:root {
  --ink: #102a43;
  --muted: #5b7083;
  --paper: #f5f8fb;
  --white: #ffffff;
  --navy: #0b2545;
  --blue: #146b8c;
  --teal: #168c86;
  --orange: #e97732;
  --amber: #fff0ce;
  --line: #d8e2ea;
  --green: #167c5a;
  --red: #b43b3b;
  --shadow: 0 14px 40px rgba(16, 42, 67, .09);
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif; color: var(--ink); background: var(--paper); font-size: 16px; line-height: 1.55; }
button, input, select, textarea { font: inherit; }
button { cursor: pointer; }
.skip-link { position: fixed; left: 1rem; top: -4rem; z-index: 100; background: white; padding: .8rem 1rem; border-radius: .5rem; color: var(--navy); }
.skip-link:focus { top: 1rem; }
.topbar { height: 76px; position: sticky; top: 0; z-index: 20; display: flex; justify-content: space-between; align-items: center; padding: 0 2.5rem; color: white; background: var(--navy); box-shadow: 0 5px 22px rgba(5, 25, 48, .2); }
.brand { display: flex; gap: .8rem; align-items: center; }
.brand-mark { display: grid; place-items: center; width: 42px; height: 42px; border: 2px solid rgba(255,255,255,.45); border-radius: 50%; font: 700 1.35rem Georgia, serif; color: #62d0c8; }
.brand div { display: flex; flex-direction: column; line-height: 1.2; }
.brand strong { font-size: 1.05rem; }
.brand span:last-child { font-size: .78rem; color: #b9cfdf; }
.progress-wrap { width: min(290px, 32vw); display: grid; grid-template-columns: auto 1fr; gap: .65rem; align-items: center; font-size: .8rem; color: #d8e6ef; }
.progress-track { height: 7px; overflow: hidden; border-radius: 10px; background: rgba(255,255,255,.18); }
.progress-bar { width: 0; height: 100%; background: #52c7bc; transition: width .35s ease; }
.app-shell { display: grid; grid-template-columns: 250px minmax(0, 1fr); min-height: calc(100vh - 76px); }
.course-nav { position: sticky; top: 76px; height: calc(100vh - 76px); padding: 2rem 1rem; overflow-y: auto; background: #eaf0f5; border-right: 1px solid var(--line); }
.nav-label { margin: 0 .75rem .8rem; color: #6e8395; font-size: .74rem; font-weight: 800; letter-spacing: .1em; text-transform: uppercase; }
.nav-item { width: 100%; display: flex; flex-direction: column; align-items: flex-start; padding: .76rem .85rem; margin: .18rem 0; border: 0; border-left: 3px solid transparent; border-radius: 0 .6rem .6rem 0; color: #304c62; background: transparent; text-align: left; }
.nav-item span { font-weight: 750; }
.nav-item small { color: #718799; }
.nav-item:hover { background: rgba(255,255,255,.7); }
.nav-item.active { color: var(--blue); background: white; border-left-color: var(--orange); box-shadow: 0 4px 15px rgba(16,42,67,.07); }
.nav-item.done span::after { content: "✓"; margin-left: .45rem; color: var(--green); }
.project-link { margin-top: 1rem; border-top: 1px solid #cfdae3; border-radius: 0; padding-top: 1.2rem; }
.course-main { width: min(100%, 1030px); margin: 0 auto; padding: 3.6rem clamp(1.5rem, 5vw, 5rem) 6rem; }
.chapter { display: none; animation: reveal .3s ease; }
.chapter.active { display: block; }
@keyframes reveal { from { opacity: 0; transform: translateY(7px); } to { opacity: 1; transform: translateY(0); } }
.chapter-kicker { margin-bottom: .6rem; color: var(--orange); font-size: .8rem; font-weight: 850; letter-spacing: .08em; text-transform: uppercase; }
h1, h2, h3 { line-height: 1.15; color: var(--navy); }
h1 { max-width: 790px; margin: 0 0 1rem; font-size: clamp(2.2rem, 5vw, 4.4rem); letter-spacing: -.045em; }
h2 { margin: 0 0 .8rem; font-size: clamp(2rem, 4vw, 3.3rem); letter-spacing: -.035em; }
h3 { margin: 0 0 .45rem; font-size: 1.15rem; }
.lead { max-width: 760px; margin: 0 0 2.5rem; color: #3f586c; font-size: 1.14rem; }
.path-choice { display: grid; grid-template-columns: repeat(2, 1fr); gap: 1rem; margin: 2rem 0 3rem; }
.path-card { display: grid; grid-template-columns: 48px 1fr; gap: .1rem 1rem; padding: 1.3rem; border: 2px solid var(--line); border-radius: 1rem; background: white; color: var(--ink); text-align: left; box-shadow: 0 6px 22px rgba(16,42,67,.04); }
.path-card:hover, .path-card.selected { border-color: var(--teal); box-shadow: var(--shadow); }
.path-card .path-number { grid-row: 1 / 3; display: grid; place-items: center; width: 45px; height: 45px; border-radius: 50%; background: #dcefee; color: var(--teal); font-weight: 900; }
.path-card strong { align-self: end; font-size: 1.06rem; }
.path-card > span:last-child { color: var(--muted); font-size: .9rem; }
.route-map { display: grid; grid-template-columns: auto 1fr auto 1fr auto 1fr auto; align-items: center; margin: 2.5rem 0; }
.route-map div { display: flex; flex-direction: column; align-items: center; gap: .3rem; font-size: .82rem; color: var(--muted); }
.route-map b { display: grid; place-items: center; width: 46px; height: 46px; border: 2px solid #9dc8c5; border-radius: 50%; color: var(--teal); background: white; }
.route-map i { height: 2px; background: #b8cfda; }
.downloads-panel { display: grid; grid-template-columns: minmax(220px, .85fr) 1.55fr; gap: 1.4rem; margin: 2.2rem 0; padding: 1.35rem; border-radius: 1rem; color: white; background: linear-gradient(125deg, var(--navy), #16486a); box-shadow: var(--shadow); }
.downloads-copy > span { color: #66d0c7; font-size: .76rem; font-weight: 850; letter-spacing: .07em; text-transform: uppercase; }
.downloads-copy h2 { margin: .35rem 0 .55rem; color: white; font-size: 1.65rem; letter-spacing: -.02em; }
.downloads-copy p { margin: 0; color: #c8dae5; font-size: .92rem; }
.download-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: .7rem; }
.download-card { display: flex; min-width: 0; flex-direction: column; padding: 1rem; border: 1px solid rgba(255,255,255,.18); border-radius: .7rem; color: var(--navy); background: white; text-decoration: none; transition: transform .18s ease, box-shadow .18s ease; }
.download-card:hover, .download-card:focus-visible { transform: translateY(-2px); box-shadow: 0 10px 24px rgba(3,20,38,.25); }
.download-card b { line-height: 1.25; }
.download-card span { margin: .25rem 0 .85rem; color: var(--muted); font-size: .8rem; }
.download-card strong { margin-top: auto; color: var(--blue); font-size: .84rem; }
.downloads-reminder { display: flex; justify-content: space-between; align-items: center; gap: 1rem; margin-top: 2rem; padding: 1.1rem 1.2rem; border: 1px solid var(--line); border-left: 4px solid var(--teal); border-radius: .65rem; background: white; }
.downloads-reminder div:first-child { display: flex; flex-direction: column; }
.downloads-reminder span { color: var(--muted); font-size: .9rem; }
.downloads-reminder div:last-child { display: flex; flex-wrap: wrap; gap: .45rem; }
.downloads-reminder a { padding: .5rem .7rem; border: 1px solid #9db0bf; border-radius: .45rem; color: var(--navy); background: #f5f8fa; font-weight: 750; text-decoration: none; }
.downloads-reminder a:hover, .downloads-reminder a:focus-visible { border-color: var(--teal); color: var(--teal); background: #eef8f7; }
.note { margin: 1.7rem 0; padding: 1rem 1.2rem; border-left: 4px solid; border-radius: .25rem .7rem .7rem .25rem; }
.note strong { display: block; margin-bottom: .2rem; }
.note.blue { background: #e7f2f7; border-color: var(--blue); }
.note.amber { background: var(--amber); border-color: #db8a1d; }
.primary, .secondary, .complete-btn { padding: .76rem 1.1rem; border-radius: .55rem; font-weight: 750; }
.primary { border: 1px solid var(--navy); color: white; background: var(--navy); }
.primary:hover { background: #173b63; }
.secondary { border: 1px solid #9db0bf; color: var(--navy); background: white; }
.complete-btn { border: 1px solid var(--teal); color: var(--teal); background: white; }
.complete-btn.completed { color: white; background: var(--green); border-color: var(--green); }
.chapter-actions { display: flex; justify-content: space-between; gap: 1rem; margin-top: 2.6rem; padding-top: 1.2rem; border-top: 1px solid var(--line); }
.concept-grid { display: grid; gap: 1rem; margin: 2rem 0; }
.concept-grid.three { grid-template-columns: repeat(3, 1fr); }
.concept-grid article { padding: 1.2rem; border: 1px solid var(--line); border-top: 4px solid #94b9c9; border-radius: .75rem; background: white; box-shadow: 0 6px 20px rgba(16,42,67,.04); }
.concept-grid article p { margin: .4rem 0; color: var(--muted); }
.concept-grid article em { display: block; margin-top: .8rem; color: #526d80; font-size: .88rem; font-style: normal; }
.concept-grid.compact article { padding-top: 1rem; }
.soap-lab { margin: 2rem 0; overflow: hidden; border-radius: 1rem; color: white; background: var(--navy); box-shadow: var(--shadow); }
.soap-title { padding: 1.4rem 1.5rem 1rem; }
.soap-title > span { color: #66d0c7; font-size: .76rem; font-weight: 850; letter-spacing: .07em; text-transform: uppercase; }
.soap-title h3 { margin-top: .25rem; color: white; font-size: 1.45rem; }
.soap-title p { margin: .4rem 0; color: #c8dae5; }
.soap-questions { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1px; background: #466078; }
.soap-questions article { padding: 1.15rem; background: white; color: var(--ink); }
.soap-questions article p { margin: .35rem 0 0; color: var(--muted); font-size: .9rem; }
.design-basics { margin: 2rem 0; }
.design-basics > div { display: grid; grid-template-columns: repeat(3, 1fr); gap: .8rem; }
.design-basics article { padding: 1rem; border: 1px solid var(--line); border-radius: .65rem; background: #eef4f7; }
.design-basics p { margin: .35rem 0 0; color: var(--muted); font-size: .9rem; }
.concept-tag { display: inline-block; padding: .25rem .55rem; margin-bottom: .7rem; border-radius: .3rem; font-size: .74rem; font-weight: 850; text-transform: uppercase; letter-spacing: .05em; }
.concept-tag.nominal { color: #7b4815; background: #ffebc9; }
.concept-tag.ordinal { color: #195f69; background: #d8eff1; }
.concept-tag.metric { color: #38579b; background: #e0e8fb; }
.exercise, .quick-check { margin: 2rem 0; padding: 1.5rem; border: 1px solid #cad8e2; border-radius: 1rem; background: white; box-shadow: var(--shadow); }
.exercise-head { display: flex; justify-content: space-between; gap: 1rem; align-items: start; margin-bottom: 1rem; }
.exercise-head span { color: var(--orange); font-size: .76rem; font-weight: 850; letter-spacing: .06em; text-transform: uppercase; }
.exercise-head h3 { font-size: 1.4rem; }
.exercise-head .score { padding: .35rem .7rem; border-radius: 1rem; color: var(--blue); background: #e5f2f5; white-space: nowrap; }
.quiz-list { display: grid; gap: .65rem; }
.quiz-item { display: grid; grid-template-columns: minmax(160px, 1fr) auto; gap: 1rem; align-items: center; padding: .75rem .85rem; border-radius: .55rem; background: #f4f7fa; }
.quiz-item strong { font-size: .95rem; }
.choice-row { display: flex; flex-wrap: wrap; gap: .55rem; }
.choice-row button, .choice-stack button, .quiz-item button { padding: .5rem .72rem; border: 1px solid #b8c8d3; border-radius: .45rem; color: var(--ink); background: white; }
.quiz-item .mini-choices { display: flex; gap: .35rem; }
.quiz-item button { padding: .38rem .55rem; font-size: .78rem; }
button.correct { border-color: var(--green) !important; color: var(--green) !important; background: #e6f5ef !important; }
button.wrong { border-color: var(--red) !important; color: var(--red) !important; background: #fbeaea !important; }
.feedback { display: none; margin-top: 1rem; padding: .8rem 1rem; border-radius: .5rem; background: #edf3f7; color: #314e62; }
.feedback.visible { display: block; }
.feedback.success { background: #e7f5ef; color: #126347; }
.feedback.error { background: #fbecec; color: #8a2f2f; }
.project-prompt { margin: 1.5rem 0; padding: 1rem 1.2rem; border: 1px dashed var(--teal); border-radius: .7rem; background: #f0faf8; }
body[data-path="examples"] .own-only { display: none; }
.measure-table { margin: 2rem 0; overflow: hidden; border: 1px solid var(--line); border-radius: .8rem; background: white; }
.table-row { display: grid; grid-template-columns: .8fr 1.2fr 1.4fr; gap: 1rem; padding: .8rem 1rem; border-top: 1px solid var(--line); }
.table-row:first-child { border-top: 0; }
.table-head { color: white; background: var(--navy); font-size: .86rem; font-weight: 800; }
.lab-bench label, .errorbar-lab label { display: block; margin: 1.2rem 0 .4rem; font-weight: 700; }
input[type="range"] { width: 100%; accent-color: var(--orange); }
.dotplot { position: relative; height: 120px; margin: 1.3rem 0; border-bottom: 2px solid #7890a2; background: repeating-linear-gradient(to right, transparent 0, transparent calc(10% - 1px), #e7edf1 calc(10% - 1px), #e7edf1 10%); }
.dotplot-axis { display: flex; justify-content: space-between; gap: 1rem; margin-top: -1rem; color: var(--muted); font-size: .78rem; }
.measurement-list { margin: .8rem 0 0; color: var(--muted); font-size: .88rem; }
.dot { position: absolute; bottom: 0; width: 17px; height: 17px; transform: translateX(-50%); border: 3px solid white; border-radius: 50%; background: var(--teal); box-shadow: 0 0 0 1px var(--teal); }
.dot.outlier { background: var(--orange); box-shadow: 0 0 0 1px var(--orange); }
.result-pair { display: grid; grid-template-columns: repeat(2, 1fr); gap: 1rem; }
.result-pair.three { grid-template-columns: repeat(3, 1fr); }
.result-pair div { padding: 1rem; border-radius: .6rem; color: var(--muted); background: #eef4f7; }
.result-pair span { display: block; font-size: .8rem; }
.result-pair strong { color: var(--navy); font-size: 1.7rem; }
.quick-check h3 { margin-bottom: .5rem; }
.distribution-intro { background: linear-gradient(120deg, var(--navy), #16486a); }
.cream-mode-lab .choice-row button.active { color: white; border-color: var(--teal); background: var(--teal); }
.frequency-plot { height: 210px; display: grid; grid-template-columns: repeat(9, 1fr); align-items: end; gap: .45rem; margin: 1.4rem 0 .8rem; padding: 1rem 1rem 2rem; border-left: 2px solid #7890a2; border-bottom: 2px solid #7890a2; background: repeating-linear-gradient(to top, transparent 0, transparent 35px, #e5edf2 36px); }
.frequency-bar { position: relative; min-height: 2px; background: var(--blue); transition: height .25s ease; }
.frequency-bar.mode { background: var(--orange); }
.frequency-bar b { position: absolute; top: -.9rem; left: 50%; transform: translateX(-50%); color: var(--navy); font-size: .75rem; }
.frequency-bar span { position: absolute; bottom: -1.65rem; left: 50%; transform: translateX(-50%); color: var(--muted); font-size: .78rem; }
.choice-stack { display: grid; gap: .55rem; }
.spread-compare { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; margin: 2rem 0; }
.spread-compare article { padding: 1.2rem; border-radius: .8rem; color: white; background: var(--navy); }
.spread-compare article:last-child { background: var(--blue); }
.spread-compare h3, .spread-compare p { color: white; }
.number-strip { display: flex; justify-content: space-between; gap: .3rem; margin: 1rem 0; }
.number-strip span { padding: .25rem .4rem; border-radius: .3rem; background: rgba(255,255,255,.14); }
.target-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: .75rem; margin: 1.2rem 0; }
.variance-flow { display: grid; grid-template-columns: 1fr auto 1.2fr auto 1.2fr auto 1fr auto 1.2fr; gap: .45rem; align-items: center; margin: 1.4rem 0; }
.variance-flow div { min-height: 82px; display: flex; align-items: center; gap: .6rem; padding: .75rem; border-radius: .6rem; background: white; border: 1px solid var(--line); }
.variance-flow b { display: grid; place-items: center; flex: 0 0 29px; height: 29px; border-radius: 50%; color: white; background: var(--teal); }
.variance-flow span { min-width: 0; font-size: .84rem; font-weight: 700; line-height: 1.25; overflow-wrap: anywhere; }
.variance-flow i { color: var(--orange); font-style: normal; font-weight: 900; }
.excel-example { margin: 1.8rem 0; overflow: hidden; padding: 1.3rem; border: 1px solid var(--line); border-radius: .8rem; background: white; box-shadow: 0 8px 26px rgba(16,42,67,.06); }
.excel-grid { display: grid; grid-template-columns: 1fr repeat(3, .8fr); gap: 1rem; padding: .68rem .8rem; border-top: 1px solid var(--line); }
.excel-grid.table-head { border-top: 0; border-radius: .4rem; }
.excel-example > p { margin: 1rem .2rem 0; color: var(--muted); }
.target-grid button { padding: .7rem; border: 1px solid var(--line); border-radius: .7rem; background: #f5f8fa; }
.target-grid button.selected { outline: 3px solid #75b8b3; }
.target { position: relative; display: block; width: 100px; height: 100px; margin: 0 auto .5rem; border: 1px solid #9aafbd; border-radius: 50%; background: radial-gradient(circle, #fff 0 13%, #dce9ee 14% 28%, #fff 29% 44%, #dce9ee 45% 60%, #fff 61%); }
.target::before { content: ""; position: absolute; width: 9px; height: 9px; border-radius: 50%; background: var(--orange); box-shadow: var(--dots); }
.target.rp::before { left: 46px; top: 45px; --dots: 7px -4px var(--orange), -5px 7px var(--orange), 4px 8px var(--orange), -7px -5px var(--orange); }
.target.ru::before { left: 46px; top: 45px; --dots: 26px -25px var(--orange), -29px 18px var(--orange), 23px 28px var(--orange), -24px -23px var(--orange); }
.target.fp::before { left: 70px; top: 21px; --dots: 6px -3px var(--orange), -5px 6px var(--orange), 4px 8px var(--orange), -7px -5px var(--orange); }
.target.fu::before { left: 64px; top: 22px; --dots: 24px 10px var(--orange), -7px 31px var(--orange), -35px 8px var(--orange), 1px 49px var(--orange); }
.normal-steps { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1rem; margin: 2rem 0; }
.why-normal { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; margin: 1.7rem 0; }
.why-normal article { padding: 1.1rem; border-top: 4px solid var(--teal); border-radius: .65rem; background: white; }
.why-normal article:last-child { border-top-color: var(--orange); }
.why-normal p { margin: .35rem 0 0; color: var(--muted); }
.shape-guide { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; margin: 1rem 0 1.7rem; }
.shape-guide article { padding: 1rem; border-left: 4px solid var(--blue); border-radius: .55rem; background: #edf4f7; }
.shape-guide article:last-child { border-left-color: var(--orange); }
.shape-guide p { margin: .35rem 0 0; color: var(--muted); }
.normal-steps > div { display: flex; gap: .8rem; padding: 1rem; border-bottom: 3px solid var(--teal); background: white; }
.normal-steps b { color: var(--orange); font-size: 1.4rem; }
.normal-steps span { display: flex; flex-direction: column; color: var(--muted); }
.normal-steps strong { color: var(--navy); }
.distribution-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: .8rem; }
.distribution-card { padding: 1rem; border: 1px solid var(--line); border-radius: .7rem; }
.histogram { height: 120px; display: flex; align-items: flex-end; justify-content: center; gap: 4px; padding: .5rem; border-bottom: 2px solid #7991a2; }
.histogram i { width: 12%; min-height: 3px; background: var(--blue); }
.distribution-card select { width: 100%; margin-top: .8rem; padding: .55rem; border: 1px solid #adbfcb; border-radius: .45rem; background: white; }
.plain-explainer { margin: 1.6rem 0; padding: 1.3rem; border-radius: .8rem; color: white; background: var(--navy); }
.plain-explainer h3, .plain-explainer p { color: white; }
.normal-number-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: .7rem; }
.normal-number-grid article { padding: .85rem; border-radius: .55rem; background: #edf4f7; }
.normal-number-grid b, .normal-number-grid span, .normal-number-grid em { display: block; }
.normal-number-grid span { margin: .35rem 0; color: var(--blue); font-size: 1.15rem; font-weight: 850; }
.normal-number-grid em { color: var(--muted); font-size: .8rem; font-style: normal; }
.hypothesis-pair { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; margin: 2rem 0; }
.significance-explainer { margin: 1.5rem 0; padding: 1.3rem; border-radius: .8rem; background: white; border: 1px solid var(--line); }
.significance-explainer > div { display: grid; grid-template-columns: repeat(3, 1fr); gap: .7rem; }
.significance-explainer span { padding: .8rem; color: var(--muted); background: #edf4f7; border-radius: .5rem; }
.significance-explainer span b { display: block; color: var(--navy); }
.significance-explainer > p { margin: 1rem 0 0; color: var(--muted); }
.hypothesis-pair > div { padding: 1.2rem; border-left: 4px solid var(--teal); background: white; }
.hypothesis-pair > div:last-child { border-left-color: var(--orange); }
.hypothesis-pair span { color: var(--muted); font-size: .78rem; font-weight: 800; text-transform: uppercase; }
.hypothesis-pair strong { display: block; margin-top: .4rem; font-size: 1.25rem; }
.hypothesis-pair p { margin-bottom: 0; color: var(--muted); }
.p-scale { position: relative; display: grid; grid-template-columns: 5% 95%; height: 48px; margin: 3.5rem 0 .7rem; border-radius: .5rem; overflow: visible; }
.p-zone { display: grid; place-items: center; overflow: hidden; color: white; font-size: .8rem; font-weight: 800; }
.p-zone.significant { background: var(--orange); border-radius: .5rem 0 0 .5rem; color: transparent; }
.p-zone.open { background: #7c95a7; border-radius: 0 .5rem .5rem 0; }
.p-marker { position: absolute; top: -28px; bottom: 0; width: 2px; background: var(--navy); }
.p-marker span { position: absolute; top: -2px; transform: translateX(-50%); font-weight: 800; }
.center-copy { text-align: center; color: var(--muted); }
.errorbar-chart { position: relative; height: 270px; display: flex; justify-content: center; align-items: flex-end; gap: 80px; padding: 20px 40px 30px 70px; border-left: 2px solid #7890a2; border-bottom: 2px solid #7890a2; background: repeating-linear-gradient(to top, transparent 0, transparent 49px, #e3eaef 50px); }
.chart-axis { position: absolute; left: -38px; top: 10px; bottom: -10px; display: flex; flex-direction: column; justify-content: space-between; color: var(--muted); font-size: .75rem; }
.bar-group { position: relative; width: 85px; height: 100%; display: flex; align-items: flex-end; justify-content: center; }
.mean-bar { position: relative; width: 62px; height: 50%; background: var(--blue); transition: height .25s ease; }
.mean-bar.orange { background: var(--orange); }
.mean-bar span { position: absolute; bottom: -27px; left: 50%; transform: translateX(-50%); color: var(--ink); font-weight: 750; }
.error-line { position: absolute; left: 50%; width: 2px; height: 70px; transform: translateX(-50%); background: var(--navy); z-index: 2; transition: bottom .25s ease; }
.error-line::before, .error-line::after { content: ""; position: absolute; left: -11px; width: 24px; height: 2px; background: var(--navy); }
.error-line::before { top: 0; }.error-line::after { bottom: 0; }
.rule-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; }
.rule-grid article { padding: 1rem; border: 1px solid var(--line); border-top: 4px solid #8ba0af; border-radius: .65rem; background: white; }
.rule-grid article.good { border-top-color: var(--green); }
.rule-grid p { margin: .3rem 0 0; color: var(--muted); }
.comparison-row { display: grid; grid-template-columns: 1.4fr 1fr .6fr .7fr; gap: .8rem; padding: .72rem .5rem; border-top: 1px solid var(--line); align-items: center; }
.comparison-row:first-of-type { border-top: 0; }
.comparison-row span { color: var(--muted); }
.comparison-row em { color: var(--muted); font-style: normal; font-weight: 800; }
.comparison-row em.sig { color: var(--green); }
.finder-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 1rem; }
.finder-grid label, .research-form label, .case-steps label { display: flex; flex-direction: column; gap: .35rem; color: var(--muted); font-size: .85rem; font-weight: 750; }
select, input[type="text"], input[type="number"], textarea { width: 100%; padding: .7rem .75rem; border: 1px solid #aebfca; border-radius: .5rem; color: var(--ink); background: white; }
select:focus, input:focus, textarea:focus, button:focus-visible { outline: 3px solid rgba(22,140,134,.3); outline-offset: 2px; }
.finder-result, .analysis-plan { margin-top: 1.2rem; padding: 1.2rem; border-radius: .7rem; background: var(--navy); color: white; }
.finder-result span, .analysis-plan span { display: block; color: #a9c8d8; font-size: .76rem; font-weight: 800; text-transform: uppercase; }
.finder-result strong, .analysis-plan strong { display: block; margin: .25rem 0; font-size: 1.45rem; }
.finder-result p, .analysis-plan p { margin: .3rem 0 0; color: #d8e5ed; }
.test-map { margin: 2rem 0; }
.test-row { display: grid; grid-template-columns: 90px 1fr 1.1fr; gap: 1rem; align-items: center; padding: .9rem .7rem; border-bottom: 1px solid var(--line); }
.test-row .concept-tag { margin: 0; text-align: center; }
.test-row p { color: var(--muted); }
.test-row small { color: var(--muted); font-weight: 500; }
.case-steps { display: grid; grid-template-columns: repeat(3, 1fr); gap: .8rem; margin: 1rem 0; }
.completion-box { display: flex; justify-content: space-between; gap: 1rem; margin: 1.5rem 0; padding: 1rem 1.2rem; border-radius: .7rem; background: #dceeed; }
.project-tabs { display: flex; gap: .4rem; margin-top: 2rem; border-bottom: 2px solid var(--line); }
.project-tabs button { padding: .8rem 1rem; border: 0; border-bottom: 3px solid transparent; color: var(--muted); background: transparent; font-weight: 800; }
.project-tabs button.active { color: var(--teal); border-bottom-color: var(--teal); }
.project-panel { display: none; padding-top: 1.5rem; }
.project-panel.active { display: block; }
.research-form { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; }
.research-form .full { grid-column: 1 / -1; }
.form-actions { display: flex; gap: .7rem; margin-top: 1rem; }
.data-workbench { margin-top: 1.3rem; padding: 1rem 1.2rem; border: 1px solid var(--line); border-radius: .7rem; background: white; }
.data-workbench summary { cursor: pointer; color: var(--blue); font-weight: 800; }
.data-workbench > p { color: var(--muted); }
.data-columns { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; margin-bottom: .8rem; }
.data-columns label { color: var(--muted); font-size: .85rem; font-weight: 750; }
.data-summary { display: grid; grid-template-columns: 1fr 1fr; gap: .7rem; margin-top: 1rem; }
.data-summary article { padding: .8rem; border-radius: .55rem; background: #edf4f7; }
.data-summary b { display: block; margin-bottom: .2rem; }
.data-summary span { color: var(--muted); font-size: .9rem; }
.example-report { padding: 1.4rem; border: 1px solid var(--line); border-left: 5px solid var(--orange); border-radius: .7rem; background: white; }
footer { display: flex; justify-content: space-between; gap: 1rem; padding: 1.2rem 2.5rem; border-top: 1px solid var(--line); color: var(--muted); background: white; font-size: .82rem; }
footer button { border: 0; color: var(--blue); background: transparent; }
@media (max-width: 820px) {
  .topbar { height: auto; min-height: 70px; padding: .7rem 1rem; }
  .progress-wrap { grid-template-columns: 1fr; gap: .25rem; width: 130px; }
  .app-shell { display: block; }
  .course-nav { position: sticky; top: 70px; z-index: 15; display: flex; height: auto; padding: .45rem .7rem; overflow-x: auto; border-right: 0; border-bottom: 1px solid var(--line); }
  .nav-label, .nav-item small { display: none; }
  .nav-item { flex: 0 0 auto; width: auto; padding: .55rem .7rem; border-left: 0; border-bottom: 3px solid transparent; border-radius: .4rem; white-space: nowrap; }
  .nav-item.active { border-left: 0; border-bottom-color: var(--orange); }
  .project-link { margin: 0 0 0 .4rem; padding-top: .55rem; border-top: 0; border-left: 1px solid #c5d2dc; }
  .course-main { padding: 2rem 1.1rem 4rem; }
  .concept-grid.three, .normal-steps, .distribution-grid, .soap-questions, .design-basics > div, .shape-guide { grid-template-columns: 1fr; }
  .variance-flow { grid-template-columns: 1fr; }
  .variance-flow i { transform: rotate(90deg); text-align: center; }
  .normal-number-grid { grid-template-columns: repeat(2, 1fr); }
  .target-grid { grid-template-columns: repeat(2, 1fr); }
  .case-steps, .research-form { grid-template-columns: 1fr; }
  .data-columns, .data-summary { grid-template-columns: 1fr; }
  .research-form .full { grid-column: auto; }
  .downloads-panel { grid-template-columns: 1fr; }
  .download-grid { grid-template-columns: repeat(3, 1fr); }
  .downloads-reminder { align-items: flex-start; flex-direction: column; }
}
@media (max-width: 590px) {
  .brand span:last-child, #progressLabel { display: none; }
  .progress-wrap { width: 90px; }
  .path-choice, .spread-compare, .hypothesis-pair, .rule-grid, .finder-grid, .why-normal, .significance-explainer > div { grid-template-columns: 1fr; }
  .route-map { grid-template-columns: repeat(4, 1fr); gap: .5rem; }
  .route-map i { display: none; }
  .download-grid { grid-template-columns: 1fr; }
  .quiz-item { grid-template-columns: 1fr; }
  .table-row { grid-template-columns: 1fr; gap: .25rem; }
  .table-head { display: none; }
  .result-pair { grid-template-columns: 1fr 1fr; }
  .result-pair.three, .normal-number-grid { grid-template-columns: 1fr; }
  .excel-grid { grid-template-columns: 1fr 1fr; }
  .excel-grid.table-head { display: none; }
  .comparison-row { grid-template-columns: 1fr 1fr; }
  .test-row { grid-template-columns: 1fr; gap: .3rem; }
  .errorbar-chart { gap: 35px; }
  .completion-box, footer { flex-direction: column; }
}
@media (prefers-reduced-motion: reduce) { * { scroll-behavior: auto !important; animation: none !important; transition: none !important; } }