body {
  background: #f2f6fa;
  font-family: Tahoma, Arial, sans-serif;
  direction: rtl;
  margin: 0;
  min-height: 100vh;
}
.container {
  max-width: 400px;
  margin: 48px auto;
  background: #fff;
  border-radius: 18px;
  box-shadow: 0 4px 20px #0001;
  padding: 32px 24px 16px;
}
h1 {
  text-align: center;
  color: #0d99ff;
  margin-bottom: 24px;
}
#messages {
  list-style: none;
  padding: 0;
  height: 260px;
  overflow-y: auto;
  margin-bottom: 14px;
  border: 1px solid #eee;
  border-radius: 8px;
  background: #f9fbfd;
}
#messages li {
  padding: 6px 10px;
  margin: 4px 0;
  border-radius: 8px;
  word-break: break-word;
}
#messages li.me { background: #e3f3ff; text-align: left; }
#messages li.system { background: #fce4ec; color: #c2185b; text-align: center; }
form {
  display: flex;
}
#input {
  flex: 1;
  padding: 10px;
  border-radius: 8px;
  border: 1px solid #bbb;
}
button {
  background: #0d99ff;
  color: #fff;
  border: none;
  border-radius: 8px;
  padding: 10px 18px;
  margin-right: 8px;
  cursor: pointer;
}
.centered { text-align: center; }
.hidden { display: none; }