:root{--bg:#0d121b;--surface:#171e29;--surface-2:#202936;--text:#f7f8fb;--muted:#8f9bad;--line:#2d3746;--blue:#5b6cff;--blue-2:#7c8aff;--green:#2dd881;--red:#ff626e;--shadow:0 30px 80px rgba(0,0,0,.35)}
*{box-sizing:border-box}body{margin:0;min-height:100vh;background:var(--bg);color:var(--text);font-family:Pretendard,'Noto Sans KR','Segoe UI',Arial,sans-serif;overflow-x:hidden}button,textarea{font:inherit}.ambient{position:fixed;border-radius:50%;filter:blur(100px);opacity:.15;pointer-events:none}.ambient-one{width:460px;height:460px;background:#536dfe;left:-180px;top:20%}.ambient-two{width:400px;height:400px;background:#16c79a;right:-220px;bottom:-100px}.topbar{height:76px;border-bottom:1px solid rgba(255,255,255,.07);display:flex;align-items:center;padding:0 max(24px,calc((100vw - 1100px)/2));position:sticky;top:0;background:rgba(13,18,27,.86);backdrop-filter:blur(18px);z-index:10}.brand{display:flex;align-items:center;gap:11px;color:var(--text);font-weight:700;font-size:21px;border:0;background:none;cursor:pointer}.brand-mark{width:34px;height:34px;border-radius:11px;background:linear-gradient(145deg,var(--blue-2),var(--blue));display:grid;place-items:center;box-shadow:0 8px 24px rgba(91,108,255,.3)}.nav-tabs{display:flex;gap:8px;margin:auto}.nav-tab{padding:10px 18px;border:0;border-radius:10px;background:transparent;color:var(--muted);cursor:pointer}.nav-tab.active{background:var(--surface-2);color:var(--text)}.icon-button{border:1px solid var(--line);border-radius:50%;background:var(--surface);color:var(--muted);width:40px;height:40px;cursor:pointer}main{width:min(100% - 40px,980px);margin:0 auto;padding:48px 0 80px}.view{display:none}.view.active{display:block}.study-heading,.manage-heading{display:flex;justify-content:space-between;align-items:flex-end;margin-bottom:28px}.eyebrow{margin:0 0 8px;font-size:12px;letter-spacing:.18em;font-weight:700;color:var(--blue-2)}h1{margin:0;font-size:clamp(30px,4vw,42px);letter-spacing:-.04em}.session-stats{display:flex;gap:10px;flex-wrap:wrap}.session-stats span{background:var(--surface);border:1px solid var(--line);border-radius:100px;padding:9px 13px;color:var(--muted);font-size:13px}.session-stats b{color:var(--text);margin-right:4px}.known-dot b{color:var(--green)}.wrong-dot b{color:var(--red)}.shortcut-hint{text-align:center;color:var(--muted);font-size:13px;margin:0 0 16px}kbd{font:inherit;font-size:11px;background:var(--surface-2);border:1px solid #414c5c;border-bottom-width:2px;border-radius:5px;padding:2px 6px}.progress-track{height:3px;background:var(--surface-2);border-radius:10px;margin-bottom:20px;overflow:hidden}.progress-track span{display:block;height:100%;background:linear-gradient(90deg,var(--blue),#8d79ff);transition:width .3s}.flashcard{display:block;position:relative;width:min(100%,800px);height:480px;margin:0 auto;border:0;background:transparent;perspective:1400px;color:var(--text);cursor:pointer;text-align:left}.card-face{position:absolute;inset:0;border-radius:34px;padding:38px 44px;background:linear-gradient(145deg,#202936,#171e29);border:1px solid rgba(255,255,255,.08);box-shadow:var(--shadow);backface-visibility:hidden;transform-style:preserve-3d;transition:transform .58s cubic-bezier(.2,.8,.2,1);display:flex;flex-direction:column}.card-back{transform:rotateY(180deg);background:linear-gradient(145deg,#222b3a,#1a2130)}.flashcard.flipped .card-front{transform:rotateY(-180deg)}.flashcard.flipped .card-back{transform:rotateY(0)}.card-meta{display:flex;justify-content:space-between;color:var(--muted);font-size:14px}.side-label{font-size:11px;letter-spacing:.16em;color:var(--blue-2)}.card-content{flex:1;display:grid;place-items:center;text-align:center;font-size:clamp(34px,5vw,57px);font-weight:600;line-height:1.35;white-space:pre-wrap;overflow-wrap:anywhere}.flip-prompt{text-align:center;color:var(--muted);font-size:13px}.flip-prompt b{font-size:18px;margin-left:6px}.study-controls{display:flex;justify-content:center;align-items:center;gap:14px;margin-top:24px}.round-button,.grade-button{border:1px solid var(--line);background:var(--surface);color:var(--text);cursor:pointer;transition:.2s}.round-button{width:54px;height:54px;border-radius:50%;font-size:23px;color:var(--muted)}.grade-button{height:64px;border-radius:18px;min-width:142px;display:flex;align-items:center;gap:12px;padding:0 14px}.grade-button:hover,.round-button:hover,.secondary-button:hover{transform:translateY(-2px);border-color:#556173}.grade-icon{font-size:27px}.grade-button span:nth-child(2){display:flex;flex-direction:column;align-items:flex-start}.grade-button small{color:var(--muted);font-size:10px}.grade-button b{font-size:15px}.grade-button kbd{margin-left:auto}.grade-button.wrong .grade-icon,.grade-button.wrong b{color:var(--red)}.grade-button.correct .grade-icon,.grade-button.correct b{color:var(--green)}button:disabled{opacity:.35;cursor:not-allowed;transform:none!important}.result-card{width:min(100%,780px);margin:20px auto;background:var(--surface);border:1px solid var(--line);border-radius:36px;padding:54px;text-align:center;box-shadow:var(--shadow)}.celebrate{font-size:40px;color:#ffd65c;margin-bottom:8px}.result-copy{color:var(--muted);margin:13px 0 30px}.result-summary{display:flex;justify-content:center;align-items:center;gap:60px;background:rgba(255,255,255,.025);border-radius:24px;padding:30px}.score-ring{--score:0;width:160px;height:160px;border-radius:50%;display:grid;place-items:center;background:conic-gradient(var(--green) calc(var(--score)*1%),var(--surface-2) 0);position:relative}.score-ring:before{content:"";position:absolute;inset:14px;border-radius:50%;background:var(--surface)}.score-ring div{position:relative;display:flex;flex-direction:column}.score-ring strong{font-size:34px}.score-ring span{color:var(--muted)}.score-details{min-width:180px}.score-details div{display:flex;justify-content:space-between;padding:12px 0;border-bottom:1px solid var(--line)}.score-details span{color:var(--muted)}.dot{display:inline-block;width:8px;height:8px;border-radius:50%;margin-right:8px}.green{background:var(--green)}.red{background:var(--red)}.result-actions,.form-actions{display:flex;justify-content:center;gap:12px;margin-top:30px}.primary-button,.secondary-button,.text-button{border:0;border-radius:13px;padding:13px 20px;cursor:pointer;font-weight:600}.primary-button{background:linear-gradient(135deg,var(--blue),#715bff);color:#fff;box-shadow:0 10px 24px rgba(91,108,255,.22)}.secondary-button{background:var(--surface-2);color:var(--text);border:1px solid var(--line)}.text-button{background:none;color:var(--muted)}.danger{color:var(--red)}.manage-heading p:not(.eyebrow){color:var(--muted);margin:8px 0 0}.file-actions{display:flex;gap:8px}.editor-card{position:relative;background:var(--surface);border:1px solid var(--line);border-radius:26px;padding:26px;display:grid;grid-template-columns:1fr 44px 1fr;gap:14px;align-items:center}.field label{display:flex;justify-content:space-between;font-size:14px;font-weight:600;margin:0 0 10px}.field label span{color:var(--muted);font-size:11px}.field textarea{resize:vertical;width:100%;min-height:130px;border:1px solid var(--line);border-radius:15px;background:#101722;color:var(--text);padding:16px;outline:none}.field textarea:focus{border-color:var(--blue);box-shadow:0 0 0 3px rgba(91,108,255,.12)}.swap-button{width:40px;height:40px;border-radius:50%;border:1px solid var(--line);background:var(--surface-2);color:var(--muted);cursor:pointer}.form-actions{grid-column:1/-1;justify-content:flex-end;margin-top:4px}.list-header{display:flex;align-items:center;justify-content:space-between;margin:34px 0 14px}.list-header h2{font-size:19px}.list-header h2 span{font-size:12px;color:var(--muted);background:var(--surface-2);border-radius:20px;padding:4px 8px}.card-list{display:grid;gap:10px}.list-card{display:grid;grid-template-columns:36px 1fr 1fr auto;gap:18px;align-items:center;background:var(--surface);border:1px solid var(--line);border-radius:16px;padding:16px 18px}.list-number{color:var(--muted);font-size:12px}.list-content{min-width:0}.list-content small{color:var(--muted);display:block;margin-bottom:4px}.list-content p{margin:0;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}.list-actions{display:flex}.list-actions button{border:0;background:none;color:var(--muted);padding:8px;cursor:pointer}.list-actions .delete-card:hover{color:var(--red)}.empty-list{text-align:center;color:var(--muted);background:var(--surface);border:1px dashed var(--line);padding:36px;border-radius:16px}.empty-state{text-align:center;background:var(--surface);border:1px solid var(--line);border-radius:30px;padding:70px 24px}.empty-state p{color:var(--muted)}.empty-icon{display:inline-grid;place-items:center;width:58px;height:58px;border-radius:18px;background:rgba(91,108,255,.15);color:var(--blue-2);font-size:30px}.hidden{display:none!important}.toast{position:fixed;left:50%;bottom:30px;transform:translate(-50%,20px);background:#f7f8fb;color:#111827;padding:11px 18px;border-radius:12px;font-size:14px;font-weight:600;opacity:0;pointer-events:none;transition:.25s;z-index:30}.toast.show{opacity:1;transform:translate(-50%,0)}
.grade-button.selected.wrong{border-color:var(--red);background:rgba(255,98,110,.08)}.grade-button.selected.correct{border-color:var(--green);background:rgba(45,216,129,.08)}
.flashcard.resetting .card-face{transition:none}
.shortcut-hint{display:flex;flex-wrap:wrap;align-items:center;justify-content:center;gap:6px 14px}.shortcut-hint>span{white-space:nowrap}.grade-count{display:inline-flex;align-items:center;justify-content:center;flex:0 0 auto;min-width:2.25em;margin-left:auto;padding:4px 8px;border-radius:8px;background:var(--surface-2);font-size:14px;font-weight:700;font-variant-numeric:tabular-nums}.grade-button.wrong .grade-count{color:var(--red)}.grade-button.correct .grade-count{color:var(--green)}
.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}.deck-picker{display:flex;align-items:center;gap:6px;margin-right:10px}.deck-picker select{max-width:180px;height:40px;border:1px solid var(--line);border-radius:11px;background:var(--surface);color:var(--text);padding:0 32px 0 12px;cursor:pointer;outline:none}.deck-picker select:focus{border-color:var(--blue)}.add-deck-button{width:40px;height:40px;border:1px solid var(--line);border-radius:11px;background:var(--surface-2);color:var(--blue-2);font-size:21px;cursor:pointer}.deck-dialog{width:min(420px,calc(100% - 32px));border:1px solid var(--line);border-radius:24px;background:var(--surface);color:var(--text);padding:0;box-shadow:var(--shadow)}.deck-dialog::backdrop{background:rgba(3,7,14,.72);backdrop-filter:blur(5px)}.deck-dialog form{padding:28px}.deck-dialog h2{margin:0 0 24px}.deck-dialog label{display:block;font-size:13px;color:var(--muted);margin-bottom:8px}.deck-dialog input{width:100%;height:50px;border:1px solid var(--line);border-radius:13px;background:#101722;color:var(--text);padding:0 14px;outline:none}.deck-dialog input:focus{border-color:var(--blue)}.dialog-actions{display:flex;justify-content:flex-end;gap:10px;margin-top:24px}
.home-heading{display:flex;align-items:flex-end;justify-content:space-between;margin-bottom:32px}.home-heading p:not(.eyebrow){color:var(--muted);margin:10px 0 0}.deck-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px}.deck-tile{position:relative;min-height:210px;border:1px solid var(--line);border-radius:24px;background:linear-gradient(145deg,var(--surface-2),var(--surface));color:var(--text);padding:24px;text-align:left;cursor:pointer;overflow:hidden;transition:.2s}.deck-tile:before{content:"";position:absolute;width:130px;height:130px;border-radius:50%;background:var(--deck-color,var(--blue));filter:blur(55px);opacity:.18;right:-30px;bottom:-45px}.deck-tile:hover{transform:translateY(-4px);border-color:#536277;box-shadow:0 20px 40px rgba(0,0,0,.2)}.deck-tile .folder-icon{display:grid;place-items:center;width:44px;height:44px;border-radius:14px;background:rgba(91,108,255,.13);color:var(--blue-2);font-size:21px;margin-bottom:30px}.deck-tile h2{margin:0 0 8px;font-size:21px}.deck-tile p{margin:0;color:var(--muted);font-size:13px}.deck-tile .deck-arrow{position:absolute;right:22px;bottom:22px;color:var(--blue-2);font-size:20px}
body.light{--bg:#f3f5fa;--surface:#fff;--surface-2:#edf0f6;--text:#151a24;--muted:#697386;--line:#dfe3eb;--shadow:0 25px 70px rgba(35,45,80,.12)}body.light .topbar{background:rgba(243,245,250,.87)}body.light .field textarea,body.light .deck-dialog input{background:#f8f9fc}.light .card-face{background:linear-gradient(145deg,#fff,#f5f7fb)}
@media(max-width:700px){.topbar{padding:0 12px;gap:6px}.brand span:last-child{display:none}.nav-tabs{margin:auto 0}.nav-tab{padding:9px 10px}.deck-picker{margin-left:auto;margin-right:0}.deck-picker select{width:112px;max-width:112px}.add-deck-button{width:36px;height:36px}.icon-button{display:none}main{width:min(100% - 24px,980px);padding-top:30px}.study-heading,.manage-heading{align-items:flex-start;gap:18px;flex-direction:column}.flashcard{height:430px}.card-face{padding:28px 24px;border-radius:26px}.study-controls{gap:8px}.grade-button{min-width:0;flex:1;padding:0 10px}.grade-button kbd{display:none}.round-button{width:48px;height:48px;flex:0 0 48px}.result-card{padding:34px 20px}.result-summary{flex-direction:column;gap:24px}.result-actions{flex-direction:column}.editor-card{grid-template-columns:1fr}.swap-button{transform:rotate(90deg);justify-self:center}.form-actions{grid-column:1}.list-card{grid-template-columns:25px 1fr auto}.list-card .list-content:nth-child(3){grid-column:2}.list-actions{grid-row:1/3;grid-column:3}.file-actions{width:100%}.file-actions button{flex:1}}
@media(max-width:700px){.home-heading{align-items:flex-start;gap:18px;flex-direction:column}.deck-grid{grid-template-columns:1fr}.deck-tile{min-height:175px}.deck-picker{display:none}.nav-tab{padding:9px 8px}}