/* ===== Base styles ===== */

:root {
  --font-heading: "Playfair Display", "Times New Roman", serif;
  --font-body: "Inter", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
    sans-serif;

  --color-bg: #f9fafb;
  --color-bg-alt: #f3f4f6;
  --color-text: #111827;
  --color-text-muted: #4b5563;
  --color-accent: #1f3a60; /* navy */
  --color-border: #e5e7eb;
  --color-highlight-bg: #e5ecf7;
  --color-button-bg: #1f3a60;
  --color-button-text: #ffffff;

  --container-max-width: 960px;
  --spacing-section: 4rem;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

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

/* ===== Layout helpers ===== */

.container {
  max-width: var(--container-max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* ===== Header and navigation ===== */

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: #ffffff;
  border-bottom: 1px solid var(--color-border);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.75rem 0;
}

.brand-link {
  text-decoration: none;
  color: inherit;
}

.brand-name {
  display: block;
  font-family: var(--font-heading);
  font-size: 1.25rem;
  letter-spacing: 0.02em;
}

.brand-title {
  display: block;
  font-size: 0.85rem;
  color: var(--color-text-muted);
}

.site-nav {
  display: flex;
  align-items: center;
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  padding: 0.25rem;
  cursor: pointer;
}

.nav-toggle-line {
  display: block;
  width: 20px;
  height: 2px;
  background-color: var(--color-text);
  margin: 4px 0;
}

.nav-list {
  list-style: none;
  display: flex;
  gap: 1.25rem;
  margin: 0;
  padding: 0;
}

.nav-link {
  text-decoration: none;
  color: var(--color-text-muted);
  font-size: 0.95rem;
  position: relative;
  padding-bottom: 0.1rem;
}

.nav-link:hover {
  color: var(--color-text);
}

.nav-link.active {
  color: var(--color-accent);
  font-weight: 500;
}

.nav-link.active::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -0.15rem;
  width: 100%;
  height: 2px;
  background-color: var(--color-accent);
}

/* ===== Hero section ===== */

.hero {
  padding: 3.5rem 0 3rem;
  background-color: #ffffff;
  border-bottom: 1px solid var(--color-border);
}

.hero-inner {
  display: grid;
  grid-template-columns: minmax(0, 2.2fr) minmax(0, 1.2fr);
  gap: 3rem;
  align-items: center;
}

.hero-name {
  font-family: var(--font-heading);
  font-size: 2.2rem;
  margin: 0 0 0.5rem;
  color: var(--color-accent);
}

.hero-title {
  font-size: 1.05rem;
  margin: 0 0 0.25rem;
}

.hero-affiliation {
  font-size: 0.95rem;
  color: var(--color-text-muted);
  margin: 0 0 1.25rem;
}

.hero-tagline {
  margin: 0;
  max-width: 32rem;
}

.hero-photo {
  display: flex;
  justify-content: flex-end;
}

.profile-photo { width: 180px; height: 180px; border-radius: 999px; object-fit: cover; border: 2px solid var(--color-accent); }

.photo-initials {
  font-family: var(--font-heading);
  font-size: 2.5rem;
  color: var(--color-accent);
}

/* ===== Highlight section ===== */

.highlight {
  padding: 2.25rem 0 0;
}

.highlight-box {
  background-color: var(--color-highlight-bg);
  border-radius: 0.75rem;
  padding: 1.75rem 1.5rem;
  border: 1px solid #cbd5f5;
}

.highlight-box p {
  margin-top: 0.75rem;
  margin-bottom: 0;
}

.highlight-note {
  font-size: 0.9rem;
  color: var(--color-text-muted);
  margin-top: 0.5rem;
}

/* ===== Sections ===== */

.section {
  padding: var(--spacing-section) 0;
  background-color: var(--color-bg);
}

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

.section-inner {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.section-header {
  border-left: 3px solid var(--color-accent);
  padding-left: 0.75rem;
}

.section-title {
  font-family: var(--font-heading);
  font-size: 1.5rem;
  margin: 0;
}

.section-content {
  max-width: 42rem;
  font-size: 0.98rem;
}

/* ===== Research ===== */

.research-block {
  margin-top: 0.5rem;
  margin-bottom: 1.75rem;
}

.subsection-title {
  font-family: var(--font-heading);
  font-size: 1.15rem;
  margin: 0 0 0.75rem;
  color: var(--color-accent);
}

.research-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.research-item {
  background-color: #ffffff;
  border-radius: 0.5rem;
  padding: 1rem 1.1rem;
  border: 1px solid var(--color-border);
}

.research-title {
  margin: 0 0 0.2rem;
  font-family: var(--font-heading);
  font-size: 1.02rem;
}

.research-meta {
  margin: 0 0 0.4rem;
  font-size: 0.9rem;
  color: var(--color-text-muted);
}

.research-abstract {
  margin: 0 0 0.65rem;
  font-size: 0.95rem;
}

.research-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.research-link {
  font-size: 0.9rem;
  text-decoration: none;
  color: var(--color-accent);
  border-bottom: 1px solid transparent;
}

.research-link:hover {
  border-color: var(--color-accent);
}

/* ===== Buttons ===== */

.button {
  display: inline-block;
  padding: 0.55rem 1.25rem;
  border-radius: 999px;
  border: 1px solid transparent;
  font-size: 0.95rem;
  text-decoration: none;
  cursor: pointer;
}

.button-primary {
  background-color: var(--color-button-bg);
  color: var(--color-button-text);
}

.button-primary:hover {
  opacity: 0.9;
}

.cv-note {
  font-size: 0.9rem;
  color: var(--color-text-muted);
}

/* ===== Contact ===== */

.contact-content {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 2rem;
}

.contact-block p {
  margin: 0.2rem 0;
}

.contact-links {
  list-style: none;
  padding: 0;
  margin: 0.25rem 0 0;
}

.contact-links li {
  margin-bottom: 0.15rem;
}

.contact-links a {
  text-decoration: none;
  color: var(--color-accent);
}

.contact-links a:hover {
  text-decoration: underline;
}

.contact-note {
  font-size: 0.9rem;
  color: var(--color-text-muted);
}

/* ===== Back to top ===== */

.back-to-top {
  position: fixed;
  right: 1.5rem;
  bottom: 1.5rem;
  width: 2.25rem;
  height: 2.25rem;
  border-radius: 999px;
  border: 1px solid var(--color-border);
  background-color: #ffffff;
  color: var(--color-accent);
  font-size: 1.2rem;
  cursor: pointer;
  display: none;
  align-items: center;
  justify-content: center;
  box-shadow: 0 8px 20px rgba(15, 23, 42, 0.08);
}

/* ===== Footer ===== */

.site-footer {
  border-top: 1px solid var(--color-border);
  background-color: #ffffff;
  padding: 1rem 0;
}

.footer-inner {
  text-align: center;
  font-size: 0.9rem;
  color: var(--color-text-muted);
}

/* ===== Responsive ===== */

@media (max-width: 768px) {
  .hero-inner {
    grid-template-columns: 1fr;
    gap: 2rem;
  }

  .hero-photo {
    justify-content: flex-start;
  }

  .photo-placeholder {
    width: 140px;
    height: 140px;
  }

  .contact-content {
    grid-template-columns: 1fr;
  }

  .nav-toggle {
    display: inline-block;
  }

  .nav-list {
    position: absolute;
    top: 100%;
    right: 0;
    background-color: #ffffff;
    flex-direction: column;
    align-items: flex-start;
    padding: 0.75rem 1.25rem;
    border: 1px solid var(--color-border);
    margin-top: 0.5rem;
    display: none;
  }

  .nav-list.open {
    display: flex;
  }
}