/* Глобальные настройки */
html {
  scroll-behavior: smooth;
}
body {
  margin: 0;
  padding: 0;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, Arial, sans-serif;
  color: #2d3748;
  background-color: #f8fafc;
  line-height: 1.6;
}
main {
  background: #ffffff;
}
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 15px 20px;
}
section {
  max-width: 1200px;
  margin: 0 auto;
  padding: 60px 20px;
}
section:nth-child(even) {
  background-color: #f8fafc;
  max-width: 100%;
  padding-left: 0;
  padding-right: 0;
}
.section-inner {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

/* Шапка и навигация */
header {
  background-color: #ffffff;
  border-bottom: 1px solid #e2e8f0;
  position: sticky;
  top: 0;
  z-index: 1000;
}
.header-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 15px 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.menu-btn, .menu-icon { display: none; }
.nav-links {
  list-style: none;
  display: flex;
  gap: 30px;
  margin: 0;
  padding: 0;
}
.nav-links a, .back-link {
  text-decoration: none;
  color: #4a5568;
  font-weight: 600;
  font-size: 16px;
  transition: color 0.2s;
}
.nav-links a:hover, .back-link:hover {
  color: #3182ce;
}

/* Заголовки и тексты */
h1 {
  font-size: 38px;
  color: #1a202c;
  margin-top: 0;
  margin-bottom: 20px;
}
h2 {
  font-size: 28px;
  color: #1a202c;
  border-left: 4px solid #3182ce;
  padding-left: 15px;
  margin-bottom: 40px;
}
.subtitle {
  font-size: 18px;
  color: #718096;
  margin-bottom: 30px;
}
.about-content {
  font-size: 18px;
  max-width: 900px;
  color: #4a5568;
}

/* Сетка каталога (Главная страница) */
.product-grid {
  display: flex;
  flex-direction: column;
  gap: 25px;
}
.product-card {
  background: #ffffff;
  border: 1px solid #e2e8f0;
  border-radius: 8px;
  padding: 30px;
  box-shadow: 0 4px 6px -1px rgba(0,0,0,0.05);
  transition: transform 0.2s, box-shadow 0.2s;
}
.product-card:hover {
  transform: translateY(-2px);
  box-shadow: 0 10px 15px -3px rgba(0,0,0,0.05);
}
.product-card h3 {
  margin-top: 0;
  font-size: 22px;
  color: #2b6cb0;
}
.product-card p {
  color: #4a5568;
  margin-bottom: 20px;
}

/* Кнопки и CTA */
.product-link, .btn-order {
  display: inline-block;
  background-color: #3182ce;
  color: #ffffff;
  text-decoration: none;
  font-weight: 600;
  padding: 10px 20px;
  border-radius: 6px;
  transition: background-color 0.2s;
}
.product-link:hover, .btn-order:hover {
  background-color: #2b6cb0;
}
.cta-box {
  background-color: #ebf8ff;
  border: 1px solid #bee3f8;
  border-radius: 8px;
  padding: 25px;
  margin-top: 40px;
  margin-bottom: 40px;
}
.cta-box p { margin-top: 0; font-size: 16px; }

/* Двухколоночный макет (Страница товара) */
.grid-layout {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 50px;
  margin-bottom: 40px;
}

/* Специфические элементы СУР-515 (Интерактивная схема) */
.scheme-container {
  background-color: #f8fafc;
  border: 2px solid #e2e8f0;
  border-radius: 8px;
  padding: 20px;
  position: relative;
  min-height: 280px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  box-sizing: border-box;
  margin-bottom: 30px;
}
.scheme-block {
  background: #ffffff;
  border: 2px solid #4a5568;
  border-radius: 4px;
  padding: 10px;
  text-align: center;
  font-weight: bold;
  font-size: 14px;
  z-index: 2;
  box-shadow: 0 4px 6px rgba(0,0,0,0.05);
}
.block-source { border-color: #e53e3e; color: #e53e3e; width: 80px; }
.block-detector { border-color: #3182ce; color: #3182ce; width: 90px; }
.block-boi { border-color: #2b6cb0; background: #2b6cb0; color: #fff; width: 110px; }
.scheme-tank {
  border-left: 4px dashed #718096;
  border-right: 4px dashed #718096;
  height: 220px;
  flex-grow: 1;
  margin: 0 20px;
  position: relative;
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
}
.tank-label {
  position: absolute;
  top: 10px;
  left: 50%;
  transform: translateX(-50%);
  color: #718096;
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}
.tank-level {
  background: rgba(49, 130, 206, 0.2);
  height: 50%;
  border-top: 2px solid #3182ce;
  text-align: center;
  color: #2b6cb0;
  font-size: 13px;
  font-weight: bold;
  padding-top: 5px;
  transition: height 0.5s ease-in-out;
}
.ray-line {
  position: absolute;
  top: 50%;
  left: -10px;
  right: -10px;
  height: 2px;
  background: repeating-linear-gradient(90deg, #e53e3e, #e53e3e 8px, transparent 8px, transparent 16px);
  z-index: 1;
}
.signal-line { height: 2px; background: #4a5568; width: 40px; margin-left: 5px; }
.composition-list { padding-left: 20px; margin: 0 0 30px 0; }
.composition-list li { margin-bottom: 8px; }

/* Таблицы характеристик */
.tech-table {
  width: 100%;
  border-collapse: collapse;
  margin: 20px 0 40px 0;
}
.tech-table th, .tech-table td {
  padding: 12px;
  text-align: left;
  border-bottom: 1px solid #e2e8f0;
}
.tech-table th { background-color: #f8fafc; font-weight: 600; }
.tech-table tr:hover { background-color: #f8fafc; }

/* Сетка контактов (Главная страница) */
.contacts-container {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 40px;
}
.contact-block {
  background: #ffffff;
  padding: 20px;
  border-radius: 6px;
}
.contact-block h3 {
  font-size: 18px;
  color: #718096;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-top: 0;
  margin-bottom: 15px;
}
.contact-block p { margin: 8px 0; font-size: 18px; font-weight: 500; }
.contact-block a { color: #2d3748; text-decoration: none; }
.contact-block a:hover { color: #3182ce; }

/* Подвал сайта (Только на Главной) */
footer {
  padding: 40px 20px;
  font-size: 14px;
  border-top: 1px solid #2d3748;
}

/* Мобильная адаптивность */
@media (max-width: 768px) {
  .header-container { position: relative; padding: 15px; }
  .nav-links {
    display: none;
    flex-direction: column;
    width: 100%;
    position: absolute;
    top: 100%;
    left: 0;
    background: #ffffff;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    padding: 20px;
    box-sizing: border-box;
    gap: 15px;
  }
  .menu-icon {
    display: block;
    cursor: pointer;
    padding: 10px;
    font-size: 24px;
    user-select: none;
  }
  .menu-btn:checked ~ .nav-links { display: flex; }
  h1 { font-size: 28px; }
  h2 { font-size: 24px; }
  .product-card { padding: 20px; }
  .grid-layout { grid-template-columns: 1fr; gap: 30px; }
}