/* ============================================
   Циркуль и линейка — учебное пособие, 7 класс
   Палитра: тёплая бумага + графит + терракотовый акцент
   ============================================ */

:root {
  /* Type scale */
  --text-xs: clamp(0.75rem, 0.7rem + 0.25vw, 0.875rem);
  --text-sm: clamp(0.875rem, 0.8rem + 0.35vw, 1rem);
  --text-base: clamp(1rem, 0.95rem + 0.25vw, 1.125rem);
  --text-lg: clamp(1.125rem, 1rem + 0.75vw, 1.5rem);
  --text-xl: clamp(1.5rem, 1.2rem + 1.25vw, 2.25rem);
  --text-2xl: clamp(2rem, 1.2rem + 2.5vw, 3.5rem);

  /* Spacing */
  --space-1: 0.25rem; --space-2: 0.5rem; --space-3: 0.75rem;
  --space-4: 1rem; --space-5: 1.25rem; --space-6: 1.5rem;
  --space-8: 2rem; --space-10: 2.5rem; --space-12: 3rem;
  --space-16: 4rem; --space-20: 5rem; --space-24: 6rem;

  /* Radius */
  --radius-sm: 0.5rem;
  --radius-md: 0.75rem;
  --radius-lg: 1rem;
  --radius-xl: 1.5rem;
  --radius-full: 9999px;

  /* Transitions */
  --tr: 200ms cubic-bezier(0.16, 1, 0.3, 1);

  /* Fonts */
  --font-body: 'Manrope', 'Helvetica Neue', sans-serif;
  --font-display: 'Unbounded', 'Manrope', sans-serif;
  --font-mono: 'JetBrains Mono', ui-monospace, monospace;

  /* Content widths */
  --content-narrow: 720px;
  --content-default: 1100px;
  --content-wide: 1280px;
}

:root, [data-theme="light"] {
  /* Surfaces — тёплая бумага */
  --color-bg: #f5f0e6;
  --color-surface: #fbf7ee;
  --color-surface-2: #ffffff;
  --color-surface-offset: #ede5d4;
  --color-divider: #e3d9c4;
  --color-border: #d6c9ad;

  /* Text — графит */
  --color-text: #1f1d1a;
  --color-text-muted: #6c655a;
  --color-text-faint: #a8a193;

  /* Accent — терракотовый */
  --color-primary: #b8472b;
  --color-primary-hover: #9a3a22;
  --color-primary-soft: #f5d9cc;

  /* Secondary — синий "карандаш" */
  --color-secondary: #2b6caf;
  --color-secondary-soft: #d9e6f4;

  /* Semantic */
  --color-success: #4f7a2c;
  --color-success-soft: #dde8cf;
  --color-error: #a83246;
  --color-error-soft: #f3d6dc;
  --color-warning: #b87f1a;

  /* Geom canvas */
  --geom-paper: #fbf7ee;
  --geom-grid: #e8dfca;
  --geom-line: #1f1d1a;
  --geom-construction: #b8472b;
  --geom-aux: #2b6caf;
  --geom-highlight: #4f7a2c;
  --geom-ghost: #c5b89c;

  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(60, 40, 20, 0.08);
  --shadow-md: 0 4px 14px rgba(60, 40, 20, 0.10);
  --shadow-lg: 0 14px 36px rgba(60, 40, 20, 0.14);
}

[data-theme="dark"] {
  --color-bg: #1a1715;
  --color-surface: #221e1b;
  --color-surface-2: #2a2522;
  --color-surface-offset: #2f2925;
  --color-divider: #3a322d;
  --color-border: #4a4039;

  --color-text: #ece6da;
  --color-text-muted: #a39c8e;
  --color-text-faint: #6e6759;

  --color-primary: #e07a5f;
  --color-primary-hover: #f08f74;
  --color-primary-soft: #4a2a1f;

  --color-secondary: #6ba6df;
  --color-secondary-soft: #1f3349;

  --color-success: #8ab058;
  --color-success-soft: #2c3a1d;
  --color-error: #d96b7e;
  --color-error-soft: #3e1f27;
  --color-warning: #d9a447;

  --geom-paper: #221e1b;
  --geom-grid: #312a25;
  --geom-line: #ece6da;
  --geom-construction: #e07a5f;
  --geom-aux: #6ba6df;
  --geom-highlight: #8ab058;
  --geom-ghost: #4a4039;

  --shadow-sm: 0 1px 2px rgba(0,0,0,0.3);
  --shadow-md: 0 4px 14px rgba(0,0,0,0.4);
  --shadow-lg: 0 14px 36px rgba(0,0,0,0.5);
}

/* ====== Base ====== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html {
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  scroll-behavior: smooth;
  scroll-padding-top: 5rem;
}
body {
  min-height: 100dvh;
  line-height: 1.6;
  font-family: var(--font-body);
  font-size: var(--text-base);
  color: var(--color-text);
  background-color: var(--color-bg);
  background-image:
    radial-gradient(1200px 600px at 90% -100px, rgba(184,71,43,0.06), transparent 60%),
    radial-gradient(900px 500px at -10% 10%, rgba(43,108,175,0.05), transparent 60%);
  background-attachment: fixed;
}
img, svg, canvas { display: block; max-width: 100%; }
button { cursor: pointer; background: none; border: none; font: inherit; color: inherit; }
a { color: var(--color-primary); text-decoration: none; }
a:hover { text-decoration: underline; }
h1,h2,h3,h4 { line-height: 1.2; text-wrap: balance; font-family: var(--font-display); font-weight: 600; letter-spacing: -0.01em; }
p { text-wrap: pretty; }
:focus-visible { outline: 2px solid var(--color-primary); outline-offset: 3px; border-radius: var(--radius-sm); }

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: 0.01ms !important; transition-duration: 0.01ms !important; }
}

/* ====== Layout ====== */
.container { max-width: var(--content-default); margin: 0 auto; padding: 0 var(--space-6); }
.container--wide { max-width: var(--content-wide); }
.container--narrow { max-width: var(--content-narrow); }

/* ====== Header ====== */
.header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(245, 240, 230, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-divider);
}
[data-theme="dark"] .header { background: rgba(26, 23, 21, 0.85); }
.header__inner {
  display: flex; align-items: center; justify-content: space-between;
  padding: var(--space-3) var(--space-6);
  max-width: var(--content-wide);
  margin: 0 auto;
  gap: var(--space-4);
}
.brand { display: flex; align-items: center; gap: var(--space-3); font-weight: 600; }
.brand__mark { color: var(--color-primary); }
.brand__title { font-family: var(--font-display); font-size: var(--text-sm); }
.nav { display: flex; gap: var(--space-2); flex-wrap: wrap; }
.nav__link {
  font-size: var(--text-sm); color: var(--color-text-muted);
  padding: var(--space-2) var(--space-3); border-radius: var(--radius-sm);
  transition: var(--tr);
}
.nav__link:hover { color: var(--color-text); background: var(--color-surface-offset); text-decoration: none; }
.nav__link.is-active { color: var(--color-primary); background: var(--color-primary-soft); }
.theme-toggle {
  display: inline-flex; align-items: center; justify-content: center;
  width: 38px; height: 38px;
  border-radius: var(--radius-full);
  color: var(--color-text-muted);
  transition: var(--tr);
}
.theme-toggle:hover { color: var(--color-primary); background: var(--color-surface-offset); }

/* ====== Hero ====== */
.hero {
  padding: clamp(var(--space-12), 8vw, var(--space-24)) 0 var(--space-12);
  position: relative;
}
.hero__grid { display: grid; gap: var(--space-10); align-items: center; }
@media (min-width: 900px) { .hero__grid { grid-template-columns: 1.2fr 1fr; } }
.hero__eyebrow {
  font-size: var(--text-xs); font-weight: 600;
  text-transform: uppercase; letter-spacing: 0.12em;
  color: var(--color-primary);
  display: inline-flex; align-items: center; gap: var(--space-2);
  padding: var(--space-2) var(--space-3);
  background: var(--color-primary-soft);
  border-radius: var(--radius-full);
  margin-bottom: var(--space-5);
}
.hero__title {
  font-size: var(--text-2xl); font-weight: 700;
  margin-bottom: var(--space-5);
}
.hero__title em { font-style: normal; color: var(--color-primary); font-family: var(--font-display); }
.hero__lead {
  font-size: var(--text-lg); color: var(--color-text-muted);
  max-width: 50ch; margin-bottom: var(--space-6);
}
.hero__actions { display: flex; gap: var(--space-3); flex-wrap: wrap; }

.hero__visual {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: var(--space-4);
  box-shadow: var(--shadow-md);
  position: relative;
  overflow: hidden;
}
.hero__visual::before {
  content: ""; position: absolute; inset: 0;
  background-image:
    linear-gradient(var(--geom-grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--geom-grid) 1px, transparent 1px);
  background-size: 28px 28px;
  opacity: 0.5;
  pointer-events: none;
}
.hero__visual canvas { position: relative; z-index: 1; }

/* ====== Buttons ====== */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: var(--space-2);
  padding: var(--space-3) var(--space-5);
  font-size: var(--text-sm); font-weight: 600;
  border-radius: var(--radius-md);
  border: 1px solid transparent;
  transition: var(--tr);
  white-space: nowrap;
}
.btn--primary { background: var(--color-primary); color: #fff; }
.btn--primary:hover { background: var(--color-primary-hover); text-decoration: none; }
.btn--ghost { background: transparent; color: var(--color-text); border-color: var(--color-border); }
.btn--ghost:hover { background: var(--color-surface-offset); text-decoration: none; }
.btn--sm { padding: var(--space-2) var(--space-3); font-size: var(--text-xs); }
.btn[disabled] { opacity: 0.45; cursor: not-allowed; }

/* ====== Sections ====== */
.section {
  padding: clamp(var(--space-10), 6vw, var(--space-16)) 0;
  border-top: 1px dashed var(--color-divider);
}
.section__head { margin-bottom: var(--space-8); max-width: 65ch; }
.section__eyebrow {
  font-size: var(--text-xs); text-transform: uppercase; letter-spacing: 0.12em;
  color: var(--color-text-muted); font-weight: 600;
  margin-bottom: var(--space-3);
}
.section__title { font-size: var(--text-xl); margin-bottom: var(--space-3); }
.section__lead { color: var(--color-text-muted); font-size: var(--text-base); }

/* ====== Cards / Theory ====== */
.theory-grid {
  display: grid; gap: var(--space-5);
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
}
.theory-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-5);
}
.theory-card__icon {
  width: 44px; height: 44px;
  display: inline-flex; align-items: center; justify-content: center;
  background: var(--color-primary-soft); color: var(--color-primary);
  border-radius: var(--radius-md);
  margin-bottom: var(--space-4);
}
.theory-card__title { font-size: var(--text-lg); margin-bottom: var(--space-2); }
.theory-card__text { color: var(--color-text-muted); font-size: var(--text-sm); }

/* Rules box */
.rules {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  margin-top: var(--space-8);
}
.rules__title { font-size: var(--text-lg); margin-bottom: var(--space-4); display: flex; align-items: center; gap: var(--space-2); }
.rules__list { list-style: none; display: grid; gap: var(--space-3); }
.rules__list li { display: flex; gap: var(--space-3); align-items: flex-start; font-size: var(--text-sm); }
.rules__list li::before {
  content: ""; flex-shrink: 0;
  width: 22px; height: 22px; border-radius: var(--radius-full);
  background: var(--color-primary-soft);
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='14' height='14' viewBox='0 0 24 24' fill='none' stroke='%23b8472b' stroke-width='3' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='20 6 9 17 4 12'/%3E%3C/svg%3E");
  background-repeat: no-repeat; background-position: center;
  margin-top: 2px;
}

/* ====== Lesson (теория + анимация рядом) ====== */
.lesson {
  display: grid; gap: var(--space-6);
  grid-template-columns: 1fr;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: var(--space-6);
  margin-bottom: var(--space-6);
  box-shadow: var(--shadow-sm);
}
@media (min-width: 980px) { .lesson { grid-template-columns: 1fr 1.1fr; } }

.lesson__header { display: flex; align-items: flex-start; gap: var(--space-3); margin-bottom: var(--space-3); flex-wrap: wrap; }
.lesson__num {
  display: inline-flex; align-items: center; justify-content: center;
  width: 36px; height: 36px;
  background: var(--color-primary); color: #fff;
  border-radius: var(--radius-full);
  font-weight: 700; font-size: var(--text-sm); flex-shrink: 0;
}
.lesson__title { font-size: var(--text-lg); }
.lesson__given { font-size: var(--text-sm); color: var(--color-text-muted); margin-top: var(--space-2); }
.lesson__given strong { color: var(--color-text); font-weight: 600; }

.lesson__body p { margin-bottom: var(--space-3); font-size: var(--text-sm); color: var(--color-text-muted); }
.lesson__body p strong { color: var(--color-text); font-weight: 600; }

.steps { display: grid; gap: var(--space-2); margin-top: var(--space-4); }
.step {
  display: grid; grid-template-columns: 28px 1fr; gap: var(--space-3);
  font-size: var(--text-sm);
  padding: var(--space-3);
  border-radius: var(--radius-sm);
  transition: var(--tr);
  border: 1px solid transparent;
}
.step__num {
  display: inline-flex; align-items: center; justify-content: center;
  width: 26px; height: 26px;
  background: var(--color-surface-offset);
  color: var(--color-text-muted);
  border-radius: var(--radius-full);
  font-size: var(--text-xs); font-weight: 700;
  font-family: var(--font-mono);
}
.step.is-active {
  background: var(--color-primary-soft);
  border-color: var(--color-primary);
}
.step.is-active .step__num { background: var(--color-primary); color: #fff; }
.step.is-done .step__num { background: var(--color-success-soft); color: var(--color-success); }

/* ====== Stage (canvas + controls) ====== */
.stage {
  display: flex; flex-direction: column; gap: var(--space-3);
  background: var(--geom-paper);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-3);
  position: relative;
  overflow: hidden;
}
.stage__canvas-wrap {
  position: relative;
  background-image:
    linear-gradient(var(--geom-grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--geom-grid) 1px, transparent 1px);
  background-size: 24px 24px;
  border-radius: var(--radius-md);
  overflow: hidden;
  aspect-ratio: 4 / 3;
}
.stage__canvas-wrap canvas { width: 100%; height: 100%; display: block; }
.stage__controls {
  display: flex; align-items: center; gap: var(--space-2); flex-wrap: wrap;
  justify-content: space-between;
}
.stage__controls-group { display: flex; gap: var(--space-2); flex-wrap: wrap; }
.stage__progress {
  font-size: var(--text-xs); color: var(--color-text-muted);
  font-family: var(--font-mono);
}

/* ====== Trainer ====== */
.trainer {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: var(--space-6);
  box-shadow: var(--shadow-sm);
}
.trainer__head { display: flex; justify-content: space-between; align-items: center; gap: var(--space-4); margin-bottom: var(--space-5); flex-wrap: wrap; }
.trainer__counter { font-size: var(--text-sm); color: var(--color-text-muted); }
.trainer__counter strong { color: var(--color-text); font-weight: 700; font-family: var(--font-mono); }
.trainer__score {
  background: var(--color-success-soft); color: var(--color-success);
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-full);
  font-size: var(--text-xs); font-weight: 700;
}

.task { display: grid; gap: var(--space-4); }
.task__topic {
  font-size: var(--text-xs); text-transform: uppercase; letter-spacing: 0.1em;
  color: var(--color-text-muted); font-weight: 600;
}
.task__question { font-size: var(--text-base); font-weight: 500; }
.task__question strong { color: var(--color-primary); }

.options { display: grid; gap: var(--space-2); }
.option {
  display: flex; align-items: center; gap: var(--space-3);
  padding: var(--space-3) var(--space-4);
  background: var(--color-surface-2);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  text-align: left;
  font-size: var(--text-sm);
  transition: var(--tr);
}
.option:hover { border-color: var(--color-primary); background: var(--color-primary-soft); }
.option__letter {
  display: inline-flex; align-items: center; justify-content: center;
  width: 28px; height: 28px; flex-shrink: 0;
  background: var(--color-surface-offset); color: var(--color-text-muted);
  border-radius: var(--radius-full);
  font-family: var(--font-mono); font-weight: 700; font-size: var(--text-xs);
}
.option.is-correct { background: var(--color-success-soft); border-color: var(--color-success); color: var(--color-success); }
.option.is-correct .option__letter { background: var(--color-success); color: #fff; }
.option.is-wrong { background: var(--color-error-soft); border-color: var(--color-error); color: var(--color-error); }
.option.is-wrong .option__letter { background: var(--color-error); color: #fff; }
.option[disabled] { cursor: default; }

.task__feedback {
  padding: var(--space-4);
  border-radius: var(--radius-md);
  font-size: var(--text-sm);
  border-left: 4px solid var(--color-primary);
  background: var(--color-primary-soft);
  color: var(--color-text);
  display: none;
}
.task__feedback.is-correct { background: var(--color-success-soft); border-color: var(--color-success); }
.task__feedback.is-wrong { background: var(--color-error-soft); border-color: var(--color-error); }
.task__feedback.is-visible { display: block; animation: slideIn 280ms cubic-bezier(0.16, 1, 0.3, 1); }
.task__feedback strong { display: block; margin-bottom: var(--space-2); }

@keyframes slideIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

.task__nav { display: flex; justify-content: space-between; gap: var(--space-3); flex-wrap: wrap; }

/* Trainer canvas helper for tasks that need a small picture */
.task__figure {
  background: var(--geom-paper);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-3);
  aspect-ratio: 16 / 9;
  position: relative;
  overflow: hidden;
}
.task__figure canvas { width: 100%; height: 100%; }

/* ====== Final ====== */
.final {
  background: linear-gradient(135deg, var(--color-primary-soft), var(--color-secondary-soft));
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: var(--space-8);
  text-align: center;
  display: none;
}
.final.is-visible { display: block; animation: slideIn 400ms cubic-bezier(0.16, 1, 0.3, 1); }
.final__score {
  font-family: var(--font-display);
  font-size: var(--text-2xl);
  font-weight: 700;
  color: var(--color-primary);
  margin: var(--space-3) 0;
}
.final__message { font-size: var(--text-base); color: var(--color-text-muted); margin-bottom: var(--space-5); }

/* ====== Footer ====== */
.footer {
  padding: var(--space-10) 0;
  border-top: 1px dashed var(--color-divider);
  text-align: center;
  font-size: var(--text-xs);
  color: var(--color-text-faint);
  margin-top: var(--space-12);
}

/* ====== Lesson tabs (внутри секции уроков) ====== */
.lesson-tabs {
  display: flex; gap: var(--space-2); flex-wrap: wrap;
  margin-bottom: var(--space-6);
  padding-bottom: var(--space-3);
  border-bottom: 1px solid var(--color-divider);
}
.lesson-tab {
  padding: var(--space-2) var(--space-4);
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--color-text-muted);
  border-radius: var(--radius-full);
  border: 1px solid transparent;
  transition: var(--tr);
}
.lesson-tab:hover { background: var(--color-surface-offset); color: var(--color-text); }
.lesson-tab.is-active {
  background: var(--color-primary); color: #fff;
}

.lessons-pane { display: none; }
.lessons-pane.is-active { display: grid; gap: var(--space-6); }

/* ====== Утилиты ====== */
.tag {
  display: inline-block;
  padding: var(--space-1) var(--space-3);
  background: var(--color-surface-offset);
  border-radius: var(--radius-full);
  font-size: var(--text-xs);
  font-weight: 600;
  color: var(--color-text-muted);
  letter-spacing: 0.04em;
}
.tag--primary { background: var(--color-primary-soft); color: var(--color-primary); }
.tag--secondary { background: var(--color-secondary-soft); color: var(--color-secondary); }

/* ===== Lesson note variant (полноширинный урок-разбор без сцены) ===== */
.lesson--note { grid-template-columns: 1fr; }
@media (min-width: 980px) { .lesson--note { grid-template-columns: 1fr; } }
.lesson__body--full { max-width: 880px; }
.lesson__num--accent {
  background: var(--color-secondary-soft);
  color: var(--color-secondary);
}

.plain-list {
  list-style: none;
  margin: var(--space-3) 0 var(--space-4);
  padding: 0;
  display: grid;
  gap: var(--space-2);
}
.plain-list li {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  padding-left: var(--space-4);
  position: relative;
  line-height: 1.55;
}
.plain-list li::before {
  content: '';
  position: absolute;
  left: 0; top: 0.65em;
  width: 6px; height: 6px;
  background: var(--color-primary);
  border-radius: 50%;
}
.plain-list li strong { color: var(--color-text); font-weight: 600; }
.plain-list--examples li {
  padding: var(--space-3);
  background: var(--color-surface-offset);
  border-radius: var(--radius-sm);
  padding-left: calc(var(--space-3) + var(--space-4));
  border-left: 3px solid var(--color-border);
}
.plain-list--examples li::before {
  left: var(--space-3);
  top: calc(var(--space-3) + 0.65em);
}

.callout {
  margin: var(--space-3) 0 var(--space-4);
  padding: var(--space-4);
  background: var(--color-primary-soft);
  border-left: 3px solid var(--color-primary);
  border-radius: var(--radius-sm);
  font-size: var(--text-sm);
  color: var(--color-text);
  line-height: 1.6;
}

.answer {
  display: inline-block;
  font-weight: 700;
  padding: 2px 8px;
  border-radius: var(--radius-sm);
  font-size: var(--text-xs);
  letter-spacing: 0.02em;
  margin-right: 4px;
}
.answer--yes {
  background: rgba(79, 122, 44, 0.15);
  color: var(--geom-highlight, #4f7a2c);
}
.answer--no {
  background: rgba(184, 71, 43, 0.15);
  color: var(--color-primary);
}

[data-theme="dark"] .answer--yes {
  background: rgba(140, 195, 100, 0.18);
  color: #b8d68d;
}
[data-theme="dark"] .answer--no {
  background: rgba(220, 110, 80, 0.18);
  color: #e29585;
}