body {
  font-family: 'Segoe UI', Arial, sans-serif;
  background: linear-gradient(120deg, #e0eafc 0%, #cfdef3 100%);
  color: #222;
  margin: 0;
  padding: 0;
  min-height: 100vh;
}

main {
  max-width: 900px;
  margin: 2.5rem auto;
  background: #fff;
  border-radius: 18px;
  box-shadow: 0 8px 32px rgba(52, 152, 219, 0.13);
  padding: 2.5rem 2.5rem 2rem 2.5rem;
  position: relative;
  animation: fadeIn 0.7s cubic-bezier(.4,0,.2,1);
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(40px); }
  to { opacity: 1; transform: none; }
}

h1 {
  text-align: center;
  color: #2d3a6a;
  margin-bottom: 2.5rem;
  letter-spacing: 0.04em;
  font-size: 2.3rem;
}

section {
  margin-bottom: 2.7rem;
}

.theory {
  background: linear-gradient(90deg, #e6f0fa 60%, #f7faff 100%);
  border-left: 6px solid #8e44ad;
  padding: 1.2rem 1.7rem;
  border-radius: 8px;
  margin-bottom: 0.7rem;
  box-shadow: 0 2px 8px rgba(142,68,173,0.06);
  transition: box-shadow 0.2s;
}
.theory:hover {
  box-shadow: 0 4px 16px rgba(142,68,173,0.13);
}

.code-example {
  background: #23272e;
  color: #f8f8f2;
  border-radius: 8px;
  padding: 1.2rem 1.7rem;
  margin-bottom: 1.7rem;
  box-shadow: 0 2px 8px rgba(52,152,219,0.10);
  border: 1.5px solid #8e44ad22;
  transition: box-shadow 0.2s, border 0.2s;
}
.code-example:hover {
  box-shadow: 0 6px 24px #8e44ad33;
  border: 1.5px solid #8e44ad;
}

.code-example pre {
  background: #181a20;
  color: #e6db74;
  padding: 0.85rem 1.1rem;
  border-radius: 5px;
  overflow-x: auto;
  font-size: 1.08rem;
  margin-bottom: 0.7rem;
  font-family: 'Fira Mono', 'Consolas', monospace;
  box-shadow: 0 1px 4px #0001;
}

.gradient-demo {
  width: 320px;
  height: 80px;
  margin: 1.2rem auto 1.2rem auto;
  border-radius: 14px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 600;
  font-size: 1.1rem;
  color: #fff;
  box-shadow: 0 2px 12px #8e44ad22;
  border: 3px solid #fff;
  transition: box-shadow 0.2s, border 0.2s, transform 0.18s;
  cursor: pointer;
  text-shadow: 0 2px 8px #0005;
  letter-spacing: 0.04em;
}
.gradient-demo:hover {
  box-shadow: 0 8px 32px #8e44ad33;
  border: 3px solid #8e44ad;
  transform: scale(1.045);
  opacity: 0.95;
}

.linear-gradient-demo {
  background: linear-gradient(90deg, #3498db, #8e44ad);
}
.radial-gradient-demo {
  background: radial-gradient(circle at 60% 40%, #f7971e, #ffd200 70%, #f7971e 100%);
}
.conic-gradient-demo {
  background: conic-gradient(from 45deg, #f7971e, #ffd200, #f7971e, #8e44ad);
}
.repeating-gradient-demo {
  background: repeating-linear-gradient(45deg, #3498db, #3498db 10px, #fff 10px, #fff 20px);
  color: #23272e;
  text-shadow: none;
}
.multiple-gradient-demo {
  background:
    linear-gradient(135deg, #8e44ad 40%, transparent 60%),
    radial-gradient(circle at 80% 20%, #ffd200 20%, transparent 60%),
    linear-gradient(90deg, #3498db, #8e44ad);
}
.angle-gradient-demo {
  background: linear-gradient(120deg, #3498db 10%, #fff 50%, #8e44ad 90%);
  color: #23272e;
  text-shadow: none;
}
.linear-gradient-diagonal {
  background: linear-gradient(45deg, #ff6a00, #ffd200, #8e44ad);
}
.linear-gradient-transparent {
  background: linear-gradient(to right, #3498db 70%, transparent);
}

.radial-gradient-ellipse {
  background: radial-gradient(ellipse at center, #8e44ad 0%, #ffd200 100%);
}

.conic-gradient-segments {
  background: conic-gradient(
    #3498db 0 25%, #ffd200 0 50%, #8e44ad 0 75%, #f7971e 0 100%
  );
}

.repeating-radial-demo {
  background: repeating-radial-gradient(circle, #8e44ad, #8e44ad 10px, #fff 10px, #fff 20px);
  color: #23272e;
  text-shadow: none;
}

.multiple-gradient-overlay {
  background:
    linear-gradient(to bottom, rgba(0,0,0,0.3), transparent),
    linear-gradient(90deg, #3498db, #8e44ad);
}

.gradient-rainbow {
  background: linear-gradient(90deg, red, orange, yellow, green, blue, indigo, violet);
}

.gradient-text {
  background: linear-gradient(90deg, #3498db, #8e44ad);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  color: transparent;
  font-size: 2.2rem;
  font-weight: 700;
  text-align: center;
  margin: 1.5rem auto;
  letter-spacing: 0.06em;
  line-height: 1.1;
}

.animated-gradient-demo {
  background: linear-gradient(270deg, #3498db, #8e44ad, #ffd200, #3498db);
  background-size: 600% 600%;
  animation: gradientMove 4s ease-in-out infinite;
}
@keyframes gradientMove {
  0% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
  100% { background-position: 0% 50%; }
}

nav {
  background: #e6f0fa;
  padding: 1.1rem 0 1.1rem 0.5rem;
  text-align: left;
  border-bottom: 1px solid #d0e2f2;
  border-radius: 0 0 12px 12px;
  box-shadow: 0 2px 8px #8e44ad11;
}

.back-btn {
  display: inline-block;
  text-decoration: none;
  background: linear-gradient(90deg, #8e44ad 60%, #3498db 100%);
  color: #fff;
  border: none;
  border-radius: 5px;
  padding: 0.6rem 1.4rem;
  font-size: 1.08rem;
  cursor: pointer;
  transition: background 0.2s, box-shadow 0.2s, transform 0.15s;
  box-shadow: 0 2px 8px #8e44ad22;
  font-weight: 500;
  letter-spacing: 0.03em;
  outline: none;
}

.back-btn:hover, .back-btn:focus {
  background: linear-gradient(90deg, #3498db 60%, #8e44ad 100%);
  box-shadow: 0 4px 16px #8e44ad33;
  transform: scale(1.06);
  color: #fff;
  text-decoration: none;
}

.gradient-image-demo {
  background:
    linear-gradient(rgba(52,152,219,0.7), rgba(142,68,173,0.7)),
    url('https://images.unsplash.com/photo-1506744038136-46273834b3fb?auto=format&fit=crop&w=600&q=80') center/cover no-repeat;
  color: #fff;
  background-blend-mode: overlay;
  text-shadow: 0 2px 8px #0008;
  border: 3px solid #fff;
  height: 300px;
  width: 100%;
}

@media (max-width: 700px) {
  main {
    padding: 1.2rem 0.3rem;
  }
  h1 {
    font-size: 1.3rem;
  }
  .gradient-demo {
    width: 98%;
    min-width: 0;
    font-size: 1rem;
  }
}