* {margin:0; padding:0; box-sizing:border-box;}
body {
  font-family:'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  line-height:1.6;
  color:#302f2f;
  background: linear-gradient(135deg,#667eea 0%,#764ba2 100%);
  min-height:100vh;
  padding:20px;  
}
.container {
  max-width:900px;
  margin:0 auto;
  background:rgba(255,255,255,0.95);
  border-radius:20px;
  box-shadow:0 20px 40px rgba(0,0,0,0.1);
  backdrop-filter: blur(10px);
  overflow:hidden;
  padding:20px; /* igual que el ejemplo */
}
.back-button {
  background: linear-gradient(45deg,#3498db,#2980b9);
  color:white; padding:12px 25px; border-radius:25px;
  text-decoration:none; margin-bottom:30px; display:inline-block;
}
.header {text-align:center; color: rgb(67, 64, 64);}
.header h1 {font-size:3em; margin-bottom:10px; text-shadow:2px 2px 4px rgba(29,16,44,0.3);}
.header p {font-size:1.2em; opacity:0.9;}
.content {padding:40px;}
.section {
  margin-bottom:40px;
  padding:30px;
  background: rgba(251,251,251,0.972);
  border-radius:15px;
  border-left:5px solid #2980b9;
  transition: transform 0.3s ease;
}
.section:hover {transform: translateY(-5px); box-shadow:0 10px 20px rgba(0,0,0,0.1);}
.section h2 {color:#2c3e50; margin-bottom:20px; font-size:2em; display:flex; align-items:center; gap:10px;}
.icon {font-size:1.2em;}
.examples-grid {
  display:grid;
  grid-template-columns:repeat(auto-fit, minmax(250px,1fr));
  gap:20px;
  margin:20px 0;
}
.example-card {
  background: linear-gradient(135deg,#f6f6f6 0%,#ffffff 100%);
  padding:20px;
  border-radius:10px;
  box-shadow:0 5px 15px rgba(0,0,0,0.1);
}
.example-card h4 {color:#2c3e50; margin-bottom:10px;}
.example-card p {margin:5px 0; font-size:1.1em;}
.key-points {
  background: linear-gradient(135deg,#ffecd2 0%,#fcb69f 100%);
  padding:30px;
  border-radius:15px;
  margin:20px 0;
}
.key-points li {
  margin:10px 0;
  padding:10px;
  background: rgba(255,255,255,0.7);
  border-radius:8px;
  border-left:4px solid #ff6b6b;
  font-weight:500;
}
.activity {
  background: linear-gradient(135deg,#d299c2 0%,#fef9d7 100%);
  padding:30px;
  border-radius:15px;
  margin:20px 0;
  text-align:center;
}
#drag-container {
  display:flex;
  flex-wrap:wrap;
  justify-content:center;
  margin-bottom:20px;
}
.drag-item {
  padding:12px 20px;
  margin:10px;
  background:linear-gradient(135deg,#36d1dc 0%,#5b86e5 100%);
  color:white;
  border-radius:25px;
  cursor:grab;
  transition: transform 0.2s ease;
}
.drag-item:hover {transform: scale(1.05);}
.drop-zone {
  display:inline-block;
  width:150px;
  min-height:60px;
  margin:10px;
  padding:10px;
  border:2px dashed #9b59b6;
  border-radius:15px;
  vertical-align:middle;
  background:#fff;
  box-shadow:0 5px 10px rgba(0,0,0,0.1);
  transition: background 0.3s, border-color 0.3s, transform 0.2s ease;
}
.drop-zone.filled {border-style:solid; transform: scale(1.02);}
.correct {background:#d4edda; border-color:#28a745;}
.incorrect {background:#f8d7da; border-color:#dc3545;}
.check-btn {
  margin-top:20px;
  background: linear-gradient(135deg,#36d1dc 0%,#5b86e5 100%);
  color:white;
  border:none;
  padding:12px 25px;
  border-radius:25px;
  cursor:pointer;
  font-size:1em;
  transition: transform 0.2s ease;
}
.check-btn:hover {transform:scale(1.05);}
.result {
  margin-top:15px;
  font-weight:bold;
  font-size:1.1em;
}