:root {
  --bg-color: #c0c0c0; /* Windows XP-like gray */
  --accent-color: #003399; /* Strong blue */
  --text-color: #000000;
  --user-bubble: #cce0ff;
  --bot-bubble: #f0f0f0;
  --input-bg: #dcdcdc;
  --font: 'Tahoma', 'Verdana', sans-serif;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  background-color: var(--bg-color);
  color: var(--text-color);
  font-family: var(--font);
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  padding: 1rem;
}

.chat-container {
  width: 100%;
  max-width: 600px;
  height: 90vh;
  background-color: #ffffff;
  border: 2px solid #999;
  border-radius: 4px;
  box-shadow: inset 0 0 0 1px #ccc, 0 0 20px rgba(0,0,0,0.2);
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.chat-header {
  padding: 12px;
  background: linear-gradient(to bottom, #e0e0e0, #b0b0b0);
  text-align: center;
  font-weight: bold;
  font-size: 1.2rem;
  border-bottom: 2px solid #888;
  color: #000080;
  text-shadow: 1px 1px #fff;
  box-shadow: inset 0 -1px 0 #fff;
}

.chat-window {
  flex: 1;
  padding: 16px;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 10px;
  background-color: #f8f8f8;
  font-size: 0.95rem;
  border-top: 1px solid #ccc;
  border-bottom: 1px solid #ccc;
}

.chat-message {
  max-width: 80%;
  padding: 10px 14px;
  border: 1px solid #aaa;
  border-radius: 6px;
  background: #fff;
  box-shadow: inset 0 1px 0 #fff, 0 1px 2px rgba(0,0,0,0.1);
  line-height: 1.4;
}

.user {
  background-color: var(--user-bubble);
  border-color: #99bbff;
  align-self: flex-end;
}

.bot {
  background-color: var(--bot-bubble);
  align-self: flex-start;
}

.chat-input-area {
  display: flex;
  padding: 10px;
  background-color: var(--input-bg);
  border-top: 2px solid #aaa;
  box-shadow: inset 0 1px 0 #fff;
}

.chat-input-area input {
  flex: 1;
  padding: 10px 12px;
  border: 1px solid #888;
  border-radius: 2px;
  background-color: #fff;
  font-size: 1rem;
  font-family: var(--font);
}

.chat-input-area button {
  margin-left: 10px;
  padding: 10px 16px;
  border: 2px outset #ccc;
  background: linear-gradient(to bottom, #c0d6f9, #7da2ce);
  color: #000;
  font-size: 1rem;
  font-weight: bold;
  font-family: var(--font);
  cursor: pointer;
}

.chat-input-area button:hover {
  background: linear-gradient(to bottom, #a0c4ff, #6890cc);
  border-color: #888;
}

@media screen and (min-width: 768px) {
  .chat-container {
    max-width: 800px;
    height: 85vh;
  }

  .chat-window {
    padding: 20px;
    gap: 14px;
  }

  .chat-message {
    font-size: 1rem;
    padding: 12px 16px;
  }

  .chat-input-area {
    padding: 12px 16px;
  }

  .chat-input-area input {
    font-size: 1.05rem;
  }

  .chat-input-area button {
    font-size: 1.1rem;
  }
}