:root {
  --primary: #28eefc;
  --secondary: #23499d;
  --on-primary: #111111;
  --on-secondary: #ffffff;
  --bg: #ffffff;
  --surface: #f6f8fb;
  --light: #e9edf3;
  --dark: #12151b;
  --muted: #566173;
}

body {
  font-family: 'Inter', sans-serif;
  color: var(--dark);
  background-color: var(--bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

h1, h2, h3, h4, h5, h6 {
  font-family: 'Plus Jakarta Sans', sans-serif;
  color: var(--dark);
  line-height: 1.15;
  letter-spacing: -0.02em;
}

.hero-headline {
  font-size: clamp(2.2rem, 5vw, 3.6rem);
  font-weight: 700;
  line-height: 1.05;
  letter-spacing: -0.03em;
  max-width: 900px;
  margin-left: auto;
  margin-right: auto;
}

.section-headline {
  font-size: clamp(1.6rem, 3vw, 2.4rem);
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: -0.02em;
}

.hero-subhead {
  font-size: clamp(1.1rem, 2vw, 1.3rem);
  color: var(--muted);
  max-width: 720px;
}

.hero-kicker {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--secondary);
  letter-spacing: 0.08em;
}

.text-primary-gradient {
  background: linear-gradient(to right, var(--primary), var(--secondary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  color: transparent;
}

.bg-primary-gradient {
  background: linear-gradient(135deg, var(--primary), var(--secondary));
}

.text-on-primary-gradient {
  color: var(--on-primary); /* Assuming on-primary works for both */
}

.logo {
  height: 40px;
  width: auto;
}

.footer-logo {
  height: 36px;
  opacity: 0.8;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: auto;
  max-width: 100%;
  padding: 15px 30px;
  margin: 8px 0;
  gap: 10px;
  border: none;
  border-radius: 12px;
  font-weight: 600;
  font-size: 16px;
  line-height: 1.2;
  text-align: center;
  text-decoration: none;
  white-space: nowrap;
  box-sizing: border-box;
  cursor: pointer;
  transition: filter .25s ease, box-shadow .25s ease, transform .25s ease;
  min-height: 48px; /* Minimum tap target height */
}

.btn-sm {
  padding: 10px 20px;
  font-size: 14px;
}

.btn-lg {
  padding: 18px 36px;
  font-size: 18px;
}

.btn-cta {
  background: var(--primary);
  color: var(--on-primary) !important;
  box-shadow: 0 10px 24px -8px rgba(18,21,27,.35);
}

.btn-secondary {
  background: var(--secondary);
  color: var(--on-secondary) !important;
}

.btn-cta:hover, .btn-secondary:hover {
  filter: brightness(.94);
  box-shadow: 0 14px 30px -10px rgba(18,21,27,.45);
  transform: translateY(-2px);
}

@media (max-width: 575.98px) {
  .btn-lg {
    display: block;
    width: 100%;
  }
  .btn-group-responsive {
    flex-direction: column;
    width: 100%;
  }
  .btn-group-responsive .btn {
    width: 100%;
  }
}

/* Header */
header {
  background-color: var(--bg);
  border-bottom: 1px solid var(--light);
  box-shadow: 0 2px 8px rgba(18,21,27,.04);
  z-index: 1030;
}

.header-scrolled {
  transition: transform 0.3s ease-out, box-shadow 0.3s ease-out;
}

/* Hero Section */
.hero {
  padding-top: clamp(80px, 12vw, 160px);
  padding-bottom: clamp(80px, 12vw, 160px);
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -20%;
  left: -20%;
  width: 140%;
  height: 140%;
  background: radial-gradient(circle at 50% 50%, var(--primary) 0%, transparent 25%), radial-gradient(circle at 20% 80%, var(--secondary) 0%, transparent 20%);
  opacity: 0.05;
  z-index: 0;
  transform: rotate(-15deg);
  pointer-events: none;
}

/* Card Styles */
.card {
  border: 1px solid var(--light);
  border-radius: 18px;
  box-shadow: 0 1px 2px rgba(18,21,27,.04), 0 8px 16px -4px rgba(18,21,27,.08);
  transition: transform .25s ease, box-shadow .25s ease;
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 2px 4px rgba(18,21,27,.06), 0 12px 24px -6px rgba(18,21,27,.12);
}

.benefit-card .card-title {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
}

.benefit-card .card-text {
  color: var(--muted);
}

.icon-chip {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 56px;
  height: 56px;
  border-radius: 12px;
  background-color: var(--primary);
  color: var(--on-primary);
  margin-bottom: 1rem;
}

.icon-chip svg {
  width: 28px;
  height: 28px;
}

.icon-chip-muted {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  border-radius: 12px;
  background-color: var(--surface);
  color: var(--muted);
}

.icon-chip-muted svg {
  width: 24px;
  height: 24px;
}

.curriculum-item {
  display: flex;
  align-items: flex-start;
  background-color: var(--bg);
}

.curriculum-item .icon-chip-muted {
  flex-shrink: 0;
}

.curriculum-item .curriculum-number {
  font-weight: 700;
  font-size: 1.2rem;
  color: var(--dark);
}

.curriculum-item p {
  font-size: 0.95rem;
}

/* Course Visual */
.course-visual {
  border-radius: 18px;
  box-shadow: 0 4px 12px rgba(18,21,27,.08), 0 18px 40px -12px rgba(18,21,27,.16);
  transition: transform .3s ease, box-shadow .3s ease;
}

.course-visual:hover {
  transform: translateY(-8px);
  box-shadow: 0 6px 16px rgba(18,21,27,.1), 0 24px 50px -16px rgba(18,21,27,.2);
}

/* List Styles */
.check-list {
  list-style: none;
  padding-left: 0;
  font-size: 1.05rem;
  max-width: 480px;
}

.check-list li {
  display: flex;
  align-items: flex-start;
  margin-bottom: 12px;
}

.check-list svg {
  flex-shrink: 0;
  margin-right: 10px;
  color: var(--primary);
  width: 20px;
  height: 20px;
}

.learn-list {
  list-style: none;
  padding-left: 0;
  font-size: 1rem;
}

.learn-list li {
  display: flex;
  align-items: flex-start;
  margin-bottom: 10px;
  color: var(--dark);
}

.learn-list svg {
  flex-shrink: 0;
  margin-right: 8px;
  color: var(--secondary);
  width: 18px;
  height: 18px;
}

/* Author Section */
.author-avatar {
  width: 80px;
  height: 80px;
  background-color: var(--light);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2.5rem;
  font-weight: 600;
  color: var(--muted);
  text-transform: uppercase;
}

/* Pricing Card */
.price-card {
  max-width: 420px;
  text-align: center;
  background-color: var(--bg);
}

.price-card .display-3 {
  font-size: clamp(2.5rem, 5vw, 3.5rem);
  font-weight: 700;
  color: var(--dark);
}

.price-card .check-list {
  max-width: 300px;
  margin-left: auto;
  margin-right: auto;
}

/* General Section Padding */
section {
  padding-block: clamp(56px, 8vw, 104px);
}

/* Footer */
footer {
  background-color: var(--dark);
  color: #ffffff;
  font-size: 0.9rem;
}

footer .footer-logo {
  filter: brightness(0) invert(1);
  opacity: 0.7;
  height: 32px;
}

/* Accessibility */
:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
  border-radius: 4px;
}

@media (prefers-reduced-motion: reduce) {
  .btn,
  .card,
  .course-visual {
    transition: none !important;
  }
  .btn:hover, .card:hover, .course-visual:hover {
    transform: none !important;
    box-shadow: none !important;
  }
}

/* Responsive adjustments */
@media (min-width: 992px) {
  .sticky-sidebar {
    position: sticky;
    top: calc(var(--bs-navbar-height, 70px) + 2rem); /* Adjust based on actual header height */
  }
}