body {
  font-family: Arial, sans-serif;
  background: #f7f7f7;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  min-height: 100vh;
}

h1 {
  margin-top: 32px;
  margin-bottom: 8px;
}

.container {
  display: flex;
  flex-direction: row;
  gap: 40px;
  margin-top: 24px;
}

.grid {
  display: flex;
  flex-direction: column;
  background: #fff;
  padding: 12px;
  border-radius: 8px;
  box-shadow: 0 2px 8px #0001;
  margin-top: 8px;
}

.grid-row {
  display: flex;
  align-items: center;
  margin-bottom: -1.1px;
}

.row-select-checkbox {
  appearance: none;
  width: 14px;
  height: 14px;
  border: 2px solid #888;
  border-radius: 3px;
  background: #fff;
  margin-right: 8px;
  cursor: pointer;
  position: relative;
}

.row-select-checkbox:checked {
  background: #cce5ff;
  border-color: #3399ff;
}

.row-select-checkbox:checked::after {
  content: "✓";
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  color: #1976d2;
  font-size: 10px;
  font-weight: bold;
}

.circle-checkbox {
  width: 14px;
  height: 14px;
  margin: 0 1px;
  cursor: pointer;
  appearance: none;
  -webkit-appearance: none;
  border: 2px solid #1976d2;
  border-radius: 50%;
  background: #fff;
  transition: background 0.2s, border-color 0.2s;
  display: flex;
  align-items: center;
  justify-content: center;
  outline: none;
}

.circle-checkbox:checked {
  background: #1976d2;
  border-color: #1976d2;
}

.circle-checkbox:focus {
  box-shadow: 0 0 0 2px #90caf9;
}

.row-selected {
  background: #e3f2fd;
}

.svg-preview {
  background: #fff;
  padding: 12px;
  border-radius: 8px;
  box-shadow: 0 2px 8px #0001;
  display: flex;
  flex-direction: column;
  align-items: center;
}

.svg-preview svg {
  display: block;
  background: #f0f0f0;
  border-radius: 4px;
  margin-bottom: 12px;
}

button {
  background: #1976d2;
  color: #fff;
  border: none;
  border-radius: 4px;
  padding: 8px 16px;
  font-size: 1rem;
  cursor: pointer;
  transition: background 0.2s;
}

button:hover {
  background: #125ea7;
}

#clearBtn {
  background: #dc3545;
}

#clearBtn:hover {
  background: #c82333;
}

.tips-box {
  background: #e8f4fd;
  border: 1px solid #bee5eb;
  border-radius: 8px;
  padding: 12px;
  margin: 16px 0;
  max-width: 600px;
  font-size: 0.9rem;
  line-height: 1.5;
}

.tips-box h3 {
  margin: 0 0 8px 0;
  color: #1976d2;
  font-size: 1rem;
}

.tips-box ul {
  margin: 8px 0 0 20px;
  padding: 0;
}

.tips-box li {
  margin-bottom: 4px;
}

@media (max-width: 900px) {
  .container {
    flex-direction: column;
    align-items: center;
  }
}