:root {
  --bg: #f4f6f2;
  --panel: #ffffff;
  --panel-alt: #eef3ea;
  --text: #1f2a1f;
  --muted: #5d6b60;
  --accent: #1d6a43;
  --accent-strong: #155235;
  --user-bubble: #1d6a43;
  --assistant-bubble: #e8f2e8;
  --border: #d6e0d4;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Segoe UI", "Helvetica Neue", sans-serif;
  color: var(--text);
  background: radial-gradient(circle at top right, #d8e7d8, var(--bg) 45%);
}

.app {
  min-height: 100vh;
  display: grid;
  grid-template-columns: 1.2fr 1fr;
  gap: 18px;
  padding: 18px;
}

.chat-panel,
.preview-panel {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 16px;
  box-shadow: 0 8px 24px rgba(31, 42, 31, 0.08);
  overflow: hidden;
}

.chat-header {
  padding: 16px 18px;
  border-bottom: 1px solid var(--border);
}

.chat-header h1 {
  margin: 0;
  font-size: 1.3rem;
}

.chat-header p {
  margin: 6px 0 0;
  color: var(--muted);
  font-size: 0.95rem;
}

.messages {
  height: calc(100vh - 270px);
  overflow: auto;
  padding: 16px;
  background: linear-gradient(180deg, #fcfefb, #f8fbf7);
}

.message {
  max-width: 82%;
  padding: 10px 12px;
  border-radius: 14px;
  margin-bottom: 10px;
  line-height: 1.4;
  white-space: pre-wrap;
}

.message.user {
  margin-left: auto;
  background: var(--user-bubble);
  color: #ffffff;
  border-bottom-right-radius: 4px;
}

.message.assistant {
  background: var(--assistant-bubble);
  border: 1px solid #d9e8d9;
  border-bottom-left-radius: 4px;
}

.composer {
  border-top: 1px solid var(--border);
  padding: 12px;
  background: var(--panel-alt);
}

textarea {
  width: 100%;
  resize: vertical;
  min-height: 80px;
  border: 1px solid #b9cabb;
  border-radius: 12px;
  padding: 10px;
  font: inherit;
}

.controls {
  margin-top: 10px;
  display: flex;
  gap: 8px;
  align-items: center;
}

select,
button {
  border-radius: 10px;
  border: 1px solid #b9cabb;
  padding: 8px 10px;
  font: inherit;
}

button {
  margin-left: auto;
  background: var(--accent);
  border: none;
  color: #fff;
  font-weight: 600;
  cursor: pointer;
}

button:hover {
  background: var(--accent-strong);
}

.preview-panel {
  padding: 16px;
}

.preview-panel h2 {
  margin-top: 0;
  margin-bottom: 10px;
}

.preview-actions {
  display: flex;
  margin-bottom: 10px;
}

#downloadDxfBtn {
  margin-left: 0;
}

.preview-box {
  width: 100%;
  height: calc(100vh - 72px);
  border-radius: 14px;
  border: 1px dashed #b8cdb8;
  background: #f6fbf5;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: auto;
  position: relative;
}

#previewImage {
  width: 100%;
  height: 100%;
  object-fit: contain;
  object-position: center;
  display: none;
}

#previewHint {
  color: var(--muted);
  padding: 16px;
  text-align: center;
}

@media (max-width: 980px) {
  .app {
    grid-template-columns: 1fr;
  }

  .messages {
    height: 45vh;
  }

  .preview-box {
    height: 45vh;
  }
}