:root {
  --c-bg: #f7f7f7;
  --c-surface: #ffffff;
  --c-text: #222222;
  --c-muted: #666666;
  --c-border: #e5e7eb;

  /* Mure accent */
  --c-accent: #b43a4a;
  --c-accent-deep: #3b0a45;

  --shadow-soft: 0 8px 24px rgba(17, 24, 39, 0.04);

  --wrap: 1100px;
  --narrow: 820px;

  --header-height: 72px;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--c-bg);
  color: var(--c-text);
  font-family:
    -apple-system, BlinkMacSystemFont, "Segoe UI",
    "Hiragino Sans", "Hiragino Kaku Gothic ProN",
    "Noto Sans JP", Meiryo, sans-serif;
  line-height: 1.8;
  letter-spacing: 0.01em;
}

img {
  display: block;
  max-width: 100%;
}

a {
  color: inherit;
}

.wrap {
  width: min(calc(100% - 32px), var(--wrap));
  margin: 0 auto;
}

.wrap.narrow {
  width: min(calc(100% - 32px), var(--narrow));
}

/* header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  min-height: var(--header-height);
  background: rgba(247, 247, 247, 0.9);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--c-border);
}

.header-inner {
  min-height: var(--header-height);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
  color: var(--c-text);
  min-width: 0;
}

.brand img {
  width: auto;
  height: 28px;
  object-fit: contain;
}

.brand-name {
  font-size: 1.05rem;
  font-weight: 500;
  line-height: 1.2;
  white-space: nowrap;
}

.site-nav ul {
  display: flex;
  align-items: center;
  gap: 24px;
  list-style: none;
  margin: 0;
  padding: 0;
}

.site-nav a {
  text-decoration: none;
  color: var(--c-muted);
  font-size: 0.95rem;
  transition: color 0.2s ease;
}

.site-nav a:hover,
.site-nav a[aria-current="page"] {
  color: var(--c-accent-deep);
}

/* main common */
main {
  min-height: calc(100vh - 140px);
}

.page-hero {
  padding: 64px 0 12px;
}

.page-head h1 {
  margin: 0;
  font-size: clamp(2rem, 4vw, 3rem);
  line-height: 1.25;
  font-weight: 500;
}

.page-head p {
  margin: 16px 0 0;
  color: var(--c-muted);
  font-size: 1rem;
}

.page-section {
  padding: 24px 0 72px;
}

.stack {
  display: grid;
  gap: 24px;
}

/* card */
.card {
  background: var(--c-surface);
  border: 1px solid var(--c-border);
  border-radius: 20px;
  padding: 28px 28px 24px;
  box-shadow: var(--shadow-soft);
}

.card p:last-child,
.card ul:last-child {
  margin-bottom: 0;
}

/* title with accent */
.section-title {
  position: relative;
  margin: 0 0 16px;
  padding-left: 14px;
  font-size: 1.25rem;
  line-height: 1.5;
  font-weight: 600;
}

.section-title::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.32em;
  width: 4px;
  height: 0.95em;
  border-radius: 999px;
  background: linear-gradient(180deg, var(--c-accent), var(--c-accent-deep));
}

.list {
  margin: 0;
  padding-left: 1.2em;
}

.list li {
  margin-bottom: 6px;
}

.note {
  margin-top: 16px;
  color: var(--c-muted);
  font-size: 0.95rem;
}

.muted {
  color: var(--c-muted);
}

/* text link */
a:not(.brand):not(.button) {
  color: var(--c-accent-deep);
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
  transition: color 0.2s ease;
}

a:not(.brand):not(.button):hover {
  color: var(--c-accent);
}

/* button if needed later */
.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 0 16px;
  border-radius: 999px;
  border: 1px solid var(--c-border);
  background: var(--c-surface);
  color: var(--c-text);
  text-decoration: none;
  transition:
    background 0.2s ease,
    color 0.2s ease,
    border-color 0.2s ease;
}

.button:hover {
  border-color: var(--c-accent);
  color: var(--c-accent-deep);
}

.button.primary {
  background: var(--c-accent-deep);
  border-color: var(--c-accent-deep);
  color: #ffffff;
}

.button.primary:hover {
  background: var(--c-accent);
  border-color: var(--c-accent);
  color: #ffffff;
}

/* footer */
.site-footer {
  padding: 28px 0 36px;
  border-top: 1px solid var(--c-border);
}

.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
  color: #8a8a8a;
  font-size: 0.9rem;
}

.footer-inner small {
  font-size: inherit;
}

/* utility sections for simple pages */
.plain-section {
  padding-top: 48px;
  margin-top: 48px;
  border-top: 1px solid var(--c-border);
}

.plain-section:first-child {
  border-top: none;
  padding-top: 0;
  margin-top: 0;
}

.plain-title {
  position: relative;
  margin: 0 0 16px;
  padding-left: 14px;
  font-size: 1.5rem;
  line-height: 1.4;
  font-weight: 500;
}

.plain-title::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.25em;
  width: 4px;
  height: 0.95em;
  border-radius: 999px;
  background: linear-gradient(180deg, var(--c-accent), var(--c-accent-deep));
}

/* responsive */
@media (max-width: 720px) {
  .wrap,
  .wrap.narrow {
    width: min(calc(100% - 24px), var(--wrap));
  }

  .header-inner {
    min-height: auto;
    padding: 14px 0;
    align-items: flex-start;
    flex-direction: column;
  }

  .site-nav ul {
    gap: 16px;
    flex-wrap: wrap;
  }

  .page-hero {
    padding-top: 44px;
  }

  .page-head h1 {
    font-size: 2rem;
  }

  .card {
    padding: 22px 18px 20px;
    border-radius: 16px;
  }

  .footer-inner {
    flex-direction: column;
    align-items: flex-start;
  }
}