsedAreaB.length)
-  const placeholderCountA = Math.max(0, teamCount - parsedAreaA.length)
-  const placeholderCountB = Math.max(0, teamCount - parsedAreaB.length)
+  const zoneGap = Math.abs(parsedAreaA.length - parsedAreaB.length)
+  const crossCount = Math.floor(zoneGap / 2)
+  const placeholderCount = zoneGap % 2
+  const teamCount = Math.ceil((parsedAreaA.length + parsedAreaB.length) / 2)
 
   function generateGroups() {
     if (parsedAreaA.length === 0 || parsedAreaB.length === 0) {
@@ -85,10 +86,11 @@ function App() {
       return
     }
 
-    const prepared = prepareParticipants(parsedAreaA, parsedAreaB)
+    const shuffledA = shuffleList(parsedAreaA)
+    const shuffledB = shuffleList(parsedAreaB)
     const nextResults = Array.from({ length: TOTAL_ROUNDS }, (_, index) => ({
       id: index + 1,
-      teams: createRoundTeams(prepared.areaA, prepared.areaB, index),
+      teams: createRoundTeams(shuffledA, shuffledB, index),
     }))
 
     setResults(nextResults)
@@ -213,8 +215,8 @@ function App() {
           <h1>羽毛球分組配對器</h1>
           <p className="hero-text">
             輸入 A 區與 B 區名單後，系統會產生 3 組完整配對。
-            每一隊都是 1 位 A 區成員搭配 1 位 B 區成員；
-            若某一區人數不足，會自動補入「那個」。
+            兩區人數有落差時，每輪會輪流讓人多的一區成員跨區支援；
+            補完後仍有缺口才會補入「那個」。
           </p>
           <div className="hero-actions">
             <button className="primary-button" type="button" onClick={generateGroups}>
@@ -241,7 +243,7 @@ function App() {
           <article className="tip-card">
             <h2>摘要</h2>
             <p>
-              每組共 {teamCount} 隊，A 區補位 {placeholderCountA} 人，B 區補位 {placeholderCountB} 人。
+              每組共 {teamCount} 隊，跨區支援 {crossCount} 人，補位「那個」{placeholderCount} 人。
             </p>
           </article>
         </div>
@@ -278,6 +280,16 @@ function App() {
           >
             讀取指定日期
           </button>
+          {results.length > 0 ? (
+            <button
+              className="primary-button upload-button"
+              type="button"
+              onClick={() => void pushToLine()}
+              disabled={actionState === 'saving' || actionState === 'loading'}
+            >
+              推送到 LINE
+            </button>
+          ) : null}
         </div>
 
         <div className="input-grid">
@@ -312,19 +324,6 @@ function App() {
           <h2>三組名單</h2>
         </div>
 
-        {results.length > 0 ? (
-          <div className="share-row">
-            <button
-              className="primary-button share-button"
-              type="button"
-              onClick={() => void pushToLine()}
-              disabled={actionState === 'saving' || actionState === 'loading'}
-            >
-              推送到 LINE
-            </button>
-          </div>
-        ) : null}
-
         {results.length > 0 ? (
           <div className="round-list">
             {results.map((round) => (
@@ -359,14 +358,30 @@ function App() {
   )
 }
 
-function prepareParticipants(areaA: string[], areaB: string[]) {
-  const targetCount = Math.max(areaA.length, areaB.length)
-  const shuffledA = shuffleList(areaA)
-  const shuffledB = shuffleList(areaB)
+function balanceZones(areaA: string[], areaB: string[], roundIndex: number) {
+  const moveCount = Math.floor(Math.abs(areaA.length - areaB.length) / 2)
+
+  if (moveCount === 0) {
+    return { areaA, areaB }
+  }
+
+  if (areaA.length > areaB.length) {
+    const { moved, remaining } = pickCrossMembers(areaA, moveCount, roundIndex)
+    return { areaA: remaining, areaB: [...areaB, ...moved] }
+  }
+
+  const { moved, remaining } = pickCrossMembers(areaB, moveCount, roundIndex)
+  return { areaA: [...areaA, ...moved], areaB: remaining }
+}
+
+function pickCrossMembers(list: string[], moveCount: number, roundIndex: number) {
+  const movedIndexes = new Set(
+    Array.from({ length: moveCount }, (_, offset) => (roundIndex * moveCount + offset) % list.length),
+  )
 
   return {
-    areaA: createParticipants(shuffledA, targetCount, 'A'),
-    areaB: createParticipants(shuffledB, targetCount, 'B'),
+    moved: list.filter((_, index) => movedIndexes.has(index)),
+    remaining: list.filter((_, index) => !movedIndexes.has(index)),
   }
 }
 
@@ -388,11 +403,16 @@ function createParticipants(players: string[], targetCount: number, zone: 'A' |
   return participants
 }
 
-function createRoundTeams(areaA: Participant[], areaB: Participant[], roundIndex: number) {
-  return areaA.map((playerA, index) => ({
+function createRoundTeams(areaA: string[], areaB: string[], roundIndex: number) {
+  const balanced = balanceZones(areaA, areaB, roundIndex)
+  const targetCount = Math.max(balanced.areaA.length, balanced.areaB.length)
+  const playersA = createParticipants(balanced.areaA, targetCount, 'A')
+  const playersB = createParticipants(balanced.areaB, targetCount, 'B')
+
+  return playersA.map((playerA, index) => ({
     id: index + 1,
     playerA,
-    playerB: areaB[(index + roundIndex) % areaB.length],
+    playerB: playersB[(index + roundIndex) % playersB.length],
   }))
 }