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@media(max-width:760px){.site-header{height:auto;min-height:116px;flex-wrap:wrap;padding:17px 20px 10px;gap:13px}.brand{font-size:16px;flex:1}.brand-number{font-size:34px}.brand small{font-size:9px}.main-nav{order:2;width:100%;justify-content:space-between;gap:5px}.main-nav button{flex:1;padding:11px 3px;font-size:11px}.main-nav button span{font-size:12px;margin-right:3px}.icon-button{font-size:23px}.cover{min-height:calc(100svh - 169px);background-position:60% center;padding:35px 25px 24px}.cover-copy{padding-bottom:35px}.cover h1{font-size:65px;letter-spacing:2px}.cover-subtitle{font-size:14px;line-height:1.8}.cover .eyebrow{font-size:10px;letter-spacing:4px}.lesson-no{font-size:10px;margin-top:22px}.cover-activities{grid-template-columns:1fr}.cover-activities button{padding:18px 20px;gap:20px}.entry-number{font-size:32px;align-self:center}.cover-activities strong{font-size:17px;display:inline}.cover-activities small{font-size:9px;display:inline;margin-right:12px;letter-spacing:1px}.cover-activities em{font-size:10px;margin-top:5px}.cover-activities b{display:block}.primary,.secondary{padding:13px 18px;min-height:44px;font-size:12px;gap:23px}.lesson-meta{padding:20px 18px 0;gap:10px;flex-wrap:wrap;font-size:11px}.student-info{gap:12px}.student-info label{gap:5px}.student-info input{width:85px;padding:7px;font-size:11px}.activity{padding:25px 18px 30px}.page-heading{margin-bottom:23px}.page-heading h2{font-size:29px}.page-heading h2 span{font-size:11px;margin-top:8px;letter-spacing:0}.eyebrow{font-size:10px;letter-spacing:1px}.chapter-number{font-size:48px;align-self:flex-start}.observation-layout{grid-template-columns:1fr;gap:23px;padding:20px}.image-stage canvas{width:148px;height:148px;border-width:3px}.zoom-badge{font-size:9px;padding:8px;left:10px;bottom:10px}.observation-figure figcaption{font-size:10px;margin-top:12px}.observe-guide .eyebrow{display:none}.observe-guide h3{font-size:24px;line-height:1.5;margin:0 0 10px}.observe-guide h3 br{display:none}.observe-guide>p:not(.eyebrow){font-size:12px;line-height:1.8}.observe-guide>p br{display:none}.guide-person{margin:8px 0 12px}.guide-person img{height:45px;width:35px}.observe-guide>.text-button{display:inline-block;margin:0 0 0 15px;font-size:11px}.worksheet{padding:24px 20px;margin-top:20px}.sheet-heading{padding-bottom:18px;margin-bottom:23px}.sheet-heading h3{font-size:22px}.sheet-heading>span{font-size:10px}.question legend{font-size:14px;line-height:1.9}.question legend>span{font-size:23px}.answer-options{gap:10px}.answer-options label{min-width:0;flex:1;padding:12px;font-size:13px;gap:9px}.feedback{font-size:12px}.section-end>span{font-size:10px;max-width:130px;line-height:1.7}.section-end{gap:12px}.section-end .primary{white-space:nowrap;font-size:11px;gap:10px;padding:12px}.activity-instruction{flex-wrap:wrap;gap:14px}.activity-instruction strong{font-size:14px}.activity-instruction p>span{font-size:12px}.cooperation{display:none}.tool-caption{height:51px;padding:0 14px;gap:10px}.tool-caption strong{font-size:12px}.tool-caption>span{display:none}.tool-caption>button{font-size:10px}.tool-shell iframe{height:700px}#board-shell iframe{height:920px}.tool-shell.expanded{inset:5px}.rgb-selects{gap:15px;display:grid;grid-template-columns:1fr 1fr}.rgb-selects label{gap:7px}.rgb-selects b{font-size:24px}.rgb-selects select{width:100%;padding:10px 8px;font-size:12px}.rgb-selects>span{font-size:10px}.rgb-selects .secondary{grid-column:1/-1;justify-self:start}.worksheet h4{font-size:14px;line-height:1.8}.field-help{font-size:11px}.table-scroll{margin-left:-7px;margin-right:-7px}.rgb-table{font-size:12px;min-width:460px}.rgb-table td,.rgb-table th{padding:10px}.rgb-table input{padding:10px 5px}.sample-color{width:65px}.material-bar{grid-template-columns:1fr 1fr;gap:3px;margin-bottom:20px}.material-bar a{padding:13px 12px;gap:12px}.material-bar img{width:42px;height:48px}.material-bar span{font-size:11px}.material-bar small{font-size:9px;margin-top:7px}.creation-statements label{font-size:13px;gap:8px}.creation-statements input{width:100%}.review-layout{grid-template-columns:1fr;padding:20px;gap:18px}.review-layout h3{font-size:21px}.review-layout output{font-size:38px;margin-top:10px}.review-items label{padding:13px;font-size:12px;gap:10px}.review-items b{font-size:20px}.lesson-footer{padding:16px 18px;flex-wrap:wrap;font-size:9px;gap:12px}.lesson-footer .footer-name{display:none}.lesson-footer #page-controls{width:100%;justify-content:space-between;gap:10px}.lesson-footer .text-button{font-size:11px}}
@media(prefers-reduced-motion:reduce){*{transition:none!important;scroll-behavior:auto!important}}

/* 第二轮课堂简化：突出唯一主操作，减少学生的选择负担。 */
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@media(max-width:760px){.cover-start{align-self:center;min-width:205px;min-height:58px;font-size:16px;gap:30px}.cover-activities>div{padding:18px 20px;gap:20px}.activity-instruction-centered{justify-content:center}.activity-instruction strong{font-size:17px}.section-end-centered{gap:12px}.section-end-centered .primary{white-space:nowrap;font-size:11px;gap:10px;padding:12px}.creation-statements select{width:100%}}