*,
*::before,
*::after {
  box-sizing: border-box;
}
html,
body {
  margin: 0;
  padding: 0;
}
html {
  font-family:
    "Noto Sans JP",
    -apple-system,
    BlinkMacSystemFont,
    "Segoe UI",
    sans-serif;
  -webkit-font-smoothing: antialiased;
  color: #0f172a;
  font-feature-settings:
    "tnum" 1,
    "lnum" 1;
}
body {
  min-height: 100vh;
  background: linear-gradient(180deg, #fff7ed 0%, #ffffff 280px, #ffffff 100%);
}
.container {
  max-width: 720px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* ナビゲーション（全ページ共通） */
nav.site-nav {
  position: relative;
  z-index: 1;
  padding: 1.25rem 0 0;
}
nav.site-nav ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  gap: 1.25rem;
  font-size: 0.8125rem;
}
nav.site-nav a {
  color: #475569;
  text-decoration: none;
  transition: color 150ms;
}
nav.site-nav a:hover {
  color: #0369a1;
}
nav.site-nav a.active {
  color: #0f172a;
  font-weight: 600;
}

/* ヒーロー（トップページのみで使用） */
header.hero {
  position: relative;
  overflow: hidden;
  padding: 3rem 0 3rem;
}
header.hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(
    135deg,
    #fff7ed 0%,
    #fed7aa 35%,
    #fdba74 60%,
    #7dd3fc 100%
  );
  opacity: 0.5;
  z-index: -1;
}

/* 小ヘッダー（下層ページ用） */
header.page {
  padding: 2rem 0 1rem;
}
header.page h1 {
  font-size: 1.75rem;
  margin: 0.75rem 0 0;
}

h1 {
  font-size: 2.5rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin: 0;
}
.tagline {
  margin: 0.5rem 0 0;
  font-size: 0.875rem;
  color: rgba(51, 65, 85, 0.9);
}
.intro {
  max-width: 32rem;
  margin: 1.5rem 0 0;
  font-size: 0.875rem;
  line-height: 1.7;
  color: #475569;
}
.byline {
  margin: 1.25rem 0 0;
  font-size: 0.8125rem;
  color: #64748b;
}
.byline a {
  color: #0284c7;
  text-decoration: none;
  border-bottom: 1px dotted rgba(2, 132, 199, 0.6);
  padding-bottom: 1px;
  transition:
    color 150ms,
    border-bottom-color 150ms;
}
.byline a:hover {
  color: #075985;
  border-bottom-color: #075985;
}
.byline .ext {
  font-size: 0.625rem;
  color: #94a3b8;
  margin-left: 0.2em;
  vertical-align: super;
}
.feedback {
  margin: 0.4rem 0 0;
  font-size: 0.75rem;
  color: #94a3b8;
}
.feedback a {
  color: #64748b;
  text-decoration: none;
  border-bottom: 1px dotted rgba(100, 116, 139, 0.5);
  padding-bottom: 1px;
  transition:
    color 150ms,
    border-bottom-color 150ms;
}
.feedback a:hover {
  color: #0369a1;
  border-bottom-color: #0369a1;
}

main {
  padding: 2.5rem 0 4rem;
}
main > .container > section {
  margin-bottom: 2.75rem;
}
main > .container > section:last-child {
  margin-bottom: 0;
}

section h2 {
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: #64748b;
  margin: 0 0 1rem;
}

/* 本文用スタイル（下層ページの読み物セクション） */
.prose h3 {
  font-size: 1.0625rem;
  font-weight: 600;
  margin: 1.75rem 0 0.5rem;
  color: #0f172a;
}
.prose h3:first-child {
  margin-top: 0;
}
.prose p,
.prose li {
  font-size: 0.9375rem;
  line-height: 1.8;
  color: #334155;
  margin: 0 0 1em;
}
.prose ul,
.prose ol {
  padding-left: 1.4em;
  margin: 0 0 1em;
}
.prose li {
  margin-bottom: 0.25em;
}
.prose a {
  color: #0284c7;
  text-decoration: underline;
  text-underline-offset: 2px;
  text-decoration-color: rgba(2, 132, 199, 0.4);
}
.prose a:hover {
  text-decoration-color: #0284c7;
}
.prose code {
  font-family:
    "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
  font-size: 0.875em;
  background: #f1f5f9;
  padding: 0.1em 0.35em;
  border-radius: 0.25rem;
}
.prose .meta {
  font-size: 0.75rem;
  color: #94a3b8;
  margin: -0.5rem 0 1.5rem;
}

.projects {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  gap: 0.75rem;
}
.project-card {
  display: block;
  padding: 1.25rem 1.5rem;
  background: white;
  border: 1px solid #e2e8f0;
  border-radius: 0.5rem;
  text-decoration: none;
  color: inherit;
  transition:
    border-color 150ms,
    box-shadow 150ms,
    transform 150ms;
}
.project-card:hover {
  border-color: #fdba74;
  box-shadow: 0 4px 14px rgba(253, 186, 116, 0.18);
  transform: translateY(-1px);
}
.project-card h3 {
  font-size: 1.125rem;
  font-weight: 600;
  margin: 0 0 0.25rem;
}
.project-card .desc {
  font-size: 0.875rem;
  line-height: 1.6;
  color: #475569;
  margin: 0;
}
.project-card .arrow {
  font-size: 0.75rem;
  color: #94a3b8;
  margin: 0.5rem 0 0;
  font-variant-numeric: tabular-nums;
}

footer {
  padding: 2rem 0;
  font-size: 0.75rem;
  color: #94a3b8;
  border-top: 1px solid #f1f5f9;
  margin-top: 1.5rem;
}
footer .container {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  justify-content: space-between;
  align-items: baseline;
}
footer nav {
  display: flex;
  gap: 1rem;
}
footer a {
  color: #64748b;
  text-decoration: none;
}
footer a:hover {
  color: #0369a1;
}