:root {
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --background: #0f172a;
  --surface: #1e293b;
  --text-primary: #f0f0f0;
  --text-muted: #a0aec0;
  --accent: #00c781;
  --shadow: rgba(37, 99, 235, 0.3);
}

body {
  margin: 0;
  font-family: 'Poppins', Arial, sans-serif;
  background-color: var(--background);
  color: var(--text-primary);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

a {
  color: var(--accent);
  text-decoration: none;
  transition: color 0.3s ease;
}
a:hover {
  color: #00a96b;
  text-decoration: underline;
}

/* Header */
.header-container {
  background-color: var(--surface);
  padding: 1rem 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-bottom: 2px solid var(--primary);
  box-shadow: 0 2px 10px var(--shadow);
}
.header-container h1 {
  margin: 0;
  font-size: 2rem;
  color: var(--primary);
}
.main-nav {
  display: flex;
  gap: 2rem;
}
.main-nav a {
  font-weight: 600;
  color: var(--primary);
  border-bottom: 2px solid transparent;
  padding-bottom: 3px;
}
.main-nav a:hover,
.main-nav a.active {
  color: var(--primary-dark);
  border-color: var(--primary-dark);
}

/* Main layout */
main {
  max-width: 1200px;
  margin: 3rem auto;
  padding: 0 2rem;
  display: flex;
  flex-wrap: wrap;
  gap: 2rem;
  justify-content: center;
}

/* Section intro */
.category-intro {
  width: 100%;
  text-align: center;
  margin-bottom: 2rem;
}
.category-intro h2 {
  font-size: 2.2rem;
  color: var(--primary);
  margin-bottom: 0.8rem;
}
.category-intro p {
  font-size: 1.15rem;
  color: var(--text-muted);
  line-height: 1.6;
}

/* Product Info Panel */
.product-info {
  flex: 1 1 400px;
  background-color: var(--surface);
  padding: 2rem;
  border-radius: 12px;
  width: 48%;
  box-shadow: 0 0 20px var(--shadow);
}
.product-info h3 {
  font-size: 1.6rem;
  margin-bottom: 1rem;
  color: var(--accent);
}
.product-info p {
  font-size: 1rem;
  color: var(--text-primary);
  line-height: 1.6;
  margin-bottom: 1rem;
}
.product-specs {
  margin-top: 1.5rem;
}
.product-specs li {
  list-style: none;
  background: rgba(0, 0, 0, 0.1);
  margin-bottom: 0.5rem;
  padding: 0.6rem 1rem;
  border-radius: 6px;
  font-size: 0.95rem;
  color: var(--text-primary);
}

/* Order Form */
.order-form {
  flex: 1 1 400px;
  background-color: var(--surface);
  padding: 2rem;
  border-radius: 20px;
  width: 48%;
  box-shadow: 0 0 20px var(--shadow);
}
.order-form label {
  display: block;
  margin-bottom: 1rem;
  font-weight: 600;
  color: var(--text-primary);
}
.order-form input,
.order-form select {
  width: 100%;
  padding: 0.7rem 1rem;
  margin-top: 0.4rem;
  border-radius: 8px;
  border: 1px solid #334155;
  background-color: var(--background);
  color: var(--text-primary);
  font-size: 1rem;
}
.order-form input:focus,
.order-form select:focus {
  border-color: var(--accent);
  outline: none;
  box-shadow: 0 0 0 2px var(--shadow);
}

/* Button */
.btn-primary {
  display: inline-block;
  background-color: var(--accent);
  color: #fff;
  font-weight: 700;
  font-size: 1.1rem;
  padding: 0.8rem 2rem;
  border: none;
  border-radius: 30px;
  cursor: pointer;
  transition: background-color 0.3s ease;
  box-shadow: 0 6px 12px rgba(0, 199, 129, 0.5);
  margin-top: 1rem;
}
.btn-primary:hover {
  background-color: #00a96b;
}

/* Order result box */
.order-result {
  margin-top: 2rem;
  background-color: var(--background);
  padding: 1.2rem 1.5rem;
  border-left: 4px solid var(--accent);
  border-radius: 8px;
  font-size: 1rem;
  color: var(--text-primary);
  box-shadow: 0 0 12px var(--shadow);
}

/* Footer */
footer {
  background-color: var(--surface);
  text-align: center;
  padding: 1.5rem 2rem;
  font-size: 0.95rem;
  color: var(--text-muted);
  border-top: 2px solid var(--primary);
  margin-top: auto;
}
footer a {
  color: var(--accent);
}
footer a:hover {
  color: #00a96b;
}

/* Responsive */
@media (max-width: 960px) {
  main {
    flex-direction: column;
    align-items: stretch;
  }
}

@media (max-width: 768px) {
  .header-container {
    flex-direction: column;
    align-items: flex-start;
    gap: 1rem;
  }
  .main-nav {
    flex-wrap: wrap;
    gap: 1rem;
  }
  .category-intro h2 {
    font-size: 1.8rem;
  }
}