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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  background: #f5f5f5;
  color: #333;
  line-height: 1.6;
}

.container {
  max-width: 720px;
  margin: 2rem auto;
  padding: 0 1rem;
}

h1 {
  font-size: 1.8rem;
  margin-bottom: 0.25rem;
}

.subtitle {
  color: #666;
  margin-bottom: 1.5rem;
}

.drop-zone {
  border: 2px dashed #aaa;
  border-radius: 8px;
  padding: 2.5rem 1rem;
  text-align: center;
  cursor: pointer;
  transition: border-color 0.2s, background 0.2s;
  margin-bottom: 1.5rem;
}

.drop-zone:hover,
.drop-zone.dragover {
  border-color: #4a90d9;
  background: #eaf2fb;
}

.sheet-selector-section {
  margin-bottom: 1.5rem;
}

.sheet-selector-section label {
  display: block;
  font-weight: 600;
  margin-bottom: 0.4rem;
}

.sheet-selector-section select {
  width: 100%;
  padding: 0.6rem;
  border: 1px solid #ccc;
  border-radius: 6px;
  font-family: inherit;
  font-size: 0.95rem;
  background: #fff;
}

.payment-msg-section {
  margin-bottom: 1.5rem;
}

.payment-msg-section label {
  display: block;
  font-weight: 600;
  margin-bottom: 0.4rem;
}

.payment-msg-section textarea {
  width: 100%;
  padding: 0.6rem;
  border: 1px solid #ccc;
  border-radius: 6px;
  font-family: inherit;
  font-size: 0.95rem;
  resize: vertical;
}

.card {
  background: #fff;
  border: 1px solid #ddd;
  border-radius: 8px;
  padding: 1.25rem;
  margin-bottom: 1rem;
  position: relative;
}

.card h2 {
  font-size: 1.1rem;
  margin-bottom: 0.5rem;
}

.card pre {
  white-space: pre-wrap;
  font-family: inherit;
  font-size: 0.93rem;
  color: #444;
}

.card .copy-btn {
  position: absolute;
  top: 1rem;
  right: 1rem;
  background: #4a90d9;
  color: #fff;
  border: none;
  border-radius: 5px;
  padding: 0.4rem 0.9rem;
  cursor: pointer;
  font-size: 0.85rem;
}

.card .copy-btn:hover {
  background: #3a7bc8;
}

.card .copy-btn.copied {
  background: #27ae60;
}