:root {
  --ink: #17324d;
  --muted: #5e7184;
  --blue: #1769aa;
  --blue-dark: #0f4f82;
  --aqua: #e9f7fb;
  --yellow: #ffd866;
  --green: #238b57;
  --green-soft: #e9f8ef;
  --orange-soft: #fff3df;
  --border: #cbd8e3;
  --white: #ffffff;
}
* { box-sizing: border-box; }
body { margin: 0; color: var(--ink); background: #f4f8fb; font-family: ui-rounded, "Avenir Next", system-ui, sans-serif; font-size: 18px; }
.side-nav { position: fixed; z-index: 20; top: 92px; left: 0; }
.side-nav summary { width: 42px; padding: 10px 8px; color: var(--blue-dark); background: var(--white); border: 1px solid var(--border); border-left: 0; border-radius: 0 12px 12px 0; cursor: pointer; list-style: none; text-align: center; }
.side-nav summary::-webkit-details-marker { display: none; }
.side-nav nav { width: min(320px, calc(100vw - 24px)); display: grid; gap: 7px; margin-top: 7px; padding: 12px; background: var(--white); border: 1px solid var(--border); border-left: 0; border-radius: 0 16px 16px 0; box-shadow: 0 10px 24px rgba(23, 50, 77, .12); }
.side-nav nav a { padding: 10px 12px; color: var(--ink); text-decoration: none; border-radius: 10px; font-size: .88rem; }
.side-nav nav a:hover, .side-nav nav .active-lesson { background: var(--aqua); color: var(--blue-dark); }
.nav-chapter { border-top: 1px solid var(--border); padding-top: 6px; }
.nav-chapter > summary { width: auto; display: grid; grid-template-columns: auto 1fr; gap: 2px; padding: 9px 12px; border: 0; border-radius: 10px; color: var(--ink); background: transparent; text-align: left; font-size: .9rem; font-weight: 900; }
.nav-chapter > summary::before { content: "▸"; grid-row: 1 / span 2; margin-right: 8px; }
.nav-chapter[open] > summary::before { content: "▾"; }
.nav-chapter > summary span { grid-column: 2; color: var(--muted); font-size: .76rem; font-weight: 700; }
.nav-lessons { display: grid; gap: 3px; padding-left: 20px; }
.nav-lessons a { padding-block: 8px !important; }
.site-header { min-height: 70px; display: flex; align-items: center; justify-content: space-between; gap: 16px; padding: 14px clamp(18px, 5vw, 64px); background: var(--white); border-bottom: 1px solid var(--border); }
.brand { color: var(--ink); font-weight: 800; text-decoration: none; }
.header-status { display: flex; align-items: center; gap: 9px; }
.lesson-pill { padding: 7px 13px; border-radius: 999px; background: var(--aqua); color: var(--blue-dark); font-weight: 700; }
.coin-badge { padding: 6px 9px; border: 1px solid #ead28a; border-radius: 999px; background: #fff9df; color: #70550b; font-size: .82rem; font-weight: 800; white-space: nowrap; }
.page-shell { width: min(880px, calc(100% - 28px)); margin: 34px auto 64px; }
.card { background: var(--white); border: 1px solid var(--border); border-radius: 24px; box-shadow: 0 12px 30px rgba(23, 50, 77, .08); padding: clamp(24px, 5vw, 52px); }
.hero { text-align: left; }
.eyebrow, .difficulty { color: var(--blue); font-weight: 800; letter-spacing: .02em; text-transform: uppercase; font-size: .85rem; }
h1 { margin: 8px 0 14px; font-size: clamp(2rem, 6vw, 3.5rem); line-height: 1.08; }
.lesson-name { color: var(--muted); font-weight: 700; }
.target { margin: 28px 0; display: flex; align-items: flex-start; gap: 14px; padding: 20px; border-radius: 18px; background: var(--aqua); }
.target span { font-size: 2rem; }.target p { margin: 5px 0 0; }
.intro { color: var(--muted); max-width: 620px; }
.primary-button, .secondary-button { display: inline-flex; justify-content: center; align-items: center; min-height: 56px; padding: 13px 28px; border: 0; border-radius: 16px; font: inherit; font-weight: 800; cursor: pointer; text-decoration: none; }
.primary-button { color: white; background: var(--blue); box-shadow: 0 5px 0 var(--blue-dark); }
.primary-button:hover { background: var(--blue-dark); }.secondary-button { color: var(--blue-dark); background: var(--aqua); }
.progress-line { display: grid; gap: 8px; color: var(--muted); font-weight: 700; }
.progress-track { height: 12px; overflow: hidden; border-radius: 99px; background: #e8eef3; }.progress-track div { height: 100%; background: var(--green); }
.question-prompt { font-size: clamp(1.65rem, 5vw, 2.45rem); margin-top: 18px; }
.visual-frame { margin: 24px 0; }
.visual-frame .visual { margin: 8px 0 0; }
.visual-label { color: var(--muted); font-size: .9rem; font-weight: 800; }
.visual { margin: 28px 0; min-height: 90px; display: flex; align-items: center; justify-content: center; gap: 12px; padding: 22px; background: #f8fbfd; border: 2px solid #dbe7ef; border-radius: 20px; }
.neutral-collection { flex-wrap: wrap; gap: 18px 24px; }
.neutral-collection--loose { max-width: 620px; justify-content: flex-start; }
.neutral-object { color: var(--blue); font-size: 2rem; line-height: 1; display: inline-block; }
.neutral-object:nth-child(3n + 2) { translate: 0 7px; rotate: 4deg; }
.neutral-object:nth-child(4n) { translate: 0 -4px; rotate: -5deg; }
.pair-visual { flex-wrap: wrap; }.pair-box { display: inline-flex; gap: 5px; padding: 7px; border: 3px solid var(--blue); border-radius: 13px; }.dot { color: var(--blue); font-size: 1.6rem; line-height: 1; }.leftover { color: #d95c28; font-size: 2rem; padding: 8px; border: 3px dashed #d95c28; border-radius: 50%; }
.rows-visual { flex-direction: column; }.counter-row { min-width: 70%; display: flex; justify-content: center; gap: 7px; padding: 8px; border-bottom: 2px solid var(--border); }.extra-object-row { min-width: 70%; display: flex; justify-content: center; gap: 7px; padding: 8px; }.leftover-row { display: flex; align-items: center; gap: 10px; color: var(--muted); }
.big-number { font-size: 4.5rem; font-weight: 900; color: var(--blue); }.small-label { font-size: 1rem; margin-right: 20px; color: var(--muted); }
.number-path span { min-width: 48px; padding: 10px; border-radius: 12px; text-align: center; background: white; border: 2px solid var(--blue); font-weight: 800; }.number-path .bound { border-style: dashed; color: var(--muted); }.visual-note { margin-top: -18px; text-align: center; color: var(--muted); }
.number-path--one-to-twenty { display: grid; grid-template-columns: repeat(10, minmax(42px, 1fr)); width: 100%; gap: 9px; }
.story-change { font-size: 1.8rem; font-weight: 800; }.speech-bubble { max-width: 620px; font-size: 1.8rem; font-weight: 800; }
.linking-cubes { --cube-size: 42px; --cube-face: #35a9cf; --cube-edge: #17698f; --cube-shine: #8bd8ed; }
.linking-cube { position: relative; width: var(--cube-size); height: var(--cube-size); flex: 0 0 var(--cube-size); display: inline-block; border: 3px solid var(--cube-edge); border-radius: 8px; background: linear-gradient(135deg, var(--cube-shine) 0 16%, var(--cube-face) 17% 100%); box-shadow: inset -5px -5px 0 rgba(10, 76, 105, .16), 0 3px 0 rgba(23, 50, 77, .12); }
.linking-cube::before { content: ""; position: absolute; width: 12px; height: 5px; top: -7px; left: 50%; translate: -50% 0; border: 2px solid var(--cube-edge); border-bottom: 0; border-radius: 5px 5px 0 0; background: var(--cube-shine); }
.linking-cube::after { content: ""; position: absolute; width: 5px; height: 12px; right: -7px; top: 50%; translate: 0 -50%; border: 2px solid var(--cube-edge); border-left: 0; border-radius: 0 5px 5px 0; background: var(--cube-face); }
.loose-cube-field { max-width: 430px; display: flex; flex-wrap: wrap; justify-content: center; gap: 18px 22px; }
.loose-cube-field .linking-cube:nth-child(3n + 2) { translate: 0 7px; rotate: 3deg; }
.loose-cube-field .linking-cube:nth-child(3n) { rotate: -4deg; }
.cube-train { display: flex; align-items: center; }
.cube-train .linking-cube + .linking-cube { margin-left: -3px; }
.split-cube-trains { display: flex; align-items: center; justify-content: center; flex-wrap: wrap; gap: 34px; }
.two-row-cube-cells { display: grid; grid-auto-flow: column; grid-template-rows: auto; align-items: start; gap: 7px; }
.cube-cell { display: grid; grid-template-rows: repeat(2, var(--cube-size)); gap: 5px; }
.cube-cell--extra { margin-left: 10px; }
.feedback-leftover-cube { outline: 4px solid #d95c28; outline-offset: 5px; }
.answer-form fieldset { display: grid; gap: 12px; padding: 0; margin: 0 0 26px; border: 0; }.answer-choice { display: flex; align-items: center; gap: 14px; min-height: 64px; padding: 14px 18px; border: 2px solid var(--border); border-radius: 16px; cursor: pointer; background: white; }.answer-choice:hover { border-color: var(--blue); background: var(--aqua); }.answer-choice input { width: 24px; height: 24px; accent-color: var(--blue); }.answer-choice:has(input:checked) { border-color: var(--blue); background: var(--aqua); box-shadow: 0 0 0 3px rgba(23, 105, 170, .12); }
.number-entry-row { display: flex; flex-wrap: wrap; align-items: center; gap: 18px 26px; margin: 24px 0 10px; }
.number-entry-row label { display: inline-flex; flex-wrap: wrap; align-items: center; gap: 9px; font-weight: 800; }
.answer-form input[type="number"] { width: 92px; min-height: 54px; padding: 8px 10px; border: 3px solid var(--blue); border-radius: 12px; color: var(--ink); background: var(--white); font: inherit; font-size: 1.25rem; font-weight: 900; text-align: center; }
.answer-form > .primary-button { margin-top: 20px; }
.comparison-equations { display: grid; gap: 14px; margin: 24px 0 8px; }
.comparison-equation { display: flex; flex-wrap: wrap; align-items: center; gap: 10px; }
.two-array-response { align-items: flex-start; }
.question-navigation { display: flex; justify-content: space-between; gap: 14px; margin-top: 28px; padding-top: 20px; border-top: 1px solid var(--border); }
.nav-button { min-height: 44px; padding: 9px 15px; font-size: .88rem; box-shadow: none; }
.nav-button:disabled { opacity: .4; cursor: not-allowed; }
.submitted-state { margin-top: 22px; padding: 18px; border-radius: 14px; background: var(--aqua); }

/* Lesson 2.1 — original add-in-any-order visuals */
.addition-fact-chart { display: grid; grid-template-columns: repeat(11, minmax(34px, 1fr)); max-width: 720px; overflow-x: auto; border: 2px solid var(--border); border-radius: 14px; background: white; }
.fact-cell { display: grid; place-items: center; min-width: 34px; min-height: 34px; border-right: 1px solid #dbe7ef; border-bottom: 1px solid #dbe7ef; font-size: .85rem; font-weight: 700; }
.fact-header, .fact-corner { background: #edf3f7; color: var(--blue-dark); font-weight: 900; }
.fact-header--given { background: #fff0b8; color: var(--ink); }
.reversed-trains { display: grid; gap: 18px; margin-top: 10px; padding: 22px; border: 2px solid #dbe7ef; border-radius: 18px; background: #f8fbfd; }
.order-train, .train-slots { display: flex; flex-wrap: wrap; align-items: center; gap: 3px; min-height: 52px; }
.order-cube { display: inline-block; width: 42px; height: 42px; flex: 0 0 42px; border: 3px solid rgba(25, 44, 56, .34); border-radius: 9px; box-shadow: inset 0 0 0 3px rgba(255, 255, 255, .28), 0 3px 0 rgba(25, 44, 56, .2); }
button.order-cube { padding: 0; cursor: grab; }
.order-cube--a { background: #3f9fdd; }
.order-cube--b { background: #6fbf73; }
.order-cube--selected { outline: 4px solid #f3bd34; outline-offset: 3px; }
.reversed-workspace { display: grid; gap: 18px; margin-top: 10px; padding: 20px; border: 2px solid var(--border); border-radius: 18px; background: #f8fbfd; }
.cube-bank { display: flex; flex-wrap: wrap; gap: 8px; min-height: 62px; padding: 10px; border: 2px dashed var(--blue); border-radius: 14px; background: white; }
.train-targets { display: grid; gap: 14px; }
.train-target { padding: 12px; border: 2px solid #dbe7ef; border-radius: 14px; background: white; }
.train-target strong { display: block; margin-bottom: 9px; }
.train-slot { width: 46px; height: 46px; padding: 0; border: 2px dashed #93a8b7; border-radius: 9px; background: #f5f8fa; }
.train-slot--a { background: rgba(63, 159, 221, .1); }
.train-slot--b { background: rgba(111, 191, 115, .12); }
.train-slot > .order-cube { width: 40px; height: 40px; vertical-align: top; }
.cube-workspace-status { margin: 0; color: var(--muted); font-weight: 700; }
.cube-workspace-actions { display: flex; flex-wrap: wrap; gap: 10px; }
.cube-workspace-actions .secondary-button { min-height: 44px; padding: 8px 18px; }
.part-whole-model { display: grid; grid-template-columns: repeat(2, minmax(120px, 1fr)); max-width: 440px; gap: 10px; margin-top: 10px; }
.whole-box, .part-box { display: grid; place-items: center; min-height: 82px; padding: 12px; border: 3px solid var(--blue); border-radius: 14px; background: white; }
.whole-box { grid-column: 1 / -1; }
.part-box--blank { border-style: dashed; }
.whole-box small, .part-box small { color: var(--muted); font-weight: 700; }
.whole-box strong, .part-box strong { font-size: 1.6rem; }
.equation-pair-fields { display: grid !important; gap: 4px !important; }
.equation-entry-strip > input[type="number"] { width: 76px; }
.worked-equation { margin: 18px 0; padding: 16px; border-radius: 14px; background: var(--aqua); font-size: 1.25rem; text-align: center; }
.submitted-state p { margin: 6px 0; }.submitted-state small { color: var(--muted); }
.page-shell:has(.practice-card) { width: min(1120px, calc(100% - 28px)); margin-top: 14px; margin-bottom: 28px; }
.practice-card { padding: clamp(18px, 2.5vw, 28px); }
.practice-card .progress-line { gap: 5px; }
.practice-card .progress-track { height: 8px; }
.practice-card .difficulty { margin-block: 10px 3px; }
.practice-card .question-prompt { margin-block: 6px 12px; font-size: clamp(1.65rem, 3.5vw, 2.1rem); }
.practice-card .visual-frame { margin-block: 12px; }
.practice-card .visual { margin-block: 6px; padding: 14px; }
.practice-card .answer-form fieldset { gap: 9px; margin-bottom: 12px; }
.practice-card .answer-choice { min-height: 54px; padding: 10px 14px; }
.practice-card .number-entry-row { margin-block: 10px 6px; }

/* Chapter 2 strategy lessons — compact, reusable math models */
.chapter2-strategy-visual { margin-block: 10px 14px; }
.counter-rows, .three-groups { display: flex; flex-wrap: wrap; gap: 14px; align-items: center; }
.counter-row, .counter-group { min-height: 58px; display: flex; flex-wrap: wrap; gap: 7px; align-items: center; padding: 10px; border: 2px solid #dbe7ef; border-radius: 14px; background: #f8fbfd; }
.math-counter { width: 36px; height: 36px; flex: 0 0 36px; border: 3px solid #235d83; border-radius: 50%; background: #8bd5ec; box-shadow: inset 0 -5px 0 rgb(35 93 131 / 14%); }
.math-counter:nth-child(even) { background: #ffd66b; border-color: #98650a; }
button.math-counter:not(:disabled) { cursor: grab; }
.math-counter.selected-counter { outline: 4px solid var(--accent); outline-offset: 2px; }
.ten-frame-workspace { display: grid; grid-template-columns: minmax(250px, 420px) minmax(180px, 1fr); gap: 14px; align-items: start; }
.ten-frame { display: grid; grid-template-columns: repeat(5, 1fr); border: 3px solid #235d83; border-radius: 12px; overflow: hidden; background: white; }
.ten-frame-cell { min-height: 62px; display: grid; place-items: center; border: 1px solid #7da6bd; }
.ten-frame-cell.filled::after { content: ''; width: 36px; height: 36px; border: 3px solid #235d83; border-radius: 50%; background: #8bd5ec; }
.counter-bank { min-height: 74px; display: flex; flex-wrap: wrap; align-content: flex-start; gap: 7px; padding: 10px; border: 2px solid #7da6bd; border-radius: 12px; background: #fff; }
.small-reset { min-height: 40px; margin-top: 8px; padding: 7px 12px; border: 2px solid var(--border); border-radius: 10px; background: white; font-weight: 800; }
.number-line { display: grid; grid-template-columns: repeat(21, minmax(30px, 1fr)); overflow-x: auto; padding: 15px 4px 5px; }
.number-tick { position: relative; min-width: 30px; height: 46px; border: 0; border-top: 4px solid #235d83; background: transparent; color: var(--ink); font-weight: 800; }
.number-tick::before { content: ''; position: absolute; top: -9px; left: 50%; height: 13px; border-left: 3px solid #235d83; }
.number-tick.visited { color: #9b3f00; background: #fff0b8; }
.completed-path-direction { display: flex; align-items: center; justify-content: center; gap: 12px; color: #7b3600; font-weight: 850; }
.path-start-marker, .path-end-marker { padding: 4px 9px; border-radius: 999px; background: #fff0b8; }
.path-direction-arrow { font-size: 1.55rem; line-height: 1; }
.manip-status { margin: 8px 0 0; font-weight: 750; }
.part-whole-model { width: min(440px, 100%); display: grid; grid-template-columns: 1fr 1fr; gap: 8px; }
.whole-box, .part-box { min-height: 58px; display: grid; place-items: center; border: 3px solid #235d83; border-radius: 12px; background: white; font-size: 1.15rem; font-weight: 850; }
.whole-box { grid-column: 1 / -1; background: #edf7fb; }
.story-plan { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.story-plan > div { min-height: 64px; padding: 14px; border: 2px dashed #7da6bd; border-radius: 12px; font-weight: 800; }
.strategy-entry-grid { display: flex; flex-wrap: wrap; gap: 10px; margin-block: 8px 12px; }
.strategy-entry-grid label { display: grid; gap: 5px; min-width: 150px; font-weight: 800; }
.strategy-entry-grid input { min-height: 48px; width: 100%; padding: 7px 10px; border: 2px solid var(--border); border-radius: 10px; font-size: 1.2rem; }
.make-ten-equation { display: flex; flex-wrap: wrap; align-items: center; gap: 10px 18px; margin-block: 8px 12px; }
.make-ten-equation-line { display: flex; flex-wrap: wrap; align-items: center; gap: 9px; padding: 10px 14px; border: 2px solid #dbe7ef; border-radius: 14px; background: #f8fbfd; font-size: 1.3rem; font-weight: 850; }
.make-ten-equation-line input { width: 70px !important; min-height: 50px !important; }
.make-ten-decomposition { width: min(460px, 100%); margin: 2px auto 10px; }
.decomposition-tree { width: 240px; margin: 0 auto; display: grid; justify-items: center; }
.decomposition-whole { min-width: 54px; min-height: 48px; display: grid; place-items: center; color: var(--blue-dark); font-size: 1.65rem; }
.decomposition-branches { width: 240px; height: 54px; overflow: visible; }
.decomposition-branch { fill: none; stroke-width: 4; stroke-linecap: round; }
.decomposition-branch--first { stroke: var(--blue); }
.decomposition-branch--first + .decomposition-branch--second { stroke: #b56a12; }
#part-arrow-first path { fill: var(--blue); }
#part-arrow-second path { fill: #b56a12; }
.decomposition-parts { width: 190px; display: grid; grid-template-columns: repeat(2, 70px); justify-content: space-between; }
.decomposition-part input { width: 70px !important; min-height: 52px !important; border-radius: 10px !important; }
.decomposition-part--first input { border-color: var(--blue) !important; }
.decomposition-part--second input { border-color: #b56a12 !important; }
.make-ten-flow { margin-top: 14px; display: grid; justify-items: center; }
.make-ten-flow-step { min-width: 270px; min-height: 54px; display: flex; align-items: center; justify-content: center; gap: 9px; font-size: 1.35rem; font-weight: 850; }
.make-ten-flow-step output { width: 58px; min-height: 46px; display: grid; place-items: center; border: 3px solid; border-radius: 10px; background: var(--white); }
.make-ten-flow-step--first output { border-color: var(--blue); }
.make-ten-flow-step--second output { border-color: #b56a12; }
.make-ten-flow-step--second input { width: 72px !important; min-height: 50px !important; }
.make-ten-flow-arrow { height: 26px; color: var(--blue-dark); font-size: 1.4rem; font-weight: 900; line-height: 24px; }
.story-answer-entry { display: flex; align-items: center; gap: 10px; color: var(--muted); font-weight: 850; }
.worked-make-ten-equation { margin: 14px auto 20px; font-size: 1.5rem; font-weight: 900; }
.lesson-2-3-practice .question-prompt { text-wrap: balance; }
.lesson-2-3-practice .make-ten-direction { margin: -4px 0 10px; color: var(--muted); font-weight: 800; }
.lesson-2-3-practice .bank-counter,
.lesson-2-3-feedback .bank-counter { border-color: #98650a; background: #ffd66b; }
.lesson-2-3-practice .bank-counter:focus-visible,
.lesson-2-3-practice .small-reset:focus-visible,
.lesson-2-3-practice .make-ten-equation input:focus-visible { outline: 4px solid var(--blue); outline-offset: 3px; }
.near-double-counter-workspace > p { margin: 6px 0; font-weight: 750; }
.near-double-counter-bank { min-height: 58px; display: flex; align-items: center; margin-top: 8px; padding: 10px; border: 2px dashed #7da6bd; border-radius: 12px; }
.near-double-response { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 10px; margin-block: 8px 12px; }
.near-double-step { min-width: 0; padding: 10px; border: 2px solid var(--border); border-radius: 12px; }
.near-double-step > strong, .near-double-step legend { display: block; margin-bottom: 8px; }
.near-double-equation { display: flex; flex-wrap: wrap; align-items: center; gap: 7px; font-size: 1.1rem; font-weight: 800; }
.near-double-equation label { display: flex; align-items: center; gap: 6px; }
.near-double-equation input { width: 62px; min-height: 44px; padding: 5px; border: 2px solid var(--border); border-radius: 9px; font-size: 1.15rem; }
.adjustment-choice { display: flex; flex-wrap: wrap; align-content: start; gap: 8px; }
.adjustment-choice legend { width: 100%; }
.adjustment-choice label { display: flex; align-items: center; gap: 5px; min-height: 44px; padding: 7px 9px; border: 2px solid var(--border); border-radius: 9px; font-weight: 850; }

/* Lesson 2.4 — select two of three, then keep the third visible */
.lesson-2-4-practice { --pair-coral: #e76f51; --pair-aqua: #2589a8; --pair-sun: #d79a08; }
.lesson-2-4-practice .question-prompt { max-width: 980px; font-size: clamp(1.45rem, 2.6vw, 1.9rem); text-wrap: balance; }
.add-three-workspace { display: grid; gap: 10px; margin-block: 4px 8px; }
.addend-selector { min-height: 102px; display: flex; align-items: center; justify-content: center; gap: 12px; padding: 12px; border: 2px solid #dbe7ef; border-radius: 20px; background: #f8fbfd; }
.addend-card, .vertical-addend { min-width: 78px; min-height: 72px; display: grid; place-items: center; gap: 5px; padding: 8px 12px; border: 3px solid #9fb3c1; border-radius: 18px; color: var(--ink); background: var(--white); font: inherit; font-size: 1.75rem; font-weight: 900; cursor: pointer; transition: border-color .14s ease, box-shadow .14s ease, translate .14s ease; }
.addend-card:hover, .vertical-addend:hover { border-color: var(--blue); translate: 0 -2px; }
.addend-card:focus-visible, .vertical-addend:focus-visible, .add-three-reset:focus-visible { outline: 4px solid var(--blue); outline-offset: 3px; }
.addend-card.is-selected, .vertical-addend.is-selected { border-color: var(--green); background: var(--green-soft); box-shadow: 0 0 0 4px rgb(35 139 87 / 18%); }
.addend-card.is-selected::after, .vertical-addend.is-selected::after { content: 'Selected'; color: #12673e; font-size: .68rem; font-weight: 900; letter-spacing: .02em; text-transform: uppercase; }
.addend-card--unknown { border-style: dashed; color: var(--muted); background: #f1f4f6; cursor: default; }
.addend-plus, .given-whole { font-size: 1.75rem; font-weight: 900; }
.addend-selector--groups { align-items: stretch; }
.addend-card--group { min-width: 180px; min-height: 100px; align-content: center; }
.addend-card--group .cube-train { --cube-size: 23px; justify-content: center; max-width: 190px; flex-wrap: wrap; row-gap: 5px; }
.group-color-0 .linking-cube { --cube-face: #ef8b74; --cube-edge: #9d3d2b; --cube-shine: #ffd2c8; }
.group-color-1 .linking-cube { --cube-face: #55b7cf; --cube-edge: #17627a; --cube-shine: #c6f1f8; }
.group-color-2 .linking-cube { --cube-face: #f0bf45; --cube-edge: #88610a; --cube-shine: #fff0a8; }
.selected-pair-stage { min-height: 48px; display: flex; align-items: center; justify-content: center; gap: 12px; padding: 6px 12px; border: 2px dashed #9fb3c1; border-radius: 14px; color: var(--muted); background: var(--white); font-size: .86rem; font-weight: 800; }
.combined-group-preview { display: flex; align-items: center; gap: 3px; padding: 4px 12px; border-bottom: 5px solid var(--green); border-radius: 0 0 18px 18px; }
.combined-group-preview .cube-train { --cube-size: 18px; }
.three-addend-flow { min-height: 72px; display: flex; flex-wrap: wrap; align-items: center; justify-content: center; gap: 9px; padding: 10px 16px; border-radius: 18px; background: #eef7fb; font-size: 1.45rem; font-weight: 900; }
.three-addend-flow input[type="number"] { width: 72px; min-height: 50px; }
.grouped-expression { padding: 6px 12px; border-bottom: 4px solid var(--green); border-radius: 0 0 14px 14px; white-space: nowrap; }
.grouped-expression output { min-width: 1ch; display: inline-block; text-align: center; }
.add-three-reset { justify-self: end; margin-top: 0; cursor: pointer; }
.story-quantity-row { display: flex; justify-content: center; gap: 10px; }
.story-quantity { min-width: 92px; display: grid; place-items: center; padding: 8px 12px; border: 2px solid var(--border); border-radius: 14px; background: var(--white); }
.story-quantity small { color: var(--muted); font-size: .72rem; font-weight: 800; }
.story-quantity strong { font-size: 1.35rem; }
.vertical-addition-layout { min-height: 196px; display: grid; grid-template-columns: 120px 180px 170px; justify-content: center; align-items: center; gap: 6px; padding: 6px 14px; border: 2px solid #dbe7ef; border-radius: 18px; background: #f8fbfd; }
.vertical-addends { position: relative; display: grid; justify-items: end; gap: 3px; padding-left: 24px; }
.vertical-addend { width: 74px; min-height: 44px; padding: 3px 10px; border-width: 2px; border-radius: 11px; font-size: 1.35rem; }
.vertical-addend.is-selected::after { content: none; }
.vertical-plus { position: absolute; left: 15px; bottom: 15px; font-size: 1.5rem; font-weight: 900; }
.vertical-rule { width: 100px; border-bottom: 4px solid var(--ink); }
.pair-branches { width: 180px; height: 170px; overflow: visible; }
.pair-branches path { fill: none; stroke: #c1cdd6; stroke-width: 3; stroke-linecap: round; transition: stroke .14s ease, stroke-width .14s ease; }
.pair-branches path.is-active { stroke: var(--green); stroke-width: 6; }
.branch-sum-box { display: grid; justify-items: center; gap: 5px; padding: 10px; border: 3px solid var(--green); border-radius: 16px; background: var(--green-soft); font-size: .78rem; font-weight: 850; text-align: center; }
.branch-sum-box input { width: 72px !important; min-height: 48px !important; }
.grouping-comparison { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px; }
.grouping-attempt { min-width: 0; display: grid; gap: 7px; padding: 10px; border: 2px solid var(--border); border-radius: 18px; }
.grouping-attempt h2 { margin: 0; color: var(--blue-dark); font-size: .92rem; }
.grouping-attempt .addend-selector { min-height: 90px; gap: 6px; padding: 7px; }
.grouping-attempt .addend-card--group { min-width: 0; width: 31%; min-height: 78px; padding: 6px; }
.grouping-attempt .addend-card--group .cube-train { --cube-size: 16px; max-width: 115px; }
.grouping-attempt .addend-card { font-size: 1.05rem; }
.grouping-attempt .addend-card.is-selected::after { font-size: .5rem; }
.grouping-attempt .selected-pair-stage { min-height: 40px; font-size: .7rem; }
.three-addend-flow--compact { min-height: 58px; gap: 5px; padding: 7px; font-size: 1rem; }
.three-addend-flow--compact input[type="number"] { width: 58px; min-height: 43px; padding: 4px; border-width: 2px; font-size: 1rem; }
.worked-three-addends { display: grid; gap: 10px; margin-block: 14px; padding: 18px; border: 2px solid #b8d8c7; border-radius: 18px; background: var(--green-soft); }
.worked-original { font-size: 1.35rem; font-weight: 900; }
.worked-grouping { display: flex; flex-wrap: wrap; justify-content: center; align-items: center; gap: 12px; font-size: 1.45rem; font-weight: 900; }
.worked-three-addends p { margin: 0; color: var(--muted); font-weight: 750; }

@media (prefers-reduced-motion: reduce) {
  .addend-card, .vertical-addend, .pair-branches path { transition: none; }
  .addend-card:hover, .vertical-addend:hover { translate: none; }
}

@media (max-width: 720px) {
  .grouping-comparison { grid-template-columns: 1fr; }
  .addend-selector { flex-wrap: wrap; }
  .addend-card--group { min-width: 135px; }
  .vertical-addition-layout { grid-template-columns: 100px 120px 130px; padding-inline: 4px; }
  .pair-branches { width: 120px; }
}

@media (max-width: 720px) {
  .ten-frame-workspace, .story-plan, .near-double-response { grid-template-columns: 1fr; }
  .math-counter { width: 32px; height: 32px; flex-basis: 32px; }
}
.practice-card .repeated-addition-entry,
.practice-card .equation-entry-strip { margin-block: 8px; padding: 12px; }
.practice-card .answer-form > .primary-button { margin-top: 8px; }
.practice-card .question-navigation { margin-top: 14px; padding-top: 12px; }
.lesson-2-1-practice .reversed-trains,
.lesson-2-1-practice .reversed-workspace { gap: 12px; padding: 14px; }
.lesson-2-1-practice .equation-pair-fields { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 10px !important; margin-bottom: 12px; }
.lesson-2-1-practice .equation-pair-fields legend { grid-column: 1 / -1; }
.lesson-2-1-practice .equation-entry-strip { margin: 8px 0; padding: 12px 8px; gap: 7px; }
.feedback-card { text-align: center; }.feedback-icon { width: 76px; height: 76px; margin: auto; display: grid; place-items: center; border-radius: 50%; font-size: 2.5rem; font-weight: 900; }.correct .feedback-icon { color: var(--green); background: var(--green-soft); }.try-again .feedback-icon { color: #a65318; background: var(--orange-soft); }.feedback-message { color: var(--muted); }.hint-box { text-align: left; margin: 26px 0; padding: 20px; border-left: 6px solid var(--yellow); border-radius: 12px; background: #fffaf0; }.hint-box p { margin-bottom: 0; }
.summary { text-align: center; }.celebration { font-size: 3rem; margin: 0; }.summary-stats { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; margin: 28px 0 36px; }.summary-stats div { padding: 18px 10px; border-radius: 16px; background: var(--aqua); }.summary-stats strong, .summary-stats span { display: block; }.summary-stats strong { font-size: 1.7rem; }.summary-stats span { margin-top: 5px; color: var(--muted); font-size: .86rem; }
.mastery-grid { display: grid; gap: 10px; text-align: left; margin-bottom: 24px; }.mastery-row { display: flex; align-items: center; justify-content: space-between; gap: 15px; padding: 16px; border: 1px solid var(--border); border-radius: 14px; }.mastery-row small { display: block; margin-top: 4px; color: var(--muted); }.status { white-space: nowrap; padding: 7px 10px; border-radius: 99px; font-size: .8rem; font-weight: 800; }.status-needs-practice { background: var(--orange-soft); }.status-developing { background: var(--aqua); }.status-proficient { color: #12673e; background: var(--green-soft); }
.dev-review { width: min(1400px, 100%); }.family-section { padding-top: 24px; margin-top: 30px; border-top: 4px solid var(--blue); }.dev-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(320px, 1fr)); gap: 18px; }.dev-card { overflow: auto; padding: 20px; background: white; border: 1px solid var(--border); border-radius: 16px; }.dev-card h3 { font-size: 1.15rem; }.dev-card .visual { transform: scale(.9); margin: 10px 0; }.dev-meta { display: flex; justify-content: space-between; color: var(--muted); font-size: .75rem; font-weight: 800; }.qc-correct { color: var(--green); font-weight: 800; }.dev-card pre { font-size: .68rem; white-space: pre-wrap; }
.paired-grid { --paired-cell-size: clamp(30px, 6vw, 50px); min-height: auto; display: grid; align-content: center; gap: 7px; overflow-x: auto; }
.paired-grid-row { display: grid; grid-template-columns: repeat(var(--paired-grid-columns), var(--paired-cell-size)); justify-content: center; gap: 7px; }
.paired-grid-cell { width: var(--paired-cell-size); aspect-ratio: 1; display: block; padding: 0; border: 3px solid #8aa7bc; border-radius: 9px; background: var(--white); box-shadow: inset 0 0 0 2px rgba(255, 255, 255, .7); }
.paired-grid-cell--filled { border-color: var(--blue-dark); background: linear-gradient(145deg, #8bd8ed 0 18%, #35a9cf 19% 100%); box-shadow: inset -5px -5px 0 rgba(10, 76, 105, .13); }
.paired-grid-cell--pair-feedback { outline: 3px solid var(--green); outline-offset: -6px; }
.paired-grid-cell--unmatched-feedback { border-color: #c44f24; outline: 4px solid #f4a261; outline-offset: 3px; }
.paired-grid-feedback-note { grid-column: 1; margin: 7px 0 0; color: #9a3d1e; font-size: .85rem; font-weight: 800; text-align: center; }
.paired-grid--interactive .paired-grid-cell { cursor: pointer; transition: translate .12s ease, box-shadow .12s ease, border-color .12s ease; }
.paired-grid--interactive .paired-grid-cell:hover, .paired-grid--interactive .paired-grid-cell:focus-visible { border-color: var(--blue); translate: 0 -2px; outline: 3px solid rgba(23, 105, 170, .22); outline-offset: 2px; }
.paired-grid-cell--partner-cue:not(.paired-grid-cell--filled) { border-color: var(--yellow); box-shadow: inset 0 0 0 4px #fff5c7; }
.equation-entry-strip { display: flex; align-items: center; justify-content: center; flex-wrap: wrap; gap: 10px; margin: 24px 0; padding: 18px; border: 2px solid #dbe7ef; border-radius: 18px; background: #f8fbfd; }
.equation-entry-field input { width: 72px; min-height: 58px; border: 3px solid var(--blue); border-radius: 12px; color: var(--ink); background: var(--white); font: inherit; font-size: 1.45rem; font-weight: 900; text-align: center; }
.equation-entry-field--total input { border-color: var(--border); background: #edf3f7; }
.equation-symbol { color: var(--blue-dark); font-size: 1.7rem; font-weight: 900; }
.story-sum, .missing-parity-model { flex-wrap: wrap; font-size: 1.45rem; font-weight: 800; }
.missing-box { min-width: 58px; padding: 10px 18px; border: 3px dashed var(--blue); border-radius: 12px; text-align: center; }
.grid-count-status { margin: 4px 0 20px; color: var(--muted); font-weight: 800; text-align: center; }
.sum-entry { margin: 22px 0; }
.sum-entry label { display: flex; align-items: center; justify-content: center; gap: 12px; font-weight: 800; }
.sum-entry input { width: 90px; min-height: 56px; border: 3px solid var(--blue); border-radius: 12px; font: inherit; font-weight: 900; text-align: center; }
.worked-equation { margin: 18px auto 26px; font-size: 1.65rem; }
.equal-groups-loose { max-width: 650px; flex-wrap: wrap; justify-content: flex-start; gap: 16px 22px; }
.group-object { width: 46px; height: 46px; display: inline-grid; place-items: center; padding: 0; border: 3px solid #7d9bb0; border-radius: 50%; color: var(--blue); background: var(--white); font: inherit; font-size: 1.45rem; line-height: 1; }
button.group-object { cursor: pointer; transition: translate .12s ease, box-shadow .12s ease; }
button.group-object:hover, button.group-object:focus-visible { translate: 0 -2px; outline: 3px solid rgba(23, 105, 170, .22); outline-offset: 2px; }
.group-object:nth-child(3n + 2) { translate: 0 6px; }
.group-object:nth-child(4n) { rotate: -4deg; }
.group-object--static { border-color: #8aa7bc; }
.group-object--selected { color: var(--ink); box-shadow: inset 0 0 0 5px rgba(255,255,255,.8), 0 0 0 3px var(--group-mark); border-color: var(--group-mark); }
.group-object--made-1 { --group-mark: #1769aa; }
.group-object--made-2 { --group-mark: #238b57; }
.group-object--made-3 { --group-mark: #a85d19; }
.group-object--made-4 { --group-mark: #7550a8; }
.group-object--made-5 { --group-mark: #a63a69; }
.group-object--small { width: 30px; height: 30px; border-width: 2px; font-size: .9rem; }
.equal-groups-model, .fair-share-model { flex-wrap: wrap; align-items: stretch; gap: 18px; }
.equal-group-container-list { width: 100%; display: flex; flex-wrap: wrap; justify-content: center; gap: 18px; }
.equal-group-container { min-width: 98px; min-height: 92px; display: flex; flex-wrap: wrap; align-content: center; justify-content: center; gap: 7px; padding: 14px; border: 3px solid #7d9bb0; border-radius: 50% 50% 43% 43%; background: var(--white); }
.equal-group-container--empty { border-style: dashed; background: #fbfdff; }
.equal-group-container--feedback { border-color: var(--green); background: var(--green-soft); }
.group-counter { color: var(--blue); font-size: 1.55rem; line-height: 1; }
.loose-share-counter-list { width: 100%; display: flex; flex-wrap: wrap; justify-content: center; gap: 7px; padding-top: 12px; border-top: 2px solid var(--border); }
.grouping-status { margin: -4px 0 20px; color: var(--muted); font-weight: 800; text-align: center; }
.equal-groups-inputs { display: flex; flex-wrap: wrap; justify-content: center; gap: 14px; margin: 22px 0; }
.equal-groups-inputs label { display: grid; gap: 7px; color: var(--muted); font-size: .86rem; font-weight: 800; text-align: center; }
.equal-groups-inputs input, .repeated-addition-entry input { width: 92px; min-height: 56px; border: 3px solid var(--blue); border-radius: 12px; color: var(--ink); background: var(--white); font: inherit; font-size: 1.35rem; font-weight: 900; text-align: center; }
.repeated-addition-entry { display: flex; align-items: center; justify-content: center; flex-wrap: wrap; gap: 9px; margin: 24px 0; padding: 18px; border: 2px solid #dbe7ef; border-radius: 18px; background: #f8fbfd; }
.repeated-addend-mirror { min-width: 52px; min-height: 56px; display: grid; place-items: center; border: 3px solid #9bb3c5; border-radius: 12px; background: var(--white); font-size: 1.35rem; font-weight: 900; }
.equal-groups-teaching { max-width: 560px; margin: 18px auto 26px; padding: 18px; border-radius: 16px; background: var(--green-soft); text-align: left; }
.equal-groups-teaching p { margin: 7px 0; }
/* ===================================================================
   Lesson 1.3 — Equal Groups digital manipulatives & visuals
   ===================================================================
   Clear, large Grade-2 counters; obvious group targets; tap+drag
   support; touch-friendly; responsive.  These replace the old tiny
   group-counter / loose-group-object / share-object classes.
   =================================================================== */

/* Counter primitive — large, clear, manipulative-like */
.eg-counter { width: 44px; height: 44px; display: inline-block; border-radius: 50%; border: 3px solid #7d9bb0; background: linear-gradient(145deg, #8bd8ed 0 18%, #35a9cf 19% 100%); box-shadow: inset -4px -4px 0 rgba(10,76,105,.14), 0 3px 0 rgba(23,50,77,.10); flex: 0 0 44px; }
.eg-counter--static { opacity: .92; }

/* Prepared equal-groups board (static / feedback) */
.equal-groups-board { display: flex; flex-wrap: wrap; align-items: flex-start; justify-content: center; gap: 20px 26px; }
.equal-groups-board--feedback { gap: 22px 28px; }
.equal-group { display: flex; flex-wrap: wrap; align-content: flex-start; justify-content: center; gap: 8px; min-width: 90px; min-height: 80px; padding: 14px 12px; border: 3px solid #7d9bb0; border-radius: 50% 50% 43% 43%; background: var(--white); }
.equal-groups-board--feedback .equal-group { border-color: var(--green); background: var(--green-soft); }
.equal-group-label { display: block; width: 100%; text-align: center; font-size: .8rem; font-weight: 800; color: var(--muted); }

/* Neutral loose collection */
.neutral-counter-collection { flex-wrap: wrap; gap: 14px 20px; justify-content: flex-start; }

/* ---------- Manipulative workspace ---------- */
.manip-workspace { flex-direction: column; align-items: stretch; gap: 16px; min-height: auto; padding: 18px; }
.manip-counter-bank { display: flex; flex-wrap: wrap; justify-content: center; gap: 12px 16px; padding: 14px; min-height: 72px; border: 2px dashed #dbe7ef; border-radius: 16px; background: #fbfdff; }
.manip-counter { width: 52px; height: 52px; padding: 0; border: 3px solid #7d9bb0; border-radius: 50%; background: linear-gradient(145deg, #8bd8ed 0 18%, #35a9cf 19% 100%); box-shadow: inset -4px -4px 0 rgba(10,76,105,.14), 0 3px 0 rgba(23,50,77,.10); cursor: pointer; flex: 0 0 52px; transition: translate .12s ease, box-shadow .12s ease, border-color .12s ease; -webkit-tap-highlight-color: transparent; }
.manip-counter:hover, .manip-counter:focus-visible { translate: 0 -3px; outline: 3px solid rgba(23,105,170,.22); outline-offset: 2px; border-color: var(--blue); }
.manip-counter:active { translate: 0 1px; }
.manip-counter--placed { border-color: var(--group-color, #7d9bb0); box-shadow: inset -4px -4px 0 rgba(10,76,105,.14), 0 0 0 3px var(--group-color, #7d9bb0); }
.manip-counter--dragging { opacity: .5; }
.manip-counter[draggable="true"] { touch-action: none; }

/* Groups area (group/arrange modes) */
.manip-groups-area { display: flex; flex-wrap: wrap; justify-content: center; gap: 16px 20px; min-height: 60px; }
.manip-group { display: flex; flex-wrap: wrap; align-content: flex-start; justify-content: center; gap: 8px; min-width: 90px; min-height: 80px; padding: 14px 12px; border: 3px solid var(--group-color, #7d9bb0); border-radius: 50% 50% 43% 43%; background: var(--white); }
.manip-group--arrange { cursor: pointer; border-radius: 16px; }
.manip-group-label { display: block; width: 100%; text-align: center; font-size: .8rem; font-weight: 800; color: var(--group-color, var(--muted)); }

/* Targets (distribute mode) */
.manip-targets { display: flex; flex-wrap: wrap; justify-content: center; gap: 16px 20px; }
.manip-target { display: flex; flex-wrap: wrap; align-content: flex-start; justify-content: center; gap: 8px; min-width: 100px; min-height: 90px; padding: 14px; border: 3px dashed #8aa7bc; border-radius: 50% 50% 43% 43%; background: #fbfdff; cursor: pointer; transition: border-color .15s ease, background .15s ease; -webkit-tap-highlight-color: transparent; }
.manip-target--container { border-radius: 18px; min-width: 110px; }
.manip-target--over { border-color: var(--blue); border-style: solid; background: var(--aqua); }
.manip-target-label { display: block; width: 100%; text-align: center; font-size: .82rem; font-weight: 800; color: var(--muted); margin-bottom: 4px; }

/* Hint text */
.manip-hint { width: 100%; text-align: center; color: var(--muted); font-weight: 800; font-size: .9rem; margin: 6px 0; }

/* Reset button */
.manip-reset-button { display: inline-flex; align-items: center; gap: 6px; align-self: center; padding: 10px 20px; border: 2px solid var(--border); border-radius: 12px; background: var(--white); color: var(--blue-dark); font: inherit; font-weight: 800; font-size: .9rem; cursor: pointer; -webkit-tap-highlight-color: transparent; }
.manip-reset-button:hover { background: var(--aqua); border-color: var(--blue); }

/* Manip-state hidden input */
input[data-manip-state] { display: none; }

/* Touch: make targets and counters a bit smaller on narrow screens */
@media (max-width: 640px) {
  .manip-counter { width: 44px; height: 44px; flex-basis: 44px; }
  .manip-group, .manip-target { min-width: 80px; min-height: 72px; }
  .manip-workspace { padding: 12px; }
}

.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: 640px) { .page-shell { margin-top: 18px; }.card { border-radius: 18px; }.summary-stats { grid-template-columns: 1fr; }.mastery-row { align-items: flex-start; flex-direction: column; }.number-path { flex-wrap: wrap; }.site-header { align-items: flex-start; }.brand { max-width: 220px; } }

/* ===================================================================
   Lesson 1.4 — Use Arrays
   =================================================================== */

/* Static array: large dots, aligned rows/columns */
.array-figure { margin: 0; }
.array-board { display: inline-flex; flex-direction: column; gap: 14px; padding: 18px 20px; background: var(--white); border: 2px solid var(--border); border-radius: 16px; }
.array-row { display: flex; gap: 14px; justify-content: center; }
.array-dot { width: 40px; height: 40px; border-radius: 50%; border: 3px solid #7d9bb0; background: linear-gradient(145deg, #8bd8ed 0 18%, #35a9cf 19% 100%); box-shadow: inset -4px -4px 0 rgba(10,76,105,.14), 0 3px 0 rgba(23,50,77,.10); flex: 0 0 40px; }
.array-board--row-guides .array-row { padding: 6px 10px; border: 2px dashed rgba(23,105,170,.35); border-radius: 12px; }
.array-board--feedback .array-row:first-child .array-dot { border-color: var(--blue); }

.array-pair { display: flex; flex-wrap: wrap; gap: 20px 32px; justify-content: center; align-items: flex-start; }

/* Interactive array workspace */
.array-workspace .array-workspace-grid { display: inline-flex; flex-direction: column; gap: 12px; padding: 14px; border: 2px dashed #dbe7ef; border-radius: 16px; background: #fbfdff; align-self: center; }
.two-stage-grid[hidden], .two-stage-action[hidden] { display: none; }
.two-stage-action { align-self: center; min-height: 48px; }
.array-row--slots { display: flex; gap: 12px; justify-content: center; }
.array-slot { width: 56px; height: 56px; padding: 0; border: 2px dashed #9db6c8; border-radius: 14px; background: var(--white); cursor: pointer; display: inline-flex; align-items: center; justify-content: center; transition: border-color .12s ease, background .12s ease; -webkit-tap-highlight-color: transparent; }
.array-slot:hover, .array-slot:focus-visible { border-color: var(--blue); background: var(--aqua); }
.array-slot--over { border-color: var(--blue); border-style: solid; background: var(--aqua); }
.array-slot .manip-counter { width: 46px; height: 46px; flex-basis: 46px; cursor: default; }
.manip-counter--selected { outline: 4px solid rgba(23,105,170,.45); outline-offset: 2px; translate: 0 -3px; }

@media (max-width: 640px) {
  .array-dot { width: 30px; height: 30px; flex-basis: 30px; }
  .array-board { gap: 10px; padding: 12px; }
  .array-row { gap: 10px; }
  .array-slot { width: 46px; height: 46px; }
  .array-slot .manip-counter { width: 38px; height: 38px; flex-basis: 38px; }
  .number-entry-row { gap: 14px 18px; }
  .answer-form input[type="number"] { width: 84px; min-height: 52px; }
}

@media (max-width: 720px) {
  .lesson-2-1-practice .equation-pair-fields { grid-template-columns: 1fr; }
  .lesson-2-1-practice .equation-pair-fields legend { grid-column: 1; }
}

@media (min-width: 721px) {
  .practice-card .answer-form > fieldset:not(.equation-pair-fields) { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (min-width: 900px) {
  .lesson-1-3-practice .manip-workspace,
  .lesson-1-4-practice .array-workspace,
  .lesson-1-5-practice .array-workspace {
    display: grid;
    grid-template-columns: minmax(300px, .9fr) minmax(0, 1.1fr);
    align-items: start;
    column-gap: 18px;
    row-gap: 10px;
  }

  .lesson-1-3-practice .manip-counter-bank,
  .lesson-1-4-practice .array-workspace .manip-counter-bank,
  .lesson-1-5-practice .array-workspace .manip-counter-bank {
    grid-column: 1;
    grid-row: 1;
    padding: 10px;
    gap: 9px 12px;
  }

  .lesson-1-3-practice .manip-hint,
  .lesson-1-4-practice .array-workspace .manip-hint,
  .lesson-1-5-practice .array-workspace .manip-hint {
    grid-column: 1;
    grid-row: 2;
    margin: 0;
  }

  .lesson-1-3-practice .manip-groups-area,
  .lesson-1-3-practice .manip-targets,
  .lesson-1-4-practice .array-workspace-grid,
  .lesson-1-5-practice .array-workspace-grid {
    grid-column: 2;
    grid-row: 1 / span 3;
  }

  .lesson-1-3-practice .manip-reset-button,
  .lesson-1-4-practice .array-workspace .manip-reset-button,
  .lesson-1-5-practice .array-workspace .manip-reset-button {
    grid-column: 1;
    grid-row: 3;
    justify-self: center;
  }

  .lesson-1-4-practice .two-stage-action {
    grid-column: 1;
    grid-row: 3;
    justify-self: center;
  }
  .lesson-1-4-practice .two-stage-array-workspace .manip-reset-button { grid-row: 4; }

  .lesson-2-1-practice .reversed-workspace {
    grid-template-columns: minmax(300px, .85fr) minmax(0, 1.15fr);
    align-items: start;
    column-gap: 18px;
  }
  .lesson-2-1-practice .reversed-workspace .cube-bank { grid-column: 1; grid-row: 1; }
  .lesson-2-1-practice .reversed-workspace .train-targets { grid-column: 2; grid-row: 1 / span 3; }
  .lesson-2-1-practice .reversed-workspace .cube-workspace-status { grid-column: 1; grid-row: 2; }
  .lesson-2-1-practice .reversed-workspace .cube-workspace-actions { grid-column: 1; grid-row: 3; }
}

/* Parent pilot — quiet family entry and learner handoff */
.skip-link { position: fixed; z-index: 100; top: 12px; left: 12px; padding: 10px 14px; border-radius: 10px; color: var(--ink); background: var(--yellow); font-weight: 850; transform: translateY(-180%); }
.skip-link:focus { transform: translateY(0); }
.auth-card, .learner-home { width: min(620px, 100%); margin-inline: auto; }
.auth-card h1, .learner-home h1 { font-size: clamp(2rem, 8vw, 3.15rem); text-wrap: balance; }
.simple-form { display: grid; gap: 12px; margin-top: 26px; }
.simple-form label { font-weight: 850; }
.simple-form input:not([type="hidden"]) { width: 100%; min-height: 56px; padding: 11px 14px; border: 2px solid var(--border); border-radius: 14px; color: var(--ink); background: var(--white); font: inherit; }
.simple-form input:not([type="hidden"]):focus-visible { border-color: var(--blue); outline: 4px solid rgb(23 105 170 / 18%); outline-offset: 2px; }
.simple-form .primary-button { margin-top: 8px; }
.privacy-note, .field-help { margin: 14px 0 0; color: var(--muted); font-size: .84rem; }
.field-help { margin-top: -4px; }
.form-error { margin: 0; color: #9a2f22; font-weight: 750; }
.development-delivery { margin: 26px 0; padding: 20px; border: 2px dashed #b56a12; border-radius: 16px; background: #fffaf0; }
.development-delivery strong { color: #8a4b0c; text-transform: uppercase; letter-spacing: .04em; font-size: .78rem; }
.development-delivery p { color: var(--muted); }
.text-link, .text-button { color: var(--blue-dark); font: inherit; font-weight: 800; }
.text-button { min-height: 44px; padding: 8px 0; border: 0; background: transparent; cursor: pointer; text-decoration: underline; }
.logout-form { margin-top: 30px; }
.learner-name { color: var(--muted); font-size: .86rem; font-weight: 800; }
.learner-snapshot { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px; margin: 26px 0; }
.learner-snapshot div { padding: 18px; border-radius: 16px; background: var(--aqua); }
.learner-snapshot span, .learner-snapshot strong { display: block; }
.learner-snapshot span { color: var(--muted); font-size: .8rem; font-weight: 750; }
.learner-snapshot strong { margin-top: 5px; font-size: 1.3rem; }
.current-learning { color: var(--muted); font-weight: 750; }
button:focus-visible, a:focus-visible, summary:focus-visible { outline: 4px solid var(--yellow); outline-offset: 3px; }

@media (max-width: 520px) {
  .auth-card, .learner-home { padding: 24px 20px; }
  .learner-snapshot { grid-template-columns: 1fr; }
  .header-status { gap: 6px; }
  .learner-name, .lesson-pill { display: none; }
}