:root{font-family:Inter,system-ui,-apple-system,"Segoe UI",sans-serif;color:#263047;background:#f7f8ff;font-synthesis:none}*{box-sizing:border-box}body{margin:0}button,input,select{font:inherit}button{cursor:pointer}button:disabled{opacity:.5;cursor:not-allowed}.shell{min-height:100vh;display:grid;grid-template-columns:240px 1fr;max-width:1440px;margin:auto}.sidebar{background:#fff;border-right:1px solid #e8eafa;padding:28px 16px;position:sticky;top:0;height:100vh}.brand{display:flex;gap:10px;align-items:center;font-weight:800;font-size:19px;color:#5646ce;margin:0 8px 28px}.brand-icon{background:#5c4bde;color:#fff;padding:10px;border-radius:14px}.nav{display:flex;flex-direction:column;gap:6px}.nav button{display:flex;align-items:center;gap:10px;border:0;background:transparent;border-radius:13px;padding:14px 16px;text-align:left;color:#67708b;font-weight:650}.nav button.active{background:#efedff;color:#5545c9}.main{padding:30px 34px 90px;min-width:0}.top{display:flex;justify-content:space-between;align-items:center;gap:12px;margin-bottom:26px}.top h1{margin:0 0 7px;font-size:clamp(23px,3vw,30px)}.muted{color:#8290a8}.small{font-size:13px}.eyebrow{color:#6857d4;font-size:13px;font-weight:750;letter-spacing:.05em}.chip{border-radius:50px;padding:8px 13px;font-size:12px;font-weight:700;background:#eae7ff;color:#5a49d2}.grid{display:grid;grid-template-columns:repeat(4,1fr);gap:15px}.panel,.stat,.tile{background:#fff;border:1px solid #e9eaf4;border-radius:20px;padding:22px;box-shadow:0 5px 20px #26304708}.tile{display:flex;flex-direction:column;gap:10px;min-height:155px;text-align:left;transition:transform .15s,border .15s}.tile:hover{transform:translateY(-2px);border-color:#b6acff}.tile .emoji{font-size:27px}.tile strong{font-size:18px}.tile small{color:#8390a8}.tile.done{border-color:#a3dfbf;background:#f8fffb}.section{margin-top:25px}.section-title{font-size:20px;margin:0 0 15px}.progress{height:9px;background:#efeff9;border-radius:30px;overflow:hidden}.progress>div{height:100%;background:linear-gradient(90deg,#7767ee,#4ec59b);border-radius:30px}.row{display:flex;align-items:center;justify-content:space-between;gap:12px}.wrap{flex-wrap:wrap}.btn{border:none;background:#5c4bde;color:#fff;border-radius:13px;padding:12px 17px;font-weight:750}.btn.secondary{background:#efedff;color:#5949cf}.btn.outline{background:#fff;border:1px solid #deddf0;color:#5148aa}.btn.green{background:#178859}.btn:focus-visible,.nav button:focus-visible{outline:3px solid #aaa0ff}.vocab{font-size:clamp(31px,5vw,48px);text-align:center;margin:16px 0 7px}.meaning{text-align:center;color:#6956d9;font-size:19px;font-weight:700}.example{padding:14px 15px;background:#f6f7fd;border-radius:13px;margin:9px 0}.example .ko{font-size:17px;font-weight:680}.example .vi{font-size:14px;color:#7e8ca5;margin-top:4px}.answers{display:grid;grid-template-columns:1fr 1fr;gap:11px;margin:18px 0}.answer{border:1px solid #e0e1ef;border-radius:12px;background:#fff;padding:15px;text-align:left;font-size:15px;min-height:60px}.answer:hover{border-color:#8576e8}.answer.correct{background:#e5f8ec;border-color:#28a56e;color:#176a47}.answer.wrong{background:#fff0f0;border-color:#e36e72;color:#a33a40}.feedback{background:#f0f6ff;padding:14px;border-radius:13px;margin:12px 0}.days{display:grid;grid-template-columns:repeat(7,1fr);gap:7px}.day{background:#fafaff;border:1px solid #eaeaf2;padding:11px 3px;border-radius:12px;text-align:center;font-size:13px}.day.completed{background:#e4f7ed;color:#15774f}.day.today{border:2px solid #7465e6}.calendar{display:grid;grid-template-columns:repeat(7,1fr);gap:6px}.calday{min-height:57px;border-radius:11px;background:#f8f9fd;text-align:center;padding:9px 3px;font-size:13px}.calday.completed{background:#e3f7eb;color:#12724c}.calday.today{border:2px solid #7362ec}.calhead{text-align:center;color:#93a0b8;font-size:12px;padding:8px 0}.subnav{display:flex;flex-wrap:wrap;gap:8px}.pill{border-radius:50px;background:#f0eff9;border:1px solid transparent;color:#5f647b;padding:9px 14px}.pill.active{background:#eceaff;border-color:#bab1f3;color:#5443cd}.stat strong{display:block;font-size:27px;margin-top:10px}.stack{display:grid;gap:13px}.split{display:grid;grid-template-columns:minmax(0,2fr) minmax(250px,1fr);gap:18px}.conversation{padding:14px 16px;border-radius:15px;background:#f6f7ff;margin:9px 0}.conversation:nth-child(even){background:#eeeaff;margin-left:25px}.koname{font-weight:720;font-size:17px}.vi{color:#76859e;margin-top:5px}.input{border:1px solid #dde1f0;border-radius:12px;padding:12px 14px;max-width:100%;width:100%;background:white}.empty{padding:38px;text-align:center;color:#8792a7}.bottomnav{display:none}.notice{padding:12px 15px;background:#fff8e5;border-radius:13px;color:#816622;font-size:13px}.success{padding:12px 15px;background:#e8f8ef;border-radius:13px;color:#20784e;font-size:13px}.question-label{font-size:13px;color:#8b96ae;margin-bottom:12px}.center{text-align:center}.setting-row{display:grid;grid-template-columns:1fr auto;gap:10px;align-items:center;padding:13px 0;border-bottom:1px solid #edf0f7}.footer{font-size:12px;color:#9aa3b6;margin-top:28px}.hidden{display:none!important}@media(max-width:1050px){.grid{grid-template-columns:repeat(2,1fr)}.split{grid-template-columns:1fr}.sidebar{width:205px}.shell{grid-template-columns:205px 1fr}}@media(max-width:720px){.shell{display:block}.sidebar{display:none}.main{padding:22px 16px 94px}.grid{grid-template-columns:repeat(2,minmax(0,1fr));gap:10px}.panel,.stat,.tile{padding:17px;border-radius:17px}.tile{min-height:140px}.tile strong{font-size:15px}.top{align-items:flex-start}.top h1{font-size:23px}.bottomnav{position:fixed;bottom:0;left:0;right:0;display:grid;grid-template-columns:repeat(6,1fr);background:#fff;border-top:1px solid #ebebf4;padding:7px 3px calc(8px + env(safe-area-inset-bottom));z-index:20}.bottomnav button{border:none;background:none;color:#8590aa;display:flex;flex-direction:column;align-items:center;gap:4px;font-size:9px;padding:6px 0}.bottomnav button.active{color:#5c4bde;font-weight:800}.bottomnav .navemoji{font-size:19px}.answers{grid-template-columns:1fr}.stat strong{font-size:23px}.calday{min-height:44px}.days{gap:4px}.day{padding:9px 2px;font-size:11px}}@media(min-width:721px) and (max-width:850px){.nav button{padding:12px 8px;font-size:13px}}
/* Additional mobile-first refinements for v2 */
.learnpanel{max-width:790px;margin:auto}.learnpanel .progress{margin:17px 0}.exam-prompt{white-space:normal;font-size:clamp(18px,2.8vw,24px);line-height:1.65;margin:20px 0 16px}.stats{grid-template-columns:repeat(4,minmax(0,1fr))}.nav .navemoji{font-size:19px;min-width:23px}.bottomnav .navemoji{font-size:20px}.conversation .vi{line-height:1.55}.input{min-height:44px}.btn{min-height:44px}.answer{line-height:1.5}.calday{line-height:1.55}.section-title{margin-bottom:12px}.question-label{margin-top:20px}.vocab{word-break:keep-all}.setting-row input[type=checkbox]{width:21px;height:21px}.learnpanel .feedback{line-height:1.6}#toast{position:fixed;bottom:calc(85px + env(safe-area-inset-bottom));left:50%;transform:translateX(-50%);z-index:99;border-radius:14px;padding:12px 20px;background:#282447;color:white;box-shadow:0 12px 24px #0002;max-width:calc(100vw - 24px);text-align:center}#toast[hidden]{display:none}
@media(max-width:720px){.main{padding-top:20px}.stats{grid-template-columns:repeat(2,minmax(0,1fr))}.answers{gap:9px}.answer{min-height:56px}.top{margin-bottom:18px}.eyebrow{font-size:10px}.chip{padding:7px 10px}.grid .tile{min-height:128px}.learnpanel{padding:18px}.row.wrap>.btn{flex-grow:1}.vocab{font-size:clamp(27px,7vw,37px)}.calday{min-height:46px}.top .chip{white-space:nowrap}.main{padding-bottom:115px}}

/* v7: timed exam */
.exam-clock{display:inline-flex;align-items:center;gap:6px;padding:9px 14px;border-radius:12px;background:#eeeaff;color:#5140c9;font-size:1.2rem;font-weight:800;font-variant-numeric:tabular-nums}
.timed-number-grid{display:grid;grid-template-columns:repeat(10,minmax(0,1fr));gap:6px;margin-top:15px}
.tiny-question{border:1px solid #d9d9ea;background:white;border-radius:7px;min-height:34px;font:inherit;cursor:pointer;color:#344057}
.tiny-question.has-answer{background:#e3f6e9;border-color:#83d39f}
.tiny-question.now{outline:2px solid #6854f3;outline-offset:1px}
.answer.selected{background:#e9e3ff;border-color:#6854f3}
@media(max-width:600px){.timed-number-grid{grid-template-columns:repeat(7,minmax(0,1fr));gap:5px}.exam-clock{font-size:1.05rem}}

/* Homework lessons */
.homework-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(175px,1fr));gap:12px;margin-top:18px}
.hw-lesson{border:1px solid #e0def4;background:#fcfbff;border-radius:16px;padding:15px;text-align:left;display:flex;flex-direction:column;gap:8px;min-height:125px;color:#34304f}
.hw-lesson:hover,.hw-lesson:focus-visible{border-color:#5c4bde;background:#f3efff;outline:none}
.hw-lesson b{color:#5849cc;font-size:15px}.hw-lesson strong{font-size:16px}.hw-lesson span{font-size:12px;color:#7f88a0}
@media(max-width:720px){.homework-grid{grid-template-columns:repeat(2,minmax(0,1fr));gap:9px}.hw-lesson{padding:12px;min-height:116px}.bottomnav{display:flex;overflow-x:auto;gap:2px;scrollbar-width:none}.bottomnav button{min-width:66px;flex:1 0 auto}.bottomnav::-webkit-scrollbar{display:none}}

/* v1.2: optional word/sentence handwriting-style typing practice */
.copy-practice{margin:11px 0 6px;text-align:left}
.copy-practice-label{display:block;font-size:13px;font-weight:650;color:#5b4eb4;margin-bottom:7px}
.copy-practice-input{box-sizing:border-box;display:block;width:100%;max-width:100%;min-height:46px;resize:vertical;border:1px solid #cbc8ed;border-radius:12px;background:#fff;padding:11px 13px;color:#29314d;font:inherit;font-size:16px;line-height:1.55;outline-offset:2px}
.copy-practice-input::placeholder{color:#a9acc1;opacity:1}
.copy-practice-input:focus{border-color:#7763e2;box-shadow:0 0 0 3px rgba(119,99,226,.12)}
@media(max-width:720px){.copy-practice-input{font-size:16px;min-height:48px}.copy-practice-label{font-size:12px}}

/* v1.3: independent, audio-first hidden Korean recall exercise */
.blind-practice{display:flex;flex-direction:column;gap:10px;text-align:left}
.blind-practice-head{display:flex;align-items:center;justify-content:space-between;gap:10px;flex-wrap:wrap}
.blind-practice-target[hidden]{display:none!important}
.blind-practice-target{font-weight:750;font-size:clamp(20px,3vw,27px);line-height:1.6;overflow-wrap:anywhere}
.blind-practice-controls{display:flex;align-items:center;gap:8px;flex-wrap:wrap}
.blind-practice .copy-practice-label{margin:2px 0 0}
.blind-practice .copy-practice-input{margin:0}
.blind-practice .vi{margin-top:2px;line-height:1.55}
@media(max-width:480px){.blind-practice-head .btn{padding:9px 12px}}

/* v1.4: date-grouped wrong answers, quiz results, accessible slow playback */
.wrong-day{border:1px solid #e1e2f0;border-radius:14px;margin:10px 0;overflow:hidden;background:#fff}
.wrong-day>summary{display:flex;align-items:center;justify-content:space-between;gap:10px;padding:16px 13px;cursor:pointer;font-weight:750;background:#f8f7ff;list-style:none}
.wrong-day>summary::-webkit-details-marker{display:none}
.wrong-day-entries{padding:5px 13px}
.wrong-entry{border-bottom:1px solid #eeeff6;padding:12px 0}
.wrong-entry:last-child{border-bottom:0}
.wrong-entry .vi{font-size:14px}
.mistake-review-box{background:#f4f2ff;padding:17px;border-radius:16px}
.mistake-review-box h3{margin:0 0 6px}
.mistake-review-box select{margin-top:6px}
.result-columns{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:14px;margin:19px 0;text-align:left}
.result-panel{background:#f7f8ff;padding:13px;border-radius:15px;max-height:420px;overflow:auto}
.result-panel h3{font-size:16px;margin:0 0 9px}
.result-word{display:flex;justify-content:space-between;gap:12px;align-items:baseline;padding:9px 0;border-bottom:1px solid #e4e7f1}
.result-word:last-child{border:0}
.result-ko{font-weight:750;overflow-wrap:anywhere}.result-vi{color:#6f7d95;font-size:13px;text-align:right;overflow-wrap:anywhere}
.speech-speed-group{display:inline-flex;align-items:center;gap:5px;margin-left:5px}
.btn.speech-speed{padding:8px 10px;min-height:40px;font-size:13px}
@media(max-width:600px){.result-columns{grid-template-columns:1fr}.result-panel{max-height:330px}.wrong-day>summary{flex-wrap:wrap}.speech-speed-group{margin-left:2px}}

/* v1.7: optional blind review of all words after a vocabulary or homework test */
.result-review-toolbar{display:flex;align-items:center;justify-content:space-between;gap:12px;text-align:left;margin-top:18px;padding:14px;background:#f3f0ff;border-radius:14px}
.result-review-toolbar p{margin:5px 0 0;line-height:1.5}
.result-review-toolbar .btn{flex-shrink:0}
.result-recall-item{display:block;text-align:left;padding:13px 2px}
.result-recall-top{display:flex;align-items:center;justify-content:space-between;gap:12px}
.result-recall-top .result-vi{font-size:15px;color:#465678;font-weight:700;text-align:left;flex:1;line-height:1.5}
.result-recall-top .btn{padding:7px 10px;min-height:38px;font-size:12px;white-space:nowrap}
.result-recall-ko{font-size:17px;font-weight:750;line-height:1.6;margin:9px 0 5px;color:#3c3582;overflow-wrap:anywhere}
.result-recall-ko[hidden]{display:none!important}
.result-recall-input{margin-top:8px;min-height:46px;font-size:16px!important;border-color:#cbc8ed;background:#fff}
@media(max-width:600px){.result-review-toolbar{flex-direction:column;align-items:stretch}.result-panel{max-height:none}.result-recall-top{align-items:flex-start}.result-recall-top .btn{flex-shrink:0}}

/* Native in-app dictionary; responsive for small mobile screens. */
.dict-search form {display:flex; gap:10px; align-items:stretch;}
.dict-search input {flex:1; min-width:145px;}
.dict-card {min-width:0; overflow-wrap:anywhere;}
.dict-card-heading {align-items:flex-start;gap:8px;}
.dict-meaning {min-width:0;flex:1;}
.dict-hidden-ko {font-size:1.22rem;line-height:1.5; font-weight:700; margin:10px 0; padding:8px 10px; background:rgba(120,110,180,.08);border-radius:8px;}
.dict-actions {gap:7px; margin:10px 0;}
.dict-actions .btn{white-space:nowrap;padding:8px 10px;}
.dict-type{display:block;width:100%;max-width:100%;min-height:42px;resize:vertical;box-sizing:border-box;font-size:16px;}
.dict-example{border-top:1px solid rgba(110,110,130,.17);margin-top:16px;padding-top:13px;}
@media(max-width:560px){.dict-card .btn{font-size:13px;}.dict-search form .btn{flex:0 0 auto;}}

/* Game centre v2.5 – touch-friendly, responsive, non-quiz minigames */
.game-area{max-width:760px;margin:16px auto;padding:22px}.game-tile{min-height:155px;text-align:left}.game-card-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:10px;margin:18px 0}.game-card{min-width:0;min-height:76px;overflow-wrap:anywhere;border:1px solid #cfd2f2;background:#fff;border-radius:14px;padding:10px;color:#29254c;font:inherit;font-weight:650;cursor:pointer;box-shadow:0 2px 8px #1e175011}.game-card.game-open{background:#e7e8ff;border-color:#8076d8}.game-card.game-found{background:#e4f9ef;color:#126e46;border-color:#5dbd8b}.game-dropzone{display:flex;flex-wrap:wrap;gap:7px;padding:14px;border:2px dashed #c9c3e9;border-radius:13px;min-height:70px;margin:16px 0;align-items:center}.game-token-grid{display:flex;flex-wrap:wrap;gap:9px;margin:12px 0 22px}.game-chip{font:inherit;border:1px solid #aea8e5;background:white;padding:11px 15px;border-radius:12px;min-height:46px;cursor:pointer;color:#2f2860}.game-chip:active,.game-card:active{transform:scale(.98)}.game-translation{font-size:1.18rem;font-weight:650}.game-clock{text-align:center;font-size:2rem;font-weight:800;margin:14px}.game-tile:disabled{opacity:.48;cursor:not-allowed}@media(max-width:550px){.game-card-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.game-card{min-height:72px;font-size:.9rem}.game-area{padding:14px}}

/* v2.6: visitor homepage with visible but inactive study menus */
.nav button.nav-locked,.bottomnav button.nav-locked{color:#a7adb9;filter:grayscale(1);opacity:.62;background:#f6f6f8}.nav button.nav-locked:hover{background:#f1f1f4}.nav-padlock{margin-left:auto;font-size:12px;line-height:1}.bottomnav .nav-padlock{font-size:10px;margin-left:0}.tile.tile-locked{background:#f5f6f9;border-color:#e7e8ed;box-shadow:none;filter:grayscale(.9);opacity:.64;color:#71788a;cursor:pointer}.tile.tile-locked:hover{transform:none;border-color:#d8dbe3}.guest-welcome{text-align:center;max-width:820px}.guest-welcome h2{font-size:1.35rem}.guest-welcome-icon{font-size:32px}.guest-login{max-width:480px;margin:0 auto}.guest-login h2{margin-top:0}@media(max-width:720px){.bottomnav button.nav-locked{background:none;opacity:.52}.bottomnav .nav-padlock{display:none}}

/* Korean-teacher-only conversational assistant */
.ai-panel{max-width:920px;margin:0 auto}.ai-chat-list{height:min(55vh,520px);min-height:300px;overflow-y:auto;display:flex;flex-direction:column;gap:12px;padding:14px 5px;margin:10px 0;border-top:1px solid #e8e4f3;border-bottom:1px solid #e8e4f3}.ai-chat-bubble{max-width:91%;padding:13px 15px;border-radius:16px;white-space:normal;overflow-wrap:anywhere}.ai-user{align-self:flex-end;background:#ece8ff;color:#34295d}.ai-assistant{align-self:flex-start;background:#f7f8fc;color:#25344f;border:1px solid #e8eaf0}.ai-chat-tag{font-size:12px;font-weight:700;opacity:.75;margin-bottom:6px}.ai-chat-text{white-space:pre-wrap;line-height:1.65}.ai-intro{margin:auto;text-align:center;color:#6b6489;padding:20px}.ai-chat-form{display:flex;flex-direction:column;gap:10px}.ai-chat-form textarea{width:100%;box-sizing:border-box;font-size:16px;resize:vertical}.ai-error{color:#b32b49;margin:8px 0;min-height:1em}@media(max-width:600px){.ai-chat-list{height:48vh;min-height:260px}.ai-chat-bubble{max-width:96%}}

/* v2.8: persistent AI tutor overlay that does not interrupt studying */
.ai-float-root{position:fixed;right:max(16px,env(safe-area-inset-right));bottom:max(18px,env(safe-area-inset-bottom));z-index:500;pointer-events:none;font-family:inherit}
.ai-float-root>*{pointer-events:auto}
.ai-float-launcher{margin-left:auto;display:flex;align-items:center;justify-content:center;gap:5px;min-width:61px;height:56px;padding:0 13px;border:0;border-radius:28px;background:#6250d7;color:white;font:inherit;font-weight:800;cursor:pointer;box-shadow:0 7px 22px rgba(42,30,126,.30)}
.ai-float-launcher>span:first-child{font-size:23px}.ai-float-launcher-text{font-size:13px}.ai-float-launcher:focus-visible,.ai-float-close:focus-visible{outline:3px solid #aa94ff;outline-offset:3px}.ai-float-locked{filter:grayscale(1);opacity:.7}
.ai-float-panel{position:absolute;right:0;bottom:66px;width:min(390px,calc(100vw - 28px));height:min(605px,calc(100dvh - 110px));max-height:calc(100dvh - 110px);display:flex;flex-direction:column;overflow:hidden;border:1px solid #dad5f3;border-radius:19px;background:#fff;color:#26324f;box-shadow:0 15px 50px rgba(24,26,71,.23)}
.ai-float-header{display:flex;align-items:center;justify-content:space-between;gap:10px;padding:13px 15px;background:#f2efff;border-bottom:1px solid #e2dbfa}.ai-float-header strong{font-size:17px}.ai-float-subtitle{font-size:11px;color:#655f7e;margin-top:3px}.ai-float-close{width:38px;height:38px;border:1px solid #d4cdef;border-radius:11px;background:#fff;color:#4c426d;font-size:17px;cursor:pointer;flex-shrink:0}
.ai-float-scroll{flex:1;min-height:0;overflow-y:auto;overscroll-behavior:contain;padding:13px;display:flex;flex-direction:column;gap:11px}.ai-float-scroll .ai-chat-bubble{max-width:92%}.ai-float-scroll .ai-intro{font-size:14px}
.ai-float-form{padding:11px 13px 13px;border-top:1px solid #e8e4f3;background:white}.ai-float-label{display:block;font-size:12px;color:#6b6489;margin-bottom:5px}.ai-float-form textarea{box-sizing:border-box;display:block;width:100%;min-height:53px;max-height:105px;resize:none;font-size:16px}.ai-float-actions{display:flex;align-items:center;gap:8px;margin-top:8px}.ai-float-actions .btn{padding:9px 11px;min-height:37px;white-space:nowrap}.ai-float-clear{font-size:12px}.ai-float-status{flex:1;min-width:0;color:#756e89;font-size:10px}.ai-float-form .ai-error{font-size:12px;margin:5px 0 0;min-height:0}
@media(max-width:720px){.ai-float-root{bottom:calc(75px + env(safe-area-inset-bottom));right:12px}.ai-float-launcher{height:49px;min-width:55px;padding:0 10px}.ai-float-panel{bottom:58px;width:min(390px,calc(100vw - 24px));height:min(65dvh,540px);max-height:calc(100dvh - 165px)}.ai-float-header{padding:9px 12px}.ai-float-scroll{padding:10px}.ai-float-form{padding:9px 11px}.ai-float-form textarea{min-height:46px}}
@media(max-width:380px){.ai-float-actions{gap:5px}.ai-float-actions .btn{padding:8px}.ai-float-status{font-size:9px}}