 absolute top-1/2 left-1/2 -translate-x-1/2 -translate-y-1/2">栈为空。</div>
            
            <!-- Stack Elements -->
            <div v-for="(item, index) in stack" :key="index"
                 class="stack-element w-4/5 bg-slate-100 border-2 border-slate-200 p-3 my-1 rounded-lg flex items-center justify-center shadow"
                 :class="{ 'highlight-top': index === top, 'highlight-add': item.highlight === 'add', 'highlight-remove': item.highlight === 'remove' }"
                 :