body {
  font-family: Arial, sans-serif;
  margin: 0;
  background: #f5f6fb;
  color: #222;
}
header {
  background: #1f3b68;
  color: #fff;
  padding: 18px 26px;
}
header h1 {
  margin: 0;
}
main {
  padding: 24px 26px 40px;
}
.course-list {
  display: flex;
  flex-wrap: wrap;
  gap: 18px;
}
.course-card {
  background:#fff;
  padding:16px 18px;
  border-radius:6px;
  box-shadow:0 1px 4px rgba(0,0,0,.08);
  max-width:360px;
  flex: 1 1 260px;
}
.course-card h2 {
  margin-top:0;
  font-size:1.1rem;
}
.btn {
  display:inline-block;
  padding:7px 14px;
  margin-top:8px;
  text-decoration:none;
  border-radius:4px;
  background:#1f3b68;
  color:#fff;
  font-size:0.9rem;
}
.btn.secondary {
  background:#555;
}
a { color:#1f3b68; }
.locked {
  color:#900;
  font-weight:bold;
}
textarea {
  width:100%;
  box-sizing:border-box;
}
.nav-links a {
  margin-right:12px;
}