/* ============================================
   TransformerGrid - Industrial B2B Website
   Professional, Clean, International Style
   ============================================ */

/* === CSS Variables === */
:root {
  --color-primary: #0d2238;
  --color-primary-light: #163a59;
  --color-accent: #2f6b9a;
  --color-cta: #d9822b;
  --color-cta-hover: #c47322;
  --color-bg: #ffffff;
  --color-bg-alt: #f4f7fa;
  --color-border: #dbe3ea;
  --color-text: #17212b;
  --color-text-secondary: #5b6977;
  --color-text-light: #8a95a1;
  --color-white: #ffffff;
  --font-primary: 'Segoe UI', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-heading: 'Segoe UI', -apple-system, BlinkMacSystemFont, sans-serif;
  --section-padding: 100px;
  --section-padding-mobile: 60px;
  --container-max: 1200px;
  --container-padding: 24px;
  --radius-sm: 8px;
  --radius-md: 16px;
  --radius-lg: 20px;
  --shadow-sm: 0 2px 8px rgba(13, 34, 56, 0.06);
  --shadow-md: 0 4px 16px rgba(13, 34, 56, 0.08);
  --shadow-lg: 0 8px 32px rgba(13, 34, 56, 0.10);
  --transition: 0.3s ease;
}

/* === Reset & Base === */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
  font-family: var(--font-primary);
  font-size: 16px;
  line-height: 1.6;
  color: var(--color-text);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
}
img { max-width: 100%; height: auto; display: block; }
a { text-decoration: none; color: inherit; transition: var(--transition); }
ul, ol { list-style: none; }
button { font-family: inherit; cursor: pointer; border: none; background: none; }
input, textarea, select { font-family: inherit; font-size: inherit; }

/* === Typography === */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: 600;
  line-height: 1.3;
  color: var(--color-primary);
}
h1 { font-size: 48px; font-weight: 700; letter-spacing: -0.5px; }
h2 { font-size: 34px; font-weight: 600; letter-spacing: -0.3px; }
h3 { font-size: 22px; font-weight: 600; }
h4 { font-size: 18px; font-weight: 600; }
p { color: var(--color-text-secondary); }

/* === Placeholder Image Styles === */
.placeholder-img {
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}
.placeholder-img svg {
  width: 60%;
  height: 60%;
  max-width: 120px;
  max-height: 120px;
}

/* Hero placeholder */
.placeholder-hero {
  background: linear-gradient(135deg, #163a59 0%, #2f6b9a 50%, #0d2238 100%);
  border-radius: var(--radius-lg);
  aspect-ratio: 4/3;
}

/* Category placeholder backgrounds */
.placeholder-cat { aspect-ratio: 16/10; }
.placeholder-pole { background: linear-gradient(135deg, #163a59 0%, #0d2238 100%); }
.placeholder-pad { background: linear-gradient(135deg, #2f6b9a 0%, #163a59 100%); }
.placeholder-dist { background: linear-gradient(135deg, #0d2238 0%, #1a3d5c 100%); }
.placeholder-dry { background: linear-gradient(135deg, #3a5a7a 0%, #163a59 100%); }
.placeholder-power { background: linear-gradient(135deg, #1a3d5c 0%, #2f6b9a 100%); }
.placeholder-sub { background: linear-gradient(135deg, #0d2238 0%, #2f6b9a 50%, #163a59 100%); }

/* Product placeholder */
.placeholder-product {
  background: linear-gradient(135deg, #163a59 0%, #2f6b9a 100%);
  aspect-ratio: 4/3;
  flex-direction: column;
  gap: 8px;
}
.placeholder-kva {
  font-size: 28px;
  font-weight: 700;
  color: rgba(255,255,255,0.9);
  letter-spacing: -0.5px;
}
.placeholder-type {
  font-size: 12px;
  font-weight: 500;
  color: rgba(255,255,255,0.6);
  text-transform: uppercase;
  letter-spacing: 2px;
}

/* Application placeholder */
.placeholder-app {
  width: 100%;
  height: 100%;
  position: absolute;
  top: 0;
  left: 0;
}

/* Blog placeholder */
.placeholder-blog {
  background: linear-gradient(135deg, #163a59 0%, #2f6b9a 100%);
  aspect-ratio: 16/9;
}

/* Intro placeholder */
.placeholder-intro {
  background: linear-gradient(135deg, #163a59 0%, #2f6b9a 50%, #0d2238 100%);
  border-radius: var(--radius-lg);
  aspect-ratio: 4/3;
}

/* === Container === */
.container { max-width: var(--container-max); margin: 0 auto; padding: 0 var(--container-padding); }

/* === Buttons === */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 14px 28px;
  font-size: 15px;
  font-weight: 500;
  border-radius: var(--radius-sm);
  transition: var(--transition);
  gap: 8px;
}
.btn-primary { background-color: var(--color-cta); color: var(--color-white); }
.btn-primary:hover { background-color: var(--color-cta-hover); transform: translateY(-2px); }
.btn-secondary { background-color: var(--color-primary); color: var(--color-white); }
.btn-secondary:hover { background-color: var(--color-primary-light); transform: translateY(-2px); }
.btn-outline { background-color: transparent; color: var(--color-primary); border: 1.5px solid var(--color-primary); }
.btn-outline:hover { background-color: var(--color-primary); color: var(--color-white); }
.btn-sm { padding: 10px 20px; font-size: 14px; }

/* === Navigation === */
.navbar { position: fixed; top: 0; left: 0; right: 0; z-index: 1000; background-color: var(--color-white); transition: var(--transition); }
.navbar.scrolled { box-shadow: var(--shadow-sm); }
.navbar-inner { display: flex; align-items: center; justify-content: space-between; padding: 0 var(--container-padding); max-width: var(--container-max); margin: 0 auto; height: 72px; }
.nav-logo { font-size: 22px; font-weight: 700; color: var(--color-primary); letter-spacing: -0.5px; }
.nav-logo span { color: var(--color-accent); }
.nav-menu { display: flex; align-items: center; gap: 32px; }
.nav-link { font-size: 15px; font-weight: 500; color: var(--color-text-secondary); position: relative; padding: 8px 0; }
.nav-link:hover, .nav-link.active { color: var(--color-primary); }
.nav-link.active::after { content: ''; position: absolute; bottom: 0; left: 0; right: 0; height: 2px; background-color: var(--color-cta); }
.nav-cta { margin-left: 16px; }
.nav-toggle { display: none; flex-direction: column; gap: 5px; padding: 8px; }
.nav-toggle span { width: 24px; height: 2px; background-color: var(--color-primary); transition: var(--transition); }

/* === Mobile Navigation === */
@media (max-width: 1024px) {
  .nav-toggle { display: flex; }
  .nav-menu {
    position: fixed; top: 72px; left: 0; right: 0; bottom: 0;
    background-color: var(--color-white);
    flex-direction: column; align-items: stretch;
    padding: 24px; gap: 0;
    transform: translateX(100%); transition: transform 0.3s ease;
    overflow-y: auto;
  }
  .nav-menu.active { transform: translateX(0); }
  .nav-link { display: block; padding: 16px 0; border-bottom: 1px solid var(--color-border); }
  .nav-cta { margin: 24px 0 0 0; }
  .nav-cta .btn { width: 100%; }
}

/* === Hero Section === */
.hero { padding-top: 72px; background-color: var(--color-bg-alt); position: relative; overflow: hidden; }
.hero-inner { display: grid; grid-template-columns: 1fr 1fr; gap: 60px; align-items: center; padding: 80px 0; }
.hero-content { max-width: 540px; }
.hero-title { margin-bottom: 24px; font-size: 48px; }
.hero-text { font-size: 17px; line-height: 1.7; margin-bottom: 32px; color: var(--color-text-secondary); }
.hero-buttons { display: flex; gap: 16px; flex-wrap: wrap; }
.hero-image { position: relative; }

@media (max-width: 900px) {
  .hero-inner { grid-template-columns: 1fr; gap: 40px; padding: 60px 0; }
  .hero-content { max-width: 100%; }
  .hero-title { font-size: 38px; }
}

/* === Section Styles === */
.section { padding: var(--section-padding) 0; }
.section-alt { background-color: var(--color-bg-alt); }
.section-header { text-align: center; margin-bottom: 60px; }
.section-title { margin-bottom: 16px; }
.section-subtitle { font-size: 17px; color: var(--color-text-secondary); max-width: 600px; margin: 0 auto; }

/* === Category Cards === */
.categories-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.category-card { background-color: var(--color-white); border-radius: var(--radius-md); border: 1px solid var(--color-border); overflow: hidden; transition: var(--transition); }
.category-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-md); }
.category-image { overflow: hidden; background-color: var(--color-bg-alt); }
.category-card:hover .category-image img { transform: scale(1.03); }
.category-content { padding: 24px; }
.category-title { font-size: 18px; margin-bottom: 12px; }
.category-desc { font-size: 14px; line-height: 1.6; margin-bottom: 20px; color: var(--color-text-secondary); }
@media (max-width: 900px) { .categories-grid { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 600px) { .categories-grid { grid-template-columns: 1fr; } }

/* === Why Choose Section === */
.features-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 32px; }
.feature-item { padding: 32px; background-color: var(--color-white); border-radius: var(--radius-md); border: 1px solid var(--color-border); }
.feature-number { font-size: 14px; font-weight: 600; color: var(--color-accent); margin-bottom: 16px; letter-spacing: 1px; }
.feature-title { font-size: 20px; margin-bottom: 12px; }
.feature-text { font-size: 15px; line-height: 1.7; }
@media (max-width: 768px) { .features-grid { grid-template-columns: 1fr; } }

/* === Product Cards === */
.products-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.product-card { background-color: var(--color-white); border-radius: var(--radius-md); border: 1px solid var(--color-border); overflow: hidden; transition: var(--transition); }
.product-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-md); }
.product-image { overflow: hidden; background-color: var(--color-bg-alt); }
.product-image img { width: 100%; height: 100%; object-fit: cover; }
.product-content { padding: 24px; }
.product-title { font-size: 17px; margin-bottom: 8px; }
.product-tagline { font-size: 13px; color: var(--color-text-secondary); margin-bottom: 16px; }
.product-specs { margin-bottom: 20px; }
.spec-row { display: flex; justify-content: space-between; padding: 8px 0; border-bottom: 1px solid var(--color-border); font-size: 13px; }
.spec-row:last-child { border-bottom: none; }
.spec-label { color: var(--color-text-secondary); }
.spec-value { font-weight: 500; color: var(--color-text); }
@media (max-width: 900px) { .products-grid { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 600px) { .products-grid { grid-template-columns: 1fr; } }

/* === Applications Section === */
.applications-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 24px; }
.app-card {
  position: relative;
  border-radius: var(--radius-md);
  overflow: hidden;
  aspect-ratio: 16/9;
}
.app-overlay { position: absolute; bottom: 0; left: 0; right: 0; padding: 32px; background: linear-gradient(to top, rgba(13, 34, 56, 0.85), transparent); }
.app-title { font-size: 20px; color: var(--color-white); margin-bottom: 8px; }
.app-desc { font-size: 14px; color: rgba(255, 255, 255, 0.8); }
@media (max-width: 768px) { .applications-grid { grid-template-columns: 1fr; } }

/* === Blog Section === */
.blog-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.blog-card { background-color: var(--color-white); border-radius: var(--radius-md); border: 1px solid var(--color-border); overflow: hidden; transition: var(--transition); }
.blog-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-md); }
.blog-image { overflow: hidden; background-color: var(--color-bg-alt); }
.blog-image img { width: 100%; height: 100%; object-fit: cover; }
.blog-content { padding: 24px; }
.blog-title { font-size: 17px; margin-bottom: 12px; line-height: 1.4; }
.blog-excerpt { font-size: 14px; line-height: 1.6; margin-bottom: 16px; color: var(--color-text-secondary); }
@media (max-width: 900px) { .blog-grid { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 600px) { .blog-grid { grid-template-columns: 1fr; } }

/* === FAQ Section === */
.faq-list { max-width: 800px; margin: 0 auto; }
.faq-item { background-color: var(--color-white); border-radius: var(--radius-md); border: 1px solid var(--color-border); margin-bottom: 16px; overflow: hidden; }
.faq-question { display: flex; align-items: center; justify-content: space-between; padding: 24px; cursor: pointer; font-size: 16px; font-weight: 500; color: var(--color-primary); transition: var(--transition); }
.faq-question:hover { background-color: var(--color-bg-alt); }
.faq-icon { font-size: 20px; font-weight: 400; color: var(--color-accent); transition: var(--transition); }
.faq-item.active .faq-icon { transform: rotate(45deg); }
.faq-answer { max-height: 0; overflow: hidden; transition: max-height 0.3s ease, padding 0.3s ease; }
.faq-item.active .faq-answer { max-height: 300px; }
.faq-answer-inner { padding: 0 24px 24px 24px; font-size: 15px; line-height: 1.7; color: var(--color-text-secondary); }

/* === CTA Section === */
.cta-section { background-color: var(--color-primary); padding: 80px 0; }
.cta-inner { text-align: center; max-width: 700px; margin: 0 auto; }
.cta-title { font-size: 32px; color: var(--color-white); margin-bottom: 16px; }
.cta-text { font-size: 17px; color: rgba(255, 255, 255, 0.8); margin-bottom: 32px; }
.cta-buttons { display: flex; gap: 16px; justify-content: center; flex-wrap: wrap; }

/* === Footer === */
.footer { background-color: var(--color-primary); padding: 60px 0 30px; }
.footer-grid { display: grid; grid-template-columns: 1.5fr 1fr 1fr 1fr; gap: 40px; margin-bottom: 40px; }
.footer-brand-name { font-size: 22px; font-weight: 700; color: var(--color-white); margin-bottom: 16px; }
.footer-brand-desc { font-size: 14px; color: rgba(255, 255, 255, 0.7); line-height: 1.7; }
.footer-title { font-size: 14px; font-weight: 600; color: var(--color-white); margin-bottom: 20px; text-transform: uppercase; letter-spacing: 1px; }
.footer-links { display: flex; flex-direction: column; gap: 12px; }
.footer-link { font-size: 14px; color: rgba(255, 255, 255, 0.7); }
.footer-link:hover { color: var(--color-white); }
.footer-contact-item { font-size: 14px; color: rgba(255, 255, 255, 0.7); margin-bottom: 12px; }
.footer-bottom { padding-top: 30px; border-top: 1px solid rgba(255, 255, 255, 0.1); text-align: center; }
.footer-copyright { font-size: 14px; color: rgba(255, 255, 255, 0.6); }
@media (max-width: 900px) { .footer-grid { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 600px) { .footer-grid { grid-template-columns: 1fr; gap: 32px; } }

/* === Page Header === */
.page-header { padding-top: 72px; background-color: var(--color-bg-alt); }
.page-header-inner { padding: 60px 0; text-align: center; }
.page-title { margin-bottom: 16px; }
.page-subtitle { font-size: 17px; color: var(--color-text-secondary); max-width: 600px; margin: 0 auto; }

/* === Intro Section === */
.intro-inner { display: grid; grid-template-columns: 1fr 1fr; gap: 60px; align-items: center; }
.intro-content h2 { margin-bottom: 20px; }
.intro-content p { margin-bottom: 16px; font-size: 16px; line-height: 1.7; }
.intro-image { overflow: hidden; border-radius: var(--radius-lg); }
@media (max-width: 900px) { .intro-inner { grid-template-columns: 1fr; gap: 40px; } }

/* === Technical Advantages === */
.advantages-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 24px; }
.advantage-item { padding: 28px; background-color: var(--color-white); border-radius: var(--radius-md); border: 1px solid var(--color-border); }
.advantage-title { font-size: 16px; margin-bottom: 8px; }
.advantage-desc { font-size: 14px; color: var(--color-text-secondary); line-height: 1.6; }
@media (max-width: 768px) { .advantages-grid { grid-template-columns: 1fr; } }

/* === Inquiry Form === */
.inquiry-form { max-width: 600px; margin: 0 auto; background-color: var(--color-white); padding: 40px; border-radius: var(--radius-md); border: 1px solid var(--color-border); }
.form-group { margin-bottom: 24px; }
.form-label { display: block; font-size: 14px; font-weight: 500; color: var(--color-primary); margin-bottom: 8px; }
.form-input, .form-textarea, .form-select { width: 100%; padding: 14px 16px; font-size: 15px; border: 1px solid var(--color-border); border-radius: var(--radius-sm); background-color: var(--color-white); transition: var(--transition); }
.form-input:focus, .form-textarea:focus, .form-select:focus { outline: none; border-color: var(--color-accent); }
.form-textarea { min-height: 120px; resize: vertical; }
.form-submit { width: 100%; }

/* === Utility Classes === */
.text-center { text-align: center; }
.mt-20 { margin-top: 20px; }
.mb-20 { margin-bottom: 20px; }

/* === Animations === */
@keyframes fadeInUp { from { opacity: 0; transform: translateY(20px); } to { opacity: 1; transform: translateY(0); } }
.fade-in-up { animation: fadeInUp 0.6s ease forwards; }

/* === Mobile Section Padding === */
@media (max-width: 768px) {
  .section { padding: var(--section-padding-mobile) 0; }
  h1 { font-size: 36px; }
  h2 { font-size: 28px; }
}