:root {
  --color-bg: #f7f7fb;
  --color-fg: #22223b;
  --color-accent: #4a6fa5;
  --color-border: #d9d9e3;
  --color-error: #c1121f;
  font-family: -apple-system, "Hiragino Kaku Gothic ProN", "Yu Gothic", sans-serif;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--color-bg);
  color: var(--color-fg);
}

.app-header {
  padding: 1.5rem 1rem;
  text-align: center;
}

.app-header h1 {
  margin: 0 0 0.25rem;
  font-size: 1.5rem;
}

.tagline {
  margin: 0;
  color: #555;
  font-size: 0.9rem;
}

.app-main {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
  max-width: 960px;
  margin: 0 auto;
  padding: 0 1rem 2rem;
}

@media (min-width: 800px) {
  .app-main {
    flex-direction: row;
    align-items: flex-start;
  }
  .input-panel,
  .preview-panel {
    flex: 1;
    min-width: 0;
  }
}

.input-panel,
.preview-panel {
  background: #fff;
  border: 1px solid var(--color-border);
  border-radius: 8px;
  padding: 1rem;
}

label {
  font-weight: bold;
}

.hint {
  font-size: 0.85rem;
  color: #666;
  margin: 0.25rem 0 0.5rem;
}

textarea,
input[type="text"] {
  width: 100%;
  padding: 0.6rem;
  border: 1px solid var(--color-border);
  border-radius: 6px;
  font-size: 1rem;
}

.shop-fields {
  border: 1px solid var(--color-border);
  border-radius: 6px;
  margin: 1rem 0;
  padding: 0.75rem;
}

.shop-fields input {
  margin-top: 0.5rem;
}

button {
  margin-top: 1rem;
  padding: 0.7rem 1.4rem;
  border: none;
  border-radius: 6px;
  background: var(--color-accent);
  color: #fff;
  font-size: 1rem;
  cursor: pointer;
}

button:disabled {
  background: #b7b7c9;
  cursor: not-allowed;
}

.validation,
.error {
  min-height: 1.2rem;
  color: var(--color-error);
  font-size: 0.85rem;
  margin-top: 0.4rem;
}

.loading {
  margin-top: 0.75rem;
  font-size: 0.9rem;
  color: var(--color-accent);
}

.preview-empty {
  color: #888;
  padding: 2rem 1rem;
  text-align: center;
  border: 1px dashed var(--color-border);
  border-radius: 6px;
}

.preview-frame {
  width: 100%;
  min-height: 420px;
  border: 1px solid var(--color-border);
  border-radius: 6px;
}

.app-footer {
  text-align: center;
  padding: 1.5rem 1rem;
  font-size: 0.85rem;
}

.app-footer a {
  color: var(--color-accent);
}