.da-lesson{max-width:1100px;margin:auto;color:#173950}.da-lesson h1{font-size:clamp(18px,3vw,26px);text-align:center;margin:3px}.da-controls,.da-navigation,.da-choices{display:flex;justify-content:center;align-items:center;flex-wrap:wrap;gap:5px;margin:5px 0}.da-lesson label{display:inline-flex;align-items:center;gap:4px;flex-wrap:wrap}.da-lesson button,.da-lesson select,.da-lesson input{font:inherit}.da-lesson button{border:2px solid #075bb6;background:#e4f1ff;color:#064278;font-weight:800;padding:5px 9px;cursor:pointer}.da-lesson button:disabled{opacity:.45;cursor:not-allowed}.da-lesson button:focus-visible{outline:3px solid #a85c00;outline-offset:2px}.da-board{border:2px solid #486d87;background:#fff;padding:6px}.da-caption{padding:5px;margin:0 0 5px;background:#fff0b4;border:1px solid #a96c00;color:#663a00;text-align:center;font-weight:800;line-height:1.5;min-height:3em}.da-intro,.da-equation{font-weight:900;font-size:clamp(25px,4vw,36px);text-align:center;padding:6px;color:#075bb6}.da-table{max-width:800px;margin:4px auto;padding:0 9px 0 23px}.da-row{display:grid;grid-template-columns:repeat(var(--da-cols),minmax(0,1fr));gap:4px;position:relative}.da-row>div{position:relative;min-width:0;text-align:center;background:#edf4ff;border:1px solid #8aa7c0;padding:3px 1px}.da-row b{font-size:clamp(24px,4vw,36px);font-weight:900;line-height:1.2}.da-row small{display:block;height:21px;font-size:18px;font-weight:900;color:#a70955;line-height:1.1}.da-first,.da-second{margin:4px 0}.da-row .da-changed b{text-decoration:line-through;color:#63788c}.da-head>div{border:0;background:none;padding:0}.da-head button{font-size:12px;padding:3px 1px;width:100%;min-height:38px}.da-row .da-active{background:#ffedac;border:2px solid #a26000}.da-row .da-added b{color:#a55000}.da-op{position:absolute;left:-22px;top:3px;font:900 28px system-ui;color:#ab0d58}.da-result{border-top:3px solid #173950;padding-top:4px}.da-result b{color:#006344}.da-boundary{border-right:3px solid #173950!important}.da-row:not(.da-head)>.da-boundary:after{content:'٫';position:absolute;right:-7px;bottom:0;font:900 28px system-ui;color:#173950;z-index:1}.da-key{font-size:14px;font-weight:800;text-align:center;color:#734400;margin:5px 0 2px}.da-model svg{display:block;width:100%;max-height:190px}.da-count{font-size:24px;font-weight:900;text-align:center;color:#075bb6;margin:2px}.da-question{background:#fff0bc;border:3px solid #a75e00;padding:8px;text-align:center;margin:6px 0}.da-question strong{font-size:17px}.da-choices button{min-width:42px;font-size:23px;background:white}.da-question p{color:#855000;font-weight:800}.da-lesson form{display:flex;align-items:center;flex-wrap:wrap;gap:7px}.da-lesson form input{width:150px}.da-lesson form small{width:100%}.da-lesson [hidden]{display:none!important}
@media(max-width:500px){.da-caption{font-size:12px}.da-controls label{font-size:12px}.da-row{gap:3px}.da-row b{font-size:25px}.da-head button{font-size:9px;min-height:36px;line-height:1.3}.da-row small{font-size:16px;height:18px}.da-key{font-size:12px}.da-count{font-size:21px}.da-choices{gap:3px}.da-choices button{min-width:37px;padding:4px}.da-table{padding-left:20px}}
@media(max-height:500px) and (min-width:650px){.da-board{padding:4px}.da-caption{min-height:0;font-size:12px;margin:2px}.da-model svg{max-height:100px}.da-row b{font-size:24px}.da-head button{min-height:27px;font-size:10px}.da-row small{height:16px;font-size:14px}.da-row>div{padding:1px}.da-first,.da-second{margin:2px}.da-key{font-size:11px;margin:2px}.da-count{font-size:20px}.da-equation{font-size:25px;padding:2px}}
.da-lesson .da-table{padding-left:9px;padding-right:23px}
.da-lesson .da-op{left:auto;right:-22px}
.da-row small.da-carry{box-sizing:border-box;width:21px;height:21px;line-height:17px;margin-inline:auto;border:2px solid #a70955;border-radius:50%;font-size:14px;background:#fff0f7;color:#a70955}
@media(max-width:500px){.da-row small.da-carry{width:18px;height:18px;line-height:14px;font-size:12px}.da-lesson .da-table{padding-right:22px}}