:root {
  --bg: #ffffff; /* white background */
  --card: #f2f6fc;
  --accent: #007bff; /* blue */
  --accent2: #ff6600; /* orange */
  --text: #1a1a1a;
  --muted: #5a6b80;
  --radius: 14px;
  --max-width: 1100px;
  --gap: 28px;
}
* {
  box-sizing: border-box;
}
html,
body {
  height: 100%;
}

.c-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 48px 20px;
}

/* Hero */
.hero {
  min-height: 70vh;
  display: grid;
  align-items: center;
  grid-template-columns: 1fr 420px;
  gap: var(--gap);
}
@media (max-width: 900px) {
  .hero {
    grid-template-columns: 1fr;
    min-height: 60vh;
  }
}

.hero-left {
  padding: 28px;
  background: var(--card);
  border-radius: var(--radius);
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.05);
  position: relative;
  overflow: hidden;
}

.eyebrow {
  display: inline-block;
  padding: 8px 12px;
  border-radius: 999px;
  background: rgba(0, 123, 255, 0.1);
  color: var(--accent);
  font-weight: 600;
  font-size: 13px;
}
h1 {
  margin: 14px 0 6px;
  font-size: 44px;
  line-height: 1.02;
  letter-spacing: -0.02em;
  color: var(--accent);
}
p.lead {
  color: var(--muted);
  margin: 0 0 24px;
  font-size: 16px;
}

.big-title {
  font-weight: 900;
  font-size: 72px;
  line-height: 0.9;
  color: var(--accent2);
  margin: 12px 0 20px;
  text-shadow: 2px 2px 8px rgba(255, 102, 0, 0.2);
}
@media (max-width: 900px) {
  .big-title {
    font-size: 44px;
  }
}

.hero-cta {
  display: flex;
  gap: 12px;
  align-items: center;
}
.btn {
  padding: 12px 16px;
  border-radius: 12px;
  background: linear-gradient(90deg, var(--accent), var(--accent2));
  border: 0;
  color: white;
  font-weight: 700;
  cursor: pointer;
  box-shadow: 0 8px 20px rgba(0, 123, 255, 0.3);
}
.btn.ghost {
  background: transparent;
  border: 1px solid var(--accent);
  color: var(--accent);
  font-weight: 600;
}

.preview-card {
  background: var(--card);
  border-radius: 20px;
  padding: 22px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  justify-content: center;
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.05);
}
.preview-card h3 {
  margin: 0;
  font-size: 18px;
  color: var(--accent2);
}
.preview-list {
  margin: 8px 0 0;
  padding: 0;
  list-style: none;
}
.preview-list li {
  display: flex;
  gap: 12px;
  align-items: flex-start;
  padding: 10px;
  border-radius: 12px;
}
.dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--accent2);
  flex: 0 0 10px;
  margin-top: 6px;
}

section.course {
  margin: 48px 0;
  padding: 28px;
  border-radius: 18px;
  background: var(--card);
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.05);
}
.course-head {
  display: flex;
  justify-content: space-between;
  gap: 20px;
  align-items: center;
}
.course-title h2 {
  margin: 0;
  font-size: 20px;
  color: var(--accent);
}
.course-meta {
  color: var(--muted);
  font-size: 14px;
}

.outline {
  display: grid;
  grid-template-columns: 1fr 380px;
  gap: 22px;
  margin-top: 18px;
}
@media (max-width: 940px) {
  .outline {
    grid-template-columns: 1fr;
  }
}

.outline-list {
  background: white;
  padding: 18px;
  border-radius: 12px;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.04);
}
.outline-list ul {
  list-style: none;
  padding: 6px;
  margin: 0;
}
.outline-list li {
  opacity: 0;
  transform: translateY(28px) scale(0.995);
  display: flex;
  gap: 12px;
  padding: 14px;
  border-radius: 10px;
  margin-bottom: 10px;
  align-items: flex-start;
  background: #fdfdfd;
  border: 1px solid #eee;
}
.outline-list li .num {
  min-width: 38px;
  height: 38px;
  border-radius: 10px;
  background: var(--accent2);
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
}
.outline-list li h4 {
  margin: 0;
  font-size: 15px;
  color: var(--accent);
}
.outline-list li p {
  margin: 6px 0 0;
  color: var(--muted);
  font-size: 14px;
}

.outline-list li.in-view {
  opacity: 1;
  transform: none;
  transition: all 650ms cubic-bezier(0.2, 0.9, 0.25, 1);
}

.course-card {
  padding: 16px;
  border-radius: 12px;
  background: white;
  border: 1px solid #eee;
  box-shadow: 0 6px 16px rgba(0, 0, 0, 0.05);
}
.course-card p {
  color: var(--muted);
  margin: 8px 0;
}
.pill {
  display: inline-block;
  padding: 8px 10px;
  border-radius: 999px;
  background: rgba(0, 123, 255, 0.1);
  color: var(--accent);
  font-weight: 700;
  margin-right: 8px;
}

.outline-list li:hover {
  transform: translateY(-6px) scale(1.01);
  box-shadow: 0 10px 20px rgba(0, 123, 255, 0.2);
}

.scroll-indicator {
  position: absolute;
  right: 18px;
  bottom: 18px;
  width: 40px;
  height: 70px;
  border-radius: 20px;
  border: 1px solid #ddd;
  display: flex;
  align-items: flex-start;
  justify-content: center;
  padding-top: 8px;
}
.mouse-dot {
  width: 8px;
  height: 8px;
  border-radius: 999px;
  background: var(--accent);
  animation: scrollDot 1.8s infinite;
}
@keyframes scrollDot {
  0% {
    transform: translateY(0);
  }
  50% {
    transform: translateY(20px);
    opacity: 0.6;
  }
  100% {
    transform: translateY(0);
  }
}