/* ============================================================
   Platform Engineering Manifesto — Stylesheet
   ============================================================ */

/* ── Custom properties ─────────────────────────────────── */
:root {
  --color-primary:      #0f172a;
  --color-primary-mid:  #1e293b;
  --color-accent:       #3b82f6;
  --color-accent-dark:  #2563eb;
  --color-accent-light: #dbeafe;
  --color-teal:         #0ea5e9;
  --color-bg:           #f8fafc;
  --color-surface:      #ffffff;
  --color-border:       #e2e8f0;
  --color-text:         #1e293b;
  --color-text-muted:   #64748b;
  --color-hero-from:    #0f172a;
  --color-hero-to:      #1e3a5f;

  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
               "Helvetica Neue", Arial, sans-serif;
  --font-mono: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;

  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;

  --shadow-sm: 0 1px 3px rgba(0,0,0,.08), 0 1px 2px rgba(0,0,0,.05);
  --shadow-md: 0 4px 12px rgba(0,0,0,.10), 0 2px 4px rgba(0,0,0,.06);
  --shadow-lg: 0 10px 30px rgba(0,0,0,.12), 0 4px 8px rgba(0,0,0,.07);

  --max-width: 1100px;
  --container-px: 1.5rem;
}

/* ── Reset / base ───────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; }

body {
  font-family: var(--font-sans);
  font-size: 1rem;
  line-height: 1.7;
  color: var(--color-text);
  background: var(--color-bg);
  -webkit-font-smoothing: antialiased;
}

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

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

/* ── Utility ─────────────────────────────────────────────── */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin-inline: auto;
  padding-inline: var(--container-px);
}

/* ── Site header ─────────────────────────────────────────── */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--color-primary);
  border-bottom: 1px solid rgba(255,255,255,.08);
  box-shadow: 0 2px 8px rgba(0,0,0,.25);
}

.site-nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 3.75rem;
  gap: 1rem;
}

.site-logo {
  display: flex;
  align-items: center;
  gap: .55rem;
  color: #fff;
  font-weight: 600;
  font-size: .95rem;
  letter-spacing: -.01em;
  text-decoration: none;
  white-space: nowrap;
}
.site-logo:hover { text-decoration: none; opacity: .85; }

.logo-icon {
  font-size: 1.35rem;
  line-height: 1;
  color: var(--color-teal);
}

.nav-link {
  display: inline-flex;
  align-items: center;
  gap: .4rem;
  color: rgba(255,255,255,.75);
  font-size: .875rem;
  font-weight: 500;
  transition: color .15s;
  text-decoration: none;
}
.nav-link:hover { color: #fff; text-decoration: none; }

.nav-links {
  display: flex;
  align-items: center;
  gap: 1.25rem;
}

/* ── Hero section ─────────────────────────────────────────── */
.hero {
  background: linear-gradient(135deg, var(--color-hero-from) 0%, var(--color-hero-to) 100%);
  color: #fff;
  padding: 5rem var(--container-px) 4rem;
  text-align: center;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background: url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='none' fill-rule='evenodd'%3E%3Cg fill='%23ffffff' fill-opacity='0.03'%3E%3Cpath d='M36 34v-4h-2v4h-4v2h4v4h2v-4h4v-2h-4zm0-30V0h-2v4h-4v2h4v4h2V6h4V4h-4zM6 34v-4H4v4H0v2h4v4h2v-4h4v-2H6zM6 4V0H4v4H0v2h4v4h2V6h4V4H6z'/%3E%3C/g%3E%3C/g%3E%3C/svg%3E");
}

.hero-inner {
  position: relative;
  max-width: 760px;
  margin-inline: auto;
}

.hero-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: .4rem;
  background: rgba(59,130,246,.25);
  border: 1px solid rgba(59,130,246,.4);
  color: #93c5fd;
  font-size: .75rem;
  font-weight: 600;
  letter-spacing: .08em;
  text-transform: uppercase;
  padding: .3rem .75rem;
  border-radius: 999px;
  margin-bottom: 1.5rem;
}

.hero h1 {
  font-size: clamp(2rem, 5vw, 3rem);
  font-weight: 800;
  line-height: 1.15;
  letter-spacing: -.025em;
  margin-bottom: 1.25rem;
}

.hero-subtitle {
  font-size: 1.125rem;
  line-height: 1.65;
  color: rgba(255,255,255,.78);
  margin-bottom: 2.5rem;
  max-width: 600px;
  margin-inline: auto;
}

.values-intro {
  color: rgba(255,255,255,.6);
  font-size: .9rem;
  margin-bottom: .75rem;
}

/* ── Values grid ──────────────────────────────────────────── */
.values-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1px;
  background: rgba(255,255,255,.12);
  border: 1px solid rgba(255,255,255,.12);
  border-radius: var(--radius-md);
  overflow: hidden;
  margin-top: 2rem;
}

.value-item {
  padding: 1.25rem 1.5rem;
  background: rgba(255,255,255,.05);
  text-align: left;
}

.value-left {
  font-weight: 700;
  color: #fff;
  font-size: .95rem;
  margin-bottom: .15rem;
}

.value-right {
  font-size: .85rem;
  color: rgba(255,255,255,.5);
}

.value-over {
  font-size: .7rem;
  font-weight: 600;
  letter-spacing: .06em;
  text-transform: uppercase;
  color: var(--color-teal);
  margin-bottom: .25rem;
}

/* ── Manifesto intro prose ───────────────────────────────── */
.manifesto-intro {
  padding: 3rem var(--container-px) 0;
}

.manifesto-intro p {
  font-size: 1.05rem;
  color: var(--color-text-muted);
  max-width: 740px;
  margin-inline: auto;
  text-align: center;
  line-height: 1.8;
}

/* ── Principles section ──────────────────────────────────── */
.principles-section {
  padding: 3rem var(--container-px) 5rem;
}

.section-heading {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-primary);
  margin-bottom: 2rem;
  display: flex;
  align-items: center;
  gap: .6rem;
}

.section-heading::after {
  content: "";
  flex: 1;
  height: 2px;
  background: var(--color-border);
  border-radius: 1px;
}

.principles-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 1.25rem;
}

/* ── Principle card ──────────────────────────────────────── */
.principle-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: .75rem;
  box-shadow: var(--shadow-sm);
  transition: transform .18s ease, box-shadow .18s ease, border-color .18s ease;
  text-decoration: none;
  color: inherit;
  position: relative;
  overflow: hidden;
}

.principle-card::before {
  content: "";
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--color-accent), var(--color-teal));
  opacity: 0;
  transition: opacity .18s;
}

.principle-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-lg);
  border-color: var(--color-accent);
  text-decoration: none;
}

.principle-card:hover::before {
  opacity: 1;
}

.card-number {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2.25rem;
  height: 2.25rem;
  background: var(--color-accent-light);
  color: var(--color-accent-dark);
  font-size: .8rem;
  font-weight: 700;
  border-radius: var(--radius-sm);
  flex-shrink: 0;
}

.card-title {
  font-size: 1rem;
  font-weight: 700;
  color: var(--color-primary);
  line-height: 1.35;
}

.card-body {
  font-size: .875rem;
  color: var(--color-text-muted);
  line-height: 1.65;
  flex: 1;
}

.card-link {
  display: inline-flex;
  align-items: center;
  gap: .35rem;
  font-size: .8rem;
  font-weight: 600;
  color: var(--color-accent-dark);
  margin-top: .25rem;
}
.card-link svg { transition: transform .15s; }
.principle-card:hover .card-link svg { transform: translateX(3px); }

/* ── Principle page ──────────────────────────────────────── */
.principle-page {
  padding: 2.5rem var(--container-px) 5rem;
}

.back-link {
  display: inline-flex;
  align-items: center;
  gap: .4rem;
  color: var(--color-text-muted);
  font-size: .875rem;
  font-weight: 500;
  margin-bottom: 2rem;
  transition: color .15s;
  text-decoration: none;
}
.back-link:hover { color: var(--color-accent-dark); text-decoration: none; }

.principle-content {
  max-width: 780px;
}

.principle-content h1 {
  font-size: clamp(1.5rem, 3.5vw, 2.1rem);
  font-weight: 800;
  color: var(--color-primary);
  line-height: 1.2;
  letter-spacing: -.02em;
  margin-bottom: 1.5rem;
}

.principle-content blockquote {
  border-left: 4px solid var(--color-accent);
  background: var(--color-accent-light);
  padding: 1rem 1.25rem;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  margin-bottom: 2.5rem;
  color: var(--color-primary-mid);
  font-size: .975rem;
  font-style: italic;
  line-height: 1.7;
}

.principle-content blockquote p { margin: 0; }

.principle-content h2 {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--color-primary);
  margin: 2.5rem 0 1.25rem;
  padding-bottom: .5rem;
  border-bottom: 2px solid var(--color-border);
}

.principle-content ol {
  list-style: none;
  padding: 0;
  counter-reset: examples;
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.principle-content ol li {
  counter-increment: examples;
  display: flex;
  gap: 1rem;
  padding: 1rem 1.25rem;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
  font-size: .925rem;
  line-height: 1.65;
  transition: border-color .15s, box-shadow .15s;
}

.principle-content ol li::before {
  content: counter(examples);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 1.75rem;
  height: 1.75rem;
  background: var(--color-accent-light);
  color: var(--color-accent-dark);
  font-size: .75rem;
  font-weight: 700;
  border-radius: var(--radius-sm);
  flex-shrink: 0;
  margin-top: .1rem;
}

.principle-content ol li:hover {
  border-color: var(--color-accent);
  box-shadow: var(--shadow-md);
}

.principle-content strong { color: var(--color-primary); font-weight: 600; }

.principle-content ul {
  list-style: none;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: .85rem;
}

.principle-content ul li {
  padding: 1rem 1.25rem;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
  font-size: .925rem;
  line-height: 1.65;
  transition: border-color .15s, box-shadow .15s;
}

.principle-content ul li:hover {
  border-color: var(--color-accent);
  box-shadow: var(--shadow-md);
}

.principle-content ul li > p { margin: 0; }

.principle-content ul li input[type="checkbox"] {
  appearance: none;
  -webkit-appearance: none;
  width: 1.15rem;
  height: 1.15rem;
  margin: 0 .75rem .15rem 0;
  vertical-align: middle;
  background: var(--color-accent-light);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  position: relative;
  cursor: default;
  flex-shrink: 0;
}

.principle-content ul li input[type="checkbox"]:checked {
  background: var(--color-accent-dark);
  border-color: var(--color-accent-dark);
}

.principle-content ul li input[type="checkbox"]:checked::after {
  content: "";
  position: absolute;
  left: .3rem;
  top: .05rem;
  width: .3rem;
  height: .6rem;
  border: solid #fff;
  border-width: 0 2px 2px 0;
  transform: rotate(45deg);
}

.principle-content hr {
  border: 0;
  border-top: 1px solid var(--color-border);
  margin: 2.5rem 0;
}

.principle-content > p {
  font-size: .975rem;
  color: var(--color-text-muted);
  line-height: 1.7;
  margin-bottom: 1.25rem;
}

.principle-content code {
  font-family: var(--font-mono);
  font-size: .85em;
  background: #f1f5f9;
  border: 1px solid var(--color-border);
  padding: .1em .4em;
  border-radius: 4px;
  color: #be185d;
}

/* ── Site footer ─────────────────────────────────────────── */
.site-footer {
  background: var(--color-primary);
  color: rgba(255,255,255,.55);
  font-size: .85rem;
  text-align: center;
  padding: 2.5rem var(--container-px);
}

.site-footer p { margin-bottom: .4rem; }
.site-footer p:last-child { margin-bottom: 0; }

.site-footer a {
  color: rgba(255,255,255,.75);
  text-decoration: none;
}
.site-footer a:hover { color: #fff; text-decoration: underline; }

/* ── Responsive ──────────────────────────────────────────── */
@media (max-width: 640px) {
  .hero { padding: 3rem var(--container-px) 2.5rem; }
  .values-grid { grid-template-columns: 1fr 1fr; }
  .principles-grid { grid-template-columns: 1fr; }
  .logo-text { display: none; }
  .principle-content ol li { flex-direction: column; gap: .5rem; }
  .principle-content ol li::before { width: 1.5rem; height: 1.5rem; }
}

@media (max-width: 400px) {
  .values-grid { grid-template-columns: 1fr; }
}