* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: Georgia, "Times New Roman", serif;
  background: #f8f3e8;
  color: #102a43;
  line-height: 1.7;
}

a {
  color: inherit;
  text-decoration: none;
}

.navbar {
  width: 100%;
  background: linear-gradient(90deg, #071f36, #0b3455);
  color: white;
  padding: 15px 7%;
  display: flex;
  justify-content: space-between;
  align-items: center;
  position: sticky;
  top: 0;
  z-index: 1000;
  box-shadow: 0 4px 18px rgba(0, 0, 0, 0.15);
}

.logo {
  font-size: 30px;
  font-weight: bold;
}

.nav-links {
  list-style: none;
  display: flex;
  align-items: center;
  gap: 28px;
  flex-wrap: wrap;
}

.nav-links a {
  color: #f7fbff;
  font-size: 16px;
  font-weight: 600;
  padding-bottom: 6px;
  border-bottom: 2px solid transparent;
  transition: 0.25s ease;
}

.nav-links a:hover {
  color: #d9b25f;
  border-bottom: 2px solid #d9b25f;
}

.hero {
  min-height: 420px;
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 34px;
  align-items: center;
  padding: 74px 7%;
  background:
    radial-gradient(circle at 85% 18%, rgba(217, 178, 95, 0.22), transparent 34%),
    linear-gradient(135deg, #fffaf0 0%, #f8f3e8 50%, #e8f3f8 100%);
}

.hero h1 {
  font-size: 52px;
  line-height: 1.12;
  color: #08233d;
  margin-bottom: 18px;
}

.hero p {
  font-size: 20px;
  color: #2d3d4d;
  max-width: 720px;
}

.hero-panel {
  background: #08233d;
  color: white;
  border-radius: 24px;
  padding: 28px;
  box-shadow: 0 18px 42px rgba(16, 42, 67, 0.18);
  border: 8px solid white;
}

.hero-panel h2 {
  color: #d9b25f;
  font-size: 24px;
  margin-bottom: 12px;
}

.hero-panel ul {
  margin-left: 20px;
}

.hero-panel li {
  margin-bottom: 8px;
}

.page-wrap {
  max-width: 1180px;
  margin: 0 auto;
  padding: 64px 7%;
}

.intro,
.card,
.source-box {
  background: white;
  border-radius: 26px;
  padding: 34px;
  margin-bottom: 32px;
  box-shadow: 0 12px 30px rgba(16, 42, 67, 0.08);
  border-left: 6px solid #d9b25f;
}

.card h2,
.intro h2,
.source-box h2 {
  color: #102a43;
  font-size: 32px;
  margin-bottom: 16px;
}

.card h3 {
  color: #102a43;
  font-size: 23px;
  margin: 22px 0 10px;
}

.card p,
.intro p,
.card li,
.source-box p {
  color: #2d3d4d;
  font-size: 18px;
  margin-bottom: 12px;
}

.topic-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 20px;
  margin-top: 22px;
}

.topic-card {
  background: #fffaf0;
  border: 1px solid #e5dac7;
  border-radius: 22px;
  padding: 24px;
  transition: 0.25s ease;
}

.topic-card:hover {
  transform: translateY(-3px);
  background: #e8f3f8;
  border-color: #b7cfdd;
}

.topic-card h3 {
  margin-top: 0;
}

.button-row {
  display: flex;
  gap: 14px;
  flex-wrap: wrap;
  margin-top: 20px;
}

.button {
  display: inline-block;
  background: #08233d;
  color: white;
  border-radius: 999px;
  padding: 11px 20px;
  font-size: 16px;
  font-weight: 700;
  transition: 0.25s ease;
}

.button:hover {
  background: #0b4f71;
  transform: translateY(-2px);
}

.button.secondary {
  background: #d9b25f;
  color: #08233d;
}

.parts-list {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(210px, 1fr));
  gap: 14px;
  margin-top: 16px;
}

.part {
  background: #fffaf0;
  border: 1px solid #e5dac7;
  border-radius: 18px;
  padding: 16px;
  color: #2d3d4d;
  font-size: 17px;
}

.wiring-map {
  background: #fffaf0;
  border: 1px solid #e5dac7;
  border-radius: 22px;
  padding: 20px;
  margin-top: 18px;
  overflow-x: auto;
}

.wiring-map svg {
  min-width: 720px;
  width: 100%;
  height: auto;
  display: block;
}

.code-block {
  background: #071f36;
  color: #f7fbff;
  border-radius: 18px;
  padding: 20px;
  overflow-x: auto;
  margin: 16px 0 24px;
  border: 1px solid rgba(217, 178, 95, 0.42);
}

.code-block code {
  font-family: Menlo, Consolas, Monaco, monospace;
  font-size: 15px;
  line-height: 1.6;
  white-space: pre;
}

.note {
  background: #e8f3f8;
  border-left: 5px solid #0b4f71;
  border-radius: 14px;
  padding: 16px 18px;
  color: #2d3d4d;
  margin: 18px 0;
  font-size: 17px;
}

.lesson-steps {
  margin-left: 24px;
}

.lesson-steps li {
  margin-bottom: 12px;
}

footer {
  padding: 28px 7%;
  color: white;
  text-align: center;
  background: linear-gradient(90deg, #071f36, #0b3455);
  font-size: 18px;
}

footer span {
  color: #d9b25f;
}

@media (max-width: 900px) {
  .navbar {
    flex-direction: column;
    gap: 14px;
  }

  .nav-links {
    justify-content: center;
    gap: 18px;
  }

  .hero {
    grid-template-columns: 1fr;
  }

  .hero h1 {
    font-size: 38px;
  }
}

@media (max-width: 600px) {
  .logo {
    font-size: 25px;
  }

  .hero {
    padding: 58px 6%;
  }

  .hero h1 {
    font-size: 32px;
  }

  .hero p {
    font-size: 18px;
  }

  .page-wrap {
    padding: 50px 6%;
  }

  .intro,
  .card,
  .source-box {
    padding: 24px;
  }
}