:root {
  --main-bg: #ffffff;
  --main-text: #333333;
  --accent: #3498db;
  --border: #e0e0e0;
  --card-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
  --heading-color: #2c3e50;
}

:root {
  --primary-color: #2c3e50;
  --secondary-color: #34495e;
  --accent-color: #e67e22;
  --text-color: #ecf0f1;
  --hover-color: #3d566e;
  --card-bg: #fff;
  --card-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
  --modal-bg: rgba(0, 0, 0, 0.7);
  --warm-white: #fffcf5;
  /* Warm white background */
  --section-bg: #ffffff;
  /* Pure white for content sections */
  --border-color: #f0f0f0;
  /* Light gray border */
  --heading-color: #d35400;
}

:root {
  --primary-color: #1a237e;
  /* --secondary-color: #3949ab; */
  --accent-color: #2d3748;
  --light-color: #f5f7fa;
  --dark-color: #263238;
  --success-color: #00c853;
  --text-color: #455a64;
  --sidebar-bg: #171b26;
  --sidebar-border: #232537;
  --sidebar-text: #ccd6f6;
  --card-shadow: 0 4px 12px rgba(2, 2, 2, 0.08);
  --hover-shadow: 0 8px 20px rgba(0, 0, 0, 0.12);
  --gradient-primary: linear-gradient(135deg, #1a237e 0%, #3949ab 100%);
  --gradient-accent: linear-gradient(135deg, #00acc1 0%, #0097a7 100%);
  --gradient-success: linear-gradient(135deg, #00c853 0%, #00a040 100%);
}

body {
  display: flex;
  min-height: 100vh;
  background-color: var(--warm-white);
  color: #333;
}

/* Main Content Styles */
.main-content {
  flex: 1;
  padding: 30px;
  margin-left: 280px;
  overflow-y: auto;
  transition: margin-left 0.3s ease;
}

/* header section */
header {
  text-align: center;
  margin-bottom: 35px;
  padding: 14px 16px;
  background-color: #2d3748;
  border-radius: 12px;
  color: white;
  box-shadow: var(--card-shadow);
  position: relative;
  overflow: hidden;
}

header::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -10%;
  width: 300px;
  height: 300px;
  background: rgba(255, 255, 255, 0.1);
  border-radius: 50%;
}

header::after {
  content: '';
  position: absolute;
  bottom: -50%;
  left: -10%;
  width: 250px;
  height: 250px;
  background: rgba(255, 255, 255, 0.1);
  border-radius: 50%;
}

h1 {
  font-size: 1.5rem;
  margin-bottom: 10px;
  position: relative;
  z-index: 1;
}

.subtitle {
  font-size: 1.1rem;
  font-weight: 300;
  position: relative;
  z-index: 1;
}

/* Content Sections */
.content-section {
  background-color: var(--section-bg);
  border-radius: 12px;
  padding: 2rem;
  margin-bottom: 2rem;
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.05);
  border: 1px solid var(--border-color);
}

.section-title {
  font-size: 1.8rem;
  color: var(--heading-color);
  margin-bottom: 1rem;
  padding-bottom: 0.5rem;
  border-bottom: 2px solid var(--border-color);
}

.section-content {
  line-height: 1.7;
  color: #333;
}

.section-content p {
  margin-bottom: 1rem;
}

.research-areas {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 1.5rem;
  margin-top: 1.5rem;
}

/* research section */
.research-area {
  background-color: var(--card-bg);
  border-radius: 8px;
  padding: 1.5rem;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
  border-left: 4px solid var(--accent-color);

}

.research-area h3 {
  color: var(--heading-color);
  margin-bottom: 0.75rem;
  font-size: 1.2rem;
}

.research-area p {
  font-size: 0.95rem;
  color: #555;
}

.thesis-highlight {
  background-color: rgba(230, 126, 34, 0.08);
  border-radius: 8px;
  padding: 1.5rem;
  margin: 1.5rem 0;
  border-left: 4px solid var(--accent-color);
}

.thesis-highlight h3 {
  color: var(--heading-color);
  margin-bottom: 0.75rem;
}


/* Back to Top Button */
.back-to-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  width: 50px;
  height: 50px;
  border-radius: 50%;
  background: var(--gradient-primary);
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transition: all 0.3s ease;
  z-index: 99;
  box-shadow: var(--hover-shadow);
}


.back-to-top.visible {
  opacity: 1;
  visibility: visible;
}

.back-to-top:hover {
  transform: translateY(-5px);
}

@media (max-width: 955px) {

  .main-content {
    margin-left: 0;
    padding: 70px 20px 30px;
  }
}

@media (max-width:768px) {
  header {
    padding: 30px 15px;
  }

  h1 {
    font-size: 1.5rem;
  }

  .research-areas {
    grid-template-columns: 1fr;
  }
}