:root {
  color-scheme: light;
  --bg: #f4f7fb;
  --surface: #ffffff;
  --surface-soft: #eaf1ff;
  --text: #14213d;
  --muted: #5c677d;
  --line: #d7dfec;
  --primary: #1d4ed8;
  --primary-strong: #173ea9;
  --accent: #facc15;
  --code: #0f172a;
  --shadow: 0 12px 30px rgba(20, 33, 61, 0.08);
  --radius-lg: 24px;
  --radius-md: 16px;
  --max-width: 1180px;
}

[data-theme="dark"] {
  color-scheme: dark;
  --bg: #09111f;
  --surface: #111c2e;
  --surface-soft: #172744;
  --text: #eef4ff;
  --muted: #aab8ce;
  --line: #2b3b53;
  --primary: #72a2ff;
  --primary-strong: #9bbcff;
  --accent: #facc15;
  --code: #e5efff;
  --shadow: 0 16px 38px rgba(0, 0, 0, 0.28);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 1rem;
  line-height: 1.6;
  transition: background-color 180ms ease, color 180ms ease;
}

button, input { font: inherit; }
button { cursor: pointer; }

.skip-link {
  position: fixed;
  top: 0.75rem;
  left: 0.75rem;
  z-index: 20;
  padding: 0.65rem 1rem;
  background: var(--text);
  color: var(--surface);
  border-radius: 0.6rem;
  transform: translateY(-150%);
}
.skip-link:focus { transform: translateY(0); }

.site-header {
  width: min(calc(100% - 2rem), var(--max-width));
  margin: 0 auto;
  min-height: 76px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.7rem;
  color: var(--text);
  text-decoration: none;
  font-weight: 800;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 2.5rem;
  height: 2.5rem;
  border-radius: 0.8rem;
  background: var(--primary);
  color: var(--surface);
  font: 800 0.95rem/1 ui-monospace, monospace;
  box-shadow: inset -7px -7px 0 color-mix(in srgb, var(--accent) 70%, transparent);
}

.theme-toggle {
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  min-height: 44px;
  padding: 0.55rem 0.85rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--surface);
  color: var(--text);
}

.theme-toggle:hover { border-color: var(--primary); }

main, footer {
  width: min(calc(100% - 2rem), var(--max-width));
  margin-inline: auto;
}

.intro {
  position: relative;
  overflow: hidden;
  display: grid;
  grid-template-columns: minmax(0, 1.6fr) minmax(280px, 0.8fr);
  gap: clamp(2rem, 5vw, 5rem);
  align-items: center;
  padding: clamp(2rem, 6vw, 5rem);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background:
    radial-gradient(circle at 8% 0%, color-mix(in srgb, var(--accent) 26%, transparent) 0 13%, transparent 14%),
    linear-gradient(135deg, var(--surface), var(--surface-soft));
  box-shadow: var(--shadow);
}

.eyebrow {
  margin: 0 0 0.5rem;
  color: var(--primary-strong);
  font-size: 0.82rem;
  font-weight: 800;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

h1, h2, h3 { line-height: 1.15; letter-spacing: -0.025em; }
h1 { max-width: 780px; margin: 0; font-size: clamp(2.2rem, 6vw, 4.7rem); }
h2 { margin: 0; font-size: clamp(1.6rem, 3vw, 2.4rem); }
h3 { margin: 0; font-size: 1.2rem; }
code { color: var(--primary-strong); font-family: ui-monospace, "Cascadia Code", monospace; }
.lead { max-width: 700px; margin: 1.25rem 0 1.5rem; color: var(--muted); font-size: 1.1rem; }

.course-stats { display: flex; flex-wrap: wrap; gap: 0.65rem; }
.course-stats span {
  padding: 0.55rem 0.8rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: color-mix(in srgb, var(--surface) 82%, transparent);
  color: var(--muted);
  font-size: 0.9rem;
}
.course-stats strong { color: var(--text); }

.lesson-rhythm {
  padding: 1.4rem;
  border-radius: var(--radius-md);
  background: var(--code);
  color: var(--bg);
  transform: rotate(1deg);
  box-shadow: 10px 10px 0 color-mix(in srgb, var(--accent) 75%, transparent);
}
[data-theme="dark"] .lesson-rhythm { color: #09111f; background: #eef4ff; }
.lesson-rhythm h2 { font-size: 1.15rem; }
.lesson-rhythm ol { margin: 1rem 0 0; padding: 0; list-style: none; }
.lesson-rhythm li { display: flex; gap: 0.7rem; padding: 0.5rem 0; border-top: 1px solid currentColor; }
.lesson-rhythm li span { min-width: 3.3rem; font-family: ui-monospace, monospace; font-weight: 800; }

.catalogue { padding: clamp(3rem, 7vw, 5.5rem) 0; }
.section-heading { display: flex; justify-content: space-between; align-items: end; gap: 1rem; }
.results-count { margin: 0; color: var(--muted); }

.filters {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  margin: 1.7rem 0;
}

.search-field {
  display: flex;
  align-items: center;
  gap: 0.55rem;
  width: min(100%, 420px);
  min-height: 48px;
  padding: 0 0.9rem;
  border: 1px solid var(--line);
  border-radius: 0.9rem;
  background: var(--surface);
}
.search-field:focus-within { outline: 3px solid color-mix(in srgb, var(--primary) 25%, transparent); border-color: var(--primary); }
.search-field input { width: 100%; border: 0; outline: 0; background: transparent; color: var(--text); }
.search-field input::placeholder { color: var(--muted); }

.filter-buttons { display: flex; flex-wrap: wrap; justify-content: flex-end; gap: 0.45rem; }
.filter-button {
  min-height: 42px;
  padding: 0.45rem 0.8rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--surface);
  color: var(--text);
}
.filter-button:hover, .filter-button.is-active { border-color: var(--primary); background: var(--primary); color: var(--surface); }
[data-theme="dark"] .filter-button.is-active { color: #09111f; }

.lesson-grid { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 1rem; }
.lesson-card {
  position: relative;
  min-height: 260px;
  padding: 1.25rem;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: var(--surface);
  box-shadow: 0 5px 18px rgba(20, 33, 61, 0.04);
  transition: transform 160ms ease, border-color 160ms ease, box-shadow 160ms ease;
}
.lesson-card:hover { transform: translateY(-4px); border-color: var(--primary); box-shadow: var(--shadow); }
.lesson-card::after { content: ""; position: absolute; inset: auto 1.25rem 0; height: 4px; border-radius: 4px 4px 0 0; background: var(--card-color); }
.lesson-top { display: flex; align-items: center; justify-content: space-between; gap: 0.7rem; }
.lesson-number { color: var(--primary-strong); font: 800 0.8rem/1 ui-monospace, monospace; letter-spacing: 0.08em; }
.lesson-stage { padding: 0.25rem 0.48rem; border-radius: 0.45rem; background: var(--surface-soft); color: var(--muted); font-size: 0.75rem; font-weight: 700; }
.lesson-card h3 { margin-top: 1rem; }
.lesson-card p { margin: 0.7rem 0 1rem; color: var(--muted); font-size: 0.92rem; }
.lesson-skills { display: flex; flex-wrap: wrap; gap: 0.35rem; margin: 0; padding: 0; list-style: none; }
.lesson-skills li { padding: 0.2rem 0.45rem; border: 1px solid var(--line); border-radius: 0.45rem; color: var(--muted); font-size: 0.76rem; }
.lesson-link { position: absolute; inset: 0; border-radius: inherit; }
.lesson-link:focus-visible { outline: 4px solid var(--accent); outline-offset: 3px; }
.lesson-status { position: absolute; right: 1.25rem; bottom: 1rem; color: var(--muted); font-size: 0.75rem; }
.empty-state { padding: 2rem; border: 1px dashed var(--line); border-radius: var(--radius-md); text-align: center; color: var(--muted); }

footer { padding: 1.5rem 0 3rem; border-top: 1px solid var(--line); color: var(--muted); font-size: 0.9rem; }
.visually-hidden { 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: 980px) {
  .lesson-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .intro { grid-template-columns: 1fr; }
  .lesson-rhythm { transform: none; }
  .filters { align-items: stretch; flex-direction: column; }
  .filter-buttons { justify-content: flex-start; }
}

@media (max-width: 580px) {
  .site-header { min-height: 68px; }
  .theme-label { display: none; }
  .intro { padding: 1.5rem; }
  .lesson-grid { grid-template-columns: 1fr; }
  .section-heading { align-items: flex-start; flex-direction: column; }
  .filter-buttons { flex-wrap: nowrap; overflow-x: auto; padding-bottom: 0.4rem; }
  .filter-button { flex: 0 0 auto; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition: none !important; }
}

/* Wspólny układ stron lekcyjnych */
.lesson-page { max-width: 1040px; }
.breadcrumbs { display: flex; gap: 0.5rem; margin: 1rem 0 1.5rem; color: var(--muted); font-size: 0.9rem; }
.breadcrumbs a { color: var(--primary-strong); }
.lesson-hero { display: grid; grid-template-columns: minmax(0, 1.5fr) minmax(260px, 0.7fr); gap: 2rem; align-items: center; padding: clamp(2rem, 6vw, 4rem); border: 1px solid var(--line); border-radius: var(--radius-lg); background: linear-gradient(135deg, var(--surface), var(--surface-soft)); box-shadow: var(--shadow); }
.lesson-hero h1 { font-size: clamp(2.2rem, 6vw, 4.2rem); }
.lesson-goals { display: flex; flex-wrap: wrap; gap: 0.5rem; }
.lesson-goals span { padding: 0.45rem 0.7rem; border: 1px solid var(--line); border-radius: 999px; background: var(--surface); color: var(--muted); font-size: 0.86rem; }
.mission-card { padding: 1.5rem; border-radius: var(--radius-md); background: var(--code); color: var(--bg); box-shadow: 8px 8px 0 var(--accent); }
[data-theme="dark"] .mission-card { color: #09111f; background: #eef4ff; }
.mission-label { margin: 0 0 0.5rem; font: 800 0.75rem/1 ui-monospace, monospace; letter-spacing: 0.1em; text-transform: uppercase; }
.mission-card h2 { font-size: 1.4rem; }
.mission-card p:last-child { margin-bottom: 0; }
.lesson-nav { position: sticky; top: 0; z-index: 5; display: grid; grid-template-columns: repeat(4, 1fr); margin: 1.2rem 0 3rem; border: 1px solid var(--line); border-radius: 1rem; background: color-mix(in srgb, var(--surface) 92%, transparent); backdrop-filter: blur(14px); overflow: hidden; }
.lesson-nav a { display: flex; align-items: center; justify-content: center; gap: 0.5rem; min-height: 54px; padding: 0.5rem; color: var(--text); text-decoration: none; border-right: 1px solid var(--line); font-weight: 700; }
.lesson-nav a:last-child { border-right: 0; }
.lesson-nav a:hover { background: var(--surface-soft); }
.lesson-nav span { color: var(--primary-strong); font: 800 0.75rem/1 ui-monospace, monospace; }
.content-section { scroll-margin-top: 90px; margin: 0 0 4.5rem; }
.section-kicker { display: flex; align-items: center; gap: 0.55rem; margin-bottom: 0.75rem; color: var(--primary-strong); font-weight: 800; text-transform: uppercase; letter-spacing: 0.08em; font-size: 0.8rem; }
.section-kicker span { padding: 0.25rem 0.5rem; border-radius: 0.45rem; background: var(--primary); color: var(--surface); }
[data-theme="dark"] .section-kicker span { color: #09111f; }
.section-intro { max-width: 760px; color: var(--muted); font-size: 1.06rem; }
.theory-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1rem; margin: 1.7rem 0; }
.concept-card, .independent-card { position: relative; padding: 1.35rem; border: 1px solid var(--line); border-radius: var(--radius-md); background: var(--surface); }
.concept-number { display: inline-block; margin-bottom: 2rem; color: var(--primary-strong); font: 800 0.8rem/1 ui-monospace, monospace; }
.concept-card p, .independent-card p { color: var(--muted); }
.knowledge-panel, .syntax-card, .task-brief { display: grid; grid-template-columns: 1fr 1fr; gap: 2rem; align-items: center; margin: 1.5rem 0; padding: 1.5rem; border: 1px solid var(--line); border-radius: var(--radius-md); background: var(--surface); }
.check-list { padding-left: 1.25rem; }
.check-list li { margin: 0.45rem 0; }
.pseudo-card, .code-block, .task-brief pre, .independent-card pre { overflow-x: auto; border-radius: 0.8rem; background: #0f172a; color: #e5efff; }
.code-title { padding: 0.6rem 0.9rem; border-bottom: 1px solid #334155; color: #94a3b8; font: 0.8rem/1.4 ui-monospace, monospace; }
pre { margin: 0; white-space: pre-wrap; }
pre code { color: inherit; }
.pseudo-card pre, .code-block, .task-brief pre, .independent-card pre { padding: 1rem; }
.code-fn { color: #93c5fd; }
.code-string { color: #fde68a; }
.note-box { padding: 1rem 1.2rem; border-left: 5px solid var(--accent); border-radius: 0 0.8rem 0.8rem 0; background: color-mix(in srgb, var(--accent) 14%, var(--surface)); }
.steps { margin: 1.5rem 0; padding: 0; list-style: none; counter-reset: step; }
.steps li { counter-increment: step; display: grid; grid-template-columns: 3rem 1fr; gap: 1rem; margin-bottom: 1rem; }
.steps li::before { content: counter(step); display: grid; place-items: center; width: 2.7rem; height: 2.7rem; border-radius: 50%; background: var(--primary); color: var(--surface); font-weight: 800; }
[data-theme="dark"] .steps li::before { color: #09111f; }
.steps p { margin: 0.2rem 0 0; color: var(--muted); }
.solution-box { border: 1px solid var(--line); border-radius: var(--radius-md); background: var(--surface); overflow: hidden; }
.solution-box summary, .independent-card summary { cursor: pointer; color: var(--primary-strong); font-weight: 800; }
.solution-box summary { padding: 1rem 1.25rem; }
.solution-content { display: grid; grid-template-columns: 1fr 1fr; gap: 1.5rem; padding: 0 1.25rem 1.25rem; }
.explanation-list p { margin-top: 0; }
.independent-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1rem; }
.difficulty { display: inline-block; margin-bottom: 1rem; padding: 0.25rem 0.5rem; border-radius: 0.4rem; background: var(--surface-soft); color: var(--primary-strong); font-size: 0.75rem; font-weight: 800; }
.quiz-form { display: grid; gap: 1rem; }
.quiz-question { margin: 0; padding: 1.25rem; border: 1px solid var(--line); border-radius: var(--radius-md); background: var(--surface); }
.quiz-question legend { padding: 0 0.35rem; font-weight: 800; }
.quiz-question legend span { display: inline-grid; place-items: center; width: 2rem; height: 2rem; margin-right: 0.45rem; border-radius: 50%; background: var(--surface-soft); color: var(--primary-strong); font: 800 0.8rem/1 ui-monospace, monospace; }
.quiz-question label { display: flex; align-items: flex-start; gap: 0.65rem; margin: 0.55rem 0; padding: 0.7rem 0.8rem; border: 1px solid transparent; border-radius: 0.7rem; background: var(--bg); cursor: pointer; }
.quiz-question label:hover { border-color: var(--primary); }
.quiz-question input { margin-top: 0.35rem; accent-color: var(--primary); }
.quiz-question.needs-answer { border-color: #d97706; box-shadow: 0 0 0 3px color-mix(in srgb, #d97706 18%, transparent); }
.quiz-question.is-correct { border-color: #16803a; }
.quiz-question.is-incorrect { border-color: #b42318; }
.quiz-question label.correct-answer { border-color: #16803a; background: color-mix(in srgb, #22c55e 15%, var(--surface)); }
.quiz-question label.wrong-answer { border-color: #b42318; background: color-mix(in srgb, #ef4444 12%, var(--surface)); }
.answer-feedback { margin: 0.9rem 0 0; padding: 0.8rem; border-radius: 0.7rem; background: var(--surface-soft); }
.quiz-actions { display: flex; flex-wrap: wrap; gap: 0.7rem; margin-top: 0.5rem; }
.primary-button, .secondary-button { min-height: 48px; padding: 0.65rem 1rem; border-radius: 0.8rem; font-weight: 800; }
.primary-button { border: 1px solid var(--primary); background: var(--primary); color: var(--surface); }
[data-theme="dark"] .primary-button { color: #09111f; }
.secondary-button { border: 1px solid var(--line); background: var(--surface); color: var(--text); }
.quiz-result:not(:empty) { padding: 1rem 1.2rem; border-radius: 0.8rem; }
.quiz-result.is-warning { background: color-mix(in srgb, #f59e0b 18%, var(--surface)); border: 1px solid #d97706; }
.quiz-result.is-success { background: color-mix(in srgb, #22c55e 16%, var(--surface)); border: 1px solid #16803a; }
.lesson-pagination { display: flex; justify-content: space-between; gap: 1rem; padding: 1.5rem 0 3rem; border-top: 1px solid var(--line); }
.lesson-pagination a { color: var(--primary-strong); font-weight: 800; }
.lesson-pagination span { color: var(--muted); }
.guided-exercises { display: grid; gap: 1.25rem; margin-top: 1.7rem; }
.guided-exercise { padding: 1.4rem; border: 1px solid var(--line); border-radius: var(--radius-md); background: var(--surface); }
.exercise-heading { display: flex; align-items: baseline; gap: 0.8rem; margin-bottom: 0.8rem; }
.exercise-heading > span { flex: 0 0 auto; padding: 0.3rem 0.55rem; border-radius: 0.45rem; background: var(--primary); color: var(--surface); font: 800 0.76rem/1.3 ui-monospace, monospace; }
[data-theme="dark"] .exercise-heading > span { color: #09111f; }
.exercise-command { margin: 0 0 1rem; padding: 0.9rem 1rem; border-left: 4px solid var(--primary); background: var(--surface-soft); }
.instruction-solution { padding: 0 1.25rem 1.25rem; }
.click-steps { padding-left: 1.4rem; }
.click-steps li { margin: 0.65rem 0; padding-left: 0.35rem; }
.expected-box { margin-top: 1rem; padding: 0.9rem 1rem; border: 1px solid var(--line); border-radius: 0.75rem; background: var(--surface-soft); }
.expected-box pre { margin-top: 0.5rem; }
.platform-note { margin-bottom: 0; color: var(--muted); font-size: 0.92rem; }

@media (max-width: 780px) {
  .lesson-hero, .knowledge-panel, .syntax-card, .task-brief, .solution-content { grid-template-columns: 1fr; }
  .theory-grid, .independent-grid { grid-template-columns: 1fr; }
  .lesson-nav a { flex-direction: column; gap: 0.2rem; font-size: 0.82rem; }
}

@media (max-width: 480px) {
  .lesson-nav { grid-template-columns: repeat(2, 1fr); position: static; }
  .lesson-nav a:nth-child(2) { border-right: 0; }
  .lesson-nav a:nth-child(-n+2) { border-bottom: 1px solid var(--line); }
  .lesson-pagination { flex-direction: column; }
}