html, body {
  margin: 0;
  padding: 0;
  height: 100%;
}

body {
  display: flex;
  justify-content: center;
  align-items: center;
  background: #e0e0e0;
  font-size: 1.125em;
  font-family: sans-serif;
  color: #222222;
}

.window {
  display: grid;
  grid-template-columns: 200px 1fr 220px;
  width: calc(100% - 60px);
  height: calc(100% - 60px);
  background: #ffffff;
  border: 2px solid #222222;
  border-radius: 12px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.25);
  overflow: hidden;
}

.nav {
  background: #cccccc;
  padding: 12px;
  border-right: 2px solid #222222;
}

.main {
  padding: 16px;
  overflow-y: auto;
}

.sidebar {
  background: #d9d9d9;
  padding: 12px;
  border-left: 2px solid #222222;
  overflow-y: auto;
}

h1, h2 {
  margin-bottom: 12px;
}

ul {
  margin: 0;
  padding: 0;
  list-style: none;
}

ul li {
  margin-bottom: 8px;
}

ul li a {
  text-decoration: none;
  color: #222222;
  font-weight: bold;
}

ul li a:hover {
  text-decoration: underline;
}

body, .main, .sidebar {
  scrollbar-width: thin;
  scrollbar-color: #555555 #f0f0f0;
}

body::-webkit-scrollbar,
.main::-webkit-scrollbar,
.sidebar::-webkit-scrollbar {
  width: 5px;
}

body::-webkit-scrollbar-thumb,
.main::-webkit-scrollbar-thumb,
.sidebar::-webkit-scrollbar-thumb {
  background-color: #555555;
  border-radius: 10px;
  border: 1px solid #222222;
}

body::-webkit-scrollbar-track,
.main::-webkit-scrollbar-track,
.sidebar::-webkit-scrollbar-track {
  background: #f0f0f0;
}