/* ============================================
   Modern Academic Portfolio
   Terminal aesthetics + Natural elements
   ============================================ */

:root {
  /* Light Mode Colors */
  --color-bg: #faf9f7;
  --color-bg-alt: #1a1a1a;
  --color-text: #1a1a1a;
  --color-text-light: #555555;
  --color-text-inverse: #f5f5f5;
  --color-accent: #2d6a4f;
  --color-accent-light: #40916c;
  --color-border: #e0e0e0;
  --color-hover: #f0efe9;
  --color-card: #ffffff;

  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono: 'JetBrains Mono', 'SF Mono', 'Monaco', monospace;
  --font-serif: 'Playfair Display', Georgia, serif;

  /* Spacing */
  --spacing-xs: 0.5rem;
  --spacing-sm: 1rem;
  --spacing-md: 2rem;
  --spacing-lg: 4rem;
  --spacing-xl: 6rem;

  /* Layout */
  --max-width: 1000px;
  --max-width-narrow: 720px;
}

/* Dark Mode */
[data-theme="dark"] {
  --color-bg: #0d1117;
  --color-bg-alt: #161b22;
  --color-text: #e6edf3;
  --color-text-light: #8b949e;
  --color-text-inverse: #1a1a1a;
  --color-accent: #40916c;
  --color-accent-light: #52b788;
  --color-border: #30363d;
  --color-hover: #21262d;
  --color-card: #161b22;
}

/* ============================================
   Reset & Base
   ============================================ */

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  font-size: 1.0625rem;
  line-height: 1.75;
  color: var(--color-text);
  background: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  transition: background 0.3s ease, color 0.3s ease;
  position: relative;
}

/* Content layers above background animations */
.nav, .hero, .section, .footer, .floating-toc {
  position: relative;
  z-index: 10;
}

/* ============================================
   Typography
   ============================================ */

h1, h2, h3, h4 {
  font-weight: 600;
  line-height: 1.3;
  letter-spacing: -0.02em;
}

h1 {
  font-size: 2.75rem;
  font-weight: 700;
}

h2 {
  font-size: 1.75rem;
  margin-bottom: var(--spacing-md);
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

h2 .section-number {
  font-family: var(--font-mono);
  font-size: 0.875rem;
  color: var(--color-accent);
  opacity: 0.8;
}

h3 {
  font-size: 1.25rem;
}

p {
  margin-bottom: var(--spacing-sm);
  color: var(--color-text-light);
}

a {
  color: var(--color-accent);
  text-decoration: none;
  transition: all 0.2s ease;
}

a:hover {
  color: var(--color-accent-light);
}

code, .mono {
  font-family: var(--font-mono);
}

strong {
  font-weight: 600;
  color: var(--color-text);
}

/* ============================================
   Navigation
   ============================================ */

.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  transition: all 0.3s ease;
}

.nav.scrolled {
  background: rgba(250, 249, 247, 0.95);
  backdrop-filter: blur(10px);
}

[data-theme="dark"] .nav.scrolled {
  background: rgba(13, 17, 23, 0.95);
}

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

.nav-logo {
  font-family: var(--font-mono);
  font-size: 0.9375rem;
  color: var(--color-text);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.nav-logo::before {
  content: '>';
  color: var(--color-accent);
}

.nav-links {
  display: flex;
  gap: var(--spacing-md);
  list-style: none;
  align-items: center;
}

.nav-links a {
  color: var(--color-text-light);
  font-size: 0.875rem;
  font-family: var(--font-mono);
  transition: color 0.2s ease;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--color-accent);
}

/* Theme Toggle */
.theme-toggle {
  background: none;
  border: 1px solid var(--color-border);
  border-radius: 6px;
  padding: 0.5rem;
  cursor: pointer;
  color: var(--color-text);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.2s ease;
}

.theme-toggle:hover {
  background: var(--color-hover);
  border-color: var(--color-accent);
}

/* ============================================
   Layout
   ============================================ */

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

.section {
  padding: var(--spacing-xl) 0;
}

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

[data-theme="dark"] .section-dark {
  background: var(--color-bg-alt);
  color: var(--color-text);
}

.hero {
  min-height: 85vh;
  display: flex;
  align-items: center;
  padding-top: 80px;
  position: relative;
  overflow: hidden;
}

/* Natural element - subtle leaf pattern */
.hero::before {
  content: '';
  position: absolute;
  top: 10%;
  right: -5%;
  width: 400px;
  height: 400px;
  background: radial-gradient(ellipse, var(--color-accent) 0%, transparent 70%);
  opacity: 0.05;
  border-radius: 50%;
  pointer-events: none;
}

.hero::after {
  content: '';
  position: absolute;
  bottom: 20%;
  left: -10%;
  width: 300px;
  height: 300px;
  background: radial-gradient(ellipse, var(--color-accent-light) 0%, transparent 70%);
  opacity: 0.04;
  border-radius: 50%;
  pointer-events: none;
}

/* ============================================
   Profile Section
   ============================================ */

.profile-grid {
  display: grid;
  grid-template-columns: 1fr 220px;
  gap: var(--spacing-lg);
  align-items: start;
}

.profile-image-wrapper {
  position: relative;
}

.profile-image {
  width: 220px;
  height: 220px;
  border-radius: 12px;
  object-fit: cover;
  filter: grayscale(20%);
  transition: all 0.4s ease;
}

.profile-image:hover {
  filter: grayscale(0%);
  transform: scale(1.02);
}

/* Natural frame around image */
.profile-image-wrapper::before {
  content: '';
  position: absolute;
  top: -8px;
  left: -8px;
  right: 8px;
  bottom: 8px;
  border: 2px solid var(--color-accent);
  border-radius: 12px;
  opacity: 0.3;
  transition: all 0.3s ease;
}

.profile-image-wrapper:hover::before {
  opacity: 0.6;
  top: -12px;
  left: -12px;
}

/* Typing animation */
.typing-name {
  display: inline-block;
  overflow: hidden;
  border-right: 3px solid var(--color-accent);
  white-space: nowrap;
  animation: typing 2s steps(20, end), blink 0.75s step-end infinite;
}

@keyframes typing {
  from { width: 0; }
  to { width: 100%; }
}

@keyframes blink {
  from, to { border-color: transparent; }
  50% { border-color: var(--color-accent); }
}

.terminal-prompt {
  font-family: var(--font-mono);
  font-size: 0.875rem;
  color: var(--color-text-light);
  margin-bottom: var(--spacing-xs);
}

.terminal-prompt::before {
  content: '$ ';
  color: var(--color-accent);
}

.profile-meta {
  display: flex;
  gap: var(--spacing-md);
  flex-wrap: wrap;
  margin-top: var(--spacing-sm);
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  color: var(--color-text-light);
}

.meta-item {
  display: flex;
  align-items: center;
  gap: 0.375rem;
}

/* Social Links */
.social-links {
  display: flex;
  gap: var(--spacing-sm);
  margin-top: var(--spacing-md);
}

.social-link {
  width: 42px;
  height: 42px;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--color-border);
  border-radius: 8px;
  color: var(--color-text-light);
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.social-link:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
  transform: translateY(-3px);
  box-shadow: 0 4px 12px rgba(45, 106, 79, 0.15);
}

/* ============================================
   Floating Table of Contents
   ============================================ */

.floating-toc {
  position: fixed;
  left: 2rem;
  top: 50%;
  transform: translateY(-50%);
  z-index: 100;
  display: none;
}

@media (min-width: 1200px) {
  .floating-toc {
    display: block;
  }
}

.floating-toc ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.floating-toc a {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  color: var(--color-text-light);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  transition: all 0.2s ease;
}

.floating-toc a::before {
  content: '';
  width: 12px;
  height: 2px;
  background: var(--color-border);
  transition: all 0.2s ease;
}

.floating-toc a:hover,
.floating-toc a.active {
  color: var(--color-accent);
}

.floating-toc a:hover::before,
.floating-toc a.active::before {
  width: 24px;
  background: var(--color-accent);
}

/* ============================================
   Publications
   ============================================ */

.publication-item {
  padding: var(--spacing-md);
  border-left: 2px solid var(--color-border);
  margin-bottom: var(--spacing-md);
  transition: all 0.3s ease;
  position: relative;
}

.publication-item::before {
  content: '';
  position: absolute;
  left: -6px;
  top: var(--spacing-md);
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--color-bg);
  border: 2px solid var(--color-border);
  transition: all 0.3s ease;
}

.publication-item:hover {
  border-left-color: var(--color-accent);
  background: var(--color-hover);
  transform: translateX(4px);
}

.publication-item:hover::before {
  border-color: var(--color-accent);
  background: var(--color-accent);
}

.publication-title {
  font-size: 1.0625rem;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: 0.375rem;
  line-height: 1.4;
}

.publication-authors {
  font-size: 0.875rem;
  color: var(--color-text-light);
  margin-bottom: 0.5rem;
  font-family: var(--font-mono);
}

.publication-venue {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 600;
  color: white;
  background: var(--color-accent);
  padding: 0.25rem 0.625rem;
  border-radius: 4px;
  margin-right: 0.5rem;
}

/* ============================================
   Projects
   ============================================ */

.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: var(--spacing-md);
}

.project-card {
  background: var(--color-card);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: var(--spacing-md);
  transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
  position: relative;
  overflow: hidden;
}

.project-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 3px;
  background: linear-gradient(90deg, var(--color-accent), var(--color-accent-light));
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.4s ease;
}

.project-card:hover {
  box-shadow: 0 12px 40px rgba(0, 0, 0, 0.1);
  border-color: var(--color-accent);
}

.project-card:hover::before {
  transform: scaleX(1);
}

.project-number {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--color-accent);
  margin-bottom: 0.5rem;
}

.project-title {
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
}

.project-description {
  font-size: 0.9375rem;
  color: var(--color-text-light);
  margin-bottom: var(--spacing-sm);
}

.project-tags {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.tag {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  color: var(--color-text-light);
  background: var(--color-hover);
  padding: 0.25rem 0.5rem;
  border-radius: 4px;
  border: 1px solid var(--color-border);
  transition: all 0.2s ease;
}

.tag:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

/* ============================================
   News
   ============================================ */

.news-item {
  display: grid;
  grid-template-columns: 100px 1fr;
  gap: var(--spacing-md);
  padding: var(--spacing-sm) 0;
  border-bottom: 1px solid var(--color-border);
  transition: all 0.2s ease;
}

.news-item:last-child {
  border-bottom: none;
}

.news-item:hover {
  padding-left: var(--spacing-sm);
  background: var(--color-hover);
  margin: 0 calc(-1 * var(--spacing-sm));
  padding-right: var(--spacing-sm);
  border-radius: 6px;
}

.news-date {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  color: var(--color-accent);
  font-weight: 500;
}

.news-content {
  font-size: 0.9375rem;
  color: var(--color-text-light);
}

/* ============================================
   Buttons
   ============================================ */

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  font-family: var(--font-mono);
  font-size: 0.875rem;
  font-weight: 500;
  border-radius: 8px;
  transition: all 0.3s ease;
  cursor: pointer;
  border: none;
}

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

.btn-primary:hover {
  background: var(--color-accent-light);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(45, 106, 79, 0.3);
  color: white;
}

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

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

/* ============================================
   Footer
   ============================================ */

.footer {
  border-top: 1px solid var(--color-border);
  padding: var(--spacing-lg) 0;
  text-align: center;
}

.footer p {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  color: var(--color-text-light);
}

/* ============================================
   Animations
   ============================================ */

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

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

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

.animate {
  opacity: 0;
}

.animate.visible {
  animation: fadeInUp 0.7s ease forwards;
}

.animate-left.visible {
  animation: slideInLeft 0.7s ease forwards;
}

.animate-right.visible {
  animation: slideInRight 0.7s ease forwards;
}

/* Stagger delays */
.delay-1 { animation-delay: 0.1s; }
.delay-2 { animation-delay: 0.2s; }
.delay-3 { animation-delay: 0.3s; }
.delay-4 { animation-delay: 0.4s; }
.delay-5 { animation-delay: 0.5s; }
.delay-6 { animation-delay: 0.6s; }

/* Hero animations - immediate on page load */
.hero-animate {
    opacity: 0;
    transform: translateY(30px);
    animation: fadeInUp 0.8s cubic-bezier(0.16, 1, 0.3, 1) forwards;
    animation-delay: calc(var(--delay, 0) * 0.12s);
}

.hero-animate-right {
    opacity: 0;
    transform: translateX(50px);
    animation: slideInRight 0.8s cubic-bezier(0.16, 1, 0.3, 1) forwards;
    animation-delay: calc(var(--delay, 0) * 0.12s);
}

/* ============================================
   Responsive
   ============================================ */

@media (max-width: 768px) {
  html {
    font-size: 15px;
  }

  h1 {
    font-size: 2rem;
  }

  .profile-grid {
    grid-template-columns: 1fr;
    text-align: center;
  }

  .profile-image-wrapper {
    margin: 0 auto var(--spacing-md);
  }

  .profile-image {
    width: 180px;
    height: 180px;
  }

  .profile-meta {
    justify-content: center;
  }

  .social-links {
    justify-content: center;
  }

  .nav-links {
    gap: var(--spacing-sm);
  }

  .news-item {
    grid-template-columns: 1fr;
    gap: 0.25rem;
  }

  .hero {
    min-height: auto;
    padding-top: 100px;
    padding-bottom: var(--spacing-lg);
  }
}

/* ============================================
   Natural Decorative Elements
   ============================================ */

.leaf-decoration {
  position: absolute;
  width: 200px;
  height: 200px;
  opacity: 0.03;
  pointer-events: none;
}

.section-nature-bg {
  position: relative;
}

.section-nature-bg::before {
  content: '';
  position: absolute;
  top: 0;
  right: 0;
  width: 50%;
  height: 100%;
  background: linear-gradient(135deg, transparent 40%, var(--color-accent) 100%);
  opacity: 0.02;
  pointer-events: none;
}