/* Guangtuo FRP Pultrusion — main.css
   Mobile-first. Charcoal + metallic gray + amber accent. Linear "drawn" motifs. */

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", Roboto, Helvetica, Arial, sans-serif;
  background: var(--gtc-bg, #f4f5f6);
  color: var(--gtc-ink, #22262b);
  line-height: 1.7;
  font-size: 16px;
}
img { max-width: 100%; height: auto; display: block; }
a { color: var(--gtc-accent-dark, #b45309); text-decoration: none; }
a:hover { text-decoration: underline; }
h1, h2, h3, h4 { line-height: 1.3; color: var(--gtc-charcoal, #1f2328); font-weight: 700; }

.container { width: 100%; max-width: var(--gtc-max, 1200px); margin: 0 auto; padding: 0 16px; }

/* ---------- Top bar ---------- */
.gtc-topbar { background: var(--gtc-charcoal, #1f2328); color: #cfd3d7; font-size: 13px; }
.gtc-topbar .container { display: flex; flex-wrap: wrap; gap: 8px 20px; padding-top: 8px; padding-bottom: 8px; }
.gtc-topbar a { color: #cfd3d7; }

/* ---------- Header ---------- */
.gtc-header { background: var(--gtc-surface, #fff); border-bottom: 1px solid var(--gtc-line, #d8dbde); }
.gtc-header .container { display: flex; align-items: center; justify-content: space-between; gap: 16px; padding-top: 14px; padding-bottom: 14px; }
.gtc-logo { font-size: 20px; font-weight: 800; letter-spacing: .5px; color: var(--gtc-charcoal, #1f2328); }
.gtc-logo span { color: var(--gtc-accent, #d97706); }
.gtc-logo-tag { display: block; font-size: 11px; font-weight: 400; color: var(--gtc-ink-soft, #4a5158); letter-spacing: 2px; text-transform: uppercase; }

.gtc-nav-toggle { background: none; border: 1px solid var(--gtc-line, #d8dbde); border-radius: var(--gtc-radius, 6px); padding: 8px 12px; cursor: pointer; font-size: 16px; }
.gtc-nav { display: none; }
.gtc-nav.is-open { display: block; position: absolute; left: 0; right: 0; top: 100%; background: #fff; border-bottom: 1px solid var(--gtc-line, #d8dbde); z-index: 90; }
.gtc-header { position: relative; }
.gtc-nav ul { list-style: none; margin: 0; padding: 0; }
.gtc-nav a { display: block; padding: 12px 16px; color: var(--gtc-ink, #22262b); border-top: 1px solid var(--gtc-line, #d8dbde); }
.gtc-nav a:hover, .gtc-nav .current-menu-item > a { color: var(--gtc-accent-dark, #b45309); text-decoration: none; }

/* ---------- Buttons ---------- */
.gtc-btn { display: inline-block; padding: 12px 22px; border-radius: var(--gtc-radius, 6px); font-weight: 600; cursor: pointer; border: 2px solid transparent; }
.gtc-btn-primary { background: var(--gtc-accent, #d97706); color: #fff; }
.gtc-btn-primary:hover { background: var(--gtc-accent-dark, #b45309); text-decoration: none; }
.gtc-btn-ghost { background: transparent; color: #fff; border-color: rgba(255,255,255,.6); }
.gtc-btn-ghost:hover { border-color: #fff; text-decoration: none; }

/* ---------- Hero ---------- */
.gtc-hero { background: linear-gradient(135deg, #1f2328 0%, #3a4048 100%); color: #e9ebee; padding: 56px 0; position: relative; overflow: hidden; }
.gtc-hero::after { content: ""; position: absolute; right: -40px; top: 0; bottom: 0; width: 40%; opacity: .12;
  background: repeating-linear-gradient(90deg, #fff 0 2px, transparent 2px 26px); }
.gtc-hero h1 { color: #fff; font-size: 30px; margin: 0 0 14px; }
.gtc-hero p { font-size: 17px; color: #c7ccd1; max-width: 640px; }
.gtc-hero .gtc-cta-row { margin-top: 26px; display: flex; flex-wrap: wrap; gap: 12px; }

/* ---------- Sections ---------- */
.gtc-section { padding: 48px 0; }
.gtc-section.alt { background: var(--gtc-surface, #fff); }
.gtc-section-head { text-align: center; margin-bottom: 32px; }
.gtc-section-head h2 { font-size: 26px; margin: 0 0 8px; }
.gtc-section-head p { color: var(--gtc-ink-soft, #4a5158); margin: 0; }
.gtc-rule { width: 56px; height: 3px; background: var(--gtc-accent, #d97706); margin: 12px auto 0; }

/* ---------- Card grid ---------- */
.gtc-grid { display: grid; gap: 20px; grid-template-columns: 1fr; }
.gtc-card { background: var(--gtc-surface, #fff); border: 1px solid var(--gtc-line, #d8dbde); border-top: 3px solid var(--gtc-accent, #d97706); border-radius: var(--gtc-radius, 6px); padding: 22px; }
.gtc-card h3 { margin-top: 0; font-size: 18px; }
.gtc-card p { color: var(--gtc-ink-soft, #4a5158); font-size: 15px; margin-bottom: 0; }

/* ---------- Process steps ---------- */
.gtc-steps { counter-reset: step; display: grid; gap: 16px; grid-template-columns: 1fr; }
.gtc-step { background: #fff; border: 1px solid var(--gtc-line, #d8dbde); border-radius: var(--gtc-radius, 6px); padding: 18px 18px 18px 64px; position: relative; }
.gtc-step::before { counter-increment: step; content: counter(step); position: absolute; left: 16px; top: 18px; width: 34px; height: 34px; line-height: 34px; text-align: center; border-radius: 50%; background: var(--gtc-charcoal, #1f2328); color: #fff; font-weight: 700; }
.gtc-step h4 { margin: 0 0 6px; font-size: 16px; }
.gtc-step p { margin: 0; font-size: 14px; color: var(--gtc-ink-soft, #4a5158); }

/* ---------- Tables ---------- */
.gtc-table-wrap { overflow-x: auto; }
table.gtc-table { width: 100%; border-collapse: collapse; background: #fff; font-size: 14px; }
table.gtc-table th, table.gtc-table td { border: 1px solid var(--gtc-line, #d8dbde); padding: 10px 12px; text-align: left; }
table.gtc-table thead th { background: var(--gtc-charcoal, #1f2328); color: #fff; }
table.gtc-table tbody tr:nth-child(even) { background: #f6f7f8; }

/* ---------- Breadcrumb ---------- */
.gtc-breadcrumb { font-size: 13px; color: var(--gtc-ink-soft, #4a5158); padding: 16px 0 0; }
.gtc-breadcrumb a { color: var(--gtc-ink-soft, #4a5158); }

/* ---------- FAQ ---------- */
.gtc-faq-item { background: #fff; border: 1px solid var(--gtc-line, #d8dbde); border-radius: var(--gtc-radius, 6px); margin-bottom: 12px; }
.gtc-faq-item summary { cursor: pointer; padding: 14px 16px; font-weight: 600; list-style: none; }
.gtc-faq-item summary::-webkit-details-marker { display: none; }
.gtc-faq-item summary::before { content: "+ "; color: var(--gtc-accent, #d97706); font-weight: 800; }
.gtc-faq-item[open] summary::before { content: "– "; }
.gtc-faq-item .gtc-faq-body { padding: 0 16px 14px; color: var(--gtc-ink-soft, #4a5158); }

/* ---------- Forms ---------- */
.gtc-form label { display: block; font-weight: 600; margin: 14px 0 6px; font-size: 14px; }
.gtc-form input, .gtc-form textarea, .gtc-form select { width: 100%; padding: 10px 12px; border: 1px solid var(--gtc-line, #d8dbde); border-radius: var(--gtc-radius, 6px); font-size: 15px; background: #fff; }
.gtc-form textarea { min-height: 120px; }
.gtc-form .gtc-btn { margin-top: 16px; }

/* ---------- Content / layout ---------- */
.gtc-content { padding: 32px 0 56px; }
.gtc-content article { background: #fff; border: 1px solid var(--gtc-line, #d8dbde); border-radius: var(--gtc-radius, 6px); padding: 24px; }
.gtc-post-list article { margin-bottom: 20px; }
.gtc-post-meta { font-size: 13px; color: var(--gtc-ink-soft, #4a5158); }

/* ---------- CTA band ---------- */
.gtc-cta-band { background: var(--gtc-charcoal, #1f2328); color: #fff; padding: 40px 0; text-align: center; }
.gtc-cta-band h2 { color: #fff; margin-top: 0; }

/* ---------- Footer ---------- */
.gtc-footer { background: #16191d; color: #9aa1a9; font-size: 14px; padding: 40px 0 20px; margin-top: 0; }
.gtc-footer h4 { color: #e9ebee; font-size: 15px; }
.gtc-footer a { color: #c7ccd1; }
.gtc-footer .container { display: grid; gap: 24px; grid-template-columns: 1fr; }
.gtc-footer-bottom { border-top: 1px solid #2c3138; margin-top: 24px; padding-top: 16px; font-size: 12px; }

.gtc-placeholder { background: #eef0f2; border: 1px dashed #9aa1a9; color: #5b6269; padding: 18px; border-radius: var(--gtc-radius, 6px); font-size: 14px; text-align: center; }

/* ---------- Responsive: >= 720px ---------- */
@media (min-width: 720px) {
  .gtc-grid { grid-template-columns: repeat(2, 1fr); }
  .gtc-steps { grid-template-columns: repeat(2, 1fr); }
  .gtc-footer .container { grid-template-columns: repeat(2, 1fr); }
  .gtc-hero h1 { font-size: 40px; }
  .gtc-nav-toggle { display: none; }
  .gtc-nav { display: block; position: static; }
  .gtc-nav ul { display: flex; gap: 4px; }
  .gtc-nav a { border-top: none; padding: 8px 12px; }
}

/* ---------- Responsive: >= 1024px ---------- */
@media (min-width: 1024px) {
  .gtc-grid { grid-template-columns: repeat(3, 1fr); }
  .gtc-steps { grid-template-columns: repeat(3, 1fr); }
  .gtc-footer .container { grid-template-columns: repeat(4, 1fr); }
  .gtc-section { padding: 64px 0; }
}