:root{
  color-scheme:light;--slate:#3a505d;--blue:#bac8d2;--pale:#e6edf1;--ink:#233944;--muted:#536a77;--line:#c4d0d8;--paper:#fff;--error:#8b303c;
  font-family:'Economica','Arial Narrow',Arial,sans-serif;font-size:20px;color:var(--ink);background:var(--pale)
}
html,body{background:#bac8d2}
.precision-note{grid-column:1/-1;margin:3px 0 6px;color:var(--slate);line-height:1.28;font-size:.85rem}
.practice-bar{display:grid;grid-template-columns:minmax(180px,1.3fr) minmax(170px,1fr) auto;align-items:end;gap:8px 18px;padding:9px 14px;background:#f9fbfc;border:1px solid #a4b7c3;border-radius:10px;margin-bottom:10px}
.practice-field{display:grid;gap:4px;min-width:0}
.practice-field>span,.stage-heading{font:700 .68rem/1.25 Arial,sans-serif;color:var(--slate)}
.practice-field select,.quiet-action,.choice-buttons button,.formula-context button,.row-pick{min-width:0;max-width:100%;font-size:.94rem;padding:5px 9px;background:#fff;color:var(--ink);border:1px solid #91a4b0;border-radius:5px}
.mode-switch{display:flex;padding:2px;background:#e6edf1;border:1px solid #bbc9d2;border-radius:7px}
.mode-switch button{border-radius:4px;padding:4px 12px;background:transparent;font-weight:bold;font-size:.91rem}
.mode-switch button[aria-pressed=true],.formula-context button[aria-pressed=true]{color:#fff;background:#3a505d}
.case-intro,.protocol-panel,.stage-heading{flex:1 1 100%;width:100%;line-height:1.4}
.case-intro{font-size:1rem}
.stage-heading{border-top:1px solid var(--line);padding-top:6px}
.protocol-panel,.worked-panel,.follow-up{background:white;border:1px solid #91a4b0;border-radius:7px;padding:6px 12px}
.protocol-panel summary,.worked-panel summary,.focus-feedback summary{font-weight:bold;color:#344c59;cursor:pointer;min-height:44px;align-content:center}
.protocol-panel p,.worked-panel p,.follow-up p{margin:5px 0;line-height:1.35}
.protocol-panel p{font-size:.9rem}
.protocol-panel table{border-collapse:collapse;width:100%;table-layout:fixed;margin:6px 0}
.protocol-panel td,.protocol-panel th{border:1px solid var(--line);padding:5px;text-align:left;font-size:.88rem;line-height:1.2;overflow-wrap:anywhere}
.protocol-panel thead,.verified-row{background:var(--pale)}
.row-pick{width:100%;font-weight:bold}
.focus-feedback{width:100%;padding:10px 14px;margin:6px 0;background:#fff6f5;color:#612b32;border:1px solid #b66c73;border-left:5px solid #ae3d4a;border-radius:6px;font-size:1.05rem;line-height:1.3}
.focus-feedback>strong{font-size:1.18rem}.focus-feedback.success,.focus-feedback.hint{background:#f8f5ea;border-color:#9c7c28;color:#39454b}
.focus-feedback summary{display:list-item;width:fit-content;font-size:.85rem;text-decoration:underline;min-height:32px;padding:5px 0}
.target-section .focus-feedback p,.focus-feedback p{color:inherit;font-size:1rem}
.target-section .target-error:has(+.focus-feedback:not([hidden])){display:none}
.check-row,.choice-buttons,.formula-context{display:flex;align-items:center;gap:8px;flex-wrap:wrap}
.quiet-action{font-weight:bold}.check-row{margin:4px 0}.check-row span{font-size:.85rem}
.formula-context{border-left:3px solid #9c7c28;padding:5px 10px;background:#f9f7ef;margin-top:6px}
.formula-context button{min-width:44px;margin:2px}
.worked-panel article{padding:8px 0;border-top:1px solid var(--line)}.worked-panel h3{font-size:1.02rem}
.worked-panel ol{margin:7px 0;padding-left:24px}
.worked-equation{display:flex;flex-wrap:wrap;align-items:center;gap:8px;background:var(--pale);padding:10px;border-radius:5px}
.worked-fraction{display:inline-grid;text-align:center;min-width:40px}.worked-fraction b:first-child{border-bottom:1.5px solid currentColor}
.follow-up{padding-block:12px}.lab-footer{padding:12px 0 4px;font-size:.76rem;color:#374b55;text-align:center}
@media(max-width:720px){.practice-bar{grid-template-columns:minmax(0,1fr) auto;padding:7px 10px;gap:6px}.practice-field:first-child{grid-column:1/-1}.mode-switch button{padding-inline:7px}.practice-bar select{font-size:.88rem}}
@media(max-width:980px){.follow-up,.worked-panel,#result-feedback{order:3}}
@media(pointer:coarse){.unit-button,.slot-button,.flip-button,.mode-switch button,.focus-feedback summary,.text-button,.choice-buttons button,.quiet-action{min-height:44px!important}.unit-button{min-width:44px}.protocol-panel summary,.worked-panel summary{padding-block:8px}}
*{box-sizing:border-box}
body{margin:0}
button,input,select{font:inherit;min-height:44px}
button,select,summary{cursor:pointer}
button{color:inherit;border:0;touch-action:manipulation}
button:disabled,select:disabled{cursor:default;opacity:.55}
button:not(:disabled),select{transition:background .16s,border-color .16s,box-shadow .16s}
button:focus-visible,select:focus-visible,input:focus-visible,summary:focus-visible{outline:3px solid var(--slate);outline-offset:3px}
button:not(:disabled):active{transform:translateY(1px)}
h1,h2,h3,p{margin:0}
h2{font-size:1.1rem;font-weight:700;line-height:1.2}
[hidden]{display:none!important}
.worked-extras ul{padding-left:1.3em;margin:4px 0}
.worked-extras{margin-block:6px 12px;border-left:3px solid #9c7c28;padding:4px 12px}.worked-extras h3{margin:0}
.visually-hidden{position:absolute;width:1px;height:1px;padding:0!important;margin:-1px!important;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}
.app-shell{max-width:1280px;margin:0 auto;padding:0 18px 12px}
.masthead{display:flex;align-items:center;gap:20px;min-height:60px;padding:7px 0;margin-bottom:10px;border-bottom:1px solid var(--line)}
.brand{display:flex;align-items:center;gap:10px;font-family:'Julius Sans One',sans-serif;font-size:.7rem;letter-spacing:.055em}
.brand-mark{width:32px;height:32px;flex-shrink:0;display:grid;place-items:center;border-radius:50%;background:var(--slate);color:#fff;font-family:'Economica',sans-serif;font-weight:700;font-size:.85rem;letter-spacing:0}
.lab-title{font-size:1.5rem;line-height:1.1;letter-spacing:-.015em;white-space:nowrap}
.lab-title>span{font-size:.85rem;letter-spacing:.04em;color:var(--muted);margin-right:4px}
.masthead #restart{margin-left:auto}
.text-button{display:inline-flex;align-items:center;justify-content:center;gap:8px;border-radius:5px;padding:5px 9px;background:transparent;color:var(--slate);font-size:.85rem;font-weight:700}
.text-button:hover{background:#d7e1e8}
.practice-layout{display:grid;grid-template-columns:minmax(0,1fr) 240px;gap:12px;align-items:start}
.problem-flow,.guidance-flow{display:grid;align-content:start;min-width:0}
.problem-flow{gap:8px}
.guidance-flow{gap:12px}
.question-section,.workspace{background:var(--paper);border:1px solid var(--line);border-radius:10px;padding:12px 14px;min-width:0}
.section-heading{display:flex;align-items:center;justify-content:space-between;gap:10px}
.problem-navigation{display:flex;align-items:center;gap:8px;min-width:0}
.problem-picker{max-width:240px;min-width:0;width:100%;border:1px solid var(--line);border-radius:4px;background:#f7f9fa;color:var(--slate);font-size:.75rem;padding:4px 6px}
.mode-label,.small-label,.coach-step{font-family:Arial,sans-serif;font-size:.65rem;font-weight:600;letter-spacing:.055em;line-height:1.35}
.mode-label{padding:4px 7px;border-radius:4px;background:var(--pale);color:var(--slate);white-space:nowrap}
.question-section{position:relative;z-index:6;display:flex;align-items:center;flex-wrap:wrap;gap:7px 16px}
.question-section>.section-heading{width:100%}
.question-copy{font-size:1.05rem;line-height:1.65;flex:1 1 320px;min-width:0}
.problem-note{width:100%;font-size:.8rem;line-height:1.2;color:var(--muted)}
.question-choices{display:flex;align-items:center;flex-wrap:wrap;gap:7px 16px;width:100%;min-width:0}
.show-starting-choices .question-choices{align-items:start;margin-top:20px}
.show-starting-choices .question-copy{border-radius:5px;outline:2px solid var(--blue);outline-offset:4px}
.show-starting-choices.needs-conversion .conversion-toggle{box-shadow:0 0 0 2px var(--blue)}
.choice-arrows{position:absolute;inset:0;width:100%;height:100%;pointer-events:none;color:var(--slate);overflow:visible}
.choice-arrow{fill:none;stroke:currentColor;stroke-width:2;stroke-linecap:round}
.source-wrap{display:inline-block;vertical-align:middle;max-width:100%;margin:3px 2px}
.source{display:inline-flex;flex-direction:column;align-items:center;justify-content:center;vertical-align:middle;min-width:85px;max-width:100%;padding:5px 9px;border:1.5px solid var(--blue);border-radius:6px;background:var(--pale);font-size:1.1rem;font-weight:700;line-height:1.15}
.source:not(:disabled):hover{border-color:var(--slate);background:#d8e4eb}
.source.selected{border-color:var(--slate);box-shadow:0 0 0 2px var(--slate);background:#d9e3ea}
.source.used{color:var(--muted);background:#f3f6f8;border-style:dashed}
.source:disabled{opacity:.7}
.source-unit{font-weight:400}
.source-status{font-family:'Economica','Arial Narrow',Arial,sans-serif;font-size:.7rem;font-weight:400;line-height:1.15;color:var(--muted);margin-top:3px}
.source.selected .source-status{color:var(--ink)}
.partner-hint{font-size:.7rem;line-height:1.15;color:var(--muted);text-align:center}
.source-hint{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap}
.conversion-copy{display:inline-grid;gap:3px;font-size:.95rem}
.conversion-toggle{display:inline-flex;align-items:center;gap:8px;padding:6px 9px;border:1.5px solid var(--slate);border-radius:5px;background:#fff;color:var(--slate);font-size:.85rem;font-weight:700}
.conversion-toggle:hover,.conversion-toggle[aria-expanded='true']{background:var(--pale)}
.conversion-toggle.selected{box-shadow:0 0 0 2px var(--slate);background:var(--pale)}
.conversion-toggle.used{border-style:dashed;background:#f3f6f8;color:var(--muted)}
.conversion-toggle[aria-disabled='true']{opacity:.65}
.conversion-menu{position:absolute;left:12px;top:calc(100% - 4px);z-index:20;width:min(270px,calc(100% - 24px));padding:6px;border:1.5px solid var(--slate);border-radius:8px;background:#f7f9fa;box-shadow:0 6px 20px #23394428}
.conversion-menu-heading{display:flex;align-items:center;justify-content:space-between;gap:6px}
.conversion-menu h3{font-size:.9rem}
.conversion-menu-heading .text-button{font-family:Arial,sans-serif;font-size:1.1rem;min-width:44px}
.menu-goal{display:none;align-items:center;gap:4px;font-size:.7rem;white-space:nowrap}
.menu-goal .goal-unit{font-size:.85rem}
.conversion-menu-hint{padding:5px 6px;margin:0 3px 3px;border-radius:4px;background:var(--pale);font-size:.75rem;line-height:1.2}
.conversion-options{display:grid;gap:3px;max-height:min(210px,32dvh);overflow-y:auto;overscroll-behavior:contain;padding:3px}
.conversion-option{display:grid;grid-template-columns:minmax(0,1fr) auto;align-items:center;gap:2px 6px;min-height:48px;padding:5px 7px;border:1px solid var(--line);border-radius:5px;background:#fff;text-align:left;line-height:1.15}
.conversion-option-name{grid-column:1/-1;font-size:.7rem;color:var(--muted)}
.conversion-option>strong{font-size:.9rem;overflow-wrap:anywhere}
.conversion-option-status{max-width:90px;font-size:.7rem;color:var(--slate);text-align:right}
.conversion-option.recommended{border-color:var(--slate);border-left-width:4px}
.conversion-option[aria-pressed='true']{border:2px solid var(--slate);background:var(--pale)}
.conversion-option:hover{background:var(--pale)}
.conversion-note{font-size:.75rem;line-height:1.25;color:var(--muted);margin:6px 4px 0}
.conversion-note a{color:var(--slate);text-underline-offset:3px}
.target-section{padding:15px;background:var(--slate);color:white;border-radius:10px;min-width:0}
.target-section .small-label{color:var(--blue);margin-bottom:7px}
.target-section h2{font-size:1.2rem;margin-bottom:12px}
.target-section form{display:flex;flex-direction:column;gap:8px}
.target-section select{width:100%;min-width:0;padding:7px 9px;border:1px solid var(--blue);border-radius:5px;background:#fff;color:var(--ink);font-size:.95rem}
.primary-button{display:inline-flex;align-items:center;justify-content:center;gap:10px;border-radius:5px;padding:8px 12px;background:var(--slate);color:#fff;font-size:.95rem;font-weight:700;white-space:nowrap}
.primary-button:hover:not(:disabled){background:#263f4d}
.target-section .primary-button{background:var(--blue);color:var(--ink);justify-content:space-between}
.target-section .primary-button:hover{background:#d5e0e7}
.target-section :focus-visible{outline-color:white}
.target-section p{font-size:.85rem;line-height:1.3;color:var(--pale)}
.target-section:has(#target-confirmed:not([hidden])){display:none}
.target-error,.goal-reminder{margin-top:9px;border-left:2px solid var(--blue);padding-left:8px}
.coach{padding:3px 2px}
.coach-step{color:var(--muted);margin-bottom:8px}
.coach h2{font-size:1.2rem;line-height:1.2;margin-bottom:9px}
.coach p{font-size:.95rem;line-height:1.35;color:var(--slate)}
.coach-progress{display:flex;gap:5px;margin:14px 0 9px}
.coach-progress span{height:3px;border-radius:2px;background:#c2cfd7;flex:1}
.coach-progress span.passed{background:var(--slate)}
.coach .coach-footnote{font-size:.8rem;color:var(--muted)}
.coach-goal{margin-top:12px;padding:10px 12px;border:1px solid var(--slate);border-radius:8px;background:#fff}
.coach-goal h3{font-size:.9rem;margin-bottom:6px}
.coach-goal-equation{display:flex;align-items:center;gap:10px}
.coach-goal-equals{font-family:Arial,sans-serif;font-size:1.1rem}
.coach-goal-fraction{flex:1;min-width:0}
.coach-goal-fraction>div{display:flex;align-items:center;justify-content:space-between;gap:8px;min-height:34px;padding:4px 0}
.coach-goal-top{border-bottom:2px solid var(--slate)}
.coach-goal-position{font-size:.7rem;color:var(--muted)}
.coach-goal-value{display:flex;align-items:center;gap:5px;font-size:1.1rem;font-weight:700}
.workspace{container-type:inline-size}
.unit-help{position:relative;flex-shrink:0}
.unit-help summary{font-size:.8rem;color:var(--muted);padding:4px 6px;border-radius:4px;min-height:28px;line-height:1.25}
.unit-help[open] summary{background:var(--pale);color:var(--ink)}
.unit-legend{position:absolute;right:0;top:calc(100% + 5px);z-index:12;display:grid;gap:10px;min-width:220px;padding:12px;background:#fff;border:1px solid var(--slate);border-radius:7px;box-shadow:0 5px 15px #23394425;font-size:.8rem;color:var(--muted)}
.unit-legend>span{display:inline-flex;gap:9px;align-items:center}
.legend-unit{position:relative;display:inline-flex;justify-content:center;align-items:center;min-width:26px;height:28px;border:1px solid var(--slate);border-radius:3px;background:#fff;color:var(--slate);font-size:.8rem}
.legend-unit .match-mark{position:absolute;right:-3px;top:-7px}
.legend-unit.canceled{background:var(--pale);text-decoration:line-through}
.selection-strip{display:flex;align-items:center;flex-wrap:wrap;gap:6px 12px;min-height:34px;margin-top:7px;padding:6px 10px;border-radius:5px;background:#f2f5f7;color:var(--muted);font-size:.85rem;line-height:1.25}
.selection-strip.active{position:sticky;top:6px;z-index:5;background:#dce7ed;border:1px solid #9fb2bf;color:var(--ink);box-shadow:0 3px 8px #23394412}
.selection-strip.error{background:#fcf4f5;color:var(--error)}
.selection-identity{display:flex;align-items:center;gap:7px;max-width:100%;flex-shrink:0}
.selection-label,.inline-coach-step{font-family:Arial,sans-serif;font-size:.65rem;font-weight:600;line-height:1.2;letter-spacing:.04em;color:var(--slate)}
.selected-piece{display:block;max-width:100%;padding:4px 9px;border:2px solid var(--slate);border-radius:5px;background:#fff;color:var(--ink);font-size:1.25rem;font-weight:700;line-height:1.1;overflow-wrap:anywhere}
.selection-instruction{flex:1 1 150px;min-width:0}
.inline-coach{display:none}
.setup-placement{position:relative}
.selection-strip.placement-callout{border:2px solid var(--slate);background:var(--pale);color:var(--ink)}
.selection-strip.show-cancel-tip{border:2px solid #9c7c28;background:var(--pale);color:var(--ink);box-shadow:0 2px 6px #23394412}
.selection-strip.show-cancel-tip .selection-identity,.selection-strip.show-cancel-tip .selection-instruction,.selection-strip.show-cancel-tip .inline-coach{display:none}
.cancellation-tip{display:flex;align-items:center;gap:9px;width:100%;min-width:0}
.cancellation-tip-mark{flex-shrink:0;color:#735b1d;font-weight:700;font-size:1.1rem}
.cancellation-tip p{flex:1;min-width:0}
.cancellation-tip strong{font-weight:700}
.cancellation-tip .text-button{flex-shrink:0;width:44px;padding:0;font-family:Arial,sans-serif;font-size:1rem}
.placement-tip-dismiss{flex-shrink:0;width:44px;padding:0;font-family:Arial,sans-serif;font-size:1rem}
.placement-arrows{position:absolute;inset:0;width:100%;height:100%;pointer-events:none;color:var(--slate);overflow:visible}
.show-placement-tip .formula{padding-top:30px}
.slot-button.placement-destination{border:2px solid var(--slate);background:var(--pale);box-shadow:0 0 0 2px #bac8d260}
.formula{display:grid;grid-template-columns:minmax(0,1fr) 16px minmax(90px,.23fr);align-items:start;gap:6px;padding:8px 0}
.factor-chain{display:grid;grid-template-columns:repeat(var(--factor-count),minmax(0,1fr));gap:6px;min-width:0}
.factor-entry{display:grid;grid-template-columns:12px minmax(0,1fr);column-gap:4px;min-width:0}
.factor-entry:first-child{grid-template-columns:minmax(0,1fr)}
.fraction-units{display:inline-flex;align-items:center;justify-content:center;flex-wrap:wrap;gap:4px;max-width:100%}
.unit-product{font-size:.8rem}
.compound-half{flex-direction:column;gap:2px}
.formula.has-compound .fraction-half{min-height:86px}
.formula.has-compound .times,.formula.has-compound .equation-equals{height:184px}
.goal-fraction{position:sticky;top:12px}
@container(max-width:740px){
 .factor-chain[data-count="4"]{grid-template-columns:repeat(2,minmax(0,1fr))}
}
@container(max-width:560px){
 .factor-chain[data-count="3"]{grid-template-columns:repeat(2,minmax(0,1fr))}
}
.fraction{min-width:0}
.fraction-core{padding:5px 8px;border:1px solid var(--line);border-radius:8px;background:#fbfcfd}
.fraction-core.filled{background:#fff;border-color:var(--blue)}
.fraction-half{display:flex;flex-wrap:wrap;align-items:center;justify-content:center;gap:6px;min-height:68px;padding:6px 0;width:100%;min-width:0}
.fraction-half:first-child{border-bottom:2px solid var(--slate)}
.slot-button{width:100%;min-height:52px;padding:3px;border:1px dashed var(--line);border-radius:4px;background:transparent;color:var(--muted);font-size:.8rem;line-height:1.1}
.slot-button:not(:disabled){color:var(--ink)}
.slot-button:not(:disabled):hover{background:var(--pale);border-color:var(--slate)}
.fraction-number{font-size:1.5rem;font-weight:700;white-space:nowrap;line-height:1.1}
.bare-one{color:#627985}
.unit-button{position:relative;min-width:44px;min-height:44px;height:44px;padding:4px 8px;border:1.5px solid var(--slate);border-radius:5px;background:#fff;color:var(--slate);font-size:1.05rem;line-height:1;white-space:nowrap}
.unit-button.matched,.legend-unit.matched{background:var(--blue);border-color:var(--slate)}
.unit-button.unit-match-cue{animation:unit-match-pulse .7s ease-in-out 2;transform-origin:center}
.unit-button.chosen{outline:3px solid var(--slate);outline-offset:3px}
.unit-button.canceled{color:var(--muted);background:var(--pale);border-color:var(--line);text-decoration:line-through;text-decoration-thickness:2px;opacity:.8}
.unit-button .match-mark{position:absolute;top:-6px;right:-5px;display:grid;place-items:center;width:13px;height:13px;border-radius:50%;background:var(--slate);color:#fff;font-family:Arial,sans-serif;font-size:.65rem;line-height:1}
.times,.equation-equals{display:flex;align-items:center;justify-content:center;height:148px;font-family:Arial,sans-serif;font-size:1rem;color:var(--slate)}
.flip-button{display:flex;justify-content:center;align-items:center;gap:6px;min-height:44px;margin:0 auto;padding:3px 10px;border-radius:5px;background:transparent;font-size:.8rem}
.flip-button:hover:not(:disabled){background:var(--pale)}
.flip-button.flip-correction-target{font-weight:700;color:#a62c37;background:#fcf4f5}
.flip-tip{display:flex;flex-wrap:wrap;align-items:center;gap:8px;margin:18px 0 10px;padding:6px 10px;border:2px solid var(--slate);border-radius:7px;background:var(--pale);font-size:.85rem;line-height:1.25}
.flip-tip p{flex:1 1 220px;min-width:0}
.flip-tip strong{color:#c5454f}
.flip-tip.flip-correction{border-color:#c5454f;background:#fcf4f5}
.flip-tip-next{min-height:44px;padding:4px 6px;background:transparent;font-size:.85rem;font-weight:700;text-decoration:underline;text-underline-offset:3px;white-space:nowrap}
.flip-tip .text-button{flex-shrink:0;width:44px;padding:0;font-family:Arial,sans-serif;font-size:1rem}
.flip-symbol{font-family:Arial,sans-serif;font-size:1rem}
.goal-core{background:var(--pale);border-color:var(--slate)}
.goal-half{flex-direction:column;gap:3px;padding:4px 0}
.goal-position{font-size:.7rem;line-height:1.1;color:var(--muted)}
.goal-value{display:flex;align-items:center;justify-content:center;gap:5px;min-height:32px}
.goal-number{font-size:1.35rem;line-height:1.1;font-weight:700}
.goal-unit{padding:3px 6px;border:1px solid #735b1d;border-radius:4px;background:#9c7c28;color:#111;font-size:1.05rem;font-weight:700;line-height:1.1}
.goal-caption{display:flex;justify-content:center;align-items:center;min-height:44px;font-size:.8rem;font-weight:700;color:var(--slate);text-align:center}
.slot-short{display:none}
.slot-button,.unit-button{scroll-margin-top:85px}
.workspace-bottom{display:grid;grid-template-columns:minmax(195px,.8fr) minmax(260px,1fr);align-items:start;gap:10px 18px;border-top:1px solid var(--line);padding-top:8px}
.unit-readout{display:grid;grid-template-columns:1fr auto;align-items:center;gap:3px 8px;min-width:0}
.unit-readout>span:first-child{font-size:.8rem;color:var(--muted)}
.residual-fraction{display:grid;grid-template-columns:max-content minmax(36px,1fr);align-items:center;column-gap:10px;grid-column:1/-1;grid-row:2;min-width:0}
.residual-label{font-size:.7rem;color:var(--muted);line-height:1.2}
.residual-fraction strong{padding:2px 5px;font-size:1.05rem;text-align:center;line-height:1.2;overflow-wrap:anywhere}
.residual-numerator{border-bottom:2px solid var(--slate)}
.target-match{grid-column:2;grid-row:1;font-size:.7rem;color:var(--slate)}
.answer-section{display:grid;grid-template-columns:1fr;gap:5px;min-width:0}
.answer-section h2{font-size:1rem;line-height:1.2}
.setup-success{display:flex;align-items:center;gap:8px;padding:6px 8px;border:1.5px solid #9c7c28;border-radius:6px;background:var(--pale);color:var(--ink);font-size:.85rem;line-height:1.25}
.setup-success p{flex:1;min-width:0}
.setup-success p>span{display:block;margin-top:3px}
.setup-success-mark{color:#735b1d;font-family:Arial,sans-serif;font-size:1.1rem;font-weight:700}
.setup-success .text-button{width:44px;padding:0;flex-shrink:0;font-family:Arial,sans-serif;font-size:1rem}
.answer-section form{display:flex;align-items:center;gap:8px;min-width:0}
.answer-input{display:grid;grid-template-columns:minmax(0,1fr) auto;align-items:center;column-gap:8px;flex:1;min-width:0;min-height:44px;padding-right:9px;border:1px solid #91a6b3;border-radius:5px;background:#fff}
.answer-input:focus-within{border-color:var(--slate);outline:2px solid var(--slate);outline-offset:2px}
.answer-input.answer-ready-cue{border-color:#9c7c28;animation:answer-entry-pulse .7s ease-in-out 2;transform-origin:center}
.answer-input:has(input:disabled){background:#f2f5f7;border-color:var(--line);color:var(--muted)}
.answer-input input{width:100%;min-width:0;padding:7px 9px;border:0;border-radius:5px;background:transparent;color:var(--ink);font-size:.95rem}
.answer-input input:focus{outline:none;box-shadow:none}
.answer-input input::placeholder{color:var(--muted)}
.answer-input span{font-size:.9rem;white-space:nowrap}
.answer-section .primary-button{font-size:.85rem;padding:8px 10px}
.feedback{background:var(--pale);border-left:3px solid var(--slate);border-radius:0 5px 5px 0;padding:8px 10px;font-size:.85rem;line-height:1.3}
.feedback.error{border-left-color:var(--error);color:var(--error);background:#fcf4f5}
.completion-actions{display:flex;align-items:center;gap:5px;flex-wrap:wrap}
.completion-actions .text-button{font-size:.8rem}
.attention-outline{outline:3px solid var(--error);outline-offset:3px}
.target-section,.question-section,.goal-fraction{scroll-margin-block:10px}
.goal-fraction:focus{outline:none}
.pulse-once{animation:attention-pulse .65s ease-in-out 1}
.pulse-twice{animation:target-pulse .65s ease-in-out 2}
.choose-unit-cue{animation:choose-unit-pulse .75s ease-in-out 2;transform-origin:center}
.goal-control-reminder{animation:choose-unit-pulse .65s ease-in-out 1;transform-origin:center}
@keyframes choose-unit-pulse{0%,100%{transform:scale(1);box-shadow:0 0 0 0 #8b303c00}50%{transform:scale(1.025);box-shadow:0 0 0 5px #c7848c;border-color:var(--error)}}
@keyframes attention-pulse{0%,100%{box-shadow:0 0 0 0 #8b303c00}50%{box-shadow:0 0 0 9px #8b303c38}}
@keyframes target-pulse{0%,100%{box-shadow:0 0 0 0 #9c7c2800}50%{box-shadow:0 0 0 9px #9c7c2860}}
@keyframes answer-entry-pulse{0%,100%{transform:scale(1);box-shadow:0 0 0 0 #9c7c2800}50%{transform:scale(1.02);box-shadow:0 0 0 5px #9c7c2850}}
@keyframes unit-match-pulse{0%,100%{transform:scale(1);box-shadow:0 0 0 0 #3a505d00}50%{transform:scale(1.09);box-shadow:0 0 0 5px #3a505d40}}
.practice-layout:has(#target-form:not([hidden])) :disabled{pointer-events:none}
.goal-tip{position:relative;display:flex;align-items:center;gap:8px;flex-basis:100%;max-width:100%;padding:6px 10px;border:2px solid var(--slate);border-radius:7px;background:var(--pale);font-size:.9rem;line-height:1.25}
.goal-tip p{flex:1;min-width:0}
.goal-tip .text-button{font-family:Arial,sans-serif;font-size:1rem;flex-shrink:0;width:44px;padding:0}
@container(max-width:580px){
 .workspace-bottom{grid-template-columns:1fr;gap:8px}
 .unit-readout{grid-template-columns:auto minmax(100px,1fr) auto;gap:8px}
 .residual-fraction{grid-column:2;grid-row:1}
 .target-match{grid-column:3;grid-row:1;max-width:75px}
 .answer-section>div:first-child{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap}
 .answer-input{max-width:none}
}
@container(max-width:440px){
 .formula{grid-template-columns:minmax(0,1fr) 10px 70px;gap:4px}
 .factor-chain{gap:4px}
 .factor-entry{grid-template-columns:8px minmax(0,1fr);gap:2px}
 .fraction-core{padding:4px}
 .fraction-half{min-height:88px;gap:3px;padding:5px 0}
 .formula.has-compound .fraction-half{min-height:126px}
 .formula.has-compound .times,.formula.has-compound .equation-equals{height:262px}
 .fraction-number{font-size:1.15rem}
 .unit-button{font-size:1rem;padding:4px 5px}
 .times,.equation-equals{height:186px;font-size:.9rem}
 .goal-number{font-size:1.15rem}
 .goal-unit{font-size:.9rem;padding:3px 5px}
 .goal-value{min-height:28px;gap:3px}
 .goal-half{gap:3px}
 .goal-caption{font-size:.75rem}
 .slot-full{display:none}
 .slot-short{display:inline}
 .flip-button{padding:3px 8px}
}
@container(max-width:340px){
 .fraction-half{flex-direction:column;min-height:88px;gap:3px;padding:5px 0}
 .goal-value{flex-wrap:wrap}
 .times,.equation-equals{height:186px}
 .fraction-number{font-size:1rem}
 .selection-identity{flex-wrap:wrap}
 .selection-strip.active .selection-instruction{flex-basis:100%}
 .residual-fraction{column-gap:5px}
 .unit-readout{gap:5px}
 .target-match{max-width:50px}
}
@media(max-width:980px){
 .practice-layout{grid-template-columns:1fr;gap:8px}
 .problem-flow,.guidance-flow{display:contents}
 .target-section{order:0;display:grid;grid-template-columns:minmax(0,1fr) minmax(250px,1fr);column-gap:14px;align-items:center;padding:12px 14px}
 .target-section .small-label{grid-column:1;margin-bottom:4px}
 .target-section h2{grid-column:1;grid-row:2;margin:0;font-size:1.1rem}
 .target-section form{grid-column:2;grid-row:1/3;display:grid;grid-template-columns:minmax(0,1fr) auto;gap:8px}
 .target-section p{grid-column:1/-1}
 .question-section{order:1}
 .workspace{order:2}
 .coach{display:none}
 .menu-goal{display:inline-flex}
 .inline-coach:not([hidden]){display:flex;align-items:baseline;flex-wrap:wrap;gap:4px 10px;font-size:.85rem;color:var(--slate)}
 .inline-coach-step{flex-shrink:0}
 .inline-coach>span:last-child{flex:1 1 230px}
 .selection-strip:not(.active):not(.error) .selection-instruction{display:none}
}
@media(max-width:600px){
 .app-shell{padding:0 10px 10px}
 .masthead{gap:10px;min-height:52px;padding:4px 0;margin-bottom:8px}
 .brand-name{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap}
 .lab-title{font-size:1.25rem}
 .lab-title>span{display:block;font-size:.75rem;margin-right:0}
 .masthead #restart{font-size:.8rem;padding:5px 3px;gap:5px}
 .target-section{display:block;padding:10px 12px}
 .target-section h2{margin-bottom:8px}
 .target-section form{display:grid;grid-template-columns:minmax(0,1fr) auto}
 .question-section,.workspace{padding:10px 12px}
 .question-section{gap:6px 12px}
 .show-starting-choices .question-choices{gap:10px}
 .show-starting-choices .conversion-toggle{min-width:0}
 .mode-label{font-size:.6rem;padding:3px 5px}
 .problem-navigation{gap:4px;flex:1;justify-content:flex-end}
 .problem-picker{max-width:155px;font-size:.7rem}
 .problem-navigation .mode-label{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap}
 h2{font-size:1.05rem}
 .question-copy{font-size:1rem}
 .source{font-size:1.05rem;padding:4px 7px}
 .conversion-toggle{font-size:.8rem;padding:5px 7px;gap:6px}
 .selection-strip{font-size:.85rem;padding:6px 8px;gap:5px 9px}
 .selected-piece{font-size:1.15rem;padding:4px 7px}
 .selection-label{font-size:.6rem}
 .selection-identity{gap:5px;flex-shrink:1}
 .formula{padding:6px 0}
 .unit-help summary{font-size:.75rem}
 .goal-tip{padding:6px 8px;font-size:.85rem}
 .conversion-menu{left:8px;width:min(260px,calc(100% - 16px))}
}
@media(max-width:340px){
 .app-shell{padding-inline:8px}
 .question-section,.workspace{padding:9px}
 .lab-title{font-size:1.1rem}
 .brand-mark{width:28px;height:28px}
 .conversion-toggle{font-size:.75rem}
 .source-status{font-size:.65rem}
 .target-section form{grid-template-columns:1fr}
}
@media(prefers-reduced-motion:reduce){
 *,*::before,*::after{transition:none!important;scroll-behavior:auto!important}
 .pulse-once,.pulse-twice,.choose-unit-cue,.goal-control-reminder,.answer-input.answer-ready-cue,.unit-button.unit-match-cue{animation:none}
 .unit-button.unit-match-cue{box-shadow:0 0 0 3px #3a505d40}
 .choose-unit-cue,.goal-control-reminder{outline:2px solid #c7848c;outline-offset:2px}
 .answer-input.answer-ready-cue{outline:2px solid #9c7c28;outline-offset:2px}
}
@container(max-width:840px){.factor-chain[data-count="5"]{grid-template-columns:repeat(3,minmax(0,1fr))}}
@container(max-width:620px){.formula:has(.factor-chain:is([data-count="3"],[data-count="4"],[data-count="5"])){grid-template-columns:minmax(0,1fr) 12px 78px;align-items:start}.factor-chain:is([data-count="3"],[data-count="4"],[data-count="5"]){grid-template-columns:repeat(2,minmax(0,1fr))}}
@container(max-width:460px){.formula:has(.factor-chain:is([data-count="3"],[data-count="4"],[data-count="5"])){grid-template-columns:minmax(0,1fr) auto}.formula:has(.factor-chain:is([data-count="3"],[data-count="4"],[data-count="5"])) .factor-chain{grid-column:1/-1}.formula:has(.factor-chain:is([data-count="3"],[data-count="4"],[data-count="5"])) .equation-equals{height:auto;text-align:right;align-self:center;justify-self:end}.formula:has(.factor-chain:is([data-count="3"],[data-count="4"],[data-count="5"])) .goal-fraction{min-width:110px}.formula:has(.factor-chain:is([data-count="3"],[data-count="4"],[data-count="5"])) .goal-half{min-height:38px}.factor-chain .fraction-half{flex-wrap:wrap}.formula .fraction-units{flex-wrap:wrap}.practice-bar{min-width:0}}