:root {
  --primary-color: #005A9C;
  --accent-color: #F4A300;
  --ink: #1F2937;
  --text-color: var(--ink);
  --bg-light: #F5F7FA;
  --max-width: 1200px;
  --spacing: 1.5rem;
  --radius: 8px;
}

* { box-sizing: border-box; margin: 0; padding: 0; font-family: 'Roboto', sans-serif; color: var(--text-color); }
html { scroll-behavior: smooth; }
section { scroll-margin-top: 80px; padding: clamp(4rem, 6vw, 6rem) 0; }
body { background: #fff; line-height: 1.6; }

.container { width: 90%; max-width: var(--max-width); margin: 0 auto; }

header { background: #fff; border-bottom: 1px solid rgba(0,0,0,.06); position: sticky; top: 0; z-index: 10; }
.header-inner { display: flex; align-items: center; justify-content: space-between; padding: var(--spacing) 0; }
.logo { height: 54px; width: auto; object-fit: contain; display: block; }

.brand { display:flex; align-items:center; gap:0.75rem; }
.brand-text { display:flex; flex-direction:column; line-height:1.1; }
.brand-name { font-weight:700; color: var(--primary-color); }
.brand-rc { font-size:.82rem; color:#666; margin-top:2px; }

nav ul { display: flex; list-style: none; }
nav li + li { margin-left: var(--spacing); }
nav a { text-decoration: none; font-weight:700; color: var(--primary-color); }

.hero { background: linear-gradient(180deg, rgba(0,90,156,.08), rgba(244,163,0,.06)); border-bottom: 1px solid rgba(0,0,0,.06); text-align: center; }
.hero .btn { margin-top: var(--spacing); box-shadow: 0 10px 24px rgba(0,90,156,.15); }
.btn:hover { transform: translateY(-1px); }
.btn { transition: background .3s, transform .2s, box-shadow .3s; }
.hero-image-wrapper { text-align: center; margin-top: 2rem; border-radius: var(--radius); overflow: hidden; box-shadow: 0 10px 30px rgba(0,0,0,0.15); aspect-ratio: 16 / 9; }
.gas-plant-image { width: 100%; height: 100%; object-fit: cover; }

.about { background: var(--bg-light); }
.about h2 { text-align: center; margin-bottom: var(--spacing); color: var(--primary-color); position: relative; display: inline-block; left: 50%; transform: translateX(-50%); padding-bottom: .4rem; }
.about h2::after { content:""; position:absolute; left:0; right:0; bottom:0; height:3px; background: linear-gradient(90deg, var(--primary-color), var(--accent-color)); border-radius: 2px; }

.services h2 { text-align: center; margin-bottom: var(--spacing); color: var(--primary-color); position: relative; display: inline-block; left: 50%; transform: translateX(-50%); padding-bottom: .4rem; }
.services h2::after { content:""; position:absolute; left:0; right:0; bottom:0; height:3px; background: linear-gradient(90deg, var(--primary-color), var(--accent-color)); border-radius: 2px; }

.service-groups { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: var(--spacing); margin-top: var(--spacing); }
.service-group { background: #fff; border: 1px solid rgba(0,0,0,.06); border-radius: var(--radius); box-shadow: 0 8px 24px rgba(0,0,0,.08); padding: var(--spacing); transition: transform .18s ease, box-shadow .18s ease; }
.service-group:hover { transform: translateY(-4px); box-shadow: 0 14px 34px rgba(0,0,0,.12); }
.service-group h3 { color: var(--primary-color); margin-bottom: 0.75rem; font-size: 1.05rem; }
.service-group ul { list-style: disc; padding-left: 1.25rem; }
.service-group li { margin-bottom: .5rem; line-height: 1.45; }

.contact form { max-width: 600px; margin: 0 auto; }
.form-group { margin-bottom: var(--spacing); }
.form-group label { display: block; margin-bottom: 0.5rem; }
.form-group input, .form-group textarea { width: 100%; padding: 0.75rem; border: 1px solid #ccc; border-radius: 6px; }

.btn { display: inline-block; padding: 0.75rem 1.5rem; background: var(--accent-color); color: white; text-decoration: none; font-weight: 700; border-radius: 6px; transition: background 0.3s; }
.btn:hover { background: var(--primary-color); }

.back-to-top { position: fixed; right: 20px; bottom: 20px; width: 44px; height: 44px; display: grid; place-items: center; text-decoration: none; border-radius: 999px; background: var(--primary-color); color: #fff; font-weight: 700; box-shadow: 0 6px 18px rgba(0,0,0,0.2); transition: opacity .25s, transform .25s, background .3s; opacity: 0; pointer-events: none; transform: translateY(6px); z-index: 20; }
.back-to-top:hover { background: var(--accent-color); }
.back-to-top.show { opacity: 1; pointer-events: auto; transform: translateY(0); }

.site-footer { background:#0a2540; color:#fff; padding:1.25rem 0; text-align:center; }
.site-footer a { color:#fff; opacity:.9; }