/* ===== Principle Perspective Engineering — base styles ===== */
:root {
  --color-primary: #0b5fff;
  --color-primary-dark: #0842b0;
  --color-text: #1a1a1a;
  --color-text-muted: #5a5a5a;
  --color-bg: #ffffff;
  --color-bg-alt: #f4f6f9;
  --color-border: #e2e5ea;
  --max-width: 1100px;
  --radius: 8px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: "Segoe UI", Roboto, Arial, sans-serif;
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.6;
}

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

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

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 20px;
}

/* ---- Header / Nav ---- */
header.site-header {
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  background: var(--color-bg);
  z-index: 10;
}

.nav-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 20px;
  max-width: var(--max-width);
  margin: 0 auto;
}

.brand {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--color-text);
}
.brand span { color: var(--color-primary); }

nav.main-nav ul {
  list-style: none;
  display: flex;
  gap: 28px;
  margin: 0;
  padding: 0;
}

nav.main-nav a {
  color: var(--color-text);
  font-weight: 500;
}

nav.main-nav a.active { color: var(--color-primary); }

.nav-toggle {
  display: none;
  background: none;
  border: none;
  font-size: 1.6rem;
  cursor: pointer;
}

/* ---- Hero ---- */
.hero {
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
  color: #fff;
  padding: 80px 20px;
  text-align: center;
}

.hero h1 {
  font-size: 2.4rem;
  margin: 0 0 16px;
}

.hero p {
  font-size: 1.15rem;
  max-width: 600px;
  margin: 0 auto 28px;
  opacity: 0.95;
}

.btn {
  display: inline-block;
  padding: 12px 28px;
  border-radius: var(--radius);
  font-weight: 600;
  background: #fff;
  color: var(--color-primary);
}
.btn:hover { background: #eaf0ff; text-decoration: none; }

.btn-primary {
  background: var(--color-primary);
  color: #fff;
}
.btn-primary:hover { background: var(--color-primary-dark); }

.btn-outline {
  background: transparent;
  color: #fff;
  border: 1px solid rgba(255,255,255,0.7);
}
.btn-outline:hover { background: rgba(255,255,255,0.12); }

.hero-actions {
  display: flex;
  gap: 16px;
  justify-content: center;
  flex-wrap: wrap;
}

/* ---- Sections ---- */
section { padding: 60px 20px; }
section.alt { background: var(--color-bg-alt); }

h2 {
  font-size: 1.8rem;
  margin-bottom: 8px;
}

.section-intro {
  color: var(--color-text-muted);
  margin-bottom: 36px;
  max-width: 650px;
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.grid-auto {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 24px;
}

.card {
  background: #fff;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 24px;
}

.card h3 { margin-top: 0; }

/* ---- Scope / criteria lists ---- */
.scope-list {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 10px 20px;
  list-style: none;
  padding: 0;
  margin: 0 0 32px;
}
.scope-list li {
  padding: 10px 16px;
  background: var(--color-bg-alt);
  border-radius: var(--radius);
  font-weight: 500;
}

.criteria-list { padding-left: 20px; }
.criteria-list li { margin-bottom: 10px; }

.callout {
  background: var(--color-bg-alt);
  border-left: 4px solid var(--color-primary);
  border-radius: var(--radius);
  padding: 20px 24px;
  margin: 32px 0;
}
.callout h3 { margin-top: 0; }

/* ---- Projects ---- */
.tag-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 14px;
  list-style: none;
  padding: 0;
  margin: 0;
}
.tag-grid li {
  background: #fff;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 16px 18px;
  font-weight: 500;
}

.company-meta {
  color: var(--color-text-muted);
  font-size: 0.95rem;
  margin-top: -4px;
}

/* ---- Contact ---- */
.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 40px;
}

form .field {
  margin-bottom: 16px;
}

form label {
  display: block;
  font-weight: 600;
  margin-bottom: 6px;
}

form input, form textarea {
  width: 100%;
  padding: 10px 12px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  font-family: inherit;
  font-size: 1rem;
}

/* ---- Footer ---- */
footer {
  border-top: 1px solid var(--color-border);
  padding: 28px 20px;
  text-align: center;
  color: var(--color-text-muted);
  font-size: 0.9rem;
}

/* ---- Responsive ---- */
@media (max-width: 760px) {
  .nav-toggle { display: block; }

  nav.main-nav {
    display: none;
    width: 100%;
  }
  nav.main-nav.open { display: block; }
  nav.main-nav ul {
    flex-direction: column;
    gap: 0;
    padding: 12px 0;
  }
  nav.main-nav li { border-top: 1px solid var(--color-border); }
  nav.main-nav a { display: block; padding: 12px 20px; }

  .nav-bar { flex-wrap: wrap; }

  .grid-3 { grid-template-columns: 1fr; }
  .contact-grid { grid-template-columns: 1fr; }
}

@media (max-width: 480px) {
  .hero-actions { flex-direction: column; align-items: stretch; }
}