:root {
  --navy: #0f3742;
  --navy-dark: #0a2830;
  --navy-deep: #061a1f;
  --accent: #0e9f95;
  --accent-dark: #0b7d76;
  --accent-soft: #e2f4f2;
  --text: #213a41;
  --muted: #54707a;
  --faint: #8aa3ac;
  --bg: #f2faf8;
  --card: #ffffff;
  --line: #d8eae4;
  --good: #0e7a50;
  --good-bg: #e9f7f0;
  --bad: #b3273a;
  --bad-bg: #fceef0;
  --warn-bg: #fdf6e6;
  --warn: #8a6414;
}

body {
  background:
    radial-gradient(circle at 80% 10%, rgba(14, 159, 149, 0.08), transparent 42%),
    var(--bg);
}

h1,
h2,
h3,
h4,
.page-head h1,
.section h2,
.section h3,
.card h3,
.course-card h3,
details.faq-item summary {
  letter-spacing: -0.01em;
}

.nav {
  margin: 0.9rem auto;
  position: sticky;
  top: 0;
  left: 0;
  right: 0;
  max-width: 1120px;
  background: rgba(255, 255, 255, 0.92);
  color: var(--text);
  border: 1px solid var(--line);
  border-radius: 999px;
  box-shadow: 0 8px 26px rgba(6, 26, 31, 0.1);
  backdrop-filter: blur(8px);
  width: calc(100% - 2rem);
}

.nav .logo {
  color: var(--navy);
}

.nav ul li a {
  color: #54707a;
  border-radius: 999px;
}

.nav ul li a:hover,
.nav ul li a.current {
  background: var(--accent-soft);
  color: var(--accent-dark);
}

.page-head {
  background: linear-gradient(135deg, #0f3742, #0b7d76);
}

.page-head p {
  color: #c8ece7;
}

.page-head .crumbs {
  color: #9fd6cf;
}

.section h2 {
  position: relative;
  padding-bottom: 0.45rem;
}

.section h2::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  width: 64px;
  height: 4px;
  border-radius: 999px;
  background: linear-gradient(90deg, var(--accent), var(--accent-dark));
}

.hero {
  border-radius: 22px;
  border: none;
  box-shadow: 0 18px 44px rgba(6, 26, 31, 0.14);
}

.card,
.course-card,
.timeline,
.accordion details,
.table-wrap,
.topic-grid div,
.author-grid div,
.term-grid div {
  border-radius: 18px;
  box-shadow: 0 10px 26px rgba(6, 26, 31, 0.08);
}

.btn {
  border-radius: 999px;
}

.btn.small {
  border-radius: 999px;
}

.course-card .level {
  border-radius: 999px;
}

table th:first-child {
  border-radius: 18px 0 0 0;
}

table th:last-child {
  border-radius: 0 18px 0 0;
}

.actionbox {
  background: linear-gradient(135deg, #0f3742 0%, #0b7d76 100%);
}

.hero-visual,
.flashcard-back {
  background: linear-gradient(135deg, #0f3742 0%, #0b7d76 100%);
}

.stat-num {
  color: var(--accent-dark);
}

footer {
  background: linear-gradient(180deg, #0a2830, #061a1f);
}