:root {
  --color-bg: #f7f8fc;
  --color-surface: #ffffff;
  --color-ink: #14123a;
  --color-ink-soft: #4b4a68;
  --color-muted: #6b6a85;
  --color-border: #e6e5f2;
  --color-primary: #4f46e5;
  --color-primary-soft: #eef0fd;
  --color-violet: #7c3aed;
}

* {
  box-sizing: border-box;
}

html {
  color-scheme: light;
}

body {
  margin: 0;
  background: var(--color-bg);
  color: var(--color-ink-soft);
  font-family: "Plus Jakarta Sans", ui-sans-serif, system-ui, -apple-system, sans-serif;
  -webkit-font-smoothing: antialiased;
  line-height: 1.6;
}

a {
  color: var(--color-primary);
}

.site-header {
  border-bottom: 1px solid var(--color-border);
  background: rgba(255, 255, 255, 0.85);
  position: sticky;
  top: 0;
  z-index: 10;
}

.site-header-inner {
  max-width: 720px;
  margin: 0 auto;
  padding: 20px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  text-decoration: none;
  font-weight: 800;
  font-size: 18px;
  letter-spacing: -0.02em;
  color: var(--color-ink);
}

.brand-mark {
  width: 28px;
  height: 28px;
  border-radius: 9px;
  background: linear-gradient(135deg, #4f46e5 0%, #7c3aed 100%);
  display: inline-flex;
  align-items: center;
  justify-content: center;
}

.brand-accent {
  color: var(--color-primary);
}

.back-link {
  font-size: 14px;
  font-weight: 600;
  text-decoration: none;
  color: var(--color-ink-soft);
}
.back-link:hover {
  color: var(--color-primary);
}

main {
  max-width: 720px;
  margin: 0 auto;
  padding: 48px 24px 80px;
}

.blog-hero h1 {
  font-size: 32px;
  letter-spacing: -0.02em;
  color: var(--color-ink);
  margin: 0 0 12px;
  line-height: 1.15;
}

.blog-hero p {
  color: var(--color-muted);
  font-size: 17px;
  margin: 0 0 32px;
}

.post-list {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.post-card {
  display: block;
  text-decoration: none;
  padding: 20px 0;
  border-bottom: 1px solid var(--color-border);
}
.post-card:first-child {
  padding-top: 0;
}

.post-card-date {
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--color-violet);
  margin: 0 0 6px;
}

.post-card h2 {
  font-size: 20px;
  color: var(--color-ink);
  margin: 0 0 6px;
  letter-spacing: -0.01em;
}

.post-card p {
  color: var(--color-muted);
  font-size: 15px;
  margin: 0;
}

article.post {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 16px;
  padding: 40px;
}

.post-meta {
  font-size: 13px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--color-violet);
  margin: 0 0 12px;
}

article.post h1 {
  font-size: 30px;
  color: var(--color-ink);
  letter-spacing: -0.02em;
  line-height: 1.2;
  margin: 0 0 8px;
}

.post-description {
  font-size: 17px;
  color: var(--color-muted);
  margin: 0 0 32px;
}

.post-body h2 {
  font-size: 21px;
  color: var(--color-ink);
  letter-spacing: -0.01em;
  margin: 36px 0 12px;
}

.post-body p {
  font-size: 16px;
  color: var(--color-ink-soft);
  margin: 0 0 16px;
}

.post-body ul,
.post-body ol {
  color: var(--color-ink-soft);
  font-size: 16px;
  padding-left: 22px;
}

.post-body hr {
  border: none;
  border-top: 1px solid var(--color-border);
  margin: 36px 0;
}

.post-body a {
  font-weight: 600;
}

.cta-banner {
  margin-top: 40px;
  padding: 24px;
  border-radius: 14px;
  background: var(--color-primary-soft);
  border: 1px solid rgba(79, 70, 229, 0.15);
}

.cta-banner p {
  margin: 0;
  color: var(--color-ink-soft);
  font-size: 15px;
}

.cta-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  margin-top: 14px;
  padding: 10px 22px;
  border-radius: 999px;
  background: var(--color-primary);
  color: #fff;
  font-weight: 700;
  font-size: 14px;
  text-decoration: none;
}

.site-footer {
  border-top: 1px solid var(--color-border);
  padding: 32px 24px;
  text-align: center;
  color: var(--color-muted);
  font-size: 13px;
}

.site-footer a {
  color: var(--color-ink-soft);
  font-weight: 600;
  text-decoration: none;
}
.site-footer a:hover {
  color: var(--color-primary);
}

@media (max-width: 640px) {
  article.post {
    padding: 28px 20px;
  }
  .blog-hero h1 {
    font-size: 26px;
  }
}