* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; background: #edf2ef; color: #203029; }
.practice-shell { width: min(900px, calc(100% - 40px)); margin: 0 auto; padding: 64px 0; }
/* DONE-01：卡片已成為子元素的定位參考點。 */
.position-card { position: relative; padding: 32px; border-radius: 18px; background: white; }
/* DONE-02：狀態標籤已位於卡片右上角。 */
.position-card__badge { position: absolute; top: 18px; right: 18px; padding: 6px 10px; border-radius: 999px; background: #f5c851; font-weight: 900; }
.practice-spacer { min-height: 900px; padding-top: 120px; }
/* DONE-03：返回按鈕已固定在視窗右下角。 */
.back-to-top { position: fixed; z-index: 3; right: 24px; bottom: 24px; display: grid; width: 52px; height: 52px; place-items: center; border-radius: 50%; background: #0c7656; color: white; text-decoration: none; }