/* --------------------------------------------------
   Base Styles
-------------------------------------------------- */

:root {
  --font-body: "Helvetica Neue", Arial, sans-serif;
  --font-heading: Georgia, serif;

  --color-bg: #ffffff;
  --color-text: #222;
  --color-accent: #003366;
  --color-accent-light: #e6eef7;

  --space-xs: 4px;
  --space-sm: 10px;
  --space-md: 20px;
  --space-lg: 40px;
  --space-xl: 60px;

  --max-width: 900px;
}

body {
  margin: 0;
  padding: 0;
  background: var(--color-bg);
  font-family: var(--font-body);
  color: var(--color-text);
  line-height: 1.6;
}

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

/* --------------------------------------------------
   Typography
-------------------------------------------------- */

h1, h2, h3 {
  font-family: var(--font-heading);
  margin-top: 0;
}

h1 {
  font-size: 2.2rem;
  margin-bottom: var(--space-xs);
}

h2 {
  font-size: 1.4rem;
  color: #555;
  margin-bottom: var(--space-lg);
}

h3 {
  font-size: 1.3rem;
  margin-bottom: var(--space-sm);
}

/* --------------------------------------------------
   Navigation Bar
-------------------------------------------------- */

.top-nav {
  background: var(--color-accent);
  padding: var(--space-sm) 0;
  margin-bottom: var(--space-lg);
}

.top-nav ul {
  list-style: none;
  display: flex;
  justify-content: center;
  gap: var(--space-lg);
  margin: 0;
  padding: 0;
}

.top-nav a {
  color: white;
  text-decoration: none;
  font-weight: bold;
  padding: var(--space-xs) var(--space-sm);
  border-radius: 4px;
}

.top-nav a:hover {
  background: rgba(255, 255, 255, 0.15);
}

/* --------------------------------------------------
   Layout: Two-Column Welcome Section
-------------------------------------------------- */

.two-column {
  display: flex;
  gap: var(--space-lg);
  align-items: flex-start;
  margin-bottom: var(--space-xl);
}

.welcome-text {
  flex: 2;
}

.welcome-photo {
  flex: 1;
}

.profile-photo {
  width: 100%;
  max-width: 260px;
  border-radius: 6px;
  display: block;
}

/* --------------------------------------------------
   Sections
-------------------------------------------------- */

.section {
  margin-bottom: var(--space-xl);
}

.paper-list {
  list-style: none;
  padding: 0;
  margin: 0;
}

.paper-list li {
  margin-bottom: var(--space-md);
  padding-bottom: var(--space-sm);
  border-bottom: 1px solid var(--color-accent-light);
}

.paper-list a {
  color: var(--color-accent);
  text-decoration: none;
}

.paper-list a:hover {
  text-decoration: underline;
}

/* --------------------------------------------------
   Contact Section
-------------------------------------------------- */

#contact p {
  background: var(--color-accent-light);
  padding: var(--space-md);
  border-radius: 6px;
  max-width: 350px;
}

/* --------------------------------------------------
   Responsive Adjustments
-------------------------------------------------- */

@media (max-width: 700px) {
  .two-column {
    flex-direction: column;
  }

  .top-nav ul {
    flex-wrap: wrap;
    gap: var(--space-md);
  }
}

/* --------------------------------------------------
   Modal (Contact Pop-up)
-------------------------------------------------- */

.modal {
  display: none;
  position: fixed;
  z-index: 1000;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  background: rgba(0,0,0,0.45);
  backdrop-filter: blur(2px);
}

.modal-content {
  background: white;
  margin: 10% auto;
  padding: 20px 30px;
  border-radius: 8px;
  width: 90%;
  max-width: 400px;
  box-shadow: 0 8px 20px rgba(0,0,0,0.2);
}

.modal-content h3 {
  margin-top: 0;
}

.close {
  float: right;
  font-size: 24px;
  cursor: pointer;
  color: #666;
}

.close:hover {
  color: black;
}