:root {
  /* Colors derived from screenshots */
  --bg-main: #004d4a; /* Deep Teal */
  --bg-cloud-yellow: #fff59d;
  --bg-cloud-blue: #b2ebf2;
  
  --btn-orange: #ffab91;
  --btn-orange-hover: #ff8a65;
  
  --btn-green: #aed581;
  --btn-green-hover: #9ccc65;
  
  --btn-blue: #81d4fa;
  --btn-blue-hover: #4fc3f7;
  
  --pill-yellow: #fff176;
  --pill-green: #a5d6a7;
  
  --text-white: #ffffff;
  --text-dark: #37474f;
  --text-red: #d32f2f;
  
  --shadow-soft: 0 4px 6px rgba(0,0,0,0.1);
  --shadow-deep: 0 8px 15px rgba(0,0,0,0.2);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background-color: var(--bg-main);
  color: var(--text-dark);
  min-height: 100vh;
  overflow-x: hidden;
  position: relative;
}

/* Background Decorations */
.bg-decor {
  position: absolute;
  z-index: -1;
}

.cloud-yellow {
  background-color: var(--bg-cloud-yellow);
  border-radius: 50% 50% 40% 40%;
  filter: blur(40px);
  opacity: 0.6;
}

.cloud-blue {
  background-color: var(--bg-cloud-blue);
  border-radius: 40% 60% 50% 50%;
  filter: blur(40px);
  opacity: 0.5;
}

/* Typography */
h1, h2, h3 {
  color: var(--text-white);
  text-transform: uppercase;
  text-align: center;
  text-shadow: 2px 2px 4px rgba(0,0,0,0.3);
  margin-top: 0;
}

h1 {
  font-size: 2.5rem;
  font-weight: 800;
  padding: 20px 0;
}

h2 {
  font-size: 1.8rem;
  margin-bottom: 20px;
}

/* Layout Containers */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 20px;
  position: relative;
  z-index: 1;
}

.grid-2-col {
  display: grid;
  grid-template-columns: 1fr 2fr;
  gap: 40px;
  align-items: center;
}

.grid-1-3 {
  display: grid;
  grid-template-columns: 1fr 3fr;
  gap: 40px;
  align-items: start;
}

/* Buttons & Interactive Elements */
.btn {
  display: block;
  width: 100%;
  padding: 15px 20px;
  margin-bottom: 15px;
  border: none;
  border-radius: 12px;
  font-weight: 700;
  font-size: 1.1rem;
  text-transform: uppercase;
  cursor: pointer;
  text-decoration: none;
  text-align: center;
  transition: transform 0.2s, box-shadow 0.2s;
  box-shadow: var(--shadow-soft);
  position: relative;
}

.btn:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-deep);
}

.btn-orange {
  background-color: var(--btn-orange);
  color: var(--text-white);
  border: 2px solid #ff8a65;
}

.btn-green {
  background-color: var(--btn-green);
  color: var(--text-dark);
  border: 2px solid #9ccc65;
}

.btn-cloud {
  border-radius: 50px;
  border: none;
  box-shadow: var(--shadow-soft);
  transition: transform 0.2s;
}
.btn-cloud:hover {
  transform: scale(1.05);
  box-shadow: var(--shadow-deep);
}

/* Specific Card Styles */
.card-cloud {
  background-color: var(--pill-yellow);
  padding: 15px 30px;
  border-radius: 50px;
  margin-bottom: 20px;
  display: flex;
  align-items: center;
  font-weight: 700;
  font-size: 1.2rem;
  box-shadow: 0 5px 0 rgba(0,0,0,0.1);
  color: var(--text-dark);
  position: relative;
  text-decoration: none;
  transition: transform 0.2s;
}

.card-cloud:hover {
  transform: scale(1.02);
}

.card-cloud .num {
  font-size: 1.5rem;
  margin-right: 15px;
  color: var(--text-red);
}

/* Image Placeholders */
.placeholder-img {
  background-color: rgba(255,255,255,0.1);
  border-radius: 20px;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

.placeholder-img img {
  width: 100%;
  height: auto;
  object-fit: contain;
}

/* Lecture Grid */
.lecture-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 20px;
}

.lecture-card {
  background-color: var(--btn-blue);
  border-radius: 20px;
  padding: 20px;
  text-align: center;
  box-shadow: var(--shadow-soft);
}

.lecture-title {
  font-weight: 800;
  margin-bottom: 15px;
  font-size: 1.1rem;
}

.action-row {
  display: flex;
  justify-content: center;
  gap: 10px;
}

.btn-small {
  padding: 5px 15px;
  font-size: 0.9rem;
  border-radius: 5px;
  text-transform: uppercase;
  font-weight: 700;
  cursor: pointer;
  border: none;
}

.btn-view {
  background-color: #ffcc80;
  color: #e65100;
}

.btn-edit {
  background-color: #ffe0b2;
  color: #e65100;
}

/* Tree Structure / Connections (Simplified) */
.tree-node {
  background-color: #66bb6a; /* Green for field */
  padding: 15px;
  margin-bottom: 15px;
  border-radius: 10px;
  color: var(--text-dark);
  font-weight: bold;
  position: relative;
}

.sub-node {
  background-color: #ef5350; /* Red/Pink for sub-fields */
  color: white;
  padding: 10px 20px;
  border-radius: 25px;
  margin: 5px 0 5px 40px; /* Indent */
  font-size: 0.9rem;
  display: inline-block;
}

/* Navigation Overlay */
.nav-fab {
  position: fixed;
  bottom: 20px;
  right: 20px;
  background: white;
  padding: 10px;
  border-radius: 50px;
  box-shadow: 0 5px 20px rgba(0,0,0,0.3);
  display: flex;
  gap: 10px;
  z-index: 100;
}

.nav-fab a {
  text-decoration: none;
  font-size: 1.5rem;
  padding: 5px;
}

/* Animations */
.float {
  animation: float 6s ease-in-out infinite;
}

@keyframes float {
  0% { transform: translateY(0px); }
  50% { transform: translateY(-10px); }
  100% { transform: translateY(0px); }
}

.star {
  position: absolute;
  color: #fff176;
  font-size: 2rem;
}

/* Responsive */
@media (max-width: 768px) {
  .grid-2-col, .grid-1-3 {
    grid-template-columns: 1fr;
  }
}