@font-face{font-family:Nunito;font-style:normal;font-weight:200 1000;font-display:swap;src:url('/ja/fonts/Nunito-Vietnamese.ttf') format('truetype')}
:root{font-family:Nunito,Arial,sans-serif;color:#172744;background:#f4f6fb;font-synthesis:none}*{box-sizing:border-box}body{margin:0}button,input{font:inherit}button{cursor:pointer;touch-action:manipulation}button:focus-visible,a:focus-visible{outline:3px solid #e8a430;outline-offset:3px}[hidden]{display:none!important}button:disabled{cursor:default;opacity:.55}a{color:inherit}button{border:0}h1,h2,h3,p{margin:0}.app{max-width:760px;margin:auto;height:100dvh;min-height:540px;padding:max(14px,env(safe-area-inset-top)) 20px max(16px,env(safe-area-inset-bottom));display:flex;flex-direction:column;gap:20px}header{display:flex;align-items:center;justify-content:space-between;flex-shrink:0}.brand{display:flex;gap:9px;align-items:center;text-decoration:none;font-weight:900;font-size:23px}.brand img{border-radius:9px}.brand small{display:block;font-size:12px;letter-spacing:2px;font-weight:600;line-height:1}.icon{width:42px;height:42px;background:transparent;border-radius:12px;color:#65738a;font-size:24px}.icon:hover{background:#e7ecf6}.study{display:flex;flex-direction:column;gap:12px;flex:1;min-height:0}#levels{display:grid;grid-template-columns:repeat(6,1fr);gap:6px}#levels button{border:1px solid #dce2ed;border-radius:10px;min-height:42px;font-size:14px;font-weight:700;background:#fff;color:#64718a;padding:5px 2px}#levels button[aria-pressed=true]{background:#2b49e9;color:white;border-color:#2b49e9}.level-note{font-size:13px;color:#7b869a;text-align:center}.cards{display:grid;grid-template-columns:1fr 1fr;gap:14px;flex:1;min-height:0}.card{perspective:1200px;min-width:0;min-height:0}.inner{position:relative;width:100%;height:100%;transform-style:preserve-3d;transition:transform .38s ease}.card.open .inner{transform:rotateY(180deg)}.face{position:absolute;inset:0;border-radius:23px;backface-visibility:hidden;-webkit-backface-visibility:hidden;padding:24px 18px;display:flex;flex-direction:column;justify-content:space-between;width:100%;height:100%;overflow:auto}.front{background:#2b49e9;color:white;text-align:center}.card:nth-child(2) .front{background:#172744}.card-top{display:flex;justify-content:space-between;gap:6px;font-size:12px;letter-spacing:1px;opacity:.75}.front .center{display:flex;flex-direction:column;gap:12px;align-items:center}.letter{font-size:clamp(54px,12vw,100px);font-weight:500;letter-spacing:-6px}.front .hint{font-size:14px}.front .bottom{font-size:12px;opacity:.6}.back{background:white;border:1px solid #dce3f0;transform:rotateY(180deg);text-align:center}.word{margin:auto 0;padding:16px 0;min-width:0}.word h2{font-size:clamp(25px,4.5vw,40px);line-height:1.25;overflow-wrap:anywhere;font-weight:900}.ipa{font-family:Nunito,Arial,sans-serif;font-size:16px;color:#8390a6;margin:10px 0 14px;overflow-wrap:anywhere}.meaning{font-size:18px;line-height:1.5;margin:16px 0 0}.sound{display:inline-flex;align-items:center;justify-content:center;width:44px;height:44px;background:#edf1ff;border-radius:50%;color:#2b49e9}.sound svg{height:22px;width:22px}.sound.playing{background:#2b49e9;color:white}.decisions{display:flex;flex-direction:column;gap:8px}.decisions button{min-height:43px;border-radius:10px;font-size:14px;font-weight:800;background:#edf1ff;color:#2b49e9}.decisions .known{background:#172744;color:white}.decisions button[aria-pressed=true]{box-shadow:0 0 0 2px #e8a430}.feedback{min-height:42px;display:flex;align-items:center;justify-content:center;gap:8px;text-align:center;font-size:13px;color:#748197}.feedback button{background:transparent;color:#2b49e9;text-decoration:underline;white-space:nowrap;padding:8px}.skip{display:flex;align-items:center;justify-content:center;gap:15px;min-height:50px;border-radius:14px;background:#e9edf5;color:#4e5d75;font-weight:700;font-size:16px;flex-shrink:0}.skip span{font-size:22px}.empty{display:flex;flex-direction:column;justify-content:center;align-items:center;height:100%;border:1px dashed #c5cedf;border-radius:23px;padding:18px;text-align:center;gap:15px;color:#66758d;font-size:15px}.empty button{padding:10px;background:#e8edfc;border-radius:10px;color:#2b49e9;font-weight:700}.paused{flex:1;display:flex;flex-direction:column;align-items:center;justify-content:center;text-align:center;gap:22px;max-width:400px;align-self:center}.paused h1{font-size:29px}.paused p{color:#738099;line-height:1.7}.paused small{font-size:12px;color:#8994a8}.pause-symbol{display:grid;place-items:center;width:80px;height:80px;border-radius:50%;background:#e5ebff;color:#2b49e9;font-size:35px}.primary,.secondary{display:block;border-radius:12px;padding:13px 17px;min-height:46px;font-weight:800;font-size:15px}.primary{background:#2b49e9;color:#fff}.secondary{background:#edf1ff;color:#2b49e9}dialog{border:1px solid #dce3ef;border-radius:22px;padding:24px;width:min(460px,calc(100% - 24px));max-height:85dvh;color:#172744}dialog::backdrop{background:#14244380;backdrop-filter:blur(4px)}.dialog-head{display:flex;justify-content:space-between;align-items:center;gap:12px}.dialog-head h2{font-size:22px}.setting-row{display:flex;justify-content:space-between;align-items:center;gap:15px;margin:22px 0;font-weight:700}.setting-row small{display:block;font-weight:400;font-size:13px;color:#738099;margin-top:6px}.setting-row input{width:21px;height:21px;accent-color:#2b49e9}#install{width:100%}#install-status,.setting-block p,.privacy{font-size:14px;color:#738099;line-height:1.65;margin:12px 0}.setting-block{border-top:1px solid #e2e7f0;margin-top:22px;padding-top:20px}.setting-block h3{font-size:17px}.privacy{padding-top:10px}dialog a{font-size:13px;color:#2b49e9}.warning{font-size:12px;color:#a24c22}.sr-only{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0,0,0,0)}
@media(max-width:480px){.app{padding-left:14px;padding-right:14px;gap:15px}.cards{gap:10px}.face{padding:18px 10px;border-radius:19px}#levels{gap:4px}#levels button{font-size:12px}.meaning{font-size:16px}.ipa{font-size:14px}.word h2{font-size:27px}.decisions button{font-size:14px}.card-top{font-size:10px}}
@media(max-height:700px){.app{gap:8px;padding-top:8px;padding-bottom:8px}.study{gap:7px}.face{padding:13px 10px}.word{padding:6px 0}.word h2{font-size:25px}.meaning{margin-top:8px;font-size:15px}.ipa{margin:6px 0 8px}.sound{height:35px;width:35px}.decisions{gap:6px}.decisions button{min-height:36px}.feedback{min-height:35px}.skip{min-height:44px}.front .bottom{display:none}}
@media(prefers-reduced-motion:reduce){.inner{transition:none}}