.site-header{max-width:1380px;padding:18px 30px;gap:24px}.brand{flex-shrink:0;display:flex}.brand img{max-width:100%;object-fit:contain}.top-nav{gap:8px}.top-nav a{padding:12px 14px;border-radius:8px;color:#46665e}.top-nav a[aria-current=page]{background:#176e5c;color:white}.korean{font-size:12px;white-space:nowrap}.layout{max-width:1380px;grid-template-columns:235px minmax(0,1fr);gap:32px}.browse{padding:18px}.browse summary{font-size:14px;padding-bottom:10px}.menu-link{display:block;text-decoration:none;padding:11px 12px;border-radius:7px;font-size:14px;margin:3px 0}.menu-link[aria-current=page]{background:#e5f2ec;color:#125847;font-weight:bold}.menu-heading{font-size:12px;font-weight:bold;color:#567367;margin:20px 10px 6px}.nested{margin-left:12px;border-left:2px solid #dbe7e1;padding-left:8px}.sidebar-note{font-size:13px;color:#567367;padding:4px 18px}.hero{padding:12px 4px 20px;border-bottom:1px solid #d2e3db;margin-bottom:26px}.hero h1{font-size:36px;margin:10px 0 14px}.hero p{max-width:650px;margin:0;color:#48665e}.eyebrow{font-size:11px}.count{font-size:12px;color:#547268}.concept-list{background:white;border:1px solid #d2e3db;border-radius:12px;overflow:hidden}.concept-row{display:flex;align-items:center;justify-content:space-between;gap:20px;padding:22px 24px;border-bottom:1px solid #e2ebe5;text-decoration:none}.concept-row:last-child{border:0}.concept-row:hover{background:#f0f7f3}.concept-row h3{margin:4px 0;color:#214c50}.concept-row p{font-size:14px;color:#526c62;max-width:620px;margin:5px 0}.row-arrow{font-size:24px}.section{margin-top:22px}.section h2:first-child{margin-top:0}.steps{display:flex;gap:12px;flex-wrap:wrap;font-size:13px;margin:20px 0}.steps span{padding:6px 12px;background:#eaf3ee;border-radius:20px}.lesson-layout{display:grid;grid-template-columns:minmax(0,1fr) 260px;gap:20px;align-items:start}.lesson-layout>.section{margin:0}.practice-box{background:#fff9ed;border:1px solid #e8d9ba;border-radius:12px;padding:20px;position:sticky;top:0}.practice-box h2{font-size:20px;margin-top:0}.practice-box p{font-size:13px}.practice-link{display:block;background:white;border:1px solid #d8dfd6;border-radius:8px;padding:12px;text-decoration:none;margin-top:12px;font-size:14px;font-weight:bold}.practice-link small{display:block;font-size:11px;color:#63776e;font-weight:normal;margin-bottom:4px}.lesson-copy svg{max-width:100%;height:auto}.lesson-copy{min-width:0}.lesson-copy h2{font-size:23px}.back-link{display:inline-block;font-size:13px;margin:8px 0 15px}.train-intro{display:flex;gap:18px;align-items:center}.operation-icon{font-size:30px;width:58px;height:58px;display:grid;place-items:center;background:#e5f2ec;border-radius:12px}.training-links{display:grid;grid-template-columns:1fr 1fr;gap:12px;margin-top:20px}.training-links a{padding:18px;border:1px solid #c9ddd6;background:white;border-radius:9px;text-decoration:none}.training-links strong{display:block}footer{display:flex;justify-content:space-between;gap:20px;max-width:1320px;color:#567367;font-size:12px}main:focus{outline:none}.empty{padding:30px;background:white;border-radius:10px}.sample-note{font-size:12px;color:#63776e;margin:14px 0}button:disabled{cursor:default}@media(max-width:1100px){.lesson-layout{grid-template-columns:1fr}.practice-box{position:static}.site-header{flex-wrap:wrap}.top-nav{order:3;width:100%}.layout{gap:20px}.hero h1{font-size:30px}}@media(max-width:760px){.site-header{padding:10px 16px;gap:6px;justify-content:space-between}.brand img{width:185px;height:40px}.top-nav{gap:4px;justify-content:space-between}.top-nav a{font-size:11px;padding:10px 7px}.layout{grid-template-columns:minmax(0,1fr);padding:10px 14px}.sidebar-note{display:none}.browse{padding:10px 14px}.browse summary{padding-bottom:0}.hero{padding-top:6px}.hero h1{font-size:28px}.concept-row{padding:16px;gap:12px}.concept-row p{font-size:13px}.training-links{grid-template-columns:1fr}.hero p{font-size:14px}footer{font-size:10px;padding:8px 14px!important}.lesson-copy{padding:18px!important}}
.brand{gap:10px;text-decoration:none;font-size:25px;font-weight:700;letter-spacing:-1px;line-height:1.1}.brand img{width:42px;height:48px}.brand-com{color:#e47850}.brand small{display:block;font-size:10px;letter-spacing:0;font-weight:400;margin-top:6px}@media(max-width:760px){.brand{font-size:21px}.brand img{width:32px;height:40px}.brand small{font-size:8px}}
.grade-group{border-top:1px solid #d2e3db;padding:10px 0}.grade-group summary{cursor:pointer;padding:8px 6px!important}.grade-group .menu-link{font-size:13px;line-height:1.5}

.site-header{flex-wrap:wrap}.worksheet-search{display:flex;align-items:center;gap:8px;margin-left:auto;background:white;border:1px solid #bcd2c8;border-radius:8px;padding:4px 6px}.worksheet-search label{display:flex;padding:0 4px}.worksheet-search input{min-width:0;width:190px;border:0;background:transparent;padding:6px;color:#214c50;font-size:14px}.worksheet-search button{font-size:12px;padding:6px 10px}.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}@media(max-width:760px){.worksheet-search{order:4;width:100%;margin:2px 0}.worksheet-search input{flex:1;width:0}}

.lesson-layout{grid-template-columns:minmax(0,1fr)}.practice-box{position:static}.practice-box .practice-link{display:block}.lesson-copy{margin-top:0!important}

#worksheet-player{display:block;width:100%;min-height:650px;border:0;background:white;margin-top:18px;border-radius:8px}.practice-link[aria-current=page]{border:2px solid #176e5c}.practice-box{padding:16px}.steps{display:none}

.training-group{border-top:1px solid #d2e3db;padding:8px 0}.training-group summary{padding:8px 4px!important;cursor:pointer}.training-group .menu-link{font-size:12px;line-height:1.4}.training-gallery{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:20px}.training-card{display:block;min-width:0;text-decoration:none;background:white;border:1px solid #c9ddd6;border-radius:10px;overflow:hidden;padding:12px}.training-card:hover{border-color:#176e5c;box-shadow:0 3px 12px #214c5015}.training-card img{display:block;width:100%;aspect-ratio:0.72;object-fit:contain;object-position:top;background:#f4f7f5}.training-card span{display:block;white-space:nowrap;overflow:hidden;text-overflow:ellipsis;font-size:14px;font-weight:700;padding-top:12px;text-align:center}@media(max-width:1100px){.training-gallery{grid-template-columns:repeat(2,minmax(0,1fr))}}@media(max-width:500px){.training-gallery{gap:10px}.training-card{padding:7px}.training-card span{font-size:11px}}

.training-domain{--domain-ink:#145b43;--domain-bg:#e7f4eb;--domain-line:#93bca2;border:1px solid var(--domain-line);border-radius:10px;margin:14px 0;overflow:hidden;background:var(--domain-bg)}
.training-domain.domain-fractions{--domain-ink:#653b8b;--domain-bg:#f3edf9;--domain-line:#bea4d5}
.training-domain.domain-decimals{--domain-ink:#235c94;--domain-bg:#eaf3fc;--domain-line:#95b9db}
.browse .domain-heading{font-size:19px;font-weight:800;line-height:1.35;letter-spacing:0;margin:0;padding:14px 12px;color:var(--domain-ink);background:var(--domain-bg);border-bottom:2px solid var(--domain-line)}
.training-domain .training-group{margin:0;padding:4px 8px;border-color:var(--domain-line)}
.training-domain .training-group summary{font-size:16px;font-weight:700;color:var(--domain-ink);padding:10px 5px!important}
.training-domain .menu-link{color:var(--domain-ink);background:#ffffff80}
.training-domain .menu-link[aria-current=page]{background:var(--domain-ink);color:white}
.training-domain .nested{border-left-color:var(--domain-line)}

.paired-gallery{grid-template-columns:repeat(2,minmax(0,1fr));align-items:start}.worksheet-pair{min-width:0;background:white;border:1px solid #c9ddd6;border-radius:10px;padding:14px}.worksheet-pair h2{font-size:16px;line-height:1.4;margin:0 0 12px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}.paired-previews{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px}.paired-previews .training-card{padding:7px}.paired-previews .training-card span{font-size:12px}@media(max-width:900px){.paired-gallery{grid-template-columns:minmax(0,1fr)}}

.separate-gallery{grid-template-columns:repeat(2,minmax(0,1fr));gap:16px}.separate-gallery .training-card{padding:10px}.separate-gallery .training-card span{font-size:12px}@media(max-width:1100px){.separate-gallery{grid-template-columns:repeat(2,minmax(0,1fr))}}@media(max-width:500px){.separate-gallery{gap:10px}.separate-gallery .training-card{padding:7px}.separate-gallery .training-card span{font-size:11px}}

/* Uniform A4 preview frame; preserve full sheet without cropping. */
.training-card>img{display:block!important;width:100%!important;height:auto!important;aspect-ratio:210/297!important;object-fit:contain!important;object-position:top center!important;background:#fff!important}