* {
  box-sizing: border-box;
}

html, body {
  height: 100%;
  margin: 0;
  display: flex;
  flex-direction: column;
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background-color: #f5f7fa;
  color: #333;
}

/* ========== HEADER ========== */
header {
  background: linear-gradient(90deg, #2c3e50, #34495e);
  color: #ffffff;
  padding: 40px 20px;
  text-align: center;
}

header h1 {
  font-size: 2.5rem;
  margin-bottom: 10px;
  text-shadow: 1px 1px 2px rgba(0, 0, 0, 0.3);
  font-weight: 600;
}

header p {
  font-size: 1.1rem;
  text-shadow: 1px 1px 1px rgba(0, 0, 0, 0.2);
  margin: 0;
  opacity: 0.95;
}

/* ========== NAVIGATION ========== */
nav {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 30px;
  padding: 15px 20px;
  background-color: #1a1a2e;
  border-bottom: 1px solid #e0e0e0;
  flex-wrap: wrap;
}

nav a {
  color: white;
  text-decoration: none;
  font-weight: 500;
  font-size: 1rem;
  padding: 8px 12px;
  position: relative;
  transition: color 0.3s ease;
  white-space: nowrap;
}

nav a:not(.dropdown-toggle)::after {
  content: '';
  position: absolute;
  width: 0%;
  height: 2px;
  bottom: 0;
  left: 0;
  background-color: #3498db;
  transition: width 0.3s ease;
}

nav a:hover {
  color: #3498db;
}

nav a:not(.dropdown-toggle):hover::after {
  width: 100%;
}

/* Dropdown */
.dropdown {
  position: relative;
  display: flex;
  align-items: center;
}

.dropdown-toggle {
  cursor: pointer;
  color: white;
  text-decoration: none;
  font-weight: 500;
  font-size: 1rem;
  padding: 8px 12px;
  position: relative;
  transition: color 0.3s;
  display: inline-block;
}

.dropdown-toggle::after {
  content: '▼';
  font-size: 0.6rem;
  transition: transform 0.3s;
  display: inline-block;
  margin-left: 5px;
}

.dropdown.active .dropdown-toggle::after {
  transform: rotate(180deg);
}

.dropdown-menu {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  background-color: white;
  min-width: 180px;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
  border-radius: 8px;
  margin-top: 10px;
  z-index: 1000;
  overflow: hidden;
}

.dropdown.active .dropdown-menu {
  display: block;
  animation: dropdownFade 0.2s ease;
}

@keyframes dropdownFade {
  from {
    opacity: 0;
    transform: translateY(-10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.dropdown-menu a {
  display: block;
  padding: 12px 20px;
  color: #333;
  text-decoration: none;
  font-weight: 400;
  transition: background-color 0.2s;
}

.dropdown-menu a:hover {
  background-color: #f5f5f5;
  color: #2c3e50;
}

.dropdown-menu a::after {
  display: none;
}

#patients-link {
  display: none;
}

/* ========== MAIN CONTENT ========== */
main {
  flex: 1;
  width: 100%;
  max-width: 1000px;
  margin: 30px auto;
  padding: 0 20px;
}

.research-container {
  background: white;
  padding: 40px;
  border-radius: 12px;
  box-shadow: 0 2px 15px rgba(0, 0, 0, 0.08);
}

.research-container h2 {
  color: #2c3e50;
  font-size: 2rem;
  margin-bottom: 30px;
  text-align: center;
  padding-bottom: 15px;
  border-bottom: 3px solid #2c3e50;
  font-weight: 600;
}

.research-section {
  margin-bottom: 35px;
}

.research-section h3 {
  color: #2c3e50;
  font-size: 1.5rem;
  margin-bottom: 15px;
  padding-bottom: 10px;
  border-bottom: 2px solid #e0e0e0;
  font-weight: 600;
}

.research-section p {
  font-size: 1.05rem;
  line-height: 1.8;
  color: #555;
  margin-bottom: 15px;
}

.research-section ul {
  padding-left: 30px;
  margin: 20px 0;
}

.research-section li {
  font-size: 1.05rem;
  line-height: 1.8;
  color: #555;
  margin-bottom: 12px;
}

.research-section strong {
  color: #2c3e50;
  font-weight: 600;
}

/* ========== HIGHLIGHT & INFO BOXES ========== */
.highlight-box {
  background: linear-gradient(135deg, #e8f5e9 0%, #f1f8e9 100%);
  border-left: 5px solid #4caf50;
  padding: 25px;
  border-radius: 10px;
  margin: 30px 0;
}

.highlight-box h4 {
  color: #2c3e50;
  margin-bottom: 12px;
  font-size: 1.25rem;
  font-weight: 600;
}

.highlight-box p {
  margin: 0;
  color: #555;
  font-size: 1.05rem;
  line-height: 1.7;
}

.info-box {
  background: linear-gradient(135deg, #e3f2fd 0%, #f1f8ff 100%);
  border-left: 5px solid #2196f3;
  padding: 25px;
  border-radius: 10px;
  margin: 30px 0;
}

.info-box h4 {
  color: #2c3e50;
  margin-bottom: 12px;
  font-size: 1.25rem;
  font-weight: 600;
}

.info-box p {
  margin: 0;
  color: #555;
  font-size: 1.05rem;
  line-height: 1.7;
}

/* ========== FOOTER ========== */
.footer {
  background-color: #2c3e50;
  color: white;
  text-align: center;
  padding: 20px 10px;
  font-size: 0.9rem;
  margin-top: auto;
  box-shadow: 0 -2px 10px rgba(0, 0, 0, 0.1);
}

.footer p {
  margin: 5px 0;
}

.footer strong {
  font-weight: 600;
}

/* ========== ACCESSIBILITY ========== */
*:focus-visible {
  outline: 2px solid #2c3e50;
  outline-offset: 2px;
}

html {
  scroll-behavior: smooth;
}

/* ========== TABLET RESPONSIVE (481px - 1024px) ========== */
@media (max-width: 1024px) and (min-width: 481px) {
  header h1 {
    font-size: 2.2rem;
  }

  header p {
    font-size: 1.05rem;
  }

  nav {
    gap: 20px;
    padding: 12px 15px;
  }

  nav a {
    font-size: 0.95rem;
    padding: 8px 10px;
  }

  main {
    padding: 0 20px;
    margin: 25px auto;
  }

  .research-container {
    padding: 35px 30px;
  }

  .research-container h2 {
    font-size: 1.85rem;
    margin-bottom: 25px;
  }

  .research-section h3 {
    font-size: 1.4rem;
  }

  .research-section p,
  .research-section li {
    font-size: 1rem;
  }

  .highlight-box,
  .info-box {
    padding: 20px;
    margin: 25px 0;
  }

  .highlight-box h4,
  .info-box h4 {
    font-size: 1.2rem;
  }

  .highlight-box p,
  .info-box p {
    font-size: 1rem;
  }
}

/* ========== MOBILE RESPONSIVE (max-width: 768px) ========== */
@media (max-width: 768px) {
  header {
    padding: 30px 20px;
  }

  header h1 {
    font-size: 2rem;
  }

  header p {
    font-size: 1rem;
  }

  nav {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 0;
  }

  nav a {
    width: 100%;
    text-align: center;
    padding: 14px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    font-size: 1rem;
  }

  nav a:not(.dropdown-toggle)::after {
    display: none;
  }

  .dropdown {
    width: 100%;
  }

  .dropdown-toggle {
    width: 100%;
    text-align: center;
  }

  .dropdown-menu {
    position: static;
    margin-top: 0;
    box-shadow: none;
    border-radius: 0;
    background-color: rgba(255, 255, 255, 0.95);
  }

  .dropdown-menu a {
    padding: 12px 20px;
    border-bottom: 1px solid #e0e0e0;
  }

  main {
    padding: 0 15px;
    margin: 20px auto;
  }

  .research-container {
    padding: 25px 20px;
    border-radius: 8px;
  }

  .research-container h2 {
    font-size: 1.6rem;
    margin-bottom: 20px;
  }

  .research-section {
    margin-bottom: 28px;
  }

  .research-section h3 {
    font-size: 1.3rem;
    margin-bottom: 12px;
  }

  .research-section p,
  .research-section li {
    font-size: 0.95rem;
    line-height: 1.7;
  }

  .research-section ul {
    padding-left: 25px;
    margin: 15px 0;
  }

  .highlight-box,
  .info-box {
    padding: 18px;
    margin: 20px 0;
  }

  .highlight-box h4,
  .info-box h4 {
    font-size: 1.15rem;
  }

  .highlight-box p,
  .info-box p {
    font-size: 0.95rem;
  }

  .footer {
    padding: 18px 10px;
    font-size: 0.85rem;
  }
}

/* ========== SMALL MOBILE (max-width: 480px) ========== */
@media (max-width: 480px) {
  header {
    padding: 25px 15px;
  }

  header h1 {
    font-size: 1.7rem;
  }

  header p {
    font-size: 0.95rem;
  }

  nav a {
    padding: 12px;
    font-size: 0.95rem;
  }

  main {
    padding: 0 12px;
    margin: 15px auto;
  }

  .research-container {
    padding: 20px 15px;
  }

  .research-container h2 {
    font-size: 1.4rem;
    margin-bottom: 18px;
    padding-bottom: 12px;
  }

  .research-section {
    margin-bottom: 25px;
  }

  .research-section h3 {
    font-size: 1.2rem;
    margin-bottom: 10px;
    padding-bottom: 8px;
  }

  .research-section p,
  .research-section li {
    font-size: 0.9rem;
    line-height: 1.65;
  }

  .research-section ul {
    padding-left: 20px;
    margin: 12px 0;
  }

  .research-section li {
    margin-bottom: 10px;
  }

  .highlight-box,
  .info-box {
    padding: 15px;
    margin: 18px 0;
    border-left-width: 4px;
  }

  .highlight-box h4,
  .info-box h4 {
    font-size: 1.1rem;
    margin-bottom: 10px;
  }

  .highlight-box p,
  .info-box p {
    font-size: 0.9rem;
    line-height: 1.65;
  }

  .footer {
    padding: 15px 10px;
    font-size: 0.8rem;
  }
}

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

.research-container {
  animation: fadeIn 0.5s ease;
}