/* ===================================
   Modern Model — Stylesheet
   =================================== */

/* CSS Custom Properties */
:root {
  /* Colors - Refined neutral palette with subtle warmth */
  --color-bg: #fafaf9;
  --color-bg-alt: #f5f5f4;
  --color-surface: #ffffff;
  --color-text: #1c1917;
  --color-text-secondary: #57534e;
  --color-text-muted: #78716c;
  --color-accent: #0f172a;
  --color-accent-hover: #1e293b;
  --color-border: #e7e5e4;
  --color-border-subtle: #f5f5f4;
  
  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-serif: 'Newsreader', Georgia, 'Times New Roman', serif;
  
  /* Font Sizes - Fluid typography */
  --text-xs: clamp(0.75rem, 0.7rem + 0.25vw, 0.875rem);
  --text-sm: clamp(0.875rem, 0.8rem + 0.35vw, 1rem);
  --text-base: clamp(1rem, 0.9rem + 0.5vw, 1.125rem);
  --text-lg: clamp(1.125rem, 1rem + 0.6vw, 1.25rem);
  --text-xl: clamp(1.25rem, 1.1rem + 0.75vw, 1.5rem);
  --text-2xl: clamp(1.5rem, 1.2rem + 1.5vw, 2rem);
  --text-3xl: clamp(1.875rem, 1.4rem + 2.4vw, 2.75rem);
  --text-4xl: clamp(2.25rem, 1.5rem + 3.75vw, 3.75rem);
  
  /* Spacing */
  --space-xs: 0.5rem;
  --space-sm: 0.75rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  --space-3xl: 4rem;
  --space-4xl: 6rem;
  --space-5xl: 8rem;
  
  /* Layout */
  --max-width: 72rem;
  --content-width: 42rem;
  
  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;
  --transition-slow: 400ms ease;
  
  /* Border Radius */
  --radius-sm: 0.25rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
}

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

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

body {
  font-family: var(--font-sans);
  font-size: var(--text-base);
  line-height: 1.6;
  color: var(--color-text);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-weight: 500;
  line-height: 1.2;
  letter-spacing: -0.02em;
}

p {
  margin-bottom: 1em;
}

p:last-child {
  margin-bottom: 0;
}

a {
  color: inherit;
  text-decoration: none;
  transition: color var(--transition-fast);
}

ul {
  list-style: none;
}

/* Layout */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

@media (min-width: 768px) {
  .container {
    padding: 0 var(--space-2xl);
  }
}

/* ===================================
   Header
   =================================== */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: rgba(250, 250, 249, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border-subtle);
}

.nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 4rem;
}

.logo {
  font-weight: 600;
  font-size: var(--text-lg);
  letter-spacing: -0.03em;
}

.nav-cta {
  font-size: var(--text-sm);
  font-weight: 500;
  padding: var(--space-xs) var(--space-md);
  background: var(--color-accent);
  color: white;
  border-radius: var(--radius-md);
  transition: background var(--transition-fast);
}

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

/* ===================================
   Hero Section
   =================================== */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding: var(--space-5xl) 0 var(--space-4xl);
  background: linear-gradient(to bottom, var(--color-bg), var(--color-bg-alt));
}

.hero .container {
  max-width: var(--content-width);
}

.hero-headline {
  font-family: var(--font-serif);
  font-size: var(--text-4xl);
  font-weight: 400;
  line-height: 1.1;
  letter-spacing: -0.03em;
  margin-bottom: var(--space-xl);
  color: var(--color-text);
}

.hero-subhead {
  font-size: var(--text-lg);
  color: var(--color-text-secondary);
  line-height: 1.7;
  margin-bottom: var(--space-lg);
}

.hero-supporting {
  font-family: var(--font-serif);
  font-style: italic;
  font-size: var(--text-xl);
  color: var(--color-text-muted);
  margin-bottom: var(--space-2xl);
}

.hero-ctas {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-md);
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-sm) var(--space-xl);
  font-size: var(--text-sm);
  font-weight: 500;
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
  cursor: pointer;
  border: none;
}

.btn-primary {
  background: var(--color-accent);
  color: white;
}

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

.btn-secondary {
  background: transparent;
  color: var(--color-text);
  border: 1px solid var(--color-border);
}

.btn-secondary:hover {
  background: var(--color-surface);
  border-color: var(--color-text-muted);
}

/* ===================================
   Sections
   =================================== */
.section {
  padding: var(--space-4xl) 0;
}

@media (min-width: 768px) {
  .section {
    padding: var(--space-5xl) 0;
  }
}

.section-alt {
  background: var(--color-bg-alt);
}

.section .container {
  max-width: var(--content-width);
}

.section-title {
  font-family: var(--font-serif);
  font-size: var(--text-3xl);
  font-weight: 400;
  letter-spacing: -0.02em;
  color: var(--color-text);
  margin-bottom: var(--space-xl);
  line-height: 1.2;
}

.content-block {
  max-width: 38rem;
}

.lead {
  font-size: var(--text-lg);
  font-weight: 500;
  line-height: 1.5;
  color: var(--color-text);
  margin-bottom: var(--space-md);
}

/* Callout */
.callout {
  margin: var(--space-2xl) 0;
  padding: var(--space-xl);
  background: var(--color-surface);
  border-left: 3px solid var(--color-accent);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
}

.callout p {
  font-size: var(--text-lg);
  margin-bottom: var(--space-sm);
}

.callout p:first-child {
  font-weight: 500;
}

/* Lists */
.feature-list,
.problem-list,
.experience-list {
  margin: var(--space-xl) 0;
}

.feature-list li,
.problem-list li,
.experience-list li {
  position: relative;
  padding-left: var(--space-xl);
  margin-bottom: var(--space-md);
  font-size: var(--text-lg);
}

.feature-list li::before,
.experience-list li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0.7em;
  width: 6px;
  height: 6px;
  background: var(--color-accent);
  border-radius: 50%;
}

.problem-list li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0.55em;
  width: 8px;
  height: 2px;
  background: var(--color-text-muted);
}

.emphasis {
  font-family: var(--font-serif);
  font-style: italic;
  font-size: var(--text-lg);
  color: var(--color-text-secondary);
  margin-top: var(--space-xl);
}

/* Key Line / Blockquote */
.key-line {
  font-family: var(--font-serif);
  font-size: var(--text-2xl);
  font-weight: 400;
  font-style: italic;
  line-height: 1.4;
  margin: var(--space-2xl) 0;
  padding-left: var(--space-xl);
  border-left: 2px solid var(--color-text-muted);
  color: var(--color-text);
}

/* Link CTA */
.link-cta {
  display: inline-block;
  margin-top: var(--space-xl);
  font-weight: 500;
  color: var(--color-accent);
  transition: all var(--transition-fast);
}

.link-cta:hover {
  color: var(--color-accent-hover);
  transform: translateX(4px);
}

/* ===================================
   Closing Section
   =================================== */
.section-closing {
  background: var(--color-accent);
  color: white;
  text-align: center;
}

.closing-content {
  max-width: 36rem;
  margin: 0 auto;
}

.closing-lead {
  font-family: var(--font-serif);
  font-size: var(--text-3xl);
  font-weight: 400;
  margin-bottom: var(--space-lg);
}

.section-closing p {
  font-size: var(--text-lg);
  opacity: 0.9;
}

.closing-statement {
  font-family: var(--font-serif);
  font-style: italic;
  font-size: var(--text-xl) !important;
  margin-top: var(--space-xl);
  opacity: 1 !important;
}

/* ===================================
   Footer
   =================================== */
.site-footer {
  padding: var(--space-2xl) 0;
  border-top: 1px solid var(--color-border);
}

.footer-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.footer-logo {
  font-weight: 600;
  font-size: var(--text-sm);
  letter-spacing: -0.02em;
}

.footer-copy {
  font-size: var(--text-xs);
  color: var(--color-text-muted);
}

/* ===================================
   Animations
   =================================== */
.fade-in {
  opacity: 0;
  transform: translateY(20px);
  animation: fadeIn 0.8s ease forwards;
}

.delay-1 { animation-delay: 0.15s; }
.delay-2 { animation-delay: 0.3s; }
.delay-3 { animation-delay: 0.45s; }

@keyframes fadeIn {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Scroll-triggered animations */
.reveal {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ===================================
   Accessibility
   =================================== */
@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
  
  .fade-in,
  .reveal {
    animation: none;
    opacity: 1;
    transform: none;
    transition: none;
  }
}

/* Focus styles */
a:focus-visible,
button:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

/* Skip link */
.skip-link {
  position: absolute;
  top: -100%;
  left: var(--space-md);
  padding: var(--space-sm) var(--space-md);
  background: var(--color-accent);
  color: white;
  border-radius: var(--radius-md);
  z-index: 1000;
  transition: top var(--transition-fast);
}

.skip-link:focus {
  top: var(--space-md);
}

/* ===================================
   Responsive Adjustments
   =================================== */
@media (max-width: 640px) {
  .hero {
    min-height: auto;
    padding: calc(4rem + var(--space-4xl)) 0 var(--space-3xl);
  }
  
  .hero-ctas {
    flex-direction: column;
  }
  
  .btn {
    width: 100%;
    padding: var(--space-md) var(--space-xl);
  }
  
  .callout {
    padding: var(--space-lg);
  }
}

/* Dark mode support */
@media (prefers-color-scheme: dark) {
  :root {
    --color-bg: #0c0a09;
    --color-bg-alt: #1c1917;
    --color-surface: #292524;
    --color-text: #fafaf9;
    --color-text-secondary: #d6d3d1;
    --color-text-muted: #a8a29e;
    --color-accent: #fafaf9;
    --color-accent-hover: #e7e5e4;
    --color-border: #292524;
    --color-border-subtle: #1c1917;
  }
  
  .site-header {
    background: rgba(12, 10, 9, 0.85);
  }
  
  .nav-cta {
    color: var(--color-bg);
  }
  
  .btn-primary {
    color: #0c0a09;
  }
  
  .section-closing {
    background: var(--color-surface);
  }
}