:root {
  --ink: #222;
  --heading: #0c104d;
  --nav: #403a96;
  --nav-dark: #302c71;
  --link: #333ccc;
  --link-hover: #0000ee;
  --muted: #555;
  --rule: #c8c8c8;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0 auto;
  max-width: 1000px;
  padding: 50px;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue",
    Arial, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  font-size: 16px;
  line-height: 1.55;
  color: var(--ink);
}

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

a:hover,
a:focus {
  color: var(--link-hover);
}

h1 {
  margin: 0 0 24px;
  font-size: 2em;
  color: var(--heading);
}

h2 {
  margin: 1.4em 0 0.6em;
  font-size: 1.2em;
}

h3 {
  margin: 1.6em 0 0.6em;
  font-size: 1.05em;
  color: var(--heading);
}

h4 {
  margin: 1.4em 0 0.5em;
  font-size: 1em;
  font-weight: 600;
  font-style: italic;
  color: var(--muted);
}

hr {
  margin: 48px 0 24px;
  border: 0;
  border-top: 1px solid var(--rule);
}

/* Navigation bar */

.nav ul {
  display: flex;
  flex-wrap: wrap;
  margin: 0;
  padding: 0;
  list-style: none;
  background: var(--nav);
  border: 1px solid var(--nav-dark);
  border-radius: 3px;
}

.nav a {
  display: block;
  padding: 15px 44px;
  color: #fff;
  font-weight: 700;
  text-shadow: 0 1px 1px rgba(0, 0, 0, 0.2);
}

.nav a:hover,
.nav a:focus,
.nav a[aria-current="page"] {
  color: #fff;
  background: var(--nav-dark);
}

/* Home page */

.intro {
  display: flex;
  align-items: flex-start;
  gap: 48px;
}

.intro-text {
  flex: 1;
}

.intro-text > h2:first-child {
  margin-top: 0;
}

.intro-text li {
  margin-bottom: 0.6em;
}

.intro-photo img {
  display: block;
  width: 270px;
  height: auto;
  padding: 5px;
  border: 1px solid #c0c0c0;
}

/* Research page */

.paper-links {
  margin-left: 0.4em;
  font-weight: normal;
  font-size: 0.9em;
}

.papers {
  padding-left: 2em;
}

.papers li {
  margin-bottom: 1.1em;
  padding-left: 0.3em;
}

.papers .authors,
.papers .venue {
  display: block;
}

.papers .authors {
  color: var(--muted);
}

.papers .venue {
  font-style: italic;
}

.papers .venue a {
  font-style: normal;
}

@media (max-width: 720px) {
  body {
    padding: 24px 20px;
  }

  h1 {
    font-size: 1.6em;
  }

  .nav a {
    padding: 12px 22px;
  }

  hr {
    margin: 28px 0 20px;
  }

  .intro {
    flex-direction: column-reverse;
    gap: 24px;
  }

  .intro-photo img {
    width: 200px;
  }
}