:root {
  --bg: #08111f;
  --bg-soft: #111d31;
  --panel: rgba(10, 18, 34, 0.82);
  --line: rgba(210, 228, 255, 0.14);
  --text: #f4f7fb;
  --muted: #a4b3cb;
  --accent: #8fd3ff;
  --glow: rgba(143, 211, 255, 0.28);
  --max-width: 1180px;
  --nav-height: 72px;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  color: var(--text);
  background:
    radial-gradient(circle at top, rgba(102, 186, 255, 0.16), transparent 28%),
    linear-gradient(180deg, #07101d 0%, #0c1728 42%, #08101d 100%);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
}

a {
  color: inherit;
  text-decoration: none;
}

main {
  position: relative;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  min-height: var(--nav-height);
  padding: 14px 24px;
  border-bottom: 1px solid var(--line);
  background: rgba(7, 16, 29, 0.76);
  backdrop-filter: blur(18px);
}

.brand {
  font-size: 1rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.site-nav {
  display: flex;
  flex-wrap: wrap;
  justify-content: flex-end;
  gap: 10px 18px;
  color: var(--muted);
}

.site-nav a {
  padding-bottom: 4px;
  border-bottom: 1px solid transparent;
  transition: color 160ms ease, text-shadow 160ms ease;
}

.site-nav a:hover,
.site-nav a:focus-visible {
  color: var(--text);
  text-shadow: 0 0 18px var(--glow);
  outline: none;
}

.tool-zone {
  min-height: 100vh;
  padding: calc(var(--nav-height) + 16px) 24px 32px;
}

.tool-frame {
  position: relative;
  width: min(100%, var(--max-width));
  height: calc(100vh - 160px);
  margin: 0 auto;
  border: 1px solid var(--line);
  border-radius: 24px;
  overflow: hidden;
  box-shadow: 0 24px 80px rgba(0, 0, 0, 0.38);
  background: var(--panel);
}

.tool-frame iframe {
  display: block;
  width: 100%;
  height: 100%;
  border: 0;
  background: #fff;
}

.iframe-fallback {
  width: min(100%, var(--max-width));
  margin: 0 auto;
}

.iframe-fallback[hidden] {
  display: none;
}

.iframe-fallback.is-visible {
  position: absolute;
  inset: 0;
  z-index: 2;
  display: grid;
  place-items: center;
  padding: 24px;
}

.iframe-fallback-card {
  width: min(100%, 640px);
  padding: 28px;
  border: 1px solid var(--line);
  border-radius: 20px;
  background: rgba(10, 18, 34, 0.92);
  box-shadow: 0 18px 48px rgba(0, 0, 0, 0.24);
}

.fallback-link {
  display: inline-flex;
  align-items: center;
  margin-top: 16px;
  padding: 10px 16px;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--text);
  background: rgba(255, 255, 255, 0.04);
}

.disclaimer {
  width: min(100%, var(--max-width));
  margin: 16px auto 0;
  color: var(--muted);
  font-size: 0.95rem;
  line-height: 1.6;
}

.content-section {
  padding: 88px 24px;
  scroll-margin-top: calc(var(--nav-height) + 24px);
}

.section-inner {
  width: min(100%, var(--max-width));
  margin: 0 auto;
  padding: 40px;
  border: 1px solid var(--line);
  border-radius: 28px;
  background: linear-gradient(180deg, rgba(16, 28, 48, 0.84), rgba(9, 16, 30, 0.9));
  box-shadow: 0 18px 64px rgba(0, 0, 0, 0.24);
}

.section-kicker {
  margin: 0 0 14px;
  color: var(--accent);
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.18em;
  text-transform: uppercase;
}

.section-inner h2 {
  margin: 0;
  font-size: clamp(1.8rem, 3vw, 2.75rem);
  line-height: 1.1;
}

.section-body,
.faq-list {
  margin-top: 18px;
  color: var(--muted);
  line-height: 1.7;
}

.section-body > ol,
.section-body > ul {
  padding-left: 1.4rem;
}

.how-to-list {
  display: grid;
  gap: 28px;
}

.how-to-list > li > h3 {
  margin-bottom: 10px;
  color: var(--text);
}

.how-to-figure {
  margin: 18px 0 0;
}

.how-to-figure img {
  display: block;
  width: min(100%, 920px);
  height: auto;
  border: 1px solid var(--line);
  border-radius: 18px;
  box-shadow: 0 18px 48px rgba(0, 0, 0, 0.24);
  background: rgba(255, 255, 255, 0.02);
}

.how-to-figure figcaption {
  margin-top: 10px;
  font-size: 0.94rem;
}

.faq-list {
  display: grid;
  gap: 12px;
}

.faq-trigger {
  width: 100%;
  padding: 16px 18px;
  border: 1px solid var(--line);
  border-radius: 16px;
  background: rgba(255, 255, 255, 0.03);
  color: var(--text);
  text-align: left;
  font: inherit;
}

.faq-panel {
  padding: 0 18px 8px;
  color: var(--muted);
}

.faq-trigger[aria-expanded='true'] + .faq-panel {
  display: block;
}

.site-footer {
  padding: 0 24px 32px;
}

.footer-inner {
  width: min(100%, var(--max-width));
  margin: 0 auto;
  padding-top: 16px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.92rem;
}

@media (max-width: 768px) {
  .topbar {
    align-items: flex-start;
    flex-direction: column;
    gap: 12px;
    padding: 16px 18px;
  }

  .site-nav {
    justify-content: flex-start;
  }

  .tool-zone {
    padding: calc(var(--nav-height) + 12px) 18px 24px;
  }

  .tool-frame {
    height: 62vh;
    border-radius: 18px;
  }

  .content-section {
    padding: 64px 18px;
    scroll-margin-top: calc(var(--nav-height) + 48px);
  }

  .section-inner {
    padding: 28px 20px;
    border-radius: 22px;
  }
}