/* Chess Learning — shared lesson styles (Tufte-inspired) */

:root {
  --text: #1a1a1a;
  --muted: #555;
  --accent: #2d5016;
  --accent-light: #e8f0e4;
  --board-light: #f0d9b5;
  --board-dark: #b58863;
  --correct: #1b6b2f;
  --incorrect: #9b2335;
  --border: #ddd;
  --font-serif: "Iowan Old Style", "Palatino Linotype", Palatino, Georgia, serif;
  --font-sans: "Helvetica Neue", Helvetica, Arial, sans-serif;
  --font-mono: "SF Mono", "Fira Code", Consolas, monospace;
}

* {
  box-sizing: border-box;
}

html {
  font-size: 18px;
}

body {
  margin: 0;
  padding: 2rem 1.5rem 4rem;
  max-width: 680px;
  margin-inline: auto;
  color: var(--text);
  font-family: var(--font-serif);
  line-height: 1.55;
  background: #fafaf8;
}

header.lesson-header {
  border-bottom: 1px solid var(--border);
  margin-bottom: 2rem;
  padding-bottom: 1rem;
}

header.lesson-header .lesson-meta {
  font-family: var(--font-sans);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted);
  margin: 0 0 0.5rem;
}

header.lesson-header h1 {
  font-size: 1.75rem;
  font-weight: 400;
  margin: 0 0 0.25rem;
  line-height: 1.2;
}

header.lesson-header .mission-link {
  font-family: var(--font-sans);
  font-size: 0.85rem;
  color: var(--muted);
}

h2 {
  font-size: 1.25rem;
  font-weight: 400;
  margin: 2rem 0 0.75rem;
  border-top: 1px solid var(--border);
  padding-top: 1.5rem;
}

h2:first-of-type {
  border-top: none;
  padding-top: 0;
  margin-top: 0;
}

p {
  margin: 0 0 1rem;
}

a {
  color: var(--accent);
}

.mission-tag {
  display: inline-block;
  background: var(--accent-light);
  color: var(--accent);
  font-family: var(--font-sans);
  font-size: 0.8rem;
  padding: 0.15rem 0.5rem;
  border-radius: 3px;
  margin-bottom: 1rem;
}

.callout {
  background: var(--accent-light);
  border-left: 3px solid var(--accent);
  padding: 0.75rem 1rem;
  margin: 1.25rem 0;
  font-size: 0.95rem;
}

.callout strong {
  display: block;
  font-family: var(--font-sans);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 0.35rem;
}

.board-diagram {
  display: grid;
  grid-template-columns: repeat(8, 1fr);
  width: min(100%, 320px);
  aspect-ratio: 1;
  border: 2px solid #333;
  margin: 1.25rem auto;
  font-family: var(--font-mono);
  font-size: 0.65rem;
}

.board-diagram .square {
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
}

.board-diagram .square.light { background: var(--board-light); }
.board-diagram .square.dark { background: var(--board-dark); }

.board-diagram .square .coord {
  position: absolute;
  font-size: 0.55rem;
  color: rgba(0,0,0,0.45);
  font-family: var(--font-sans);
}

.board-diagram .square .coord.file { bottom: 2px; right: 3px; }
.board-diagram .square .square-label {
  font-size: 1.1rem;
  opacity: 0.85;
}

figure {
  margin: 1.5rem 0;
}

figcaption {
  font-family: var(--font-sans);
  font-size: 0.8rem;
  color: var(--muted);
  text-align: center;
  margin-top: 0.5rem;
}

.citation {
  font-family: var(--font-sans);
  font-size: 0.8rem;
  color: var(--muted);
  margin: 1.5rem 0;
  padding-top: 0.75rem;
  border-top: 1px solid var(--border);
}

.citation a {
  color: var(--muted);
}

/* Quiz component */
.quiz {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 1.25rem;
  margin: 1.5rem 0;
}

.quiz h3 {
  font-family: var(--font-sans);
  font-size: 0.85rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  margin: 0 0 1rem;
  color: var(--muted);
}

.quiz .question {
  font-size: 1.05rem;
  margin-bottom: 1rem;
}

.quiz .options {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.quiz button.option {
  font-family: var(--font-sans);
  font-size: 0.95rem;
  text-align: left;
  padding: 0.65rem 0.85rem;
  border: 1px solid var(--border);
  border-radius: 3px;
  background: #fff;
  cursor: pointer;
  transition: background 0.15s, border-color 0.15s;
}

.quiz button.option:hover:not(:disabled) {
  background: var(--accent-light);
  border-color: var(--accent);
}

.quiz button.option:disabled {
  cursor: default;
}

.quiz button.option.correct {
  background: #e6f4ea;
  border-color: var(--correct);
  color: var(--correct);
}

.quiz button.option.incorrect {
  background: #fce8ea;
  border-color: var(--incorrect);
  color: var(--incorrect);
}

.quiz button.option.reveal-correct {
  background: #e6f4ea;
  border-color: var(--correct);
}

.quiz .feedback {
  font-family: var(--font-sans);
  font-size: 0.9rem;
  margin-top: 0.85rem;
  padding: 0.65rem 0.85rem;
  border-radius: 3px;
  display: none;
}

.quiz .feedback.show {
  display: block;
}

.quiz .feedback.correct {
  background: #e6f4ea;
  color: var(--correct);
}

.quiz .feedback.incorrect {
  background: #fce8ea;
  color: var(--incorrect);
}

.quiz-progress {
  font-family: var(--font-sans);
  font-size: 0.75rem;
  color: var(--muted);
  margin-bottom: 0.75rem;
}

.next-lesson {
  margin-top: 2.5rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
  font-family: var(--font-sans);
  font-size: 0.9rem;
}

.ask-agent {
  background: #f5f5f3;
  border: 1px dashed var(--border);
  padding: 1rem;
  margin-top: 2rem;
  font-family: var(--font-sans);
  font-size: 0.85rem;
  color: var(--muted);
  border-radius: 4px;
}

ul, ol {
  margin: 0 0 1rem;
  padding-left: 1.25rem;
}

li {
  margin-bottom: 0.35rem;
}

@media print {
  body { background: #fff; font-size: 12pt; }
  .quiz button.option { border: 1px solid #999; }
}