:root {
  --bg: #f6f7fb;
  --white: #ffffff;
  --text-main: #2c2f36;
  --text-muted: #666b78;
  --accent: #2563eb;
  --accent-soft: #dbeafe;
  --border-soft: #e2e5ef;
  --radius: 12px;
}

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

body {
  margin: 0;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Hiragino Sans",
    "Yu Gothic", "Noto Sans JP", sans-serif;
  color: var(--text-main);
  background: var(--bg);
  line-height: 1.7;
}

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

a:hover {
  text-decoration: underline;
}

/* layout */

.container {
  width: min(1100px, 100% - 32px);
  margin-inline: auto;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(246, 247, 251, 0.9);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border-soft);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-block: 10px;
}

.logo {
  font-weight: 700;
  letter-spacing: 0.08em;
}

.nav a {
  margin-left: 16px;
  font-size: 0.9rem;
  color: var(--text-muted);
}

.nav a:hover {
  color: var(--accent);
}

/* hero */

.hero {
  padding: 72px 0 56px;
}

.hero-inner {
  max-width: 640px;
}

.hero h1 {
  font-size: clamp(1.6rem, 3.4vw, 2.2rem);
  margin-bottom: 12px;
}

.hero p {
  color: var(--text-muted);
  margin-bottom: 24px;
}

.btn-primary {
  display: inline-block;
  padding: 10px 22px;
  border-radius: 999px;
  background: var(--accent);
  color: var(--white);
  font-size: 0.95rem;
  text-decoration: none;
}

.btn-primary:hover {
  filter: brightness(1.05);
}

/* sections */

.section {
  padding: 48px 0;
}

.section-gray {
  background: var(--accent-soft);
}

.section-title {
  font-size: 1.3rem;
  margin-bottom: 20px;
}

/* cards */

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 18px;
}

.card {
  background: var(--white);
  padding: 18px;
  border-radius: var(--radius);
  box-shadow: 0 4px 12px rgba(15, 23, 42, 0.06);
}

.card h3 {
  margin-top: 0;
  margin-bottom: 6px;
  font-size: 1.05rem;
}

.card p {
  margin-top: 0;
  margin-bottom: 12px;
  color: var(--text-muted);
}

.card-link {
  font-size: 0.9rem;
}

/* skills */

.skill-list {
  list-style: none;
  padding: 0;
  margin: 0;
}

.skill-list li {
  margin-bottom: 8px;
}

.skill-list span {
  font-weight: 600;
}

/* contact */

.contact-list {
  list-style: none;
  padding: 0;
  margin: 8px 0 0;
}

.contact-list li {
  margin-bottom: 4px;
}

/* footer */

.site-footer {
  padding: 20px 0;
  text-align: center;
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* responsive */

@media (max-width: 640px) {
  .header-inner {
    flex-direction: column;
    align-items: flex-start;
    gap: 6px;
  }

  .nav a {
    margin-left: 0;
    margin-right: 12px;
  }
}