:root {
  --bg: #f7f9f7;
  --surface: #ffffff;
  --text: #1f2937;
  --muted: #5b6675;
  --brand: #2f7f56;
  --brand-dark: #1f5c3d;
  --accent: #c2622f;
  --border: #e3e8e3;
  --radius: 14px;
  --shadow: 0 4px 16px rgba(31, 41, 55, 0.06);
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: "Pretendard", "Apple SD Gothic Neo", "Malgun Gothic", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.65;
}

img { max-width: 100%; display: block; }

/* ---------- Header / Nav ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(6px);
  border-bottom: 1px solid var(--border);
}

.navbar {
  max-width: 1100px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 20px;
}

.brand {
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--brand-dark);
  text-decoration: none;
}

.nav-links {
  list-style: none;
  display: flex;
  gap: 20px;
  margin: 0;
  padding: 0;
  flex-wrap: wrap;
}

.nav-links a {
  text-decoration: none;
  color: var(--text);
  font-size: 0.92rem;
  font-weight: 500;
}

.nav-links a:hover { color: var(--brand); }

.nav-toggle {
  display: none;
  background: none;
  border: none;
  font-size: 1.4rem;
  cursor: pointer;
  color: var(--brand-dark);
}

/* ---------- Hero ---------- */
.hero {
  max-width: 1100px;
  margin: 0 auto;
  padding: 48px 20px 20px;
  display: grid;
  grid-template-columns: 1.1fr 1fr;
  gap: 32px;
  align-items: center;
}

.eyebrow {
  color: var(--brand);
  font-weight: 700;
  letter-spacing: 0.04em;
  margin: 0 0 6px;
}

.hero h1 {
  font-size: 2.6rem;
  margin: 0 0 14px;
  color: var(--brand-dark);
}

.lead { color: var(--muted); font-size: 1.05rem; }

.hero-img {
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

/* ---------- Intro grid ---------- */
.intro-panel {
  max-width: 1100px;
  margin: 20px auto 0;
  padding: 20px;
}

.intro-panel h2 {
  text-align: center;
  color: var(--brand-dark);
  margin-bottom: 20px;
}

.intro-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
}

.intro-card {
  background: var(--surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 20px;
  position: relative;
}

.intro-card .num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 34px;
  height: 34px;
  border-radius: 50%;
  background: var(--brand);
  color: #fff;
  font-weight: 700;
  margin-bottom: 10px;
}

.intro-card h3 { margin: 4px 0 8px; color: var(--brand-dark); font-size: 1.05rem; }
.intro-card p { color: var(--muted); margin: 0; font-size: 0.9rem; }

/* ---------- Unit sections ---------- */
.unit {
  max-width: 1100px;
  margin: 40px auto 0;
  padding: 20px;
}

.unit.alt { background: #eaf3ec; border-radius: 24px; }

.unit-head {
  display: grid;
  grid-template-columns: 280px 1fr;
  gap: 28px;
  align-items: center;
  margin-bottom: 24px;
}

.unit-img {
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.unit-label {
  font-size: 1rem;
  color: var(--accent);
  font-weight: 800;
  margin: 0;
}

.unit-head h2 { margin: 4px 0 10px; color: var(--brand-dark); }
.unit-desc { color: var(--muted); margin: 0; }

/* ---------- Topic accordion cards ---------- */
.topic-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  margin-bottom: 14px;
  overflow: hidden;
}

.topic-card summary {
  cursor: pointer;
  padding: 16px 20px;
  font-weight: 600;
  color: var(--brand-dark);
  list-style: none;
  position: relative;
}

.topic-card summary::-webkit-details-marker { display: none; }

.topic-card summary::after {
  content: "+";
  position: absolute;
  right: 20px;
  top: 14px;
  font-size: 1.3rem;
  color: var(--brand);
}

.topic-card[open] summary::after { content: "−"; }

.topic-body { padding: 0 20px 20px; color: var(--text); }

.topic-body ul, .topic-body ol { padding-left: 20px; }
.topic-body li { margin-bottom: 6px; }

.goal {
  background: #eef6f0;
  border-left: 4px solid var(--brand);
  padding: 10px 14px;
  border-radius: 8px;
  margin: 6px 0 14px;
}

.materials {
  background: #f2f6fb;
  border-left: 4px solid #3f7fae;
  padding: 10px 14px;
  border-radius: 8px;
  margin: 14px 0;
}

.activity {
  background: #fdf3e8;
  border-left: 4px solid var(--accent);
  padding: 10px 14px;
  border-radius: 8px;
  margin: 14px 0;
}

.caution {
  background: #fbeaea;
  border-left: 4px solid #c0392b;
  padding: 10px 14px;
  border-radius: 8px;
  margin: 14px 0;
}

/* ---------- Mini quiz ---------- */
.quiz-mini {
  margin-top: 16px;
  padding: 14px 16px;
  background: #f7f9fb;
  border-radius: 10px;
  border: 1px dashed var(--border);
}

.quiz-mini p { margin: 0 0 10px; font-weight: 600; }

.quiz-mini button {
  margin: 0 8px 8px 0;
  padding: 8px 14px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: #fff;
  cursor: pointer;
  font-size: 0.9rem;
}

.quiz-mini button:hover { border-color: var(--brand); }

.quiz-mini button.correct { background: #d9f2e6; border-color: #2f9e6f; }
.quiz-mini button.wrong { background: #fadede; border-color: #d9534f; }

.feedback { font-weight: 600; min-height: 1.2em; margin-top: 6px !important; }

/* ---------- Safety / Report panels ---------- */
.panel.two-col {
  max-width: 1100px;
  margin: 50px auto;
  padding: 20px;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 22px;
}

.panel-card {
  background: var(--surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 24px;
}

.panel-card h2 { margin-top: 0; color: var(--brand-dark); }

.checklist { padding-left: 22px; }
.checklist li { margin-bottom: 10px; }

/* ---------- Quiz summary ---------- */
.quiz-summary {
  max-width: 700px;
  margin: 0 auto 60px;
  padding: 30px;
  text-align: center;
  background: var(--surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.quiz-summary h2 { color: var(--brand-dark); }

.score-box {
  margin-top: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 16px;
}

#scoreDisplay {
  font-size: 1.6rem;
  font-weight: 800;
  color: var(--brand);
}

#resetQuiz {
  padding: 8px 16px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: #fff;
  cursor: pointer;
}

#resetQuiz:hover { border-color: var(--brand); }

/* ---------- Footer ---------- */
.site-footer {
  text-align: center;
  padding: 24px;
  color: var(--muted);
  font-size: 0.85rem;
}

/* ---------- Responsive ---------- */
@media (max-width: 860px) {
  .hero { grid-template-columns: 1fr; }
  .intro-grid { grid-template-columns: 1fr 1fr; }
  .unit-head { grid-template-columns: 1fr; }
  .panel.two-col { grid-template-columns: 1fr; }

  .nav-toggle { display: block; }
  .nav-links {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: #fff;
    flex-direction: column;
    padding: 14px 20px;
    border-bottom: 1px solid var(--border);
  }
  .nav-links.open { display: flex; }
}

@media (max-width: 520px) {
  .intro-grid { grid-template-columns: 1fr; }
}