* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

body {
  background: #f7f8fa;
  color: #333;
}

a {
  text-decoration: none;
  color: inherit;
}

header {
  background: #3b82f6;
  color: #fff;
  padding: 1rem;
  text-align: center;
}

.container {
  max-width: 860px;
  margin: 2rem auto;
  padding: 0 1rem;
}

.back-link {
  display: inline-block;
  margin-bottom: 1rem;
  color: #3b82f6;
  font-size: 0.95rem;
}

.tool-title {
  font-size: 1.4rem;
  margin-bottom: 0.5rem;
  text-align: center;
  color: #3b82f6;
}

.tool-desc {
  text-align: center;
  color: #666;
  margin-bottom: 2rem;
  line-height: 1.6;
}

.card {
  background: #fff;
  border-radius: 12px;
  padding: 1.5rem;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.06);
  margin-bottom: 1.5rem;
}

label {
  display: block;
  margin-bottom: 0.5rem;
  font-weight: 500;
}

input,
select,
textarea {
  width: 100%;
  border: 1px solid #ddd;
  border-radius: 8px;
  padding: 0.8rem;
  font-size: 1rem;
  outline-color: #3b82f6;
}

textarea {
  min-height: 120px;
  resize: vertical;
}

.btn {
  display: inline-block;
  background: #3b82f6;
  color: #fff;
  border: none;
  border-radius: 8px;
  padding: 0.8rem 1.5rem;
  font-size: 1rem;
  cursor: pointer;
  margin-top: 1rem;
}

.btn:hover {
  background: #2563eb;
}

.result-item {
  margin-top: 1rem;
}

.result-item label {
  font-size: 0.9rem;
  color: #555;
}

.result-box {
  background: #f8f9fa;
  border: 1px solid #eee;
  border-radius: 8px;
  padding: 0.8rem;
  font-family: monospace;
  word-break: break-all;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 0.5rem;
}

.result-value {
  flex: 1;
}

.result-textarea {
  min-height: 220px;
  font-family: monospace;
  background: #f8f9fa;
}

.copy-btn {
  background: #fff;
  color: #3b82f6;
  border: 1px solid #3b82f6;
  border-radius: 6px;
  padding: 0.4rem 0.8rem;
  font-size: 0.85rem;
  cursor: pointer;
  white-space: nowrap;
}

.copy-btn:hover {
  background: #eff6ff;
}

.row {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1rem;
}

.checkbox-group {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem 1rem;
  margin-top: 0.75rem;
}

.checkbox-group label {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  margin-bottom: 0;
  font-weight: 400;
}

.checkbox-group input {
  width: auto;
  padding: 0;
}

.preview-box {
  min-height: 220px;
  background: #f8f9fa;
  border: 1px solid #eee;
  border-radius: 8px;
  padding: 1rem;
  display: flex;
  justify-content: center;
  align-items: center;
  overflow: auto;
}

.preview-box canvas,
.preview-box svg {
  max-width: 100%;
}

.color-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1rem;
}

.color-card {
  border: 1px solid #eee;
  border-radius: 10px;
  overflow: hidden;
}

.color-swatch {
  height: 100px;
}

.color-meta {
  padding: 0.9rem;
}

.color-code {
  display: block;
  font-family: monospace;
  margin-top: 0.5rem;
}

.info {
  font-size: 0.9rem;
  color: #666;
  line-height: 1.6;
}

footer {
  text-align: center;
  padding: 2rem 1rem;
  color: #999;
  font-size: 0.9rem;
}

@media (max-width: 640px) {
  .row,
  .color-grid {
    grid-template-columns: 1fr;
  }

  .result-box {
    flex-direction: column;
    align-items: flex-start;
  }
}