:root {
  --bg: #15121f;
  --panel: #1a1628;
  --panel2: #1e1a2e;
  --violet: #7c4dff;
  --pink: #ff6b9d;
  --mint: #18c2a6;
  --amber: #ff9f1c;
  --ink: #ede9f5;
  --dim: #8a80a6;
  --round: "M PLUS Rounded 1c", sans-serif;
  --gothic: "Zen Kaku Gothic New", sans-serif;
}
* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; overflow-x: hidden; }
body {
  background: var(--bg);
  color: var(--ink);
  font-family: var(--gothic);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}
a { color: inherit; text-decoration: none; }
.wrap { max-width: 1040px; margin: 0 auto; padding: 0 20px; }
h1, h2, h3, .logo { font-family: var(--round); }

/* nav */
nav {
  position: sticky; top: 0; z-index: 20;
  backdrop-filter: blur(12px);
  background: rgba(21, 18, 31, 0.72);
  border-bottom: 1px solid rgba(255, 255, 255, 0.06);
}
nav .wrap { display: flex; align-items: center; justify-content: space-between; height: 60px; }
.logo { display: inline-flex; align-items: center; gap: 8px;
  font-weight: 800; font-size: 22px; letter-spacing: 0.04em; }
.logo img { width: 26px; height: 26px; flex: none; }
.logo span { background: linear-gradient(90deg, var(--violet), var(--pink));
  -webkit-background-clip: text; background-clip: text; color: transparent; }
.nav-links { display: flex; gap: 22px; align-items: center; font-size: 14px; color: var(--dim); }
.nav-links a:hover { color: var(--ink); }

.btn {
  display: inline-block; font-family: var(--round); font-weight: 700;
  border-radius: 999px; padding: 11px 22px; cursor: pointer; transition: transform 0.12s ease, filter 0.12s ease;
}
.btn:hover { transform: translateY(-1px); filter: brightness(1.08); }
.btn-primary { background: linear-gradient(90deg, var(--violet), var(--pink)); color: #fff; }
.btn-ghost { border: 1px solid rgba(255, 255, 255, 0.18); color: var(--ink); }

/* article */
.article-wrap { max-width: 720px; margin: 0 auto; padding: 56px 20px 80px; }
.breadcrumb { font-size: 13px; color: var(--dim); margin-bottom: 24px; }
.breadcrumb a:hover { color: var(--ink); }
.eyebrow { color: var(--pink); font-family: var(--round); font-weight: 700; font-size: 13px; letter-spacing: 0.08em; }
article h1 { font-size: clamp(28px, 5vw, 40px); font-weight: 800; line-height: 1.35; margin: 10px 0 16px; }
.lede { color: var(--dim); font-size: 16.5px; margin-bottom: 40px; }
article h2 { font-size: clamp(20px, 3vw, 25px); font-weight: 800; margin: 48px 0 16px; }
article h3 { font-size: 17px; font-weight: 700; margin: 24px 0 8px; color: var(--ink); }
article p { margin-bottom: 16px; font-size: 15.5px; }
article ul, article ol { padding-left: 1.4em; margin: 0 0 16px; display: grid; gap: 8px; }
article li { font-size: 15.5px; }
article strong { color: #fff; }
article a:not(.btn) { color: var(--mint); text-decoration: underline; text-underline-offset: 2px; }
article a:not(.btn):hover { color: var(--ink); }

.callout {
  background: var(--panel); border: 1px solid rgba(255, 255, 255, 0.08); border-radius: 16px;
  padding: 18px 22px; margin: 24px 0; font-size: 14.5px; color: var(--dim);
}
.callout strong { color: var(--amber); }

.chat-demo { margin: 20px 0 24px; display: flex; flex-direction: column; gap: 8px; }
.bubble { max-width: 78%; padding: 10px 14px; border-radius: 14px; font-size: 14px; }
.bubble.me { align-self: flex-end; background: linear-gradient(90deg, var(--violet), var(--pink)); color: #fff; border-bottom-right-radius: 4px; }
.bubble.ai { align-self: flex-start; background: var(--panel); border: 1px solid rgba(255,255,255,0.08); border-bottom-left-radius: 4px; }

/* cta band (index.htmlと共通デザイン) */
.cta-band { text-align: center; background: linear-gradient(135deg, rgba(124,77,255,0.18), rgba(255,107,157,0.18));
  border: 1px solid rgba(255, 255, 255, 0.08); border-radius: 28px; padding: 56px 24px; margin: 56px 0 0; }
.cta-band h2 { margin-top: 0; font-size: clamp(22px, 4vw, 30px); }
.cta-band p { color: var(--dim); margin: 12px 0 28px; }

/* footer（index.htmlと共通デザイン） */
footer.site-footer { border-top: 1px solid rgba(255, 255, 255, 0.06); margin-top: 72px; padding: 40px 0; color: var(--dim); font-size: 13.5px; }
footer.site-footer .wrap { display: flex; flex-wrap: wrap; gap: 18px; justify-content: space-between; align-items: center; }
footer.site-footer a:hover { color: var(--ink); }
.footer-brand { display: flex; align-items: center; }
.foot-links { display: flex; gap: 18px; flex-wrap: wrap; align-items: center; }