/* Reset & Base Course */
* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: "Segoe UI", Tahoma, Arial, sans-serif;
  color: #172033;
  background-color: #f0fdf4;
  line-height: 1.55;
}
a { color: #047857; text-decoration: none; }

/* 1. Sticky Nav */
nav.sticky-nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: #047857;
  color: #ffffff;
  padding: 12px 24px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.15);
}
.nav-wrapper {
  display: flex;
  justify-content: space-between;
  align-items: center;
  max-width: 1280px;
  margin: 0 auto;
  flex-wrap: wrap;
  gap: 12px;
}
.brand-logo { font-size: 20px; font-weight: 700; color: #a7f3d0; }
ul.nav-menu {
  display: flex;
  justify-content: flex-end;
  align-items: center;
  list-style: none;
  margin: 0;
  padding: 0;
  gap: 16px;
  flex-wrap: wrap;
}
ul.nav-menu li a {
  color: #ffffff;
  font-weight: 600;
  font-size: 13.5px;
  padding: 5px 10px;
  border-radius: 4px;
}
ul.nav-menu li a:hover { background: #065f46; }

/* 2. Main Layout Flexbox */
main.course-page-main {
  padding: 24px;
  max-width: 1280px;
  margin: 0 auto;
  min-height: 900px;
}
.course-two-cols {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 24px;
  flex-wrap: wrap;
}
.col-course-info {
  flex: 3.5 1 660px;
}

/* Relative / Absolute pairs */
.course-cover-card {
  position: relative;
  background: #ffffff;
  border: 1px solid #a7f3d0;
  border-radius: 8px;
  padding: 32px 24px 20px;
  margin-bottom: 20px;
}
.abs-badge {
  position: absolute;
  padding: 4px 10px;
  border-radius: 4px;
  font-size: 11px;
  font-weight: 700;
}
.ribbon-bestseller {
  top: 14px;
  left: 14px;
  background: #f59e0b;
  color: #451a03;
}
.stamp-accredit {
  top: 14px;
  right: 14px;
  background: #047857;
  color: #ffffff;
}
.course-cover-card h2 { margin: 12px 0 8px; font-size: 22px; color: #064e3b; line-height: 1.35; }
.course-summary-desc { font-size: 14px; color: #334155; margin: 0 0 14px; }
.meta-pill {
  display: inline-block;
  background: #ecfdf5;
  color: #065f46;
  font-size: 12px;
  font-weight: 600;
  padding: 3px 10px;
  border-radius: 999px;
  margin-right: 8px;
  border: 1px solid #a7f3d0;
}

/* 3. Hover tương tác */
.syllabus-hover-interactive {
  position: relative;
  margin-bottom: 20px;
}
.hover-week-trigger {
  display: inline-block;
  background: #ecfdf5;
  color: #047857;
  border: 1px dashed #059669;
  padding: 8px 14px;
  border-radius: 6px;
  font-size: 13px;
  font-weight: 600;
  cursor: help;
}
.hover-lesson-flyout {
  display: none;
  position: absolute;
  top: 110%;
  left: 0;
  z-index: 50;
  background: #064e3b;
  color: #ecfdf5;
  padding: 16px;
  border-radius: 8px;
  box-shadow: 0 8px 24px rgba(0,0,0,0.25);
  width: 350px;
}
.syllabus-hover-interactive:hover .hover-lesson-flyout {
  display: block;
}
.hover-lesson-flyout h4 { margin: 0 0 8px; font-size: 13.5px; color: #a7f3d0; }
.hover-lesson-flyout p { margin: 4px 0; font-size: 12px; }

/* 4. 6 Thẻ Flexbox kích thước không đều */
.modules-flex-group {
  display: flex;
  flex-wrap: wrap;
  justify-content: flex-start;
  align-items: stretch;
  gap: 16px;
}
.course-unit-card {
  background: #ffffff;
  border: 1px solid #a7f3d0;
  border-radius: 8px;
  padding: 16px;
  box-shadow: 0 1px 3px rgba(4, 120, 87, 0.05);
}
.course-unit-card.c1 { flex: 2.7 1 330px; }
.course-unit-card.c2 { flex: 1 1 160px; }
.course-unit-card.c3 { flex: 1.4 1 200px; align-self: flex-start; }
.course-unit-card.c4 { flex: 2 1 250px; }
.course-unit-card.c5 { flex: 1.1 1 170px; }
.course-unit-card.c6.highlight-capstone {
  flex: 2.5 1 310px;
  order: -1;
  background: #ecfdf5;
  border-color: #6ee7b7;
}
.unit-tag {
  display: inline-block;
  font-size: 11px;
  font-weight: 700;
  padding: 2px 6px;
  border-radius: 4px;
  background: #d1fae5;
  color: #065f46;
  margin-bottom: 6px;
}
.highlight-tag { background: #059669; color: #ffffff; }
.course-unit-card h3 { margin: 0 0 6px; font-size: 15px; color: #064e3b; }
.course-unit-card p { margin: 0; font-size: 13px; color: #475569; }

/* Display none */
.syllabus-note-hidden { display: none; }

/* 5. Cột học phí Sticky & Iframe */
aside.col-sticky-pricing {
  flex: 1 1 280px;
  position: sticky;
  top: 70px;
  align-self: flex-start;
  background: #ffffff;
  border: 1px solid #a7f3d0;
  border-radius: 8px;
  padding: 18px;
}
.pricing-card {
  position: relative;
  background: #f0fdf4;
  border: 1px solid #86efac;
  border-radius: 6px;
  padding: 26px 14px 16px;
  margin-bottom: 16px;
}
.guarantee-seal {
  top: 6px;
  right: 6px;
  background: #059669;
  color: #ffffff;
  font-size: 10px;
}
.pricing-card h3 { margin: 0 0 8px; font-size: 16px; color: #065f46; }
.pricing-display { margin: 0 0 6px; font-size: 16px; }
.pricing-display del { color: #94a3b8; font-size: 14px; margin-right: 8px; }
.pricing-display strong { color: #dc2626; font-size: 20px; }
.class-start-date { margin: 0 0 12px; font-size: 12.5px; color: #475569; }
.enroll-now-btn {
  display: block;
  text-align: center;
  background: #047857;
  color: #ffffff;
  font-weight: 700;
  padding: 10px;
  border-radius: 6px;
  font-size: 14px;
}
.enroll-now-btn:hover { background: #065f46; }

aside.col-sticky-pricing h4 { margin: 0 0 6px; font-size: 14px; color: #065f46; }
aside.col-sticky-pricing p { margin: 0 0 10px; font-size: 12.5px; color: #64748b; }
.embedded-lecture {
  width: 100%;
  height: 180px;
  border: none;
  border-radius: 6px;
}

/* 6. Footer */
footer.course-footer {
  background: #064e3b;
  color: #ecfdf5;
  padding: 28px 24px;
  margin-top: 40px;
}
.footer-wrapper {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  flex-wrap: wrap;
  gap: 20px;
  max-width: 1280px;
  margin: 0 auto;
}
.footer-col { flex: 1 1 220px; }
.footer-col h4 { margin: 0 0 10px; font-size: 15px; color: #ffffff; }
.footer-col p { margin: 0; font-size: 13px; color: #a7f3d0; }
.footer-col ul { list-style: none; margin: 0; padding: 0; font-size: 13px; }
.footer-col ul li { margin-bottom: 6px; color: #a7f3d0; }