/* -----------------------------------------
   Theme colors
   ----------------------------------------- */

:root {
  --background: #ffffff;
  --surface: #f5f6f7;
  --text: #27272a;
  --secondary-text: #64646b;
  --heading: #18181b;
  --link: #2774ae;
  --border: #dedee3;
  --nav-background: rgba(255, 255, 255, 0.94);
}

html[data-theme="dark"] {
  --background: #17181a;
  --surface: #222326;
  --text: #e4e4e7;
  --secondary-text: #aaaab2;
  --heading: #fafafa;
  --link: #78b7e5;
  --border: #37383d;
  --nav-background: rgba(23, 24, 26, 0.94);
}


/* -----------------------------------------
   General settings
   ----------------------------------------- */

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  min-height: 100vh;
  margin: 0;
  font-family:
    -apple-system,
    BlinkMacSystemFont,
    "Segoe UI",
    Helvetica,
    Arial,
    sans-serif;
  font-size: 16px;
  line-height: 1.7;
  color: var(--text);
  background: var(--background);
  transition:
    color 0.2s ease,
    background-color 0.2s ease;
}

a {
  color: var(--link);
  text-decoration: none;
}

a:hover,
a:focus {
  text-decoration: underline;
}


/* -----------------------------------------
   Top navigation
   ----------------------------------------- */

.topbar {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--nav-background);
  border-bottom: 1px solid var(--border);
  backdrop-filter: blur(10px);
}

.navigation {
  display: flex;
  align-items: center;
  justify-content: space-between;
  max-width: 1120px;
  min-height: 68px;
  margin: 0 auto;
  padding: 0 32px;
}

.site-name {
  color: var(--heading);
  font-size: 1.05rem;
  font-weight: 650;
  text-decoration: none;
}

.site-name:hover {
  text-decoration: none;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 25px;
}

.nav-links a {
  color: var(--secondary-text);
  font-size: 0.95rem;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--heading);
  text-decoration: none;
}

.nav-links a.active {
  font-weight: 600;
}


/* -----------------------------------------
   Light/dark-mode button
   ----------------------------------------- */

.theme-toggle {
  display: grid;
  width: 35px;
  height: 35px;
  padding: 0;
  color: var(--heading);
  font-size: 1.1rem;
  cursor: pointer;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 50%;
  place-items: center;
}

.theme-toggle:hover {
  background: var(--surface);
}


/* -----------------------------------------
   Main two-column layout
   ----------------------------------------- */

.page-layout {
  display: grid;
  grid-template-columns: 250px minmax(0, 700px);
  gap: 75px;
  justify-content: center;
  max-width: 1120px;
  margin: 0 auto;
  padding: 70px 32px;
}


/* -----------------------------------------
   Profile sidebar
   ----------------------------------------- */

.profile {
  text-align: center;
}

.profile-photo {
  display: block;
  width: 190px;
  height: 190px;
  margin: 0 auto 24px;
  object-fit: cover;
  object-position: center;
  border: 1px solid var(--border);
  border-radius: 50%;
}

.profile h1 {
  margin: 0 0 9px;
  color: var(--heading);
  font-size: 1.45rem;
  line-height: 1.3;
}

.profile-position {
  margin: 0;
  color: var(--text);
  font-size: 0.97rem;
  line-height: 1.5;
}

.profile-university {
  margin: 3px 0 20px;
  color: var(--secondary-text);
}

.profile-links {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 7px;
  margin-top: 20px;
}

.profile-links a {
  font-size: 0.95rem;
}


/* -----------------------------------------
   Main content
   ----------------------------------------- */

.content {
  min-width: 0;
}

.content h2 {
  margin: 0 0 28px;
  padding-bottom: 13px;
  color: var(--heading);
  font-size: 2rem;
  line-height: 1.25;
  border-bottom: 1px solid var(--border);
}

.content h3 {
  margin: 42px 0 15px;
  color: var(--heading);
  font-size: 1.35rem;
  line-height: 1.35;
}

.content p {
  margin: 0 0 18px;
}

.content ul {
  margin: 0 0 22px;
  padding-left: 23px;
}

.content li {
  margin-bottom: 6px;
}


/* -----------------------------------------
   CV and research entries
   ----------------------------------------- */

.entry {
  margin: 0;
  padding: 23px 0;
  border-bottom: 1px solid var(--border);
}

.entry:first-of-type {
  padding-top: 0;
}

.entry:last-child {
  border-bottom: 0;
}

.entry h3 {
  margin: 0 0 6px;
  font-size: 1.12rem;
}

.entry-meta {
  margin-bottom: 8px;
  color: var(--secondary-text);
  font-size: 0.93rem;
}

.entry p:last-child {
  margin-bottom: 0;
}

.cv-link {
  display: inline-block;
  margin: 0 15px 25px 0;
  font-weight: 600;
}


/* -----------------------------------------
   Footer
   ----------------------------------------- */

footer {
  max-width: 1120px;
  margin: 0 auto;
  padding: 25px 32px 40px;
  color: var(--secondary-text);
  font-size: 0.9rem;
  text-align: right;
  border-top: 1px solid var(--border);
}

footer p {
  margin: 0;
}


/* -----------------------------------------
   Accessibility
   ----------------------------------------- */

a:focus-visible,
button:focus-visible {
  outline: 3px solid rgba(39, 116, 174, 0.35);
  outline-offset: 3px;
}


/* -----------------------------------------
   Tablet layout
   ----------------------------------------- */

@media (max-width: 850px) {
  .page-layout {
    grid-template-columns: 200px minmax(0, 1fr);
    gap: 45px;
  }

  .profile-photo {
    width: 155px;
    height: 155px;
  }
}


/* -----------------------------------------
   Mobile layout
   ----------------------------------------- */

@media (max-width: 650px) {
  .navigation {
    align-items: flex-start;
    flex-direction: column;
    gap: 12px;
    padding: 17px 20px;
  }

  .nav-links {
    width: 100%;
    gap: 16px;
  }

  .theme-toggle {
    margin-left: auto;
  }

  .page-layout {
    display: block;
    padding: 45px 20px;
  }

  .profile {
    margin-bottom: 55px;
  }

  .profile-photo {
    width: 170px;
    height: 170px;
  }

  .content h2 {
    font-size: 1.75rem;
  }

  footer {
    padding: 25px 20px 35px;
    text-align: center;
  }
}