* {
  box-sizing: border-box;
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
}

body {
  background: #02203f;
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100vh;
}

#app {
  width: 75%;
  height: 75%;
  background: #fff;
  border-radius: 8px;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
  display: flex;
  flex-direction: column;
}

header {
  background: #0078d7;
  color: #fff;
  padding: 16px;
  text-align: center;
  font-size: 1.5em;
}

main {
  padding: 16px;
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.messages {
  flex: 1;
  overflow-y: auto;
  border: 1px solid #ddd;
  padding: 8px;
  background: #f9f9f9;
}

.msg {
  padding: 8px;
  margin: 4px 0;
  border-radius: 4px;
  background: #e1f5fe;
  color: #0078d7;
}

.send {
  display: flex;
  gap: 8px;
}

.send input {
  flex: 1;
  padding: 8px;
  border: 1px solid #ddd;
}

.send button {
  padding: 8px;
  background: #0078d7;
  color: #fff;
  border: none;
  border-radius: 4px;
  cursor: pointer;
}