:root {
  --brand-900: #0f2c37;
  --brand-700: #1f4e5f;
  --brand-600: #2a6478;
  --brand-500: #2f7f8f;
  --accent: #1f9d6f;
  --accent-dark: #167a56;
  --bg: #f6f9f9;
  --surface: #ffffff;
  --text: #16242a;
  --text-muted: #55707a;
  --border: #e1e8ea;
  --danger: #c0392b;
  --danger-bg: #fdecea;
  --success-bg: #e9f8f1;
  --radius: 10px;
  --shadow: 0 1px 2px rgba(15, 44, 55, 0.06), 0 6px 20px rgba(15, 44, 55, 0.06);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.55;
}
img, svg { max-width: 100%; display: block; }
a { color: var(--brand-500); }
a:hover { color: var(--accent-dark); }
.container { max-width: 1080px; margin: 0 auto; padding: 0 20px; }
.container-narrow { max-width: 760px; margin: 0 auto; padding: 0 20px; }

/* Header */
.site-header {
  background: var(--brand-900);
  color: #fff;
  position: sticky;
  top: 0;
  z-index: 40;
}
.site-header .container { display: flex; align-items: center; justify-content: space-between; height: 64px; gap: 16px; }
.brand { display: flex; align-items: center; gap: 10px; color: #fff; text-decoration: none; font-weight: 700; font-size: 1.08rem; white-space: nowrap; }
.brand-mark { width: 30px; height: 30px; border-radius: 8px; background: linear-gradient(135deg, var(--accent), var(--brand-500)); display: flex; align-items: center; justify-content: center; color: #fff; font-weight: 800; font-size: 0.95rem; }
nav.main-nav { display: flex; align-items: center; gap: 4px; flex-wrap: wrap; }
nav.main-nav a { color: #d7e6ea; text-decoration: none; font-size: 0.92rem; padding: 8px 10px; border-radius: 6px; }
nav.main-nav a:hover, nav.main-nav a.active { color: #fff; background: rgba(255,255,255,0.08); }
nav.main-nav details { position: relative; }
nav.main-nav summary { list-style: none; cursor: pointer; color: #d7e6ea; font-size: 0.92rem; padding: 8px 10px; border-radius: 6px; }
nav.main-nav summary::-webkit-details-marker { display: none; }
nav.main-nav details[open] summary, nav.main-nav summary:hover { color: #fff; background: rgba(255,255,255,0.08); }
nav.main-nav details .dropdown { position: absolute; right: 0; top: 40px; background: #fff; border-radius: 8px; box-shadow: var(--shadow); min-width: 230px; padding: 6px; }
nav.main-nav details .dropdown a { color: var(--text); display: block; padding: 9px 12px; border-radius: 6px; font-size: 0.9rem; }
nav.main-nav details .dropdown a:hover { background: var(--bg); }

/* Hero */
.hero { padding: 48px 0 32px; }
.hero h1 { font-size: clamp(1.7rem, 3.4vw, 2.5rem); margin: 0 0 12px; color: var(--brand-900); line-height: 1.2; }
.hero .lede { font-size: 1.1rem; color: var(--text-muted); max-width: 700px; margin: 0 0 8px; }
.breadcrumbs { font-size: 0.82rem; color: var(--text-muted); padding: 14px 0 0; }
.breadcrumbs a { color: var(--text-muted); text-decoration: none; }
.breadcrumbs a:hover { text-decoration: underline; }

/* Trust strip */
.trust-strip { display: flex; flex-wrap: wrap; gap: 10px 22px; margin: 18px 0 0; padding: 0; list-style: none; font-size: 0.86rem; color: var(--text-muted); }
.trust-strip li { display: flex; align-items: center; gap: 6px; }
.trust-strip li::before { content: "✓"; color: var(--accent); font-weight: 700; }

/* Converter widget */
.converter { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); box-shadow: var(--shadow); padding: 22px; margin: 20px 0 8px; }
.dropzone { border: 2px dashed #c3d6da; border-radius: var(--radius); padding: 34px 18px; text-align: center; cursor: pointer; transition: border-color .15s, background .15s; }
.dropzone:hover, .dropzone.dragover { border-color: var(--accent); background: var(--success-bg); }
.dropzone svg { margin: 0 auto 10px; width: 40px; height: 40px; color: var(--brand-500); }
.dropzone p { margin: 4px 0; }
.dropzone .hint { color: var(--text-muted); font-size: 0.82rem; }
.link-btn { background: none; border: none; color: var(--brand-500); text-decoration: underline; cursor: pointer; font: inherit; padding: 0; }
.file-chosen { font-weight: 600; color: var(--brand-900); }

.format-picker { display: flex; flex-wrap: wrap; align-items: center; gap: 8px 14px; margin: 16px 0; font-size: 0.92rem; }
.format-picker span:first-child { color: var(--text-muted); font-weight: 600; }
.format-picker label { display: inline-flex; align-items: center; gap: 6px; padding: 6px 10px; border: 1px solid var(--border); border-radius: 20px; cursor: pointer; }
.format-picker label:has(input:checked) { border-color: var(--accent); background: var(--success-bg); }

.btn-primary { display: inline-flex; align-items: center; justify-content: center; gap: 8px; background: var(--accent); color: #fff; border: none; padding: 12px 22px; border-radius: 8px; font-size: 1rem; font-weight: 700; cursor: pointer; text-decoration: none; }
.btn-primary:hover { background: var(--accent-dark); }
.btn-primary:disabled { background: #a9c3c9; cursor: not-allowed; }
.btn-secondary { display: inline-flex; align-items: center; gap: 8px; background: #fff; color: var(--brand-700); border: 1px solid var(--border); padding: 11px 20px; border-radius: 8px; font-weight: 600; text-decoration: none; }

.status { margin-top: 12px; font-size: 0.92rem; }
.status.error { color: var(--danger); background: var(--danger-bg); padding: 10px 12px; border-radius: 8px; }
.status.busy { color: var(--brand-700); }
.status.warn { color: #8a6d1a; background: #fdf6e3; padding: 10px 12px; border-radius: 8px; }

.result-panel { margin-top: 18px; border-top: 1px solid var(--border); padding-top: 18px; }
.result-panel .result-actions { display: flex; align-items: center; gap: 14px; flex-wrap: wrap; margin-top: 12px; }
.preview-table-wrap { overflow-x: auto; border: 1px solid var(--border); border-radius: 8px; }
table.preview-table { border-collapse: collapse; width: 100%; font-size: 0.85rem; white-space: nowrap; }
table.preview-table th, table.preview-table td { padding: 7px 10px; border-bottom: 1px solid var(--border); text-align: left; }
table.preview-table th { background: var(--brand-700); color: #fff; position: sticky; top: 0; }
table.preview-table tr:nth-child(even) td { background: #f8fafa; }
.preview-note { font-size: 0.8rem; color: var(--text-muted); margin-top: 8px; }

/* Content sections */
section.block { padding: 34px 0; }
section.block h2 { font-size: 1.5rem; color: var(--brand-900); margin: 0 0 14px; }
section.block h3 { font-size: 1.1rem; color: var(--brand-900); margin: 0 0 8px; }
.steps { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 18px; list-style: none; padding: 0; margin: 0; counter-reset: step; }
.steps li { counter-increment: step; background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 18px; }
.steps li::before { content: counter(step); display: inline-flex; align-items: center; justify-content: center; width: 28px; height: 28px; border-radius: 50%; background: var(--accent); color: #fff; font-weight: 700; font-size: 0.85rem; margin-bottom: 10px; }

.grid-2 { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 18px; }
.card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 18px; }

.faq { margin-top: 6px; }
.faq details { background: var(--surface); border: 1px solid var(--border); border-radius: 8px; padding: 4px 16px; margin-bottom: 10px; }
.faq summary { cursor: pointer; font-weight: 600; padding: 12px 0; list-style: none; display: flex; justify-content: space-between; gap: 10px; }
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after { content: "+"; color: var(--accent); font-weight: 700; font-size: 1.2rem; flex-shrink: 0; }
.faq details[open] summary::after { content: "\2212"; }
.faq p { margin: 0 0 14px; color: var(--text-muted); }

.callout { background: var(--success-bg); border: 1px solid #bfe6d3; border-radius: var(--radius); padding: 18px 20px; }
.callout.warn { background: #fdf6e3; border-color: #f0d98c; }

.tool-links { display: flex; flex-wrap: wrap; gap: 10px; }
.tool-links a { background: var(--surface); border: 1px solid var(--border); border-radius: 20px; padding: 8px 14px; text-decoration: none; color: var(--brand-700); font-size: 0.88rem; font-weight: 600; }
.tool-links a:hover { border-color: var(--accent); color: var(--accent-dark); }

/* CTA band */
.cta-band { background: var(--brand-900); color: #fff; padding: 44px 0; text-align: center; }
.cta-band h2 { color: #fff; margin-bottom: 10px; }
.cta-band p { color: #cfe3e8; margin-bottom: 20px; }

/* Footer */
.site-footer { background: var(--brand-900); color: #b9cdd3; padding: 40px 0 26px; margin-top: 40px; font-size: 0.88rem; }
.site-footer .footer-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(160px, 1fr)); gap: 22px; padding-bottom: 24px; }
.site-footer h4 { color: #fff; font-size: 0.85rem; text-transform: uppercase; letter-spacing: 0.04em; margin: 0 0 10px; }
.site-footer a { color: #b9cdd3; text-decoration: none; display: block; padding: 4px 0; }
.site-footer a:hover { color: #fff; }
.footer-bottom { border-top: 1px solid rgba(255,255,255,0.12); padding-top: 18px; display: flex; justify-content: space-between; flex-wrap: wrap; gap: 8px; font-size: 0.8rem; }

@media (max-width: 720px) {
  .site-header .container { height: auto; padding: 10px 16px; flex-wrap: wrap; }
  nav.main-nav { width: 100%; justify-content: flex-start; gap: 2px; }
  .hero { padding: 30px 0 20px; }
}