.header{min-height:100px;border-bottom:1px solid #ccc}.title{display:block;font-family:sans-serif;font-size:35px;font-weight:700;text-align:center;padding-top:25px;color:#333}.banner{margin-top:30px;text-align:center;display:block}.banner img{width:500px}.container{margin:20px 0;text-align:center}.panel_content{width:500px;display:block;margin:auto;border-radius:10px}.panel_content .title{background:#efefef;width:500px;display:block;margin-bottom:15px;font-size:20px;padding:10px 0;border-radius:10px 10px 0 0}.panel_content .row{padding-bottom:10px;background:#fafafa;margin-bottom:15px;border-radius:10px}.card{width:100%;height:100%;border-radius:12px;position:relative;transform-style:preserve-3d;transition:transform 0.8s}.card_img{width:180px;margin:20px auto;cursor:pointer;border-radius:10px;transition:transform 0.8s ease-in-out}.card_answer{display:block;padding:10px 20px 15px 20px}.flipping{transform:rotateY(180deg)}.flip_smooth{transform-style:preserve-3d}.btn_retry{background-color:#007bff;color:#fff;border:none;cursor:pointer;padding:10px 15px;border-radius:10px;font-size:18px;font-weight:500;margin:30px auto;width:97px}.footer{margin:30px 0 60px 0;text-align:center}a{text-decoration:none;color:inherit}h3{display:inline-block;color:royalblue;font-weight:700;font-size:16px}@media (max-width:768px){.header{min-height:85px;border-bottom:1px solid #ccc}.title{display:block;font-family:sans-serif;font-size:28px;font-weight:700;text-align:center;padding-top:20px;color:#333}.banner{margin-top:15px;text-align:center;display:block}.banner img{width:96%}.container{margin-bottom:10px;text-align:center}.panel_content{width:96%;display:block;margin:auto;border-radius:10px}.panel_content .title{background:#efefef;width:100%;display:block;margin-bottom:15px;font-size:18px;padding:10px 0;border-radius:10px 10px 0 0}.panel_content .row{padding-bottom:15px;background:#fafafa;margin-bottom:15px;border-radius:10px}.card{width:100%;height:100%;border-radius:12px;position:relative;transform-style:preserve-3d;transition:transform 0.8s}.card_img{width:180px;margin:20px auto;cursor:pointer;border-radius:10px;transition:transform 0.8s ease-in-out}.card_answer{display:block;padding:10px 20px 15px 20px}.flipping{transform:rotateY(180deg)}.flip_smooth{transform-style:preserve-3d}.btn_retry{background-color:#007bff;color:#fff;border:none;cursor:pointer;padding:10px 15px;border-radius:10px;font-size:18px;font-weight:500;margin:30px auto;width:97px}.footer{margin:30px 0 60px 0;text-align:center}a{text-decoration:none;color:inherit}h3{display:inline-block;color:royalblue;font-weight:700;font-size:16px}}@media (min-width:768px) and (max-width:1024px){.header{min-height:100px;border-bottom:1px solid #ccc}.title{display:block;font-family:sans-serif;font-size:35px;font-weight:700;text-align:center;padding-top:25px;color:#333}.banner{margin-top:30px;text-align:center;display:block}.banner img{width:500px}.container{margin:20px 0;text-align:center}.panel_content{width:500px;display:block;margin:auto;border-radius:10px}.panel_content .title{background:#efefef;width:500px;display:block;margin-bottom:15px;font-size:20px;padding:10px 0;border-radius:10px 10px 0 0}.panel_content .row{padding-bottom:15px;background:#fafafa;margin-bottom:15px;border-radius:10px}.card{width:100%;height:100%;border-radius:12px;position:relative;transform-style:preserve-3d;transition:transform 0.8s}.card_img{width:180px;margin:20px auto;cursor:pointer;border-radius:10px;transition:transform 0.8s ease-in-out}.card_answer{display:block;padding:10px 20px 15px 20px}.flipping{transform:rotateY(180deg)}.flip_smooth{transform-style:preserve-3d}.btn_retry{background-color:#007bff;color:#fff;border:none;cursor:pointer;padding:10px 15px;border-radius:10px;font-size:18px;font-weight:500;margin:30px auto;width:97px}.footer{margin:30px 0 60px 0;text-align:center}a{text-decoration:none;color:inherit}h3{display:inline-block;color:royalblue;font-weight:700;font-size:16px}}