:root {
  --primary-dark: #0d1b2a;
  --primary-darker: #000000;
  --accent-neon: #00ff7f;
  --accent-blue: #1e90ff;
  --accent-purple: #9d00ff;
  --text-light: #ffffff;
  --text-gray: #b8c2cc;
  --card-bg: #1a1a2e;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: 'Montserrat', sans-serif;
  background: linear-gradient(135deg, var(--primary-darker), var(--primary-dark));
  color: var(--text-light);
  line-height: 1.6;
  letter-spacing: 0.5px;
  min-height: 100%;
  overflow-x: hidden;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

.header {
  text-align: center;
  padding: 60px 0 40px;
  position: relative;
}

.header::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 200px;
  height: 3px;
  background: linear-gradient(90deg, transparent, var(--accent-blue), transparent);
}

h1 {
  font-size: 2.8rem;
  margin-bottom: 20px;
  background: linear-gradient(90deg, var(--accent-blue), var(--accent-neon));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  text-shadow: 0 0 10px rgba(30, 144, 255, 0.3);
}

h2 {
  font-size: 1.8rem;
  margin: 40px 0 20px;
  color: var(--accent-blue);
  position: relative;
  padding-left: 15px;
}

h2::before {
  content: "";
  position: absolute;
  left: 0;
  top: 50%;
  transform: translateY(-50%);
  width: 5px;
  height: 80%;
  background: var(--accent-neon);
  border-radius: 3px;
}

h3 {
  font-size: 1.5rem;
  margin: 30px 0 15px;
  color: var(--accent-purple);
}

p {
  margin-bottom: 20px;
  font-size: 1.1rem;
}

.note {
  background-color: rgba(30, 144, 255, 0.1);
  border-left: 4px solid var(--accent-blue);
  padding: 15px;
  margin: 20px 0;
  border-radius: 0 4px 4px 0;
}

.grid-system {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 30px;
  margin: 40px 0;
}

.card {
  background-color: var(--card-bg);
  border-radius: 10px;
  padding: 25px;
  box-shadow: 0 10px 20px rgba(0, 0, 0, 0.2);
  transition: transform 0.3s, box-shadow 0.3s;
  position: relative;
  overflow: hidden;
}

.card:hover {
  transform: translateY(-10px);
  box-shadow: 0 15px 30px rgba(0, 0, 0, 0.3);
}

.card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 5px;
  background: linear-gradient(90deg, var(--accent-blue), var(--accent-neon));
}

.card-img {
  width: 100%;
  height: 200px;
  object-fit: cover;
  border-radius: 6px;
  margin-bottom: 20px;
  box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
  transition: transform 0.3s;
}

.card:hover .card-img {
  transform: scale(1.05);
}

.code-container {
  background-color: #162447;
  border-radius: 8px;
  padding: 20px;
  margin: 25px 0;
  position: relative;
  overflow: hidden;
}

.code-container::before {
  content: "CSS";
  position: absolute;
  top: 0;
  right: 0;
  background: var(--accent-blue);
  color: white;
  padding: 5px 15px;
  border-radius: 0 0 0 8px;
  font-size: 0.8rem;
}

pre {
  margin: 0;
  white-space: pre-wrap;
  font-family: 'Courier New', monospace;
  font-size: 0.9rem;
  line-height: 1.5;
  color: var(--text-light);
  overflow-x: auto;
}

code {
  font-family: 'Courier New', monospace;
  background-color: rgba(0, 0, 0, 0.3);
  padding: 2px 5px;
  border-radius: 3px;
  font-size: 0.9rem;
}

.footer {
  text-align: center;
  padding: 40px 0;
  margin-top: 60px;
  border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.footer p {
  color: var(--text-gray);
  font-size: 0.9rem;
}

@media (max-width: 768px) {
  h1 {
    font-size: 2rem;
  }
  
  h2 {
    font-size: 1.5rem;
  }
  
  h3 {
    font-size: 1.3rem;
  }
  
  .grid-system {
    grid-template-columns: 1fr;
  }
}

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

.floating {
  animation: float 3s ease-in-out infinite;
}

/* Decorative elements */
.decorative-line {
  height: 2px;
  background: linear-gradient(90deg, transparent, var(--accent-neon), transparent);
  margin: 40px 0;
  opacity: 0.5;
}

.polygon-shape {
  width: 100px;
  height: 100px;
  background: var(--accent-purple);
  clip-path: polygon(50% 0%, 100% 50%, 50% 100%, 0% 50%);
  position: absolute;
  right: 5%;
  top: 10%;
  opacity: 0.3;
  z-index: -1;
  animation: float 4s ease-in-out infinite;
}

.polygon-shape:nth-child(2) {
  background: var(--accent-blue);
  left: 5%;
  top: 30%;
  clip-path: polygon(0% 0%, 100% 0%, 100% 100%, 0% 100%);
  animation-delay: 0.5s;
}

.polygon-shape:nth-child(3) {
  background: var(--accent-neon);
  right: 10%;
  bottom: 10%;
  clip-path: circle(50% at 50% 50%);
  animation-delay: 1s;
}

.reference-note {
  background: rgba(255, 255, 255, 0.1);
  padding: 15px;
  border-radius: 8px;
  margin: 30px 0;
  text-align: center;
  font-size: 0.9rem;
  color: var(--text-gray);
  border: 1px dashed rgba(255, 255, 255, 0.3);
}