補上先攻勾選顯示並更新 README

src/App.css

@@ -547,6 +547,7 @@
 }
 
 .serve-lane {
+  position: relative;
   display: grid;
   grid-template-columns: 32px auto 1fr;
   align-items: center;
@@ -579,11 +580,29 @@
     0 10px 18px rgba(8, 47, 73, 0.12);
 }
 
+.serve-lane-prompt {
+  background: rgba(255, 248, 232, 0.12);
+  box-shadow: inset 0 0 0 1px rgba(255, 236, 202, 0.12);
+}
+
+.serve-lane-arrow {
+  display: none;
+}
+
 .serve-lane small {
   justify-self: end;
   color: rgba(248, 244, 234, 0.72);
 }
 
+.serve-lane-prompt > span:nth-of-type(2) {
+  color: #f7ffbe;
+  font-weight: 800;
+  text-shadow:
+    0 0 12px rgba(235, 248, 164, 0.5),
+    0 0 22px rgba(235, 248, 164, 0.24);
+  animation: serve-label-pulse 0.9s ease-in-out infinite;
+}
+
 .serve-lane-locked {
   box-shadow: inset 0 0 0 1px rgba(214, 225, 100, 0.42);
 }
@@ -593,6 +612,39 @@
   height: 24px;
   border-radius: 4px;
   background: linear-gradient(180deg, #fff8e8, #f0dfbd);
+  box-shadow: inset 0 0 0 1px rgba(195, 154, 88, 0.22);
+}
+
+.serve-lane-box-checked {
+  position: relative;
+  background: linear-gradient(180deg, #ebf8a4, #d6e164);
+  box-shadow:
+    inset 0 0 0 1px rgba(111, 128, 27, 0.26),
+    0 0 0 1px rgba(214, 225, 100, 0.14);
+}
+
+.serve-lane-box-checked::after {
+  content: '✓';
+  position: absolute;
+  inset: 0;
+  display: grid;
+  place-items: center;
+  font-size: 1rem;
+  font-weight: 800;
+  color: #38501f;
+}
+
+@keyframes serve-label-pulse {
+  0%,
+  100% {
+    transform: scale(1);
+    opacity: 0.82;
+  }
+
+  50% {
+    transform: scale(1.08);
+    opacity: 1;
+  }
 }
 
 .score-panel-surface {
@@ -1479,6 +1531,10 @@
     padding: 4px 6px;
   }
 
+  .serve-lane-arrow {
+    left: 52px;
+  }
+
   .team-number {
     width: 28px;
     height: 28px;

src/pages/ScoreboardPage.tsx

@@ -276,6 +276,7 @@ export function ScoreboardPage({
             onSwapTeams={onSwapMatchup}
             score={scoreState.scoreLeft}
             serviceCourt={scoreState.serving === 'left' ? servingCourt : null}
+            showServingPrompt={scoreState.serving === null}
             team={leftTeam}
             teamSlot="top"
           />
@@ -303,6 +304,7 @@ export function ScoreboardPage({
             onSwapTeams={onSwapMatchup}
             score={scoreState.scoreRight}
             serviceCourt={scoreState.serving === 'right' ? servingCourt : null}
+            showServingPrompt={scoreState.serving === null}
             team={rightTeam}
             teamSlot="bottom"
           />
@@ -379,6 +381,7 @@ type ScoreboardTeamPanelProps = {
   onSwapTeams: () => void
   score: number
   serviceCourt: CourtSide | null
+  showServingPrompt: boolean
   team: GroupTeam | null
   teamSlot: 'top' | 'bottom'
 }
@@ -395,6 +398,7 @@ function ScoreboardTeamPanel({
   onSwapTeams,
   score,
   serviceCourt,
+  showServingPrompt,
   team,
   teamSlot,
 }: ScoreboardTeamPanelProps) {
@@ -450,13 +454,22 @@ function ScoreboardTeamPanel({
   const serveBar = (
     <button
       className={
-        currentServer && !canArrangeMatch ? 'serve-lane serve-lane-locked' : 'serve-lane'
+        currentServer && !canArrangeMatch
+          ? 'serve-lane serve-lane-locked'
+          : showServingPrompt
+            ? 'serve-lane serve-lane-prompt'
+            : 'serve-lane'
       }
       disabled={!canArrangeMatch || !team}
       type="button"
       onClick={onSetServing}
     >
-      <span className="serve-lane-box" />
+      {showServingPrompt ? (
+        <span aria-hidden="true" className="serve-lane-arrow">
+          {teamSlot === 'top' ? '↓' : '↑'}
+        </span>
+      ) : null}
+      <span className={currentServer ? 'serve-lane-box serve-lane-box-checked' : 'serve-lane-box'} />
       <span>先攻</span>
       {currentServer ? (
         <small>