/* The lesson HTML, diagrams, and guide scripts remain the teaching source. */
html { font-size: 16px; scroll-padding-top: 28px; }
.learning-page {
  --accent: #152f43;
  --accent-bright: #dbeab2;
  --ink: #152c3a;
  --gray: #506570;
  --line: #cfddde;
  --soft: #e0eeee;
  --font: "Atkinson Hyperlegible Mono", monospace;
  background: #f5f7f6;
  color: #152c3a;
  font-family: "Foxode Sans", -apple-system, BlinkMacSystemFont, "Hiragino Kaku Gothic ProN", "Yu Gothic", Meiryo, sans-serif;
  font-size: 16px;
  line-height: 1.9;
}
.learning-page fixed-width { width: 100%; max-width: none; margin: 0; padding: 0; overflow: visible; }
.learning-page .course-main,
.learning-page .lesson-main { width: min(1080px, calc(100% - 96px)); max-width: none; margin: 0 auto 96px; }
.learning-page .lesson-main { width: min(960px, calc(100% - 96px)); }
.learning-page .breadcrumbs { margin: 32px 0 44px; gap: 10px; font-size: 12px; color: #506570; }
.learning-page .breadcrumbs a { color: #2b676b; text-decoration-color: #83a7a7; }
.learning-page .eyebrow,
.learning-page header-small,
.learning-page .principle-number,
.learning-page .lesson-order,
.learning-page .scene-number,
.learning-page .voice-meta,
.learning-page .lesson-meta dt { font-family: var(--font); }
.learning-page .eyebrow { margin-bottom: 18px; color: #2b676b; font-size: 11px; letter-spacing: .12em; }
.learning-page .course-hero { padding: 40px 0 64px; background: none; border: 0; border-bottom: 1px solid var(--line); border-radius: 0; }
.learning-page .course-hero h1 { max-width: 960px; font-size: clamp(34px, 4.8vw, 59px); line-height: 1.5; font-weight: 800; letter-spacing: -.025em; }
.learning-page .course-hero h1 em { color: #2b676b; }
.learning-page .course-lead { max-width: 680px; margin-top: 28px; font-size: 16px; line-height: 2; color: #506570; }
.learning-page .primary-link { margin-top: 30px; padding: 16px 23px; gap: 24px; min-height: 54px; border: 1px solid #152f43; border-radius: 9px; background: #152f43; color: #ffffff; font-size: 14px; }
.learning-page .primary-link:hover { background: #102537; color: #ffffff; }
.learning-page .learning-principles { margin-top: 64px; }
.learning-page .section-head { text-align: left; margin-bottom: 30px; }
.learning-page .section-head header-small { margin: 0 0 12px; font-size: 11px; color: #2b676b; letter-spacing: .12em; }
.learning-page .section-head p { font-size: clamp(23px, 3vw, 32px); line-height: 1.6; font-weight: 800; color: var(--ink); }
.learning-page .principle-grid { gap: 32px; }
.learning-page .principle-grid article { padding: 25px 0 0; border: 0; border-top: 2px solid #83a7a7; border-radius: 0; background: none; }
.learning-page .principle-number { color: #2b676b; font-size: 11px; }
.learning-page .principle-grid h3 { margin: 15px 0 10px; font-size: 19px; }
.learning-page .principle-grid p { color: #506570; font-size: 14px; line-height: 1.9; }
.learning-page .course-path { margin-top: 74px; padding: 44px; border-radius: 24px; background: #e0eeee; color: var(--ink); }
.learning-page .path-heading { gap: 30px; margin-bottom: 30px; }
.learning-page .path-heading h2 { font-size: 27px; line-height: 1.5; }
.learning-page .path-heading > p { max-width: 310px; color: #506570; font-size: 13px; line-height: 1.9; }
.learning-page .lesson-catalog { gap: 16px; }
.learning-page .lesson-catalog .lesson-card { min-width: 0; margin: 0; padding: 27px; gap: 12px; border: 1px solid #cfddde; border-radius: 13px; background: #ffffff; color: var(--ink); }
.learning-page .lesson-card-active:hover { border-color: #2b676b; box-shadow: 0 6px 20px #152c3a09; }
.learning-page .lesson-order { font-size: 10px; letter-spacing: .06em; color: #506570; }
.learning-page .lesson-status { padding: 3px 9px; border-radius: 30px; background: #e0eeee; color: #2b676b; font-size: 10px; }
.learning-page .lesson-card strong { font-size: 23px; line-height: 1.5; }
.learning-page .lesson-description { grid-column: 1 / -1; color: #506570; font-size: 14px; line-height: 1.9; }
.learning-page .lesson-go { grid-column: 1 / -1; margin-top: 8px; font-size: 12px; color: #152f43; }
.learning-page .lesson-go > span { margin-left: 12px; }
.learning-page .mascot-note { margin-top: 48px; padding: 28px 30px; gap: 26px; border: 1px solid #cfddde; border-radius: 15px; background: #e0eeee; }
.learning-page .mascot-placeholder { width: 66px; border: 1px solid #83a7a7; background: #d7e7e6; font-size: 28px; }
.learning-page .mascot-note h2 { font-size: 20px; line-height: 1.7; }
.learning-page .mascot-note p:last-child { color: #506570; font-size: 14px; }
.learning-page .mascot-note .eyebrow { margin-bottom: 8px; font-size: 10px; }

/* A spacious reading column; fixed-width numeric diagrams keep their own scroll. */
.learning-page .lesson-hero { padding: 44px; gap: 36px; border: 1px solid #cfddde; border-radius: 23px; background: #e0eeee; }
.learning-page .lesson-hero h1 { font-size: clamp(31px, 4.8vw, 53px); line-height: 1.4; letter-spacing: -.03em; }
.learning-page .lesson-lead { margin-top: 23px; color: #506570; font-size: 16px; line-height: 1.95; }
.learning-page .lesson-meta { margin-top: 27px; gap: 16px 20px; }
.learning-page .lesson-meta div { min-width: 0; padding-right: 19px; border-right: 1px solid #cfddde; }
.learning-page .lesson-meta div:last-child { border-right: 0; }
.learning-page .lesson-meta dt { font-size: 10px; letter-spacing: .08em; }
.learning-page .lesson-meta dd { margin-top: 5px; color: #506570; font-size: 12px; }
.learning-page .binary-hero-mark { width: clamp(130px, 18vw, 185px); border: 0; background: #152f43; transform: rotate(-7deg); }
.learning-page .binary-hero-mark span { font-family: var(--font); font-size: clamp(31px, 4.5vw, 54px); }
.learning-page .binary-hero-mark span:last-child { background: #2b676b; }
.learning-page .script-notice { margin: 26px 0 44px; padding: 19px 22px; gap: 17px; border-left: 3px solid #2b676b; border-radius: 0 10px 10px 0; background: #e0eeee; }
.learning-page .script-notice strong { font-size: 14px; }
.learning-page .script-notice p { margin-top: 5px; color: #506570; font-size: 13px; line-height: 1.9; }
.learning-page .script-notice-icon { color: #2b676b; font-size: 12px; padding-top: 3px; }
.learning-page .scene-list { gap: 32px; }
.learning-page .lesson-scene { min-width: 0; padding: 38px; border: 1px solid #cfddde; border-radius: 18px; background: #ffffff; scroll-margin-top: 28px; }
.learning-page .scene-heading { gap: 18px; margin-bottom: 27px; }
.learning-page .scene-number { width: 47px; border-radius: 12px; background: #e0eeee; color: #152f43; font-size: 14px; }
.learning-page .scene-heading p { color: #506570; font-size: 12px; font-weight: 600; }
.learning-page .scene-heading h2 { margin-top: 4px; font-size: clamp(21px, 2.7vw, 28px); line-height: 1.6; }
.learning-page .voice-card { margin-top: 24px; padding: 22px 24px; border-left: 3px solid #83a7a7; border-radius: 0 12px 12px 0; background: #edf3f2; }
.learning-page .voice-meta { flex-wrap: wrap; gap: 4px 15px; margin-bottom: 12px; font-size: 10px; letter-spacing: .06em; color: #2b676b; }
.learning-page .voice-id { color: #506570; }
.learning-page .voice-card p { color: #152c3a; font-size: 16px; line-height: 2; }
.learning-page .voice-card.is-correct { border-left-color: #2b676b; background: #e0eeee; }
.learning-page .voice-card.is-correct .voice-speaker { color: #2b676b; }
.learning-page .voice-card.is-retry { border-left-color: #83a7a7; background: #edf3f2; }
.learning-page .voice-card.is-retry .voice-speaker { color: #2b676b; }
.learning-page .scene-screen,
.learning-page .counting-line,
.learning-page .big-equation,
.learning-page .quantity-visual,
.learning-page .symbol-strip,
.learning-page .formula-panel,
.learning-page .calculation-board,
.learning-page .bitwise-board { border-radius: 12px; background: #152f43; }
.learning-page .scene-screen { gap: 12px; padding: 25px; }
.learning-page .scene-screen span { border-color: #506d7a; font-size: 15px; }
.learning-page .scene-screen strong { font-size: 24px; }
.learning-page .scene-screen b { font-size: 25px; }
.learning-page .place-value-row { gap: 10px; }
.learning-page .place-value-row span { border: 1px solid #83a7a7; border-radius: 10px; font-family: var(--font); font-size: clamp(20px, 4vw, 34px); }
.learning-page .place-value-row span:last-child { background: #152f43; color: #ffffff; border-color: #152f43; }
.learning-page .state-pair > div,
.learning-page .use-pair > div { min-height: 155px; padding: 23px; border-color: #cfddde; border-radius: 12px; background: #f5f7f6; }
.learning-page .state-pair strong,
.learning-page .use-pair strong { font-family: var(--font); font-size: 40px; }
.learning-page .state-pair small,
.learning-page .use-pair span { color: #506570; font-size: 14px; }
.learning-page .state-light { width: 34px; background: #506570; box-shadow: 0 0 0 7px #e0eeee; }
.learning-page .state-light.is-on { background: #dbeab2; box-shadow: 0 0 20px 7px #dbeab280; }
.learning-page .number-system-compare div { padding: 20px; border-radius: 11px; background: #f5f7f6; }
.learning-page .number-system-compare small { color: #506570; font-size: 13px; }
.learning-page .number-system-compare strong { font-family: var(--font); font-size: clamp(19px, 3vw, 28px); letter-spacing: .02em; }
.learning-page .counting-line { padding: 22px; font-family: var(--font); font-size: 17px; }
.learning-page .counting-line small { width: 108px; font-size: 13px; }
.learning-page .screen-caption { color: #2b676b; font-size: 15px; }
.learning-page .big-equation { min-height: 146px; padding: 22px; gap: 15px; flex-wrap: wrap; font-family: var(--font); font-size: clamp(22px, 4vw, 36px); }
.learning-page .big-equation b { background: #506d7a; }
.learning-page .big-equation.compact { min-height: auto; }
.learning-page .table-scroll { max-width: 100%; overflow-x: auto; border-radius: 10px; scrollbar-color: #83a7a7 #edf3f2; }
.learning-page .binary-table { font-family: var(--font); font-size: 16px; }
.learning-page .binary-table th,
.learning-page .binary-table td { padding: 16px 13px; border-color: #cfddde; }
.learning-page .binary-table th:first-child { font-family: "Foxode Sans", sans-serif; font-size: 13px; color: #506570; }
.learning-page .binary-table thead th { background: #e0eeee; }
.learning-page .binary-answer-row td { background: #e0eeee; color: #152f43; font-size: 25px; }
.learning-page .binary-conclusion { color: #506570; font-size: clamp(22px, 4vw, 34px); }
.learning-page .quiz-options { gap: 12px; margin-top: 24px; }
.learning-page .quiz-options li { min-width: 0; gap: 14px; padding: 18px; border: 1px solid #cfddde; border-radius: 10px; }
.learning-page .quiz-options span { flex-shrink: 0; width: 30px; font-size: 13px; color: #2b676b; }
.learning-page .quiz-options code { font-size: 22px; overflow-wrap: anywhere; }
.learning-page .quiz-answer { margin-top: 20px; border: 1px solid #83a7a7; border-radius: 12px; background: #ffffff; }
.learning-page .quiz-answer summary { padding: 18px 20px; border-radius: 11px; color: #152f43; font-size: 15px; }
.learning-page .quiz-answer summary:hover { background: #edf3f2; }
.learning-page .quiz-answer summary:focus-visible { outline: 3px solid #2b676b; outline-offset: 4px; }
.learning-page .answer-reveal { padding: 0 20px 20px; }
.learning-page .answer-title { padding: 15px; border-radius: 9px; background: #152f43; color: #ffffff; font-size: 16px; }
.learning-page .branch-grid { gap: 16px; }
.learning-page .branch-grid .voice-card { height: auto; }
.learning-page .summary-rule { grid-template-columns: repeat(auto-fit, minmax(min(215px, 100%), 1fr)); gap: 15px; }
.learning-page .summary-rule p { min-height: 115px; border: 1px solid #cfddde; border-radius: 11px; background: #edf3f2; font-size: 15px; }
.learning-page .summary-rule strong { font-size: 19px; }
.learning-page .lesson-finish { font-size: clamp(22px, 3vw, 29px); line-height: 1.7; }
.learning-page .lesson-end-nav { margin-top: 32px; gap: 14px; }
.learning-page .lesson-end-nav a { padding: 17px 20px; border: 1px solid #cfddde; border-radius: 10px; background: #e0eeee; color: #152f43; font-size: 14px; }
.learning-page .lesson-end-nav a:hover { background: #d7e7e6; border-color: #83a7a7; }
.learning-page .quantity-visual { padding: 25px; gap: 20px; }
.learning-page .quantity-dots { gap: 10px; flex-wrap: wrap; }
.learning-page .quantity-dots span { width: 28px; }
.learning-page .quantity-equivalence { gap: 12px; font-family: var(--font); font-size: clamp(23px, 4vw, 35px); }
.learning-page .radix-example-grid,
.learning-page .use-case-grid,
.learning-page .logic-gate-grid { gap: 14px; }
.learning-page .radix-example-grid > div,
.learning-page .use-case-grid > div,
.learning-page .logic-gate-card { padding: 20px; border-radius: 11px; border-color: #cfddde; background: #f5f7f6; }
.learning-page .radix-example-grid small,
.learning-page .use-case-grid small,
.learning-page .logic-gate-card small { color: #2b676b; font-size: 12px; }
.learning-page .radix-example-grid strong,
.learning-page .use-case-grid strong,
.learning-page .logic-gate-card strong { font-size: 18px; }
.learning-page .radix-example-grid p,
.learning-page .use-case-grid p,
.learning-page .logic-gate-card p { color: #506570; font-size: 14px; }
.learning-page .symbol-strip { padding: 23px; gap: 8px; }
.learning-page .symbol-strip span { width: 46px; border-color: #506d7a; border-radius: 8px; font-family: var(--font); font-size: 21px; }
.learning-page .symbol-strip span.is-letter,
.learning-page .symbol-strip span.is-focus { background: #2b676b; border-color: #dbeab2; }
.learning-page .symbol-strip.value-strip span { min-width: 68px; padding: 11px; }
.learning-page .formula-panel { padding: 25px; gap: 12px; }
.learning-page .formula-panel .formula-main { font-size: clamp(21px, 3.7vw, 32px); overflow-wrap: anywhere; }
.learning-page .formula-panel .formula-note { color: #c7dcdf; font-size: 14px; }
.learning-page .bit-group-demo { padding: 24px; border-radius: 12px; border-color: #cfddde; gap: 18px; }
.learning-page .bit-group-demo > div { min-width: 0; }
.learning-page .bit-group-demo small { color: #506570; font-size: 13px; }
.learning-page .bit-group-demo code { font-size: clamp(21px, 3.5vw, 32px); overflow-wrap: anywhere; }
.learning-page .bit-group-demo b { font-size: 28px; }
.learning-page .calculation-rules { gap: 12px; }
.learning-page .calculation-rule { min-width: 0; padding: 17px; flex-wrap: wrap; gap: 8px; border-radius: 10px; }
.learning-page .calculation-rule code { font-size: 19px; }
.learning-page .calculation-rule span { font-size: 13px; color: #506570; }
.learning-page .calculation-board { padding: 26px; }
.learning-page .calculation-board pre { font-size: clamp(23px, 4vw, 32px); line-height: 1.65; }
.learning-page .overflow-panel { padding: 24px; gap: 15px; border: 1px solid #cfddde; border-radius: 12px; background: #edf3f2; }
.learning-page .overflow-panel p { color: #506570; font-size: 15px; }
.learning-page .overflow-panel strong { color: #2b676b; font-size: 20px; }
.learning-page .condition-example { padding: 20px; border-left: 3px solid #83a7a7; border-radius: 0 10px 10px 0; color: #152c3a; font-size: 15px; }
.learning-page .logic-gate-card code { background: #152f43; font-size: 14px; }
.learning-page .truth-table-compact td:last-child { font-size: 20px; }
.learning-page .bitwise-board { padding: 25px; gap: 10px; overflow-x: auto; }
.learning-page .bitwise-row { grid-template-columns: 75px minmax(max-content, 1fr); gap: 15px; border-color: #506d7a; }
.learning-page .bitwise-row span { font-family: var(--font); font-size: 14px; }
.learning-page .bitwise-row code { font-size: 21px; }

@media (max-width: 900px) {
  .learning-page .course-main,
  .learning-page .lesson-main { width: calc(100% - 48px); }
  .learning-page .course-hero { padding-top: 24px; }
  .learning-page .course-path { padding: 30px; }
  .learning-page .path-heading { align-items: flex-start; flex-direction: column; gap: 16px; }
  .learning-page .path-heading > p { max-width: 560px; }
  .learning-page .principle-grid { gap: 22px; }
  .learning-page .lesson-hero { padding: 32px; gap: 24px; }
  .learning-page .lesson-scene { padding: 28px; }
  .learning-page .branch-grid { grid-template-columns: 1fr; }
  .learning-page .radix-example-grid,
  .learning-page .use-case-grid,
  .learning-page .logic-gate-grid { grid-template-columns: 1fr; }
}
@media (max-width: 640px) {
  .learning-page .course-main,
  .learning-page .lesson-main { width: calc(100% - 36px); margin-bottom: 58px; }
  .learning-page .breadcrumbs { margin: 22px 0 28px; font-size: 11px; gap: 8px; }
  .learning-page .course-hero { padding: 14px 0 40px; }
  .learning-page .course-hero h1 { font-size: clamp(30px, 7.7vw, 42px); line-height: 1.55; }
  .learning-page .course-lead { margin-top: 21px; font-size: 14px; }
  .learning-page .primary-link { width: 100%; padding: 15px 17px; margin-top: 24px; gap: 13px; font-size: 13px; }
  .learning-page .learning-principles { margin-top: 40px; }
  .learning-page .principle-grid { gap: 24px; }
  .learning-page .principle-grid article { padding-top: 20px; }
  .learning-page .principle-grid h3 { margin-top: 9px; font-size: 19px; }
  .learning-page .course-path { margin-top: 44px; padding: 23px 16px; border-radius: 18px; }
  .learning-page .path-heading h2 { font-size: 23px; }
  .learning-page .path-heading > p { font-size: 12px; }
  .learning-page .lesson-catalog .lesson-card { grid-template-columns: 1fr auto; padding: 22px 18px; gap: 10px; }
  .learning-page .lesson-card strong { grid-column: 1 / -1; font-size: 22px; }
  .learning-page .lesson-status { justify-self: end; }
  .learning-page .lesson-description { font-size: 13px; }
  .learning-page .mascot-note { grid-template-columns: auto minmax(0, 1fr); margin-top: 30px; gap: 16px; padding: 22px 17px; }
  .learning-page .mascot-placeholder { width: 44px; font-size: 23px; align-self: start; }
  .learning-page .mascot-note h2 { font-size: 18px; }
  .learning-page .mascot-note p:last-child { font-size: 13px; }
  .learning-page .mascot-note .eyebrow { font-size: 9px; letter-spacing: .025em; }
  .learning-page .lesson-hero { padding: 25px 22px; gap: 23px; border-radius: 18px; }
  .learning-page .lesson-hero h1 { font-size: clamp(29px, 7.2vw, 40px); }
  .learning-page .lesson-lead { font-size: 14px; margin-top: 18px; }
  .learning-page .lesson-meta { margin-top: 20px; gap: 12px; }
  .learning-page .lesson-meta div { display: grid; grid-template-columns: 55px 1fr; gap: 9px; padding: 0; border: 0; }
  .learning-page .lesson-meta dd { margin: 0; }
  .learning-page .binary-hero-mark { width: 100px; }
  .learning-page .binary-hero-mark span { font-size: 31px; }
  .learning-page .script-notice { margin: 22px 0 28px; padding: 17px; gap: 12px; }
  .learning-page .script-notice strong { font-size: 13px; }
  .learning-page .script-notice p { font-size: 12px; }
  .learning-page .scene-list { gap: 22px; }
  .learning-page .lesson-scene { padding: 23px 18px; border-radius: 15px; }
  .learning-page .scene-heading { gap: 12px; margin-bottom: 22px; }
  .learning-page .scene-number { width: 37px; border-radius: 9px; font-size: 12px; }
  .learning-page .scene-heading p { font-size: 11px; }
  .learning-page .scene-heading h2 { font-size: 20px; }
  .learning-page .voice-card { margin-top: 20px; padding: 18px 16px; }
  .learning-page .voice-card p { font-size: 14px; line-height: 2; }
  .learning-page .voice-meta { font-size: 9px; letter-spacing: .025em; }
  .learning-page .scene-screen { padding: 19px 13px; gap: 8px; }
  .learning-page .scene-screen span { padding: 9px 4px; font-size: 13px; }
  .learning-page .scene-screen strong { font-size: 20px; }
  .learning-page .place-value-row { gap: 6px; }
  .learning-page .place-value-row span { font-size: 19px; border-radius: 8px; }
  .learning-page .number-system-compare div { padding: 16px; }
  .learning-page .number-system-compare strong { font-size: 19px; }
  .learning-page .big-equation { padding: 19px 12px; gap: 10px; min-height: 120px; font-size: 23px; }
  .learning-page .binary-conclusion { font-size: 23px; }
  .learning-page .screen-caption { font-size: 13px; }
  .learning-page .quiz-options li { padding: 14px; }
  .learning-page .quiz-options code { font-size: 20px; }
  .learning-page .quiz-answer summary { padding: 16px; font-size: 14px; }
  .learning-page .answer-reveal { padding: 0 12px 12px; }
  .learning-page .answer-title { padding: 14px 10px; font-size: 14px; }
  .learning-page .symbol-strip { padding: 18px 12px; gap: 7px; }
  .learning-page .symbol-strip span { width: 39px; font-size: 19px; }
  .learning-page .symbol-strip.value-strip span { min-width: 59px; padding: 9px; }
  .learning-page .quantity-visual,
  .learning-page .formula-panel,
  .learning-page .bit-group-demo,
  .learning-page .calculation-board,
  .learning-page .bitwise-board { padding: 20px 16px; }
  .learning-page .quantity-dots { gap: 8px; }
  .learning-page .quantity-dots span { width: 23px; }
  .learning-page .quantity-equivalence { font-size: 23px; }
  .learning-page .formula-panel .formula-main { font-size: 21px; }
  .learning-page .formula-panel .formula-note { font-size: 12px; }
  .learning-page .overflow-panel { padding: 20px 16px; }
  .learning-page .overflow-panel p { font-size: 14px; }
  .learning-page .overflow-panel strong { font-size: 18px; }
  .learning-page .bitwise-row { grid-template-columns: 55px minmax(max-content, 1fr); gap: 9px; }
  .learning-page .bitwise-row span { font-size: 12px; }
  .learning-page .bitwise-row code { font-size: 18px; }
  .learning-page .lesson-end-nav a { font-size: 13px; padding: 16px; }
}
@media (prefers-reduced-motion: reduce) {
  .learning-page *, .learning-page *::before, .learning-page *::after { animation: none !important; transition: none !important; }
}