/* Global Styles & Variables */
:root {
  --primary-color: #003366; /* Deep Navy - Trust/Academic */
  --secondary-color: #4aaaa5; /* Teal/Soft Green - Health/Environment */
  --accent-color: #f0f4f8; /* Light Blue-Grey */
  --text-color: #333333;
  --text-light: #666666;
  --white: #ffffff;
  --surface: #f8f9fa;
  
  --font-main: 'Noto Sans KR', sans-serif;
  --font-heading: 'Noto Sans KR', sans-serif; /* Can switch to serif if needed */
  
  --max-width: 1200px;
  --header-height: 80px;
  --spacing-unit: 1rem;
}

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

body {
  font-family: var(--font-main);
  color: var(--text-color);
  line-height: 1.6;
  background-color: var(--white);
  padding-top: var(--header-height); /* Space for fixed header */
}

a {
  text-decoration: none;
  color: inherit;
  transition: color 0.3s ease;
}

ul {
  list-style: none;
}

img {
  max-width: 100%;
  display: block;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  color: var(--primary-color);
  font-weight: 700;
  margin-bottom: 1rem;
  line-height: 1.3;
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; position: relative; padding-bottom: 0.5rem; }
h3 { font-size: 1.5rem; }

/* Utility Classes */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 20px;
}

.section {
  padding: 80px 0;
}

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

.text-center { text-align: center; }
.mb-1 { margin-bottom: 1rem; }
.mb-2 { margin-bottom: 2rem; }
.mb-4 { margin-bottom: 4rem; }

/* Button Styles */
.btn {
  display: inline-block;
  padding: 12px 24px;
  background-color: var(--primary-color);
  color: var(--white);
  border-radius: 4px;
  font-weight: 500;
  transition: all 0.3s ease;
  border: 1px solid var(--primary-color);
}

.btn:hover {
  background-color: transparent;
  color: var(--primary-color);
}

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

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

/* Header & Navigation */
header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: var(--header-height);
  background-color: rgba(255, 255, 255, 0.95);
  box-shadow: 0 2px 10px rgba(0,0,0,0.05);
  z-index: 1000;
  display: flex;
  align-items: center;
  backdrop-filter: blur(5px);
}

header .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  width: 100%;
}

.logo a {
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--primary-color);
  display: flex;
  flex-direction: column;
  line-height: 1.1;
}

.logo span {
  font-size: 0.8rem;
  font-weight: 400;
  color: var(--secondary-color);
}

.nav-links {
  display: flex;
  gap: 30px;
}

.nav-links a {
  font-weight: 500;
  color: var(--text-color);
  position: relative;
  font-size: 0.95rem;
}

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

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -5px;
  left: 0;
  width: 0;
  height: 2px;
  background-color: var(--secondary-color);
  transition: width 0.3s ease;
}

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

/* Footer */
footer {
  background-color: var(--primary-color);
  color: var(--white);
  padding: 60px 0 30px;
}

.footer-content {
  display: grid;
  grid-template-columns: 1.5fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 40px;
}

.footer-logo h3 {
  color: var(--white);
  margin-bottom: 15px;
}

.footer-info p {
  color: #cccccc;
  font-size: 0.9rem;
  margin-bottom: 10px;
}

.footer-links h4 {
  color: var(--secondary-color);
  font-size: 1.1rem;
  margin-bottom: 20px;
}

.footer-links ul li {
  margin-bottom: 10px;
}

.footer-links a {
  color: #cccccc;
  font-size: 0.9rem;
}

.footer-links a:hover {
  color: var(--white);
}

.footer-bottom {
  border-top: 1px solid rgba(255,255,255,0.1);
  padding-top: 20px;
  text-align: center;
  font-size: 0.85rem;
  color: #999999;
}

/* Mobile Menu */
.hamburger {
  display: none;
  cursor: pointer;
}

.bar {
  width: 25px;
  height: 3px;
  background-color: var(--primary-color);
  margin: 5px 0;
  transition: 0.3s;
}

@media (max-width: 1024px) {
  .nav-links {
    gap: 20px;
  }
}

@media (max-width: 768px) {
  .hamburger {
    display: block;
    z-index: 1001;
  }
  
  .hamburger.active .bar:nth-child(1) {
    transform: rotate(-45deg) translate(-5px, 6px);
  }
  
  .hamburger.active .bar:nth-child(2) {
    opacity: 0;
  }
  
  .hamburger.active .bar:nth-child(3) {
    transform: rotate(45deg) translate(-5px, -6px);
  }
  
  .nav-links {
    position: fixed;
    top: 0;
    right: -100%;
    width: 70%;
    height: 100vh;
    background-color: var(--white);
    flex-direction: column;
    justify-content: center;
    align-items: center;
    box-shadow: -5px 0 15px rgba(0,0,0,0.1);
    transition: 0.3s ease-in-out;
    z-index: 1000;
  }
  
  .nav-links.active {
    right: 0;
  }
  
  .footer-content {
    grid-template-columns: 1fr;
    text-align: center;
  }
}

/* Page Specific Overrides */
/* Hero Section (Home) */
.hero {
  height: 80vh;
  min-height: 500px;
  background: linear-gradient(rgba(0,51,102,0.8), rgba(0,51,102,0.7)), url('https://images.unsplash.com/photo-1532094349884-543bc11b234d?auto=format&fit=crop&w=1920&q=80');
  background-size: cover;
  background-position: center;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  color: var(--white);
}

.hero h1 {
  color: var(--white);
  font-size: 3rem;
  margin-bottom: 1.5rem;
  text-shadow: 0 2px 4px rgba(0,0,0,0.3);
}

.hero p {
  font-size: 1.25rem;
  max-width: 800px;
  margin: 0 auto 2rem;
  font-weight: 300;
}

/* Member Cards */
.member-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 30px;
}

.member-card {
  background: var(--white);
  border: 1px solid #eee;
  border-radius: 8px;
  overflow: hidden;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.member-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 10px 20px rgba(0,0,0,0.05);
}

.member-img {
  width: 100%;
  height: 280px;
  background-color: #eee; /* Placeholder */
  object-fit: cover;
}

.member-info {
  padding: 20px;
}

.member-name {
  color: var(--primary-color);
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: 5px;
}

.member-role {
  color: var(--secondary-color);
  font-size: 0.9rem;
  font-weight: 500;
  margin-bottom: 10px;
}

.member-desc {
  font-size: 0.9rem;
  color: var(--text-light);
}

/* Research Areas */
.research-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 30px;
}

.research-item {
  padding: 30px;
  background: var(--white);
  border-radius: 8px;
  border-left: 4px solid var(--secondary-color);
  box-shadow: 0 4px 6px rgba(0,0,0,0.02);
}

.research-item h3 {
  margin-bottom: 15px;
}

/* Publication List */
.pub-year {
  font-size: 1.5rem;
  color: var(--primary-color);
  margin: 30px 0 15px;
  border-bottom: 2px solid var(--secondary-color);
  display: inline-block;
}

.pub-list li {
  padding: 15px 0;
  border-bottom: 1px solid #eee;
}

.pub-title {
  font-weight: 600;
  color: var(--text-color);
  display: block;
  margin-bottom: 5px;
}

.pub-meta {
  font-size: 0.9rem;
  color: var(--text-light);
}

/* ARECC Framework */
.arecc-container {
  display: flex;
  justify-content: space-around;
  flex-wrap: wrap;
  gap: 20px;
  margin: 40px 0;
}

.arecc-step {
  text-align: center;
  flex: 1;
  min-width: 150px;
  position: relative;
}

.arecc-circle {
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background-color: var(--surface);
  border: 2px solid var(--secondary-color);
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 15px;
  font-weight: 700;
  color: var(--primary-color);
  font-size: 1.2rem;
  transition: all 0.3s ease;
}

.arecc-step:hover .arecc-circle {
  background-color: var(--secondary-color);
  color: var(--white);
}