:root {
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --accent: #16a34a;
  --accent-dark: #15803d;
  --text: #1f2937;
  --muted: #6b7280;
  --bg-alt: #f8fafc;
  --border: #e5e7eb;
  --radius: 10px;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  color: var(--text);
  background: #fff;
  line-height: 1.6;
}

.wrap { max-width: 1100px; margin: 0 auto; padding: 0 20px; }

a { color: var(--primary); text-decoration: none; }
a:hover { text-decoration: underline; }

h1, h2, h3 { line-height: 1.25; margin-top: 0; }

/* Header */
.site-header { border-bottom: 1px solid var(--border); position: sticky; top: 0; background: #fff; z-index: 50; }
.header-inner { display: flex; align-items: center; justify-content: space-between; padding: 14px 20px; }
.logo { font-size: 20px; font-weight: 800; color: var(--text); }
.logo span { color: var(--primary); }
.main-nav a { margin-left: 22px; color: var(--text); font-weight: 500; font-size: 15px; }
.main-nav a:hover { color: var(--primary); text-decoration: none; }
.nav-toggle { display: none; background: none; border: none; font-size: 22px; cursor: pointer; }

@media (max-width: 780px) {
  .main-nav { display: none; flex-direction: column; position: absolute; top: 60px; left: 0; right: 0; background: #fff; border-bottom: 1px solid var(--border); padding: 10px 20px; }
  .main-nav.open { display: flex; }
  .main-nav a { margin: 8px 0; }
  .nav-toggle { display: block; }
}

/* Hero */
.hero { padding: 48px 0 20px; text-align: center; }
.hero h1 { font-size: 34px; max-width: 780px; margin: 0 auto 14px; }
.hero-sub { color: var(--muted); max-width: 620px; margin: 0 auto; font-size: 17px; }

@media (max-width: 600px) {
  .hero h1 { font-size: 26px; }
}

/* Tool box */
.tool-box { padding: 30px 0 50px; }
.drop-zone {
  border: 2px dashed #cbd5e1;
  border-radius: var(--radius);
  background: var(--bg-alt);
  padding: 40px 20px;
  text-align: center;
  cursor: pointer;
  transition: border-color .15s ease, background .15s ease;
}
.drop-zone.dragover { border-color: var(--primary); background: #eff6ff; }
.drop-title { font-weight: 600; font-size: 17px; margin: 0 0 4px; }
.drop-sub { color: var(--muted); margin: 6px 0; }
.drop-hint { color: var(--muted); font-size: 13px; margin-top: 10px; }
.preview-img { max-width: 100%; max-height: 320px; border-radius: 8px; margin: 0 auto; display: block; }

.controls { display: flex; flex-wrap: wrap; align-items: center; gap: 12px; margin-top: 18px; }
.controls label { font-weight: 600; font-size: 14px; }
.controls input[type=number], .controls select {
  padding: 9px 12px; border: 1px solid var(--border); border-radius: 8px; font-size: 15px; width: 130px;
}
.controls select { width: 150px; }

.btn {
  display: inline-block;
  padding: 11px 22px;
  border-radius: 8px;
  border: none;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  text-decoration: none;
}
.btn:hover { text-decoration: none; }
.btn-primary { background: var(--primary); color: #fff; }
.btn-primary:hover { background: var(--primary-dark); }
.btn-accent { background: var(--accent); color: #fff; }
.btn-accent:hover { background: var(--accent-dark); }
.btn-ghost { background: transparent; color: var(--text); border: 1px solid var(--border); margin-left: 10px; }

.privacy-note { font-size: 13px; color: var(--muted); margin-top: 14px; }

.result-box { margin-top: 24px; padding: 22px; border-radius: var(--radius); background: #f0fdf4; border: 1px solid #bbf7d0; }
.error-box { margin-top: 20px; padding: 16px; border-radius: 8px; background: #fef2f2; border: 1px solid #fecaca; color: #b91c1c; }

/* Sections */
.section { padding: 46px 0; }
.section.alt { background: var(--bg-alt); }
.section h2 { text-align: center; font-size: 26px; margin-bottom: 30px; }

.steps-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.step { text-align: center; padding: 20px; }
.step-num { width: 36px; height: 36px; border-radius: 50%; background: var(--primary); color: #fff; display: flex; align-items: center; justify-content: center; font-weight: 700; margin: 0 auto 14px; }

@media (max-width: 780px) {
  .steps-grid { grid-template-columns: 1fr; }
}

.link-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; }
.link-card { display: block; background: #fff; border: 1px solid var(--border); border-radius: 8px; padding: 16px; text-align: center; font-weight: 600; color: var(--text); }
.link-card:hover { border-color: var(--primary); color: var(--primary); text-decoration: none; }

@media (max-width: 780px) {
  .link-grid { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 480px) {
  .link-grid { grid-template-columns: 1fr; }
}

.faq { max-width: 760px; margin: 0 auto; }
.faq details { border-bottom: 1px solid var(--border); padding: 14px 0; }
.faq summary { font-weight: 600; cursor: pointer; }
.faq p { color: var(--muted); margin: 10px 0 0; }

/* Static content pages */
.content-page { padding: 40px 0 60px; max-width: 780px; margin: 0 auto; }
.content-page h1 { font-size: 30px; }
.content-page h2 { font-size: 21px; margin-top: 30px; }

/* Footer */
.site-footer { background: #0f172a; color: #cbd5e1; padding: 46px 0 24px; margin-top: 20px; }
.site-footer h4 { color: #fff; margin-bottom: 12px; font-size: 15px; }
.site-footer p { color: #94a3b8; font-size: 14px; }
.footer-cols { display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 24px; }
.footer-links { list-style: none; padding: 0; margin: 0; }
.footer-links li { margin-bottom: 8px; }
.footer-links a { color: #cbd5e1; font-size: 14px; }
.footer-links a:hover { color: #fff; }
.copyright { text-align: center; color: #64748b; font-size: 13px; margin-top: 30px; border-top: 1px solid #1e293b; padding-top: 20px; }

@media (max-width: 780px) {
  .footer-cols { grid-template-columns: 1fr 1fr; }
}