/* Keep the original models; let their reading and input areas grow on small screens. */
@media(max-width:720px){
 body[data-reading-lesson] .shell{width:calc(100% - 24px);padding:12px 0 24px}
 body[data-reading-lesson] .stage{gap:14px}
 body[data-reading-lesson] .panel{padding:17px 16px}
 body[data-reading-lesson] .head{margin-bottom:16px}
 body[data-reading-lesson] .chapter{font-size:12px;letter-spacing:.06em}
 body[data-reading-lesson] h1{font-size:24px;line-height:1.5;margin:6px 0}
 body[data-reading-lesson] .problem{font-size:16px;line-height:1.85}
 body[data-reading-lesson] .ask,body[data-reading-lesson] .questions{font-size:16px;line-height:1.8;padding:10px 12px;margin-top:12px}
 body[data-reading-lesson] .label{font-size:13px;margin-bottom:10px}
 body[data-reading-lesson] .instruction{font-size:15px;line-height:1.75;min-height:0;margin:8px 0 15px}
 body[data-reading-lesson] .answerline{font-size:16px;gap:8px;line-height:1.8}
 body[data-reading-lesson] .answerline input{font-size:18px;min-height:44px;width:86px;padding:8px}
 body[data-reading-lesson] .feedback,body[data-reading-lesson] .hint-message{font-size:15px;line-height:1.8;min-height:25px}
 body[data-reading-lesson] .actions{gap:10px;margin-top:12px}
 body[data-reading-lesson] button.btn{font-size:15px!important;min-height:46px!important;padding:10px 15px!important;line-height:1.6!important;white-space:normal}
 body[data-reading-lesson] .step-title{font-size:12px}
 body[data-reading-lesson] .equation{font-size:18px;line-height:1.8;height:auto;min-height:36px}
 body[data-reading-lesson] .calc-note{font-size:13px;line-height:1.7}
 body[data-reading-lesson] .visuals{grid-template-columns:1fr;gap:14px}
 body[data-reading-lesson] .area-svg,body[data-reading-lesson] .money-svg,body[data-reading-lesson] .shape-box svg,body[data-reading-lesson] .figure-box svg{height:auto;min-height:220px}
 body[data-reading-lesson] .diagram-panel .diagram{min-height:240px}
 body[data-reading-lesson] .diagram-panel .row{margin:12px 0}
 body[data-reading-lesson] .rowname{font-size:14px}
 body[data-reading-lesson] .barwrap{height:46px}
 body[data-reading-lesson] .bar{height:36px;font-size:12px}
 body[data-reading-lesson] .sum-label{font-size:13px}
 body[data-reading-lesson] .legend{font-size:12px;line-height:1.8}
 body[data-reading-lesson] .pond-box,body[data-reading-lesson] .parts-box{min-height:240px;padding:14px}
 body[data-reading-lesson] .pond-box svg{height:240px}
 body[data-reading-lesson] .not-scale{font-size:12px;line-height:1.6;margin-top:6px}
 body[data-reading-lesson] .parts-title{font-size:14px;margin-bottom:12px}
 body[data-reading-lesson] .ratio-row{grid-template-columns:42px minmax(0,1fr) 55px;margin:9px 0}
 body[data-reading-lesson] .ratio-name,body[data-reading-lesson] .times{font-size:12px}
 body[data-reading-lesson] .unitbar{height:28px}
 body[data-reading-lesson] .total-parts,body[data-reading-lesson] .one-part,body[data-reading-lesson] .target-calc{font-size:15px;line-height:1.8;padding:8px;margin-top:10px}
 body[data-reading-lesson] .footer{font-size:12px;line-height:1.7}
}