/* Main Styles - Eliana Brereton Portfolio */

/* Base Styles */
html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font-sans);
  font-size: var(--text-base);
  line-height: 1.7; /* Increased for better flow */
  color: var(--color-text-primary);
  background-color: var(--color-background);
  letter-spacing: var(--letter-spacing-normal);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Typography Hierarchy - Premium System */
h1, h2, h3, h4, h5, h6 {
  color: var(--color-text-primary);
  margin: 0;
}

/* H1 - Hero/Page Titles */
h1 {
  font-family: var(--font-sans);
  font-size: var(--text-5xl); /* 3rem / 48px */
  font-weight: var(--font-bold); /* 700 */
  line-height: 1.2;
  letter-spacing: var(--letter-spacing-tight);
  margin-bottom: 1.5rem;
}

/* H2 - Section Titles */
h2 {
  font-family: var(--font-sans);
  font-size: var(--text-3xl); /* 2.25rem / 36px */
  font-weight: var(--font-semibold); /* 600 */
  line-height: 1.3;
  letter-spacing: var(--letter-spacing-normal);
  margin-top: 3rem;
  margin-bottom: 1.5rem;
}

/* H3 - Card Titles - Sans, Bold */
h3 {
  font-family: var(--font-sans);
  font-size: var(--text-2xl); /* 1.875rem / 30px */
  font-weight: var(--font-semibold);
  line-height: 1.4;
  letter-spacing: var(--letter-spacing-normal);
  margin-bottom: 1rem;
}

/* H4 - Subsection Headers - Sans, Medium */
h4 {
  font-family: var(--font-sans);
  font-size: var(--text-lg); /* 1.125rem / 18px */
  font-weight: var(--font-medium);
  line-height: 1.5;
  letter-spacing: var(--letter-spacing-wide);
  margin-bottom: 0.75rem;
  text-transform: uppercase; /* Subtle sophistication */
}

/* Paragraph spacing for flow */
p {
  margin-bottom: 1.25rem;
  color: var(--color-text-secondary);
}

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

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

a:hover {
  color: var(--color-accent-hover);
  text-decoration: underline;
}

a:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
  border-radius: var(--border-radius-sm);
}

strong {
  font-weight: var(--font-semibold);
  color: var(--color-text-primary);
}

/* Navigation */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  background-color: rgba(250, 250, 250, 0.95);
  backdrop-filter: blur(8px);
  border-bottom: var(--border-width) solid var(--color-border);
  z-index: var(--z-nav);
  transition: box-shadow var(--transition-base);
}

.nav.scrolled {
  box-shadow: var(--shadow-sm);
}

.nav-container {
  max-width: var(--max-width-content);
  margin: 0 auto;
  padding: 0 var(--container-padding);
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-brand {
  font-size: var(--text-lg);
  font-weight: var(--font-semibold);
  color: var(--color-text-primary);
}

.nav-menu {
  display: flex;
  gap: var(--space-4);
  align-items: center;
}

.nav-link {
  color: var(--color-text-secondary);
  font-size: var(--text-sm);
  font-weight: var(--font-medium);
  transition: color var(--transition-fast);
}

.nav-link:hover,
.nav-link.active {
  color: var(--color-accent);
  text-decoration: none;
}

/* Mobile menu toggle (hidden by default) */
.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--space-1);
}

/* Main Layout */
main {
  margin-top: var(--nav-height);
  min-height: calc(100vh - var(--nav-height));
}

.container {
  max-width: var(--max-width-content);
  margin: 0 auto;
  padding: var(--space-6) var(--container-padding);
}

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

/* Hero Section (Homepage) */
.hero {
  display: grid;
  grid-template-columns: 1fr 2fr;
  gap: var(--space-8);
  align-items: center;
  justify-items: center;
  min-height: calc(100vh - var(--nav-height) - var(--space-12));
  padding: var(--space-8) 0;
  text-align: center;
}

.hero-image {
  width: 100%;
  max-width: 300px;
  margin: 0 auto;
}

.hero-image img {
  width: 100%;
  height: auto;
  border-radius: var(--border-radius-full);
  box-shadow: var(--shadow-md);
}

.hero-content h1 {
  margin-bottom: var(--space-2);
}

/* Hero Subtitle - Distinctive styling */
.hero-subtitle {
  font-family: var(--font-sans);
  font-size: var(--text-xl);
  font-weight: var(--font-medium);
  letter-spacing: var(--letter-spacing-wider);
  text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: 1.5rem;
}

.hero-description {
  font-size: var(--text-lg);
  color: var(--color-text-secondary);
  margin-bottom: var(--space-4);
  line-height: var(--leading-relaxed);
}

/* Buttons */
.btn {
  display: inline-block;
  padding: var(--space-2) var(--space-4);
  background-color: var(--color-accent);
  color: var(--color-surface);
  font-weight: var(--font-medium);
  border-radius: var(--border-radius-md);
  transition: all var(--transition-base);
  border: none;
  cursor: pointer;
}

.btn:hover {
  background-color: var(--color-accent-hover);
  text-decoration: none;
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

.btn-secondary {
  background-color: transparent;
  color: var(--color-accent);
  border: var(--border-width) solid var(--color-accent);
}

.btn-secondary:hover {
  background-color: var(--color-accent);
  color: var(--color-surface);
}

/* Section Styles */
.section {
  margin-bottom: var(--space-12);
}

.section-title {
  font-size: var(--text-4xl);
  margin-bottom: var(--space-6);
  padding-bottom: var(--space-2);
  border-bottom: 2px solid var(--color-border);
}

/* Card Components */
.card {
  background-color: var(--color-surface);
  border: var(--border-width) solid var(--color-border);
  border-radius: var(--border-radius-lg);
  padding: var(--space-4);
  margin-bottom: var(--space-4);
  transition: all var(--transition-base);
}

.card:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}

.card-title {
  font-size: var(--text-2xl);
  margin-bottom: var(--space-2);
}

.card-subtitle {
  font-size: var(--text-base);
  color: var(--color-text-tertiary);
  margin-bottom: var(--space-3);
}

.card-content {
  color: var(--color-text-secondary);
}

/* Lists */
ul, ol {
  margin-bottom: var(--space-3);
  padding-left: var(--space-4);
}

ul {
  list-style: disc;
}

ol {
  list-style: decimal;
}

li {
  margin-bottom: var(--space-1);
  color: var(--color-text-secondary);
}

/* Dividers */
hr {
  border: none;
  border-top: var(--border-width) solid var(--color-border);
  margin: var(--space-6) 0;
}

/* Skills/Tags */
.tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1);
  margin-top: var(--space-2);
}

.tag {
  display: inline-block;
  padding: var(--space-1) var(--space-2);
  background-color: var(--color-border-light);
  color: var(--color-text-secondary);
  font-size: var(--text-sm);
  border-radius: var(--border-radius-full);
  font-weight: var(--font-medium);
}

/* Footer */
.footer {
  background-color: var(--color-surface);
  border-top: var(--border-width) solid var(--color-border);
  padding: var(--space-6) 0;
  margin-top: var(--space-12);
}

.footer-content {
  max-width: var(--max-width-content);
  margin: 0 auto;
  padding: 0 var(--container-padding);
  text-align: center;
  color: var(--color-text-tertiary);
  font-size: var(--text-sm);
}

/* ========================================
   SPECIAL TYPOGRAPHY CLASSES
   ======================================== */

/* Section Title - Enhanced with accent underline */
.section-title {
  font-family: var(--font-sans);
  font-size: var(--text-4xl);
  font-weight: var(--font-bold);
  letter-spacing: var(--letter-spacing-tight);
  padding-bottom: 1.5rem;
  margin-top: var(--space-12);
  margin-bottom: 3rem;
  border-bottom: 2px solid var(--color-accent);
  position: relative;
  text-align: center;
}

.section-title::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 50%;
  transform: translateX(-50%);
  width: 80px;
  height: 4px;
  background: var(--color-accent);
  border-radius: 2px;
}

/* Card Title - Updated */
.card-title {
  font-family: var(--font-sans);
  font-size: var(--text-2xl);
  font-weight: var(--font-semibold);
  letter-spacing: var(--letter-spacing-normal);
  color: var(--color-text-primary);
  margin-bottom: 0.5rem;
}

/* Card Subtitle - Metadata */
.card-subtitle {
  font-family: var(--font-sans);
  font-size: var(--text-sm);
  font-weight: var(--font-regular);
  color: var(--color-text-secondary);
  letter-spacing: var(--letter-spacing-wide);
  margin-bottom: 1rem;
}

/* Lead paragraph - Hero intro */
.lead {
  font-size: var(--text-lg);
  line-height: 1.8;
  color: var(--color-text-secondary);
  font-weight: var(--font-regular);
}

/* ========================================
   ANIMATION SYSTEM
   ======================================== */

/* Scroll Reveal Animations - Intersection Observer Triggered */
.scroll-reveal {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity var(--transition-smooth),
              transform var(--transition-smooth);
}

.scroll-reveal.revealed {
  opacity: 1;
  transform: translateY(0);
}

/* Staggered entrance delays */
.scroll-reveal:nth-child(1) { transition-delay: 0ms; }
.scroll-reveal:nth-child(2) { transition-delay: 100ms; }
.scroll-reveal:nth-child(3) { transition-delay: 200ms; }
.scroll-reveal:nth-child(4) { transition-delay: 300ms; }
.scroll-reveal:nth-child(5) { transition-delay: 400ms; }
.scroll-reveal:nth-child(6) { transition-delay: 500ms; }

/* Fade-in on page load */
.fade-in {
  animation: fadeIn var(--transition-smooth) var(--ease-out-expo);
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Hero entrance animation */
.hero-entrance {
  animation: heroEntrance 1s var(--ease-out-expo);
}

@keyframes heroEntrance {
  from {
    opacity: 0;
    transform: translateY(40px) scale(0.98);
  }
  to {
    opacity: 1;
    transform: translateY(0) scale(1);
  }
}

/* Enhanced Card Hover States */
.card {
  position: relative;
  overflow: hidden;
}

.card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--color-accent), transparent);
  transform: translateX(-100%);
  transition: transform var(--transition-smooth);
}

.card:hover::before {
  transform: translateX(0);
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 24px rgba(0, 0, 0, 0.08),
              0 4px 8px rgba(0, 0, 0, 0.04);
  border-color: var(--color-accent);
}

/* Enhanced Button Hover with Ripple */
.btn {
  position: relative;
  overflow: hidden;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.btn::before {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  width: 0;
  height: 0;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.3);
  transform: translate(-50%, -50%);
  transition: width 0.6s, height 0.6s;
}

.btn:active::before {
  width: 300px;
  height: 300px;
}

.btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 16px rgba(0, 0, 0, 0.15),
              0 4px 8px rgba(0, 0, 0, 0.1);
  opacity: 0.9;
}

.btn:active {
  transform: translateY(-1px);
}

/* Navigation Active Indicator - Smooth Slide */
.nav-link {
  position: relative;
  transition: color var(--transition-base);
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--color-accent);
  transition: width var(--transition-base) var(--ease-out-expo);
}

.nav-link:hover::after,
.nav-link.active::after {
  width: 100%;
}

/* Tag/Badge Hover Animation */
.tag {
  transition: all var(--transition-fast);
  cursor: default;
}

.tag:hover {
  background: var(--color-accent);
  color: white;
  border-color: var(--color-accent);
  transform: translateY(-2px) scale(1.05);
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
}

/* Link Underline Animation */
a:not(.btn):not(.nav-link):not(.card) {
  position: relative;
  background-image: linear-gradient(to right, var(--color-accent), var(--color-accent));
  background-size: 0% 2px;
  background-repeat: no-repeat;
  background-position: left bottom;
  transition: background-size var(--transition-base) var(--ease-out-expo);
}

a:not(.btn):not(.nav-link):not(.card):hover {
  background-size: 100% 2px;
  text-decoration: none;
}

/* Image hover effects */
img {
  transition: transform var(--transition-smooth);
}

.hero-image img:hover {
  transform: scale(1.05);
}

/* Pulse animation for important CTAs */
@keyframes pulse {
  0%, 100% {
    box-shadow: 0 0 0 0 rgba(0, 0, 0, 0.4);
  }
  50% {
    box-shadow: 0 0 0 12px rgba(0, 0, 0, 0);
  }
}

.btn-pulse {
  animation: pulse 2s infinite;
}

/* Performance optimizations */
.card,
.btn,
.nav-link,
.scroll-reveal {
  will-change: transform, opacity;
}

/* Reduce motion for accessibility */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }

  .scroll-reveal {
    opacity: 1;
    transform: none;
  }

  .hero-entrance,
  .fade-in {
    animation: none;
  }
}

/* Utility Classes */
.text-center {
  text-align: center;
}

.mt-1 { margin-top: var(--space-1); }
.mt-2 { margin-top: var(--space-2); }
.mt-3 { margin-top: var(--space-3); }
.mt-4 { margin-top: var(--space-4); }
.mt-6 { margin-top: var(--space-6); }
.mt-8 { margin-top: var(--space-8); }

.mb-1 { margin-bottom: var(--space-1); }
.mb-2 { margin-bottom: var(--space-2); }
.mb-3 { margin-bottom: var(--space-3); }
.mb-4 { margin-bottom: var(--space-4); }
.mb-6 { margin-bottom: var(--space-6); }
.mb-8 { margin-bottom: var(--space-8); }

/* Responsive Design - Mobile */
@media (max-width: 768px) {
  :root {
    --nav-height: 56px;
    --container-padding: var(--space-3);
  }

  h1 {
    font-size: var(--text-4xl);
  }

  h2 {
    font-size: var(--text-2xl);
  }

  h3 {
    font-size: var(--text-xl);
  }

  .hero {
    grid-template-columns: 1fr;
    gap: var(--space-4);
    text-align: center;
    padding: var(--space-6) 0;
  }

  .hero-image {
    max-width: 200px;
  }

  .nav-menu {
    display: none;
    position: absolute;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background-color: var(--color-background);
    flex-direction: column;
    gap: 0;
    padding: var(--space-2) 0;
    border-bottom: var(--border-width) solid var(--color-border);
    box-shadow: var(--shadow-md);
  }

  .nav-menu.active {
    display: flex;
  }

  .nav-link {
    padding: var(--space-2) var(--container-padding);
    width: 100%;
  }

  .nav-toggle {
    display: block;
  }
}

/* Tablet */
@media (max-width: 1024px) and (min-width: 769px) {
  .hero {
    gap: var(--space-6);
  }
}

/* Greyscale Redesign - New Components */

/* How I Can Help Section */
.help-grid {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-6);
  margin-top: var(--space-6);
  max-width: 700px;
  margin-left: auto;
  margin-right: auto;
}

.help-item {
  text-align: center;
  width: 100%;
}

.help-item h3 {
  font-size: var(--text-xl);
  font-weight: var(--font-semibold);
  margin-bottom: var(--space-2);
}

.help-item p {
  color: var(--color-text-secondary);
  line-height: 1.7;
}

/* Technical Skills Section */
.skill-category {
  margin-bottom: var(--space-6);
}

.skill-category h3 {
  font-size: var(--text-lg);
  font-weight: var(--font-semibold);
  margin-bottom: var(--space-3);
  color: var(--color-text-primary);
}

/* Resume Button in Navigation */
.btn-resume {
  position: absolute;
  right: var(--container-padding);
  top: 50%;
  transform: translateY(-50%);
  padding: var(--space-2) var(--space-4);
  font-size: var(--text-sm);
}

/* Research Figures Page Components */
.research-summary {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--border-radius-lg);
  padding: var(--space-6);
  margin: var(--space-6) 0;
}

.research-summary p {
  margin-bottom: var(--space-3);
}

.research-summary p:last-child {
  margin-bottom: 0;
}

.figure-container {
  margin: var(--space-8) 0;
  padding: var(--space-4);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--border-radius-lg);
}

.research-figure {
  width: 100%;
  height: auto;
  border-radius: var(--border-radius-md);
  margin-bottom: var(--space-4);
}

.figure-caption {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  line-height: 1.7;
  padding: var(--space-2);
}

.figure-caption strong {
  display: block;
  font-size: var(--text-base);
  color: var(--color-text-primary);
  margin-bottom: var(--space-2);
}

@media (max-width: 768px) {
  .btn-resume {
    display: none; /* Hide on mobile, accessible via hamburger menu */
  }
}

/* Print Styles */
@media print {
  .nav,
  .footer {
    display: none;
  }

  main {
    margin-top: 0;
  }

  a {
    text-decoration: underline;
  }
}