* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: #faf6f1;
  color: #2c2c2c;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  line-height: 1.6;
}

a {
  color: #8b1a1a;
}

a:focus-visible,
button:focus-visible,
input:focus-visible {
  outline: 3px solid #e67e22;
  outline-offset: 3px;
}

.lesson-header {
  padding: 32px 20px 28px;
  background: linear-gradient(135deg, #8b1a1a, #c0392b, #a83232);
  color: #fff;
  text-align: center;
}

.header-icon {
  margin-bottom: 8px;
  font-size: 2.5rem;
}

.eyebrow {
  margin: 0 0 8px;
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 1.5px;
  opacity: 0.9;
}

.lesson-header h1 {
  max-width: 920px;
  margin: 0 auto 10px;
  font-size: clamp(1.7rem, 4vw, 2.35rem);
  line-height: 1.2;
}

.intro {
  max-width: 680px;
  margin: 0 auto;
  opacity: 0.92;
}

.back-link {
  display: inline-block;
  margin-top: 16px;
  color: rgba(255, 255, 255, 0.9);
  text-decoration: none;
}

.back-link:hover {
  color: #fff;
  text-decoration: underline;
}

main {
  width: min(940px, 100%);
  margin: 0 auto;
  padding: 26px 20px 48px;
}

.lesson-note,
.information-box {
  padding: 16px 18px;
  border-left: 4px solid #c0392b;
  border-radius: 10px;
  background: #fff;
}

.lesson-note {
  margin-bottom: 22px;
}

.contents {
  padding: 20px 22px;
  margin-bottom: 28px;
  border: 1px solid #eaded2;
  border-radius: 14px;
  background: #fff;
}

.contents h2 {
  margin: 0 0 8px;
  color: #8b1a1a;
  font-size: 1.15rem;
}

.contents ol {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 4px 24px;
  margin: 0;
  padding-left: 22px;
}

.lesson-section {
  padding: 26px;
  margin: 24px 0;
  border-radius: 16px;
  background: #fff;
  box-shadow: 0 2px 12px rgba(0, 0, 0, 0.06);
  scroll-margin-top: 16px;
}

.section-label {
  margin: 0 0 4px;
  color: #a83232;
  font-size: 0.75rem;
  font-weight: 800;
  letter-spacing: 1.7px;
}

.lesson-section > h2 {
  margin: 0 0 8px;
  color: #8b1a1a;
  font-size: clamp(1.35rem, 3vw, 1.75rem);
  line-height: 1.3;
}

.lesson-section > p:not(.section-label) {
  margin-top: 0;
}

.question-list {
  padding-left: 24px;
}

.question-list li {
  margin: 8px 0;
}

.table-wrap {
  overflow-x: auto;
  margin-top: 16px;
  border: 1px solid #eaded2;
  border-radius: 10px;
}

table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
}

th,
td {
  padding: 11px 13px;
  border-bottom: 1px solid #eee5dc;
  vertical-align: top;
}

thead th {
  background: #f5e9e1;
  color: #702020;
}

tbody th {
  min-width: 175px;
  font-weight: 700;
}

tbody tr:last-child th,
tbody tr:last-child td {
  border-bottom: 0;
}

.practice-list {
  display: grid;
  gap: 14px;
  margin-top: 18px;
}

.practice-card {
  padding: 17px 18px;
  border: 1px solid #eee3d9;
  border-radius: 12px;
  background: #fffdfa;
}

.practice-card h3 {
  margin: 0 0 10px;
  color: #342b28;
  font-size: 1.05rem;
  line-height: 1.4;
}

.practice-card > p {
  margin: 8px 0;
}

.reveal-button {
  min-height: 42px;
  padding: 9px 16px;
  border: 0;
  border-radius: 22px;
  background: #c0392b;
  color: #fff;
  font: inherit;
  font-size: 0.9rem;
  font-weight: 700;
  cursor: pointer;
}

.reveal-button:hover {
  background: #8b1a1a;
}

.answer {
  padding: 12px 15px;
  margin-top: 12px;
  border-left: 3px solid #c0392b;
  border-radius: 0 8px 8px 0;
  background: #f8eee8;
}

.answer p {
  margin: 0;
}

.follow-up,
.vocab-line {
  color: #554b46;
  font-size: 0.94rem;
}

.information-box {
  margin: 16px 0;
  background: #fff8f1;
}

.information-box p {
  margin: 0 0 10px;
}

.information-box p:last-child {
  margin-bottom: 0;
}

.checklist {
  padding: 18px 20px;
  margin-top: 20px;
  border-radius: 12px;
  background: #f5eee8;
}

.checklist h3 {
  margin: 0 0 8px;
  color: #702020;
}

.checklist ul {
  padding-left: 0;
  margin: 0;
  list-style: none;
}

.checklist li {
  margin: 9px 0;
}

.checklist label {
  cursor: pointer;
}

.checklist input {
  margin-right: 8px;
  accent-color: #a83232;
}

.resources-section ul {
  padding-left: 22px;
}

.resources-section li {
  margin: 9px 0;
}

footer {
  padding: 24px 20px;
  background: #332a26;
  color: #eee;
  text-align: center;
}

footer p {
  margin: 0 0 4px;
}

footer a {
  color: #f0c7b6;
}

@media (max-width: 640px) {
  .lesson-header {
    padding: 26px 16px 24px;
  }

  main {
    padding: 18px 14px 34px;
  }

  .contents ol {
    grid-template-columns: 1fr;
  }

  .lesson-section {
    padding: 20px 16px;
    margin: 16px 0;
  }

  .practice-card {
    padding: 15px 14px;
  }

  table {
    min-width: 680px;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
}