*{-webkit-tap-highlight-color:transparent;box-sizing:border-box}body{font-family:-apple-system,BlinkMacSystemFont,Segoe UI,PingFang SC,Hiragino Sans GB,Microsoft YaHei,sans-serif;background-color:#f8fafc;color:#1e293b;max-width:480px;margin:0 auto;min-height:100vh}.flashcard{perspective:1000px}.flashcard-inner{transition:transform .5s;transform-style:preserve-3d;position:relative;width:100%;height:13rem}.flashcard-inner.flipped{transform:rotateY(180deg)}.flashcard-front,.flashcard-back{backface-visibility:hidden;-webkit-backface-visibility:hidden;position:absolute;top:0;left:0;width:100%;height:100%;border-radius:1rem;display:flex;flex-direction:column;align-items:center;justify-content:center;padding:1.5rem}.flashcard-front{background:#fff;box-shadow:0 1px 3px #0000001a;border:1px solid #e2e8f0}.flashcard-back{transform:rotateY(180deg);background:#eff6ff;box-shadow:0 1px 3px #0000001a;border:1px solid #bfdbfe}