:root {
  color-scheme: light;
  --bg: #f2f4f0;
  --surface: rgba(255, 255, 255, 0.88);
  --surface-strong: #ffffff;
  --ink: #1c2920;
  --muted: #687169;
  --line: rgba(31, 61, 40, 0.14);
  --mint: #d6e8da;
  --mint-strong: #316b49;
  --sky: #e1e5e1;
  --peach: #efe3bd;
  --danger: #a14a4a;
  --success: #34725d;
  --learning-neutral: #fbfaf6;
  --learning-neutral-strong: #f0f1ed;
  --learning-correct: #14733f;
  --learning-correct-bg: #dff5e7;
  --learning-incorrect: #b92f3b;
  --learning-incorrect-bg: #fde3e5;
  --learning-new: #2468c9;
  --learning-new-bg: #e2efff;
  --shadow: 0 18px 50px rgba(37, 62, 44, 0.1);
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --bg: #121713;
  --surface: rgba(28, 37, 30, 0.9);
  --surface-strong: #1d261f;
  --ink: #f2f5f1;
  --muted: #adb7af;
  --line: rgba(237, 244, 238, 0.14);
  --mint: #273a2d;
  --mint-strong: #a6ceb0;
  --sky: #28332c;
  --peach: #4b4228;
  --danger: #e3a3a7;
  --success: #9bd1b6;
  --learning-neutral: #202721;
  --learning-neutral-strong: #2a322c;
  --learning-correct: #7fe0a6;
  --learning-correct-bg: #163c29;
  --learning-incorrect: #ff9ba4;
  --learning-incorrect-bg: #4c2026;
  --learning-new: #86baff;
  --learning-new-bg: #19395f;
  --shadow: 0 24px 64px rgba(0, 0, 0, 0.3);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  min-height: 100vh;
  background:
    radial-gradient(circle at 8% 0%, rgba(214, 232, 218, 0.92), transparent 35%),
    radial-gradient(circle at 95% 12%, rgba(239, 227, 189, 0.78), transparent 34%),
    var(--bg);
  color: var(--ink);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}
:root[data-theme="dark"] body {
  background:
    radial-gradient(circle at 8% 0%, rgba(39, 58, 45, 0.75), transparent 35%),
    radial-gradient(circle at 95% 12%, rgba(75, 66, 40, 0.48), transparent 34%),
    var(--bg);
}
button, input, select { font: inherit; }
button { color: inherit; }

.app-header, main, footer { width: min(1120px, calc(100% - 32px)); margin-inline: auto; }
.app-header {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 24px;
  padding: 38px 0 24px;
}
h1, h2, p { margin-top: 0; }
h1 { margin-bottom: 0; font-family: Georgia, serif; font-size: clamp(2.1rem, 5vw, 4rem); font-weight: 500; letter-spacing: -0.045em; }
h2 { margin-bottom: 12px; font-family: Georgia, serif; font-size: clamp(1.45rem, 3vw, 2.2rem); font-weight: 500; letter-spacing: -0.025em; }
.eyebrow { margin-bottom: 8px; color: var(--mint-strong); font-size: 0.75rem; font-weight: 800; letter-spacing: 0.13em; text-transform: uppercase; }
.header-score { min-width: 120px; padding: 14px 18px; border: 1px solid var(--line); border-radius: 18px; background: rgba(255,255,255,.66); text-align: right; }
.header-score span { display: block; color: var(--muted); font-size: .76rem; }
.header-score strong { font-size: 1.35rem; }

.view { display: none; }
.view.active { display: block; }
.aviation-section-nav {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  width: min(1120px, calc(100% - 32px));
  margin: 0 auto 20px;
  gap: 8px;
}
.aviation-section-nav a {
  display: grid;
  min-height: 50px;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: var(--surface);
  color: var(--ink);
  font-size: .82rem;
  font-weight: 850;
  text-align: center;
  text-decoration: none;
}
.aviation-section-nav a:hover,
.aviation-section-nav a:focus-visible,
.aviation-section-nav a[aria-current="page"] {
  border-color: var(--mint-strong);
  background: var(--mint);
  outline: 0;
}
.intro-grid { display: grid; grid-template-columns: minmax(0, 1.2fr) minmax(300px, .8fr); gap: 20px; }
.panel { border: 1px solid var(--line); border-radius: 28px; background: var(--surface); box-shadow: var(--shadow); backdrop-filter: blur(18px); }
.setup-panel, .history-panel, .search-panel, .question-card, .results-card { padding: clamp(22px, 4vw, 40px); }
.field-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; margin: 26px 0 22px; }
.field-grid label:first-child { grid-column: 1 / -1; }
label span { display: block; margin-bottom: 7px; color: var(--muted); font-size: .76rem; font-weight: 750; letter-spacing: .04em; }
.chapter-picker { min-width: 0; margin: 0; border: 1px solid var(--line); border-radius: 14px; padding: 13px; background: var(--surface-strong); }
.chapter-picker legend { padding: 0 5px; color: var(--muted); font-size: .76rem; font-weight: 750; letter-spacing: .04em; }
.chapter-picker-actions { display: flex; gap: 7px; margin-bottom: 9px; }
.chapter-picker-actions button { border: 1px solid var(--line); border-radius: 999px; background: var(--surface); padding: 5px 9px; cursor: pointer; color: var(--ink); font-size: .68rem; font-weight: 800; }
.chapter-options { display: grid; max-height: 210px; gap: 5px; overflow: auto; padding-right: 4px; }
.chapter-option { display: grid; grid-template-columns: auto minmax(0, 1fr); align-items: start; gap: 8px; border-radius: 9px; padding: 7px 8px; cursor: pointer; }
.chapter-option:hover { background: var(--mint); }
.chapter-option input { width: 17px; min-height: 17px; margin: 1px 0 0; accent-color: var(--mint-strong); }
.chapter-option span { margin: 0; color: var(--ink); line-height: 1.35; }
select, input { width: 100%; min-height: 48px; border: 1px solid var(--line); border-radius: 14px; background: var(--surface-strong); color: var(--ink); padding: 0 14px; outline: none; }
select:focus, input:focus { border-color: var(--mint-strong); box-shadow: 0 0 0 4px rgba(44, 111, 90, .12); }
.button { min-height: 48px; border: 0; border-radius: 999px; padding: 0 20px; cursor: pointer; font-weight: 800; }
.button.primary { background: var(--ink); color: white; }
.button.secondary { background: var(--mint); color: #19352c; }
.button:disabled { cursor: not-allowed; opacity: .45; }
.text-button { border: 0; background: none; color: var(--mint-strong); padding: 8px 0; cursor: pointer; font-weight: 800; }
.fine-print, footer, .search-heading p { color: var(--muted); font-size: .86rem; line-height: 1.55; }
.fine-print { margin: 14px 0 0; }
.panel-heading, .quiz-topline, .quiz-progress-copy, .question-meta { display: flex; justify-content: space-between; gap: 16px; align-items: start; }
.history-list { display: grid; gap: 10px; max-height: 330px; overflow: auto; }
.history-item { display: grid; grid-template-columns: 1fr auto; gap: 4px 14px; padding: 13px 14px; border-radius: 15px; background: rgba(220,235,245,.58); }
.history-item strong { font-size: 1.05rem; }
.history-item small { color: var(--muted); }
.empty { padding: 18px 0; color: var(--muted); }
.search-panel { margin-top: 20px; }
.search-heading { align-items: end; }
.search-form { display: flex; gap: 8px; width: min(440px, 100%); }
.search-results { display: grid; gap: 10px; margin-top: 22px; }
.search-result { padding: 16px; border-radius: 16px; background: rgba(246,221,205,.45); }
.search-result h3 { margin: 0 0 7px; font-size: 1rem; }
.search-result p { margin: 0; color: var(--muted); font-size: .9rem; line-height: 1.5; }

.quiz-topline { margin: 18px 4px 12px; align-items: center; }
.quiz-progress-copy { color: var(--muted); font-size: .85rem; }
.quiz-progress-copy strong { color: var(--ink); }
.progress-track { height: 7px; margin-bottom: 20px; overflow: hidden; border-radius: 99px; background: rgba(39,72,64,.1); }
.progress-track span { display: block; width: 0; height: 100%; border-radius: inherit; background: var(--mint-strong); transition: width .25s ease; }
.question-card { max-width: 860px; margin: 0 auto; }
.question-meta { margin-bottom: 25px; color: var(--muted); font-size: .76rem; font-weight: 750; }
.question-card h2 { font-family: inherit; font-size: clamp(1.3rem, 3vw, 1.8rem); line-height: 1.35; }
.answer-options { display: grid; gap: 11px; margin: 26px 0; }
.answer-option { display: flex; gap: 12px; align-items: center; width: 100%; border: 1px solid var(--line); border-radius: 17px; background: var(--learning-neutral); padding: 15px; text-align: left; cursor: pointer; transition: border-color .18s ease, background .18s ease, box-shadow .18s ease, transform .18s ease; }
.answer-option .letter { display: grid; place-items: center; flex: 0 0 32px; height: 32px; border-radius: 50%; background: var(--sky); font-weight: 850; }
.answer-option:hover:not(:disabled), .answer-option:focus-visible { border-color: var(--ink); background: var(--learning-neutral-strong); outline: 3px solid color-mix(in srgb, var(--ink) 12%, transparent); outline-offset: 2px; }
.answer-option.selected { border-color: var(--ink); background: var(--learning-neutral-strong); box-shadow: 0 0 0 3px color-mix(in srgb, var(--ink) 10%, transparent); }
.answer-option.correct { z-index: 1; border: 2px solid var(--learning-correct); background: var(--learning-correct-bg); color: var(--learning-correct); box-shadow: 0 12px 28px color-mix(in srgb, var(--learning-correct) 24%, transparent); transform: scale(1.018); animation: correct-pop .34s ease-out; }
.answer-option.correct .letter { background: var(--learning-correct); color: #fff; }
.answer-option.incorrect { border: 2px solid var(--learning-incorrect); background: var(--learning-incorrect-bg); color: var(--learning-incorrect); box-shadow: 0 8px 22px color-mix(in srgb, var(--learning-incorrect) 18%, transparent); }
.answer-option.incorrect .letter { background: var(--learning-incorrect); color: #fff; }
.answer-option.incorrect .answer-text { text-decoration: line-through; text-decoration-thickness: 2px; text-decoration-color: currentColor; }
.answer-option:disabled { opacity: 1; cursor: default; }
.answer-result { display: inline-flex; flex: 0 0 auto; align-items: center; gap: 5px; margin-left: auto; border: 1px solid currentColor; border-radius: 999px; padding: 5px 9px; font-size: .72rem; font-weight: 900; white-space: nowrap; }
.answer-feedback { margin: 18px 0; border: 1px solid var(--line); border-radius: 17px; padding: 17px 18px; background: var(--learning-neutral); line-height: 1.55; }
.answer-feedback.state-correct { border-color: var(--learning-correct); background: var(--learning-correct-bg); color: var(--learning-correct); box-shadow: 0 10px 24px color-mix(in srgb, var(--learning-correct) 15%, transparent); }
.answer-feedback.state-incorrect { border-color: var(--learning-incorrect); background: var(--learning-incorrect-bg); color: var(--learning-incorrect); }
.answer-feedback strong { display: block; margin-bottom: 6px; }
.answer-feedback span { color: var(--ink); }
.answer-feedback small { display: block; margin-top: 9px; color: var(--muted); }
.question-actions { display: flex; flex-wrap: wrap; justify-content: flex-end; gap: 10px; }
.question-actions #previous-question { margin-right: auto; }

@keyframes correct-pop {
  0% { transform: scale(.985); box-shadow: 0 0 0 color-mix(in srgb, var(--learning-correct) 0%, transparent); }
  70% { transform: scale(1.03); }
  100% { transform: scale(1.018); box-shadow: 0 12px 28px color-mix(in srgb, var(--learning-correct) 24%, transparent); }
}
.wrong-bank-panel { display: flex; align-items: center; justify-content: space-between; gap: 14px; margin-top: 18px; padding-top: 18px; border-top: 1px solid var(--line); }
.wrong-bank-panel span { color: var(--muted); font-size: .9rem; }
.wrong-bank-panel strong { color: var(--ink); font-size: 1.1rem; }

.pricing-panel { margin-top: 20px; padding: 0; overflow: hidden; }
.pricing-panel > summary { display: flex; align-items: center; justify-content: space-between; gap: 20px; padding: 22px 26px; cursor: pointer; list-style: none; }
.pricing-panel > summary::-webkit-details-marker { display: none; }
.pricing-panel > summary span { display: grid; gap: 3px; }
.pricing-panel > summary small { color: var(--muted); font-size: .72rem; font-weight: 800; letter-spacing: .12em; text-transform: uppercase; }
.pricing-panel > summary strong { font-size: clamp(1.15rem, 2vw, 1.45rem); }
.pricing-panel > summary b { border-radius: 999px; background: var(--ink); color: var(--bg); padding: 9px 13px; font-size: .85rem; white-space: nowrap; }
.pricing-panel > summary::after { content: "+"; font-size: 1.35rem; font-weight: 700; }
.pricing-panel[open] > summary::after { content: "−"; }
.pricing-content { display: grid; gap: 18px; border-top: 1px solid var(--line); padding: 0 26px 26px; }
.pricing-table-wrap { overflow-x: auto; margin: 0 -26px; }
.pricing-table-wrap table { width: 100%; min-width: 1080px; border-collapse: collapse; }
.pricing-table-wrap th, .pricing-table-wrap td { border-bottom: 1px solid var(--line); padding: 14px 16px; text-align: left; vertical-align: top; }
.pricing-table-wrap thead th { background: rgba(220,235,245,.55); color: var(--muted); font-size: .73rem; letter-spacing: .06em; text-transform: uppercase; }
.pricing-table-wrap tbody td { font-size: .88rem; line-height: 1.4; }
.pricing-table-wrap td small { display: block; margin-top: 3px; color: var(--muted); }
.pricing-table-wrap tfoot th, .pricing-table-wrap tfoot td { border-bottom: 0; background: rgba(234,211,154,.28); font-weight: 800; }
.school-link, .address-link { color: inherit; text-decoration-color: color-mix(in srgb, currentColor 34%, transparent); text-underline-offset: 3px; }
.school-link:hover, .address-link:hover { text-decoration-color: currentColor; }
.address-link { color: var(--muted); }
.price-cell { font-weight: 800; white-space: nowrap; }
.pricing-summary-grid { display: grid; grid-template-columns: 1fr .8fr 1fr; gap: 12px; }
.pricing-summary-grid section { border: 1px solid var(--line); border-radius: 15px; background: rgba(220,235,245,.32); padding: 17px; }
.pricing-summary-grid h3 { margin: 0 0 12px; font-size: 1rem; }
.pricing-summary-grid ul { display: grid; gap: 10px; margin: 0; padding: 0; list-style: none; }
.pricing-summary-grid li { display: grid; gap: 2px; }
.pricing-summary-grid li strong { font-size: .96rem; }
.pricing-summary-grid li span, .all-in-card span { color: var(--muted); font-size: .8rem; line-height: 1.35; }
.pricing-summary-grid .all-in-card { display: grid; align-content: center; justify-items: center; background: rgba(234,211,154,.34); text-align: center; }
.all-in-card small { color: var(--muted); font-weight: 800; text-transform: uppercase; }
.all-in-card > strong { margin: 7px 0 3px; font-size: clamp(1.35rem, 3vw, 2rem); }
.multi-engine-section { overflow: hidden; border: 1px solid var(--line); border-radius: 16px; background: rgba(220,235,245,.2); }
.comparison-heading { display: flex; align-items: center; justify-content: space-between; gap: 16px; padding: 18px; }
.comparison-heading small { color: var(--muted); font-size: .68rem; font-weight: 850; letter-spacing: .1em; text-transform: uppercase; }
.comparison-heading h3 { margin: 3px 0 0; font-size: 1.08rem; }
.comparison-winners { display: flex; flex-wrap: wrap; justify-content: flex-end; gap: 7px; }
.comparison-winners span { border: 1px solid var(--line); border-radius: 999px; background: var(--surface); padding: 7px 10px; color: var(--muted); font-size: .74rem; }
.comparison-winners b { color: var(--ink); }
.comparison-table-wrap { margin: 0; border-top: 1px solid var(--line); }
.comparison-table-wrap table { min-width: 1040px; }
.best-price { color: #197044; }
.comparison-note { margin: 0; padding: 15px 18px 17px; color: var(--muted); font-size: .79rem; line-height: 1.5; }
.comparison-note strong { color: var(--ink); }
.flight-reminder { width: min(620px, 100%); margin: 4px auto; border: 1px solid rgba(131,96,18,.24); border-radius: 3px 18px 4px 14px; background: #fff0a8; box-shadow: 0 10px 22px rgba(82,61,8,.12); padding: 20px 22px; color: #45360f; transform: rotate(-.35deg); }
.flight-reminder > strong { display: block; margin-bottom: 10px; font: 800 1.06rem "Newsreader", serif; letter-spacing: .04em; text-transform: uppercase; }
.flight-reminder ul { display: grid; gap: 8px; margin: 0; padding-left: 19px; }
.flight-reminder li { font-size: .84rem; line-height: 1.42; }
.pricing-note { margin: 0; color: var(--muted); font-size: .84rem; text-align: center; }

.results-card { max-width: 760px; margin: 18px auto 20px; text-align: center; }
.result-ring { display: grid; place-items: center; width: 110px; height: 110px; margin: 0 auto 20px; border-radius: 50%; background: var(--mint); font-size: 1.7rem; font-weight: 900; }
.result-actions { display: flex; justify-content: center; flex-wrap: wrap; gap: 10px; margin-top: 24px; }
.wrong-list { display: grid; gap: 12px; max-width: 860px; margin: 0 auto; }
.wrong-item { border: 1px solid var(--line); border-radius: 18px; background: var(--surface); padding: 18px; }
.wrong-item summary { cursor: pointer; font-weight: 800; }
.wrong-item p { margin: 12px 0 0; color: var(--muted); line-height: 1.55; }

.admin-lock { position: fixed; inset: 0; z-index: 50; display: grid; place-items: center; padding: 20px; background: rgba(235,242,237,.94); backdrop-filter: blur(16px); }
.admin-lock[hidden] { display: none; }
.unlock-card { width: min(430px, 100%); border: 1px solid var(--line); border-radius: 28px; background: white; box-shadow: var(--shadow); padding: 34px; }
.unlock-card h1 { margin-bottom: 12px; font-size: 2.3rem; }
.unlock-card > p:not(.eyebrow):not(.form-error) { color: var(--muted); line-height: 1.55; }
.unlock-card label { display: block; margin: 22px 0 8px; }
.unlock-card .button { width: 100%; margin-top: 8px; }
.mini-mark { display: grid; place-items: center; width: 42px; height: 42px; margin-bottom: 20px; border-radius: 14px; background: var(--mint); }
.form-error { min-height: 20px; margin: 5px 0; color: var(--danger); font-size: .85rem; }
footer { padding: 28px 0 44px; text-align: center; }

:root[data-theme="dark"] .header-score,
:root[data-theme="dark"] .history-item,
:root[data-theme="dark"] .search-result,
:root[data-theme="dark"] .answer-feedback { background: var(--surface); }
:root[data-theme="dark"] .button.secondary { color: var(--ink); }
:root[data-theme="dark"] .button.primary { background: var(--mint-strong); color: #121713; }
:root[data-theme="dark"] .admin-lock { background: rgba(10, 15, 12, 0.94); }
:root[data-theme="dark"] .unlock-card { background: var(--surface-strong); }
:root[data-theme="dark"] .pricing-table-wrap thead th,
:root[data-theme="dark"] .pricing-summary-grid section { background: rgba(33,50,40,.86); }
:root[data-theme="dark"] .pricing-table-wrap tfoot th,
:root[data-theme="dark"] .pricing-table-wrap tfoot td,
:root[data-theme="dark"] .pricing-summary-grid .all-in-card { background: rgba(88,75,44,.64); }

@media (max-width: 760px) {
  .app-header { align-items: center; padding-top: 24px; }
  .header-score { min-width: 102px; padding: 10px 13px; }
  .intro-grid { grid-template-columns: 1fr; }
  .field-grid { grid-template-columns: 1fr; }
  .field-grid label:first-child { grid-column: auto; }
  .search-heading { display: block; }
  .search-form { margin-top: 18px; }
  .question-card { padding: 22px 18px; }
  .answer-result { padding: 4px 7px; font-size: .66rem; }
}

@media (max-width: 500px) {
  .app-header, main, footer { width: min(100% - 20px, 1120px); }
  .aviation-section-nav { width: min(100% - 20px, 1120px); grid-template-columns: repeat(2, 1fr); }
  .app-header h1 { font-size: 2rem; }
  .app-header .eyebrow { display: none; }
  .panel { border-radius: 22px; }
  .setup-panel, .history-panel, .search-panel { padding: 22px 18px; }
  .pricing-panel > summary { gap: 10px; padding: 18px; }
  .pricing-panel > summary b { padding: 7px 10px; font-size: .75rem; }
  .pricing-content { padding: 0 18px 18px; }
  .pricing-table-wrap { margin: 0 -18px; }
  .comparison-heading { align-items: flex-start; flex-direction: column; }
  .comparison-winners { justify-content: flex-start; }
  .comparison-table-wrap { margin: 0; }
  .flight-reminder { padding: 17px 18px; transform: none; }
  .pricing-summary-grid { grid-template-columns: 1fr; }
  .search-form { display: grid; }
  .quiz-progress-copy { display: grid; gap: 2px; text-align: right; }
  .result-actions .button { width: 100%; }
  .question-actions .button { flex: 1 1 130px; }
  .question-actions #previous-question { margin-right: 0; }
}

@media (prefers-reduced-motion: reduce) {
  .answer-option.correct { animation: none; }
}

/* Universal button-border contract: every enabled button renders a visible 1px border. */
button:not(:disabled) {
  border-style: solid !important;
  border-width: 1px !important;
}