body {
  font-family: Arial, sans-serif;
  background: #f5f7fa;
  margin: 0;
}

header {
  width: min(1180px, calc(100% - 24px));
  margin: 18px auto 0;
  background: #ffffff;
  color: #1f2937;
  padding: 20px;
  text-align: center;
  border: 1px solid #dddddd;
  border-radius: 16px;
}

.tabs {
  display: flex;
  justify-content: center;
  width: min(1180px, calc(100% - 24px));
  margin: 12px auto 0;
  background: rgba(255, 255, 255, 0.78);
  border: 1px solid #dddddd;
  border-radius: 16px;
  padding: 6px;
  gap: 6px;
  box-sizing: border-box;
}

.tab {
  padding: 12px 20px;
  cursor: pointer;
  font-weight: bold;
  border-radius: 999px;
}

.tab.active {
  background: #ffffff;
  color: #1c2f6e;
  box-shadow: none;
}

.container {
  width: min(1180px, calc(100% - 24px));
  margin: 18px auto;
  padding: 24px;
  background: white;
  border: 1px solid #dddddd;
  border-radius: 16px;
  box-shadow: none;
}

.section {
  border-bottom: 1px solid #ddd;
  padding: 16px 0;
}

.section h2 {
  cursor: pointer;
  display: flex;
  justify-content: space-between;
}

.content { display:none; padding:10px 20px; }
.subsection { margin-left:20px; padding:3px 0; }

.flashcard {
  max-width:600px;
  min-height:150px;
  margin:auto;
  background:#2563eb;
  color:white;
  display:flex;
  align-items:center;
  justify-content:center;
  text-align:center;
  padding:20px;
  border-radius:8px;
  cursor:pointer;
}

.flashcard.back { background:#16a34a; }

button {
  min-height: 42px;
  min-width: clamp(120px, 14vw, 180px);
  max-width: 220px;
  padding: 9px 12px;
  margin: 6px;
  border: 1px solid #6b92ef;
  border-radius: 10px;
  background: #6b92ef;
  color:white;
  font-weight:bold;
  cursor:pointer;
  box-shadow: 0 10px 20px rgba(107, 146, 239, 0.2);
  transition: background-color 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
}

button:hover,
button:focus {
  background: #5078d8;
  border-color: #5078d8;
  box-shadow: 0 14px 26px rgba(80, 120, 216, 0.22);
  outline: none;
}

.feedback.correct { color:#16a34a; }
.feedback.incorrect { color:#dc2626; }

/* Published-site shell */
body {
  background:
    radial-gradient(circle at top, rgba(114, 168, 255, 0.16), transparent 30%),
    linear-gradient(180deg, #f4f7fb 0%, #eef3f8 100%);
  color: #1f2937;
}

.mainTitle {
  font-family: 'Roboto', sans-serif;
  font-size: 2rem;
  font-weight: 900;
  text-transform: uppercase;
  letter-spacing: 1px;
  text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.1);
  background: linear-gradient(135deg, #1e3a8a, #72a8ff);
  color: transparent;
  background-clip: text;
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  display: block;
  width: fit-content;
  margin: 12px auto 6px;
  padding: 10px;
}

.mainTitle:hover {
  transform: scale(1.05);
}

.tabmenu {
  display: flex;
  flex-wrap: wrap;
  width: min(1180px, calc(100% - 24px));
  margin: 0 auto;
  justify-content: center;
  align-items: center;
  gap: 6px;
  padding: 6px;
  list-style: none;
  border-radius: 16px;
  background: rgba(255, 255, 255, 0.78);
  box-shadow: 0 16px 34px rgba(15, 23, 42, 0.08);
  backdrop-filter: blur(10px);
}

.tabmenu li {
  flex: 0 1 auto;
}

.tabmenu a {
  display: block;
  padding: 10px 16px;
  border: 1px solid #a9bee9;
  border-radius: 999px;
  background: #eef4ff;
  color: #2850a5;
  font-size: 14px;
  font-weight: 600;
  text-decoration: none;
  box-shadow: none;
  transition: all 0.25s ease;
}

.tabmenu a:hover,
.tabmenu a.active {
  background: #dbe8ff;
  border-color: #a9bee9;
  color: #2850a5;
  box-shadow: none;
}

@media (max-width: 600px) {
  header,
  .tabs,
  .container {
    width: calc(100% - 16px);
  }

  .tabmenu {
    width: calc(100% - 16px);
    gap: 4px;
    padding: 6px;
  }

  .tabmenu li {
    flex: 1 1 auto;
  }

  .tabmenu a {
    padding: 9px 12px;
    font-size: 13px;
  }

  button {
    width: 100%;
    min-width: 0;
    max-width: none;
    margin: 6px 0;
  }
}

/* HVACChecks unified tab menu override */
.tabmenu {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  border-radius: 8px;
  padding: 4px;
  margin: 0;
  list-style: none;
  gap: 4px;
  background: transparent;
  box-shadow: none;
}

.tabmenu li {
  flex: 1 1 auto;
  text-align: center;
}

.tabmenu a {
  display: block;
  padding: 8px 14px;
  color: #2850a5;
  background-color: #eef4ff;
  text-align: center;
  font-size: 15px;
  font-weight: 500;
  border-radius: 6px;
  box-shadow: none;
  white-space: nowrap;
  transition: all 0.25s ease;
  border: 1px solid #a9bee9;
}

.tabmenu a:hover,
.tabmenu a.active {
  background-color: #dbe8ff;
  color: #2850a5;
  box-shadow: none;
}

@media (max-width: 600px) {
  .tabmenu {
    justify-content: space-around;
    padding: 3px;
    gap: 3px;
  }

  .tabmenu a {
    font-size: 14px;
    padding: 7px 12px;
    border-radius: 5px;
  }
}