/*
 * HarinathBabu.com main stylesheet
 * Minimal, mobile-first, optimized for Core Web Vitals
 * No frameworks. No external dependencies.
 */

:root {
  --navy: #0F2A5A;
  --off-white: #F7F9FC;
  --emerald: #1A8F4C;
  --amber: #F5A623;
  --gray-900: #1a1a1a;
  --gray-700: #4a4a4a;
  --gray-500: #8a8a8a;
  --gray-300: #d0d0d0;
  --gray-100: #f0f0f0;
  --max-width: 1100px;
  --content-width: 720px;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
  --font-mono: 'JetBrains Mono', 'Courier New', monospace;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  line-height: 1.6;
  color: var(--gray-900);
  background: #ffffff;
  font-size: clamp(1rem, 0.95rem + 0.2vw, 1.125rem);
}

/* Skip link for accessibility */
.skip-link {
  position: absolute;
  top: -40px;
  left: 0;
  background: var(--navy);
  color: white;
  padding: 0.5rem 1rem;
  z-index: 100;
  text-decoration: none;
}
.skip-link:focus { top: 0; }

/* ----- LAYOUT ----- */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.25rem;
}

.content {
  max-width: var(--content-width);
  margin: 0 auto;
  padding: 0 1.25rem;
}

/* ----- HEADER ----- */
.site-header {
  background: white;
  border-bottom: 1px solid var(--gray-100);
  position: sticky;
  top: 0;
  z-index: 50;
}

.site-header-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0.9rem 1.25rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  flex-wrap: wrap;
}

.site-logo {
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--navy);
  text-decoration: none;
  letter-spacing: -0.02em;
}

.site-logo:hover { color: var(--emerald); }

.site-nav {
  display: flex;
  gap: 1.5rem;
  flex-wrap: wrap;
}

.site-nav a {
  color: var(--gray-700);
  text-decoration: none;
  font-size: 0.95rem;
  font-weight: 500;
  transition: color 0.15s;
}

.site-nav a:hover,
.site-nav a[aria-current="page"] {
  color: var(--navy);
}

/* ----- TYPOGRAPHY ----- */
h1, h2, h3, h4 {
  font-weight: 700;
  line-height: 1.2;
  color: var(--navy);
  margin-bottom: 0.75rem;
  letter-spacing: -0.02em;
}

h1 { font-size: clamp(2rem, 1.5rem + 2vw, 3rem); margin-bottom: 1rem; }
h2 { font-size: clamp(1.5rem, 1.2rem + 1vw, 2rem); margin-top: 2.5rem; }
h3 { font-size: clamp(1.25rem, 1.1rem + 0.5vw, 1.5rem); margin-top: 1.5rem; }
h4 { font-size: 1.1rem; margin-top: 1.25rem; }

p {
  margin-bottom: 1rem;
  max-width: 70ch;
}

a {
  color: var(--emerald);
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}

a:hover { color: var(--navy); }

strong { font-weight: 700; color: var(--navy); }
em { color: var(--gray-700); }

ul, ol {
  margin-bottom: 1rem;
  padding-left: 1.5rem;
}

li { margin-bottom: 0.4rem; max-width: 65ch; }

blockquote {
  border-left: 4px solid var(--emerald);
  padding-left: 1rem;
  margin: 1.5rem 0;
  font-style: italic;
  color: var(--gray-700);
}

code {
  background: var(--gray-100);
  padding: 0.1rem 0.4rem;
  border-radius: 3px;
  font-family: var(--font-mono);
  font-size: 0.9em;
}

pre {
  background: var(--gray-100);
  padding: 1rem;
  border-radius: 6px;
  overflow-x: auto;
  margin: 1rem 0;
  font-size: 0.85rem;
}

pre code { background: transparent; padding: 0; }

hr {
  border: none;
  border-top: 1px solid var(--gray-300);
  margin: 2.5rem 0;
}

/* ----- HERO ----- */
.hero {
  padding: 4rem 1.25rem 3rem;
  text-align: center;
  background: linear-gradient(180deg, #f7f9fc 0%, #ffffff 100%);
}

.hero h1 {
  max-width: 20ch;
  margin: 0 auto 1rem;
  font-size: clamp(2rem, 1.5rem + 2.5vw, 3.5rem);
}

.hero-subtitle {
  max-width: 50ch;
  margin: 0 auto 1.5rem;
  font-size: clamp(1.1rem, 1rem + 0.5vw, 1.35rem);
  color: var(--gray-700);
  line-height: 1.5;
}

/* ----- BUTTONS ----- */
.btn {
  display: inline-block;
  padding: 0.85rem 1.75rem;
  background: var(--navy);
  color: white;
  text-decoration: none;
  border-radius: 6px;
  font-weight: 600;
  font-size: 1rem;
  transition: all 0.15s;
  border: none;
  cursor: pointer;
}

.btn:hover {
  background: var(--emerald);
  color: white;
  transform: translateY(-1px);
}

.btn-secondary {
  background: transparent;
  color: var(--navy);
  border: 2px solid var(--navy);
}

.btn-secondary:hover {
  background: var(--navy);
  color: white;
}

.btn-amber {
  background: var(--amber);
  color: var(--gray-900);
}

/* ----- SECTIONS ----- */
section {
  padding: 3rem 0;
}

.section-intro {
  max-width: 60ch;
  margin: 0 auto 2.5rem;
  text-align: center;
  color: var(--gray-700);
}

/* ----- CARD GRID ----- */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.25rem;
  margin: 2rem 0;
}

.card {
  background: white;
  border: 1px solid var(--gray-100);
  border-radius: 8px;
  padding: 1.5rem;
  transition: all 0.15s;
  display: block;
  text-decoration: none;
  color: inherit;
}

.card:hover {
  border-color: var(--emerald);
  box-shadow: 0 4px 20px rgba(15, 42, 90, 0.08);
  transform: translateY(-2px);
}

.card h3 {
  color: var(--navy);
  margin-top: 0;
  font-size: 1.25rem;
}

.card-meta {
  font-size: 0.85rem;
  color: var(--gray-500);
  margin-bottom: 0.5rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  font-weight: 600;
}

.card p {
  color: var(--gray-700);
  margin-bottom: 0;
}

/* ----- PILLAR CARDS (homepage) ----- */
.pillar-card {
  background: white;
  border: 2px solid var(--gray-100);
  border-radius: 8px;
  padding: 1.75rem;
  text-decoration: none;
  color: inherit;
  display: block;
  transition: all 0.15s;
}

.pillar-card:hover {
  border-color: var(--navy);
  color: inherit;
}

.pillar-card .pillar-num {
  color: var(--emerald);
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.pillar-card h3 {
  color: var(--navy);
  margin: 0.5rem 0 0.75rem;
  font-size: 1.35rem;
}

.pillar-card p {
  color: var(--gray-700);
  font-size: 0.95rem;
  margin-bottom: 0;
}

/* ----- ARTICLE LAYOUT ----- */
article {
  padding: 2rem 0;
}

article h1 {
  margin-bottom: 0.5rem;
}

.article-meta {
  color: var(--gray-500);
  font-size: 0.9rem;
  margin-bottom: 2rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--gray-100);
}

.article-meta a { color: var(--gray-700); }

/* ----- BREADCRUMBS ----- */
.breadcrumbs {
  font-size: 0.85rem;
  color: var(--gray-500);
  margin-bottom: 1.5rem;
}

.breadcrumbs a {
  color: var(--gray-700);
  text-decoration: none;
}

.breadcrumbs a:hover { color: var(--navy); }

/* ----- CTA BOX ----- */
.cta-box {
  background: var(--navy);
  color: white;
  padding: 2rem;
  border-radius: 8px;
  margin: 2.5rem 0;
  text-align: center;
}

.cta-box h3 { color: white; margin-top: 0; }
.cta-box p { color: var(--off-white); }
.cta-box .btn { background: var(--amber); color: var(--navy); }
.cta-box .btn:hover { background: var(--emerald); color: white; }

/* ----- FOOTER ----- */
.site-footer {
  background: var(--navy);
  color: var(--off-white);
  padding: 3rem 0 2rem;
  margin-top: 4rem;
}

.site-footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.25rem;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 2rem;
}

.site-footer h4 {
  color: white;
  font-size: 0.9rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: 1rem;
}

.site-footer a {
  color: var(--off-white);
  text-decoration: none;
  display: block;
  margin-bottom: 0.5rem;
  font-size: 0.95rem;
  opacity: 0.8;
}

.site-footer a:hover { opacity: 1; color: var(--amber); }

.site-footer-bottom {
  max-width: var(--max-width);
  margin: 2.5rem auto 0;
  padding: 1.5rem 1.25rem 0;
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  text-align: center;
  font-size: 0.85rem;
  opacity: 0.7;
}

/* ----- FORMS ----- */
form {
  max-width: 100%;
}

.form-group {
  margin-bottom: 1rem;
}

input[type="email"],
input[type="text"] {
  width: 100%;
  padding: 0.85rem 1rem;
  border: 1px solid var(--gray-300);
  border-radius: 6px;
  font-size: 1rem;
  font-family: inherit;
}

input:focus {
  outline: 2px solid var(--emerald);
  outline-offset: 1px;
  border-color: var(--emerald);
}

/* ----- RESPONSIVE ----- */
@media (max-width: 640px) {
  .site-header-inner {
    padding: 0.75rem 1rem;
  }

  .site-nav {
    gap: 1rem;
    font-size: 0.9rem;
  }

  .hero { padding: 2.5rem 1rem 2rem; }
  section { padding: 2rem 0; }
  .site-footer { padding: 2rem 0 1.5rem; }
}

/* ----- UTILITIES ----- */
.text-center { text-align: center; }
.mt-4 { margin-top: 2rem; }
.mb-4 { margin-bottom: 2rem; }
.highlight { background: rgba(245, 166, 35, 0.15); padding: 0.1em 0.3em; border-radius: 3px; }