.flashcard-grid-container{padding:20px 0}.flashcard-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(300px,1fr));gap:30px;justify-content:center;align-items:stretch;max-width:1200px;margin:0 auto}.flashcard{position:relative;width:100%;min-height:370px;perspective:1000px;box-shadow:0 10px 20px rgba(0,0,0,.2);border-radius:15px;background-color:#fff;overflow:hidden;transition:transform .3s ease,box-shadow .3s ease}.flashcard:hover{transform:translateY(-8px);box-shadow:0 15px 30px rgba(0,0,0,.3)}.flashcard-inner{position:relative;width:100%;height:100%;text-align:center;transition:transform .8s cubic-bezier(.68,-.55,.27,1.55);transform-style:preserve-3d;border-radius:12px}.flashcard.flipped .flashcard-inner{transform:rotateY(180deg)}.flashcard-front,.flashcard-back{position:absolute;width:100%;height:100%;backface-visibility:hidden;-webkit-backface-visibility:hidden;display:flex;flex-direction:column;justify-content:center;align-items:center;border-radius:12px;padding:25px;box-sizing:border-box;color:#333;font-family:'Segoe UI',Tahoma,Geneva,Verdana,sans-serif}.flashcard-front{background:linear-gradient(135deg,#e0f7fa 0%,#80deea 100%);border:1px solid #4dd0e1;transform:rotateY(0deg)}.flashcard-back{background:linear-gradient(135deg,#fff3e0 0%,#ffb74d 100%);border:1px solid #ff8a65;transform:rotateY(180deg)}.flashcard-content{max-width:100%;overflow-y:auto;display:flex;flex-direction:column;align-items:center;justify-content:center;height:100%}.japanese-word{font-size:2.8em;margin-bottom:8px;line-height:1.2;color:#004d40;font-weight:700}.furigana-reading,.romaji-reading{font-size:1.3em;color:#00796b;margin-top:0;margin-bottom:12px}.tu-loai{font-size:.95em;color:#424242;display:block;margin-bottom:10px;background-color:rgba(255,255,255,.5);padding:3px 8px;border-radius:5px}.vietnamese-meaning{font-size:1.9em;color:#d84315;margin-bottom:18px;font-weight:600}.example-sentence,.example-translation{font-size:1.15em;color:#5d4037;margin-bottom:8px;line-height:1.4}.example-sentence{font-style:italic}.flashcard-image img{max-width:90%;max-height:120px;height:auto;margin-top:15px;border-radius:8px;box-shadow:0 2px 4px rgba(0,0,0,.1)}audio{width:100%;max-width:200px;margin-top:15px;filter:sepia(20%) saturate(70%) hue-rotate(180deg) brightness(90%) contrast(90%)}.flip-card-button{margin-top:10px;background-color:transparent;color:#007bff;border:none;padding:5px 10px;border-radius:5px;cursor:pointer;font-size:.9em;transition:color .3s ease}.flip-card-button:hover{background-color:transparent;color:#0056b3}@media (max-width:768px){.flashcard-grid{grid-template-columns:repeat(auto-fit,minmax(250px,1fr))}.japanese-word{font-size:2.2em}.vietnamese-meaning{font-size:1.6em}.flashcard-grid-container{padding:20px 15px}}@media (max-width:480px){.flashcard-grid{grid-template-columns:1fr}.flashcard{min-height:350px}.japanese-word{font-size:1.8em}.furigana-reading,.romaji-reading{font-size:1.1em}.vietnamese-meaning{font-size:1.3em}.flashcard-content{overflow-y:auto;padding:15px}.flashcard-grid-container{padding:15px 10px}}