*{box-sizing:border-box}
:root{--ink:#23263b;--muted:#687087;--blue:#4751ce;--blue-dark:#3540ad;--line:#e0e3eb;--paper:#fff;--bg:#f6f5f1;--soft:#eef0ff;--green:#286953;--amber:#826021;--radius:20px}
html{scroll-behavior:smooth}
body{margin:0;background:var(--bg);color:var(--ink);font:16px/1.65 "Noto Sans CJK KR","Malgun Gothic",system-ui,sans-serif}
button,input,textarea,select{font:inherit}
button,input,textarea,select,a{outline-offset:4px}
button{border:0;cursor:pointer}
button:disabled{cursor:not-allowed;opacity:.5}
[hidden]{display:none!important}
a{color:var(--blue)}
h1,h2,h3,p{margin:0}
h1,h2,h3,.lead,.question-text{word-break:keep-all;overflow-wrap:break-word}
h1{font-size:38px;line-height:1.35;letter-spacing:-1.5px}
h2{font-size:25px;line-height:1.45;letter-spacing:-.6px}
h3{font-size:18px;line-height:1.5}
p+p{margin-top:12px}
small,.muted{color:var(--muted)}
.skip-link{position:absolute;top:-70px;left:20px;background:var(--paper);padding:12px 18px;z-index:20;border:2px solid var(--blue);border-radius:10px}
.skip-link:focus{top:12px}
.site-header{max-width:1240px;margin:auto;padding:22px 32px;display:flex;justify-content:space-between;align-items:center;gap:20px;border-bottom:1px solid var(--line)}
.brand{display:flex;align-items:center;gap:12px;text-decoration:none;color:var(--ink);font-size:21px;font-weight:800;line-height:1.25}
.brand small{display:block;font-size:11px;font-weight:500;margin-top:5px;letter-spacing:.02em}
.brand-mark{display:grid;place-items:center;background:var(--blue);color:#fff;width:42px;height:42px;border-radius:13px;flex:0 0 42px;font-size:23px}
.header-nav{display:flex;align-items:center;gap:8px}
.text-button{padding:8px 10px;background:transparent;color:var(--muted);font-size:13px;border-radius:8px}
.text-button:hover{background:#eaeaf2;color:var(--ink)}
main{max-width:1176px;min-height:60vh;margin:auto;padding:40px 0 56px}
.eyebrow{color:var(--blue);font-size:12px;font-weight:800;letter-spacing:.12em;margin-bottom:12px}
.lead{color:var(--muted);max-width:720px;font-size:17px;margin-top:18px}
.intro{display:grid;grid-template-columns:1.25fr .75fr;gap:48px;align-items:center;margin:16px 0 38px}
.intro h1{max-width:620px}
.intro-visual{padding:28px;background:var(--soft);border:1px solid #dce0f7;border-radius:24px;position:relative}
.visual-label{font-size:12px;font-weight:750;color:var(--blue);margin-bottom:20px}
.visual-row{display:flex;gap:14px;align-items:flex-start;margin:16px 0}
.visual-num{display:grid;place-items:center;width:32px;height:32px;flex:0 0 32px;border-radius:50%;background:white;color:var(--blue);font-size:13px;font-weight:800}
.visual-row b{font-size:15px}
.visual-row p{font-size:13px;color:var(--muted);margin-top:2px}
.pills{display:flex;flex-wrap:wrap;gap:8px;margin-top:24px}
.pill,.tag{display:inline-flex;align-items:center;border-radius:99px;background:#e9ebf5;color:#535d82;padding:5px 11px;font-size:12px;font-weight:650}
.pill{background:#fff;border:1px solid var(--line)}
.tag.green{background:#e6f1e9;color:var(--green)}
.tag.amber{background:#fff2d4;color:var(--amber)}
.panel{padding:28px;background:var(--paper);border:1px solid var(--line);border-radius:var(--radius)}
.panel+.panel{margin-top:22px}
.panel-heading{display:flex;justify-content:space-between;align-items:flex-start;gap:16px;margin-bottom:18px}
.panel-heading p{color:var(--muted);font-size:14px;margin-top:6px}
.welcome-grid{display:grid;grid-template-columns:1fr 1fr;gap:26px;align-items:start}
.unit-overview{display:grid;gap:0;list-style:none;padding:0;margin:10px 0 0}
.unit-overview li{padding:15px 0;display:flex;gap:12px;border-bottom:1px solid var(--line)}
.unit-overview li:last-child{border-bottom:0;padding-bottom:0}
.unit-number{width:29px;height:29px;background:var(--soft);color:var(--blue);font-size:12px;font-weight:800;display:grid;place-items:center;border-radius:9px;flex:0 0 29px}
.unit-overview b{font-size:15px}
.unit-overview p{font-size:13px;color:var(--muted);margin-top:3px}
fieldset{border:0;margin:0;padding:0;min-width:0}
legend,label.label{display:block;font-size:14px;font-weight:750;margin-bottom:9px}
.mode-options{display:grid;grid-template-columns:1fr 1fr;gap:12px}
.mode-option{border:1px solid var(--line);border-radius:13px;padding:15px;cursor:pointer;display:block;font-size:14px}
.mode-option:has(input:checked){border-color:var(--blue);background:#f6f7ff;box-shadow:0 0 0 1px var(--blue)}
.mode-option input{margin:0 7px 0 0;accent-color:var(--blue)}
.mode-option b{font-size:14px}
.mode-option small{display:block;line-height:1.5;margin-top:7px;font-size:12px}
.check-label{display:flex;align-items:flex-start;gap:10px;font-size:13px;color:var(--muted);margin-top:22px;cursor:pointer}
.check-label input{width:18px;height:18px;flex:0 0 18px;accent-color:var(--blue);margin:4px 0 0}
.fine{font-size:12px;line-height:1.7;color:var(--muted);margin-top:14px;word-break:keep-all;overflow-wrap:break-word}
.actions{display:flex;flex-wrap:wrap;gap:10px;align-items:center;margin-top:24px}
.primary,.secondary,.quiet-button{min-height:46px;padding:11px 19px;border-radius:11px;font-size:14px;font-weight:750;line-height:1.45}
.primary{background:var(--blue);color:white}
.primary:hover:not(:disabled){background:var(--blue-dark)}
.secondary{background:#eceef5;color:#454e72}
.secondary:hover:not(:disabled){background:#e1e4ef}
.quiet-button{background:white;color:var(--muted);border:1px solid var(--line)}
.quiet-button:hover:not(:disabled){border-color:#bbc3dc;color:var(--ink)}
.page-heading{display:flex;align-items:flex-start;justify-content:space-between;gap:24px;margin-bottom:26px}
.page-heading h1{font-size:32px}
.page-heading .lead{font-size:15px;margin-top:12px}
.mode-badge{white-space:nowrap}
.summary-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:16px;margin:24px 0}
.stat{background:#fff;border:1px solid var(--line);border-radius:16px;padding:20px 24px}
.stat span{display:block;font-size:13px;color:var(--muted)}
.stat strong{display:block;font-size:30px;letter-spacing:-1px;line-height:1.5}
.stat strong small{font-size:14px;font-weight:500}
.stat p{font-size:12px;color:var(--muted);margin-top:4px}
.diagnostic-strip{display:flex;justify-content:space-between;align-items:center;gap:22px;background:var(--soft);border:1px solid #dce0f7;border-radius:16px;padding:20px 24px;margin-bottom:30px}
.diagnostic-strip p{font-size:13px;color:var(--muted);margin-top:4px}
.diagnostic-strip .actions{margin:0;flex:0 0 auto}
.section-heading{display:flex;justify-content:space-between;gap:16px;align-items:center;margin:32px 0 18px}
.section-heading p{font-size:13px;color:var(--muted)}
.units-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:20px}
.unit-card{padding:24px;background:#fff;border:1px solid var(--line);border-radius:18px;display:flex;flex-direction:column;min-width:0}
.unit-card-top{display:flex;justify-content:space-between;align-items:center;gap:10px;margin-bottom:18px}
.unit-card h3{font-size:21px;margin-bottom:8px}
.unit-desc{font-size:13px;color:var(--muted);min-height:44px;margin-bottom:18px;word-break:keep-all}
.progress-track{height:6px;border-radius:10px;background:#ecedf3;overflow:hidden;margin:9px 0}
.progress-fill{height:100%;background:var(--blue);border-radius:10px}
.progress-caption{display:flex;justify-content:space-between;gap:10px;font-size:12px;color:var(--muted)}
.unit-first{font-size:12px;color:var(--muted);margin:6px 0 15px}
select,input[type=text],input[type=number],textarea{width:100%;border:1px solid #cbd1df;background:white;border-radius:11px;padding:12px 14px;color:var(--ink)}
select{font-size:14px}
input:focus,textarea:focus,select:focus{border-color:var(--blue)}
textarea{min-height:116px;resize:vertical}
.unit-card .label{font-size:12px}
.unit-card .primary{width:100%;margin-top:11px}
.unit-card .grow{flex:1}
.score-mini{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:6px;border-top:1px solid var(--line);padding-top:16px;margin-top:20px}
.score-mini span{font-size:10px;color:var(--muted);display:block}
.score-mini b{font-size:15px}
.score-mini small{font-size:10px;display:block;color:var(--amber)}
.unit-assessments{display:flex;flex-wrap:wrap;gap:8px;margin-top:13px}
.unit-assessments button{padding:9px 10px;font-size:12px;min-height:38px}
.unit-note{font-size:11px;line-height:1.6;color:var(--muted);margin-top:10px}
.assessment-note{padding:20px 24px;background:#efefeb;border-radius:16px;margin-top:28px;color:var(--muted);font-size:13px}
.assessment-note b{color:var(--ink)}
.topline{display:flex;justify-content:space-between;gap:16px;align-items:center;margin-bottom:20px}
.back-button{font-size:13px;color:var(--muted);padding:7px 0;background:none}
.question-layout{display:grid;grid-template-columns:minmax(0,1.65fr) minmax(260px,1fr);gap:24px;align-items:start}
.question-layout.exam{max-width:820px;margin:auto;display:block}
.question-card{padding:32px}
.question-top{display:flex;align-items:center;justify-content:space-between;gap:12px;margin-bottom:24px}
.question-position{font-size:13px;color:var(--muted)}
.question-text{font-size:24px;line-height:1.7;font-weight:750;margin:18px 0 28px}
.question-skill{font-size:12px;color:var(--muted);margin-bottom:12px}
.answer-input{display:flex;align-items:center;gap:12px;max-width:400px;margin-bottom:24px}
.answer-input input{font-size:20px;min-width:0}
.answer-input span{color:var(--muted);white-space:nowrap}
.label-row{display:flex;justify-content:space-between;align-items:center;gap:10px;margin:18px 0 9px}
.label-row label{font-size:14px;font-weight:750}
.optional{font-size:11px;color:var(--muted)}
.hints{margin-top:24px;background:#fff8e8;border:1px solid #eddfbf;border-radius:14px;padding:18px}
.hints h3{font-size:14px;color:var(--amber);margin-bottom:10px}
.hints ol{margin:0;padding-left:20px;font-size:14px;color:#745b2b}
.hints li+li{margin-top:9px}
.hint-actions{display:flex;justify-content:space-between;align-items:center;gap:16px;margin-top:18px}
.hint-actions .fine{margin:0}
.lesson-panel{background:#f0f1fb}
.lesson-panel .eyebrow{margin-bottom:10px}
.lesson-panel h2{font-size:21px;margin-bottom:14px}
.lesson-body{font-size:14px;white-space:pre-line;word-break:keep-all;overflow-wrap:break-word}
.example{background:#fff;border:1px solid #e1e4f5;border-radius:13px;padding:18px;margin-top:20px;font-size:14px}
.example h3{font-size:14px;color:var(--blue);margin-bottom:10px}
.example p,.example ol{margin-top:10px}
.example ol{padding-left:20px}
.prerequisite{padding-top:16px;border-top:1px solid #d9dced;font-size:12px;color:var(--muted);margin-top:20px}
.assessment-banner{border:1px solid #dce0f7;background:var(--soft);padding:16px 20px;border-radius:13px;font-size:13px;color:#525f8d;margin-bottom:20px}
.result-heading{display:flex;align-items:center;gap:14px;margin:12px 0 22px}
.result-icon{display:grid;place-items:center;width:52px;height:52px;flex:0 0 52px;border-radius:50%;font-size:24px;font-weight:800;background:#e7f2e9;color:var(--green)}
.result-icon.again{background:#fff2d7;color:var(--amber)}
.answer-box{padding:22px;border:1px solid #dce7df;background:#f0f7f2;border-radius:15px;margin-bottom:20px}
.answer-box small{color:var(--green)}
.answer-value{font-size:25px;font-weight:800;margin-top:5px}
.explanation{white-space:pre-line;font-size:15px;margin-top:16px}
.misconception{padding:15px 18px;border-left:3px solid #d8b36b;background:#fff8e9;color:#7b602e;border-radius:0 10px 10px 0;margin-top:18px;font-size:14px;white-space:pre-line}
.feedback-question{color:var(--muted);font-size:14px;margin-bottom:18px;word-break:keep-all}
.saved-reason{border-top:1px solid var(--line);margin-top:22px;padding-top:18px}
.saved-reason p{font-size:14px;color:var(--muted);white-space:pre-wrap;overflow-wrap:anywhere}
.saved-reason h3{font-size:14px;margin-bottom:8px}
.ai-panel{margin-top:24px;padding:22px;border:1px solid #dce0f7;border-radius:15px;background:#f8f9ff}
.ai-panel h3{font-size:17px}
.ai-response{padding:18px;background:#fff;border:1px solid #e1e4f5;border-radius:12px;margin:18px 0;font-size:14px;white-space:pre-line}
.ai-response blockquote{border-left:3px solid #c4cbed;margin:14px 0 0;padding-left:12px;color:var(--muted);font-size:13px}
.message{padding:15px 20px;border-radius:13px;margin-bottom:20px;font-size:14px;overflow-wrap:anywhere}
.error-message{background:#fff0ed;border:1px solid #ecc6bf;color:#8b382c}
.info-message{background:#edf4ef;border:1px solid #d1e3d7;color:var(--green)}
.busy-status{position:fixed;bottom:22px;left:50%;transform:translateX(-50%);background:var(--ink);color:#fff;padding:14px 22px;border-radius:14px;box-shadow:0 8px 35px #20253b22;z-index:10;max-width:calc(100% - 32px);font-size:14px}
.loading{text-align:center;padding:75px 16px}
.loading h1{font-size:24px;margin:20px 0 10px}
.loading p{color:var(--muted)}
.loading-dot{display:inline-block;width:25px;height:25px;border:3px solid #dce0f5;border-top-color:var(--blue);border-radius:50%;animation:spin 1s linear infinite}
@keyframes spin{to{transform:rotate(360deg)}}
.site-footer{max-width:1240px;margin:auto;padding:26px 32px;border-top:1px solid var(--line);display:flex;align-items:center;justify-content:space-between;flex-wrap:wrap;gap:16px;font-size:12px;color:var(--muted)}
.site-footer strong{font-size:12px;font-weight:650}
.site-footer p{font-size:11px;margin-top:4px}
.site-footer nav{display:flex;gap:3px;flex-wrap:wrap}
.site-footer .text-button{font-size:11px;padding:7px}
.previous-link{font-size:11px;color:var(--muted)}
dialog{border:1px solid var(--line);border-radius:22px;max-width:610px;width:calc(100% - 32px);padding:30px;color:var(--ink);max-height:85vh;overflow:auto}
dialog::backdrop{background:#25283b88}
dialog h2{font-size:23px;margin-bottom:18px}
dialog h3{font-size:16px;margin:22px 0 8px}
dialog p,dialog li{font-size:14px;color:var(--muted)}
dialog ol,dialog ul{padding-left:21px}
dialog li+li{margin-top:10px}
.dialog-close-row{display:flex;justify-content:flex-end;margin-top:24px}
dialog .code-block{background:#f0f1f7;border-radius:12px;padding:16px;margin:18px 0;overflow-wrap:anywhere;display:block;font-size:16px;user-select:all}
dialog .danger{background:#9a3f36;color:white}
.restore-form label{margin-top:20px}
.noscript{padding:30px;text-align:center}
@media(max-width:1240px){main{margin:0 32px}.units-grid{gap:16px}.unit-card{padding:21px}}
@media(max-width:950px){.units-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.intro{gap:28px}.intro h1{font-size:33px}.welcome-grid{gap:20px}.panel{padding:23px}.question-layout{grid-template-columns:minmax(0,1.4fr) minmax(245px,1fr)}.question-card{padding:26px}}
@media(max-width:700px){.site-header{padding:17px 20px;gap:10px}.brand{font-size:18px;gap:9px}.brand small{display:none}.brand-mark{width:35px;height:35px;flex-basis:35px;font-size:20px;border-radius:11px}.header-nav{gap:0}.header-nav .text-button{font-size:12px;padding:7px}.site-footer{padding:24px 20px;display:block}.site-footer nav{margin-top:14px}.previous-link{display:inline-block;margin-top:14px}main{margin:0 20px;padding:30px 0 40px}.intro{grid-template-columns:1fr;gap:25px;margin:4px 0 25px}.intro h1{font-size:32px}.intro-visual{padding:20px}.visual-label{margin-bottom:12px}.visual-row{margin:12px 0}.lead{font-size:15px}.welcome-grid{grid-template-columns:1fr}.panel{padding:22px}.welcome-grid .overview-panel{order:2}.mode-options{gap:9px}.mode-option{padding:12px}.page-heading{gap:12px;flex-wrap:wrap}.page-heading h1{font-size:28px}.page-heading .lead{font-size:14px}.summary-grid{gap:9px}.stat{padding:14px 11px}.stat strong{font-size:24px}.stat strong small{font-size:11px}.stat span{font-size:11px}.stat p{font-size:10px}.diagnostic-strip{align-items:flex-start;flex-direction:column;padding:19px;gap:15px}.units-grid{grid-template-columns:1fr;gap:16px}.unit-desc{min-height:0}.unit-card h3{font-size:22px}.section-heading{align-items:flex-start;flex-direction:column;gap:6px}.section-heading h2{font-size:23px}.question-layout{display:block}.question-layout .lesson-panel{margin-top:22px}.question-card{padding:23px}.question-text{font-size:21px;margin-bottom:24px}.question-top{margin-bottom:18px}.question-position{font-size:12px}.topline{align-items:flex-start;gap:10px}.topline .tag{font-size:11px}.answer-input input{font-size:18px}.actions{gap:9px}.actions .primary{flex-grow:1;text-align:center}.question-card .actions .secondary{flex-grow:1}.hint-actions{align-items:flex-start;flex-direction:column;gap:9px}.ai-panel{padding:17px}.result-heading h1{font-size:25px}.result-icon{width:46px;height:46px;flex-basis:46px}.feedback-question{font-size:13px}.score-mini span{font-size:11px}.score-mini b{font-size:17px}.unit-assessments button{font-size:13px}.unit-note{font-size:12px}.fine{font-size:12px}.assessment-note{padding:18px}.mode-badge{font-size:11px}dialog{padding:24px}.panel-heading{gap:10px}.panel-heading h2{font-size:23px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}.loading-dot{animation:none}}
@media print{.site-header,.site-footer,.actions,.topline,button,#alert,#notice,#busy-status{display:none}body{background:white}main{max-width:none;margin:0;padding:0}.panel,.unit-card{break-inside:avoid}.units-grid{grid-template-columns:repeat(2,1fr)}}


/* Native progress follows the strict production content security policy. */
progress.progress-track {display:block;width:100%;height:7px;border:0;border-radius:99px;overflow:hidden;background:#e9e8e2;color:var(--primary);appearance:none;}
progress.progress-track::-webkit-progress-bar {background:#e9e8e2;border-radius:99px;}
progress.progress-track::-webkit-progress-value {background:#4751ce;border-radius:99px;}
progress.progress-track::-moz-progress-bar {background:#4751ce;border-radius:99px;}
.score-mini .score-total {display:inline;}