* {
  box-sizing: border-box;
}

:root {
  --bg: #0f1117;
  --bg-soft: #171a23;
  --panel: #1c202b;
  --border: #2a2f3d;
  --text: #e8eaf0;
  --text-dim: #9aa2b5;
  --accent: #4f8cff;
  --accent-2: #8b5cf6;
  --ok: #34d399;
  --warn: #fbbf24;
  --danger: #f87171;
}

html {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Sans", "Noto Sans JP", sans-serif;
  color-scheme: dark;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-size: 15px;
  line-height: 1.7;
}

a {
  color: var(--accent);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

header.nav {
  position: sticky;
  top: 0;
  z-index: 50;
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 12px 24px;
  background: rgba(15, 17, 23, 0.92);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
}

header.nav .brand {
  font-weight: 700;
  font-size: 16px;
  display: flex;
  align-items: center;
  gap: 8px;
}

header.nav .brand .dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
}

header.nav nav {
  margin-left: auto;
  display: flex;
  gap: 16px;
  align-items: center;
}

main {
  max-width: 1100px;
  margin: 0 auto;
  padding: 24px;
}

.btn {
  display: inline-block;
  padding: 9px 18px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--panel);
  color: var(--text);
  font-size: 14px;
  cursor: pointer;
  transition: filter 0.15s, border-color 0.15s;
}

.btn:hover {
  border-color: var(--accent);
  filter: brightness(1.15);
}

.btn.primary {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  border: none;
  font-weight: 600;
}

.card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 18px;
}

.tag {
  display: inline-block;
  font-size: 12px;
  padding: 2px 10px;
  border-radius: 999px;
  border: 1px solid var(--border);
  color: var(--text-dim);
  background: var(--bg-soft);
}

code, pre {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}

pre {
  background: var(--bg-soft);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 14px;
  overflow-x: auto;
  font-size: 13px;
  line-height: 1.55;
}

.hero {
  text-align: center;
  padding: 64px 24px 40px;
}
.hero h1 {
  font-size: 40px;
  margin: 0 0 12px;
  letter-spacing: -0.02em;
}
.hero h1 .grad {
  background: linear-gradient(135deg, #4f8cff, #8b5cf6);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.hero p.lead {
  font-size: 17px;
  color: var(--text-dim);
  max-width: 640px;
  margin: 0 auto 28px;
}
.hero .cta {
  display: flex;
  gap: 12px;
  justify-content: center;
  flex-wrap: wrap;
}
.hero .badges {
  margin-top: 20px;
  display: flex;
  gap: 8px;
  justify-content: center;
  flex-wrap: wrap;
}

section.block {
  padding: 40px 0;
}
section.block h2 {
  font-size: 24px;
  margin: 0 0 20px;
}

.features {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 14px;
}
.features .card h3 {
  margin: 0 0 6px;
  font-size: 16px;
}
.features .card p {
  margin: 0;
  color: var(--text-dim);
  font-size: 13.5px;
}

.steps {
  counter-reset: step;
  display: flex;
  flex-direction: column;
  gap: 16px;
}
.steps .step {
  position: relative;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 20px 20px 20px 64px;
}
.steps .step::before {
  counter-increment: step;
  content: counter(step);
  position: absolute;
  left: 16px;
  top: 20px;
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
}
.steps .step h3 {
  margin: 0 0 8px;
  font-size: 17px;
}
.steps .step p {
  color: var(--text-dim);
  margin: 0 0 10px;
}

.tips {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 14px;
}

.faq details {
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 12px 16px;
  margin-bottom: 10px;
  background: var(--panel);
}
.faq summary {
  cursor: pointer;
  font-weight: 600;
}
.faq p {
  color: var(--text-dim);
  margin: 8px 0 0;
  font-size: 14px;
}

.note {
  border-left: 3px solid var(--warn);
  background: rgba(251, 191, 36, 0.08);
  padding: 12px 16px;
  border-radius: 0 8px 8px 0;
  font-size: 14px;
  color: var(--text-dim);
}

footer.nav {
  border-top: 1px solid var(--border);
  margin-top: 40px;
  padding: 20px 24px;
  color: var(--text-dim);
  font-size: 13px;
}