/* =========================================================
   style.css — CSS Variables, Reset & Typography
   Dra. Erika Piedrahita — Medical Epigenetics Website
   ========================================================= */

/* ---------------------------------------------------------
   1. Google Fonts Import
   --------------------------------------------------------- */
@import url('https://fonts.googleapis.com/css2?family=Playfair+Display:ital,wght@0,400;0,500;0,600;0,700;0,800;1,400;1,500&family=Inter:wght@300;400;500;600;700&display=swap');

/* ---------------------------------------------------------
   2. CSS Custom Properties (Design Tokens)
   --------------------------------------------------------- */
:root {
  /* Colors */
  --color-bg:           #FAF7F4;
  --color-primary:      #C4A882;
  --color-primary-dark: #A8896A;
  --color-primary-light:#E8D9C4;
  --color-accent:       #D4B8C7;
  --color-accent-light: #EDE0E8;
  --color-text:         #2C2C2C;
  --color-text-muted:   #7A6E6A;
  --color-dark-cta:     #3D2B2B;
  --color-white:        #FFFFFF;
  --color-surface:      #F5F0EB;
  --color-border:       #E8E0D8;

  /* Typography */
  --font-heading: 'Playfair Display', Georgia, serif;
  --font-body:    'Inter', system-ui, sans-serif;

  /* Font sizes — fluid scale */
  --text-xs:   0.75rem;   /* 12px */
  --text-sm:   0.875rem;  /* 14px */
  --text-base: 1rem;      /* 16px */
  --text-lg:   1.125rem;  /* 18px */
  --text-xl:   1.25rem;   /* 20px */
  --text-2xl:  1.5rem;    /* 24px */
  --text-3xl:  1.875rem;  /* 30px */
  --text-4xl:  2.25rem;   /* 36px */
  --text-5xl:  3rem;      /* 48px */
  --text-6xl:  3.75rem;   /* 60px */

  /* Spacing */
  --space-1:  0.25rem;
  --space-2:  0.5rem;
  --space-3:  0.75rem;
  --space-4:  1rem;
  --space-5:  1.25rem;
  --space-6:  1.5rem;
  --space-8:  2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;

  /* Layout */
  --container-max: 1200px;
  --container-pad: 1.5rem;

  /* Borders */
  --radius-sm:  0.375rem;
  --radius-md:  0.75rem;
  --radius-lg:  1.25rem;
  --radius-xl:  2rem;
  --radius-full: 9999px;

  /* Shadows */
  --shadow-sm:  0 1px 3px rgba(44,44,44,0.08), 0 1px 2px rgba(44,44,44,0.06);
  --shadow-md:  0 4px 16px rgba(44,44,44,0.10), 0 2px 6px rgba(44,44,44,0.06);
  --shadow-lg:  0 10px 40px rgba(44,44,44,0.12), 0 4px 12px rgba(44,44,44,0.08);
  --shadow-xl:  0 20px 60px rgba(44,44,44,0.15);

  /* Transitions */
  --transition-fast:   150ms ease;
  --transition-base:   250ms ease;
  --transition-slow:   400ms ease;

  /* Z-index layers */
  --z-base:     1;
  --z-dropdown: 100;
  --z-sticky:   200;
  --z-overlay:  300;
  --z-modal:    400;
  --z-float:    500;
}

/* ---------------------------------------------------------
   3. CSS Reset & Normalize
   --------------------------------------------------------- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

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

body {
  font-family: var(--font-body);
  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;
  overflow-x: hidden;
}

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

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

ul, ol {
  list-style: none;
}

button {
  font-family: var(--font-body);
  cursor: pointer;
  border: none;
  background: none;
}

input, textarea, select {
  font-family: var(--font-body);
  font-size: var(--text-base);
}

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  line-height: 1.2;
  font-weight: 700;
  color: var(--color-text);
}

p {
  color: var(--color-text-muted);
  line-height: 1.75;
}

/* ---------------------------------------------------------
   4. Typography Scale
   --------------------------------------------------------- */
.text-xs   { font-size: var(--text-xs); }
.text-sm   { font-size: var(--text-sm); }
.text-base { font-size: var(--text-base); }
.text-lg   { font-size: var(--text-lg); }
.text-xl   { font-size: var(--text-xl); }
.text-2xl  { font-size: var(--text-2xl); }
.text-3xl  { font-size: var(--text-3xl); }
.text-4xl  { font-size: var(--text-4xl); }
.text-5xl  { font-size: var(--text-5xl); }
.text-6xl  { font-size: var(--text-6xl); }

.font-light    { font-weight: 300; }
.font-normal   { font-weight: 400; }
.font-medium   { font-weight: 500; }
.font-semibold { font-weight: 600; }
.font-bold     { font-weight: 700; }

.text-center { text-align: center; }
.text-left   { text-align: left; }
.text-right  { text-align: right; }

.text-primary  { color: var(--color-primary); }
.text-muted    { color: var(--color-text-muted); }
.text-white    { color: var(--color-white); }
.text-dark     { color: var(--color-text); }

.italic { font-style: italic; }

/* ---------------------------------------------------------
   5. Utility Classes
   --------------------------------------------------------- */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border-width: 0;
}

.container {
  width: 100%;
  max-width: var(--container-max);
  margin-inline: auto;
  padding-inline: var(--container-pad);
}

.section {
  padding-block: var(--space-20);
}

@media (max-width: 768px) {
  .section {
    padding-block: var(--space-16);
  }
}

/* Section headers */
.section-eyebrow {
  display: inline-block;
  font-family: var(--font-body);
  font-size: var(--text-sm);
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-primary);
  margin-bottom: var(--space-3);
}

.section-title {
  font-family: var(--font-heading);
  font-size: clamp(var(--text-3xl), 4vw, var(--text-5xl));
  font-weight: 700;
  line-height: 1.15;
  color: var(--color-text);
  margin-bottom: var(--space-4);
}

.section-subtitle {
  font-size: var(--text-lg);
  color: var(--color-text-muted);
  line-height: 1.75;
  max-width: 600px;
}

.section-header {
  margin-bottom: var(--space-12);
}

.section-header.centered {
  text-align: center;
}

.section-header.centered .section-subtitle {
  margin-inline: auto;
}

/* Dividers */
.divider {
  width: 60px;
  height: 3px;
  background: linear-gradient(90deg, var(--color-primary), var(--color-accent));
  border-radius: var(--radius-full);
  margin-bottom: var(--space-6);
}

.divider.centered {
  margin-inline: auto;
}

/* Background variants */
.bg-surface { background-color: var(--color-surface); }
.bg-white   { background-color: var(--color-white); }
.bg-dark    { background-color: var(--color-dark-cta); }

/* ---------------------------------------------------------
   6. Animations & Keyframes
   --------------------------------------------------------- */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fadeInLeft {
  from {
    opacity: 0;
    transform: translateX(-30px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

@keyframes fadeInRight {
  from {
    opacity: 0;
    transform: translateX(30px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

@keyframes fadeIn {
  from { opacity: 0; }
  to   { opacity: 1; }
}

@keyframes scaleIn {
  from {
    opacity: 0;
    transform: scale(0.92);
  }
  to {
    opacity: 1;
    transform: scale(1);
  }
}

@keyframes pulse {
  0%, 100% { transform: scale(1); }
  50%       { transform: scale(1.05); }
}

@keyframes float {
  0%, 100% { transform: translateY(0px); }
  50%       { transform: translateY(-8px); }
}

@keyframes shimmer {
  0%   { background-position: -200% center; }
  100% { background-position: 200% center; }
}

.animate-fadeInUp    { animation: fadeInUp 0.7s ease forwards; }
.animate-fadeInLeft  { animation: fadeInLeft 0.7s ease forwards; }
.animate-fadeInRight { animation: fadeInRight 0.7s ease forwards; }
.animate-fadeIn      { animation: fadeIn 0.5s ease forwards; }
.animate-scaleIn     { animation: scaleIn 0.5s ease forwards; }
.animate-float       { animation: float 4s ease-in-out infinite; }

.delay-100 { animation-delay: 0.1s; }
.delay-200 { animation-delay: 0.2s; }
.delay-300 { animation-delay: 0.3s; }
.delay-400 { animation-delay: 0.4s; }
.delay-500 { animation-delay: 0.5s; }
.delay-600 { animation-delay: 0.6s; }
.delay-700 { animation-delay: 0.7s; }

/* Scroll-triggered reveal */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.7s ease, transform 0.7s ease;
}

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

.reveal-left {
  opacity: 0;
  transform: translateX(-30px);
  transition: opacity 0.7s ease, transform 0.7s ease;
}

.reveal-left.is-visible {
  opacity: 1;
  transform: translateX(0);
}

.reveal-right {
  opacity: 0;
  transform: translateX(30px);
  transition: opacity 0.7s ease, transform 0.7s ease;
}

.reveal-right.is-visible {
  opacity: 1;
  transform: translateX(0);
}