* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 20px;
  background: #f3f4f6;
  font-family: Arial, sans-serif;
}

.chat-container {
  width: 100%;
  max-width: 600px;
  background: #ffffff;
  border-radius: 12px;
  padding: 24px;
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.08);
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
}

.messages {
  height: 350px;
  overflow-y: auto;
  padding: 16px;
  margin: 20px 0;
  background: #f9fafb;
  border-radius: 8px;
}

.message {
  padding: 10px;
  margin-bottom: 10px;
  background: #e5e7eb;
  border-radius: 8px;
  overflow-wrap: anywhere;
}

input {
  min-width: 0;
  padding: 12px;
  border: 1px solid #d1d5db;
  border-radius: 6px;
}

button {
  padding: 12px 16px;
  border: none;
  border-radius: 6px;
  background: #2563eb;
  color: white;
  cursor: pointer;
}

button:disabled,
input:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.user-panel,
#message-form {
  display: flex;
  gap: 8px;
}

.user-panel input,
#message-form input {
  flex: 1;
}

@media (max-width: 480px) {
  .chat-container {
    padding: 14px;
  }

  header {
    align-items: flex-start;
    flex-direction: column;
  }
}