:root {
  --primary-color: #004d40; /* Deep Green */
  --secondary-color: #0288d1; /* Medical Blue */
  --accent-color: #d81b60; /* Alert/Action Red */
  --text-color: #333;
  --bg-color: #f9f9f9;
  --white: #ffffff;
  --font-main: 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
  --padding-container: 2rem 5%;
}

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

body {
  font-family: var(--font-main);
  background-color: var(--bg-color);
  color: var(--text-color);
  line-height: 1.6;
}

a {
  text-decoration: none;
  color: inherit;
}

ul {
  list-style: none;
}

/* Header & Nav */
header {
  background-color: var(--white);
  box-shadow: 0 2px 5px rgba(0,0,0,0.1);
  position: sticky;
  top: 0;
  z-index: 1000;
}

.top-bar {
  background-color: var(--primary-color);
  color: var(--white);
  display: flex;
  justify-content: space-between;
  padding: 0.5rem 5%;
  font-size: 0.9rem;
}

.nav-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem 5%;
}

.logo img {
  height: 60px;
}

nav ul {
  display: flex;
  gap: 2rem;
}

nav a {
  font-weight: 600;
  color: var(--primary-color);
  transition: color 0.3s;
}

nav a:hover {
  color: var(--secondary-color);
}

.mobile-menu-btn {
  display: none;
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
}

/* Hero Section */
.hero {
  background: linear-gradient(rgba(0, 77, 64, 0.8), rgba(2, 136, 209, 0.6)), url('https://placehold.co/1920x1080?text=Healthcare+Without+Borders') center/cover no-repeat;
  color: var(--white);
  padding: 8rem 5%;
  text-align: center;
}

.hero h1 {
  font-size: 3rem;
  margin-bottom: 1rem;
}

.hero p {
  font-size: 1.25rem;
  margin-bottom: 2rem;
  max-width: 800px;
  margin-left: auto;
  margin-right: auto;
}

.btn {
  display: inline-block;
  padding: 0.8rem 1.5rem;
  border-radius: 5px;
  font-weight: 600;
  transition: transform 0.2s, background-color 0.2s;
  border: none;
  cursor: pointer;
}

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

.btn-primary:hover {
  background-color: #ad1457;
  transform: translateY(-2px);
}

.btn-secondary {
  background-color: var(--white);
  color: var(--primary-color);
  margin-left: 1rem;
}

.btn-secondary:hover {
  background-color: #f1f1f1;
  transform: translateY(-2px);
}

/* Sections */
section {
  padding: 4rem 5%;
}

.section-title {
  text-align: center;
  margin-bottom: 3rem;
  color: var(--primary-color);
  font-size: 2.2rem;
}

.grid-4 {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 2rem;
}

.feature-card {
  background: var(--white);
  padding: 2rem;
  border-radius: 8px;
  box-shadow: 0 4px 6px rgba(0,0,0,0.05);
  text-align: center;
  transition: transform 0.3s;
}

.feature-card:hover {
  transform: translateY(-5px);
}

.feature-icon {
  font-size: 2.5rem;
  color: var(--secondary-color);
  margin-bottom: 1rem;
}

/* Service Highlights */
.service-preview {
  display: flex;
  flex-direction: column;
  background: var(--white);
  border-radius: 8px;
  overflow: hidden;
  box-shadow: 0 4px 10px rgba(0,0,0,0.1);
}

.service-preview img {
  height: 200px;
  object-fit: cover;
}

.service-content {
  padding: 1.5rem;
}

.service-content h3 {
  color: var(--primary-color);
  margin-bottom: 0.5rem;
}

/* Footer */
footer {
  background-color: #1a1a1a;
  color: #fff;
  padding: 4rem 5% 1rem;
}

.footer-content {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 2rem;
  margin-bottom: 2rem;
}

.footer-logo h2 {
  color: var(--white);
  margin-bottom: 1rem;
}

.footer-links h3, .footer-contact h3 {
  color: var(--secondary-color);
  margin-bottom: 1rem;
}

.footer-links ul li {
  margin-bottom: 0.5rem;
}

.social-links {
  display: flex;
  gap: 1rem;
  margin-top: 1rem;
}

.copyright {
  text-align: center;
  border-top: 1px solid #333;
  padding-top: 2rem;
  font-size: 0.9rem;
  color: #888;
}

/* Responsive */
@media (max-width: 768px) {
  nav ul {
    display: none; /* Mobile menu implementation later */
  }
  .mobile-menu-btn {
    display: block;
  }
  .hero h1 {
    font-size: 2rem;
  }
}