.spb {
  --spb-border: #dfe6ff;
  --spb-text: #0f172a;
  --spb-muted: #64748b;
  --spb-accent: #4f46e5;
  --spb-accent-strong: #4338ca;
  --spb-bg: #f8faff;
  --spb-surface: #ffffff;
  --spb-code-bg: #f8fafc;
  --spb-shadow: 0 18px 40px rgba(79, 70, 229, 0.14);

  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans JP", sans-serif;
  color: var(--spb-text);
  max-width: 1080px;
  margin: 2rem auto;
}

.spb__card {
  background: linear-gradient(180deg, #ffffff 0%, var(--spb-bg) 100%);
  border: 1px solid var(--spb-border);
  border-radius: 18px;
  box-shadow: var(--spb-shadow);
  padding: 28px;
}

.spb__title {
  margin: 0 0 8px;
  font-size: clamp(1.4rem, 2.2vw, 1.9rem);
  letter-spacing: 0.01em;
}

.spb__subtitle {
  margin: 0 0 24px;
  color: var(--spb-muted);
  font-size: 0.98rem;
}

.spb__layout {
  display: grid;
  gap: 18px;
  grid-template-columns: 1fr;
}

@media (min-width: 900px) {
  .spb__layout {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, 1fr);
    align-items: start;
  }
}

.spb__input-column,
.spb__preview-column {
  background: var(--spb-surface);
  border: 1px solid var(--spb-border);
  border-radius: 14px;
  padding: 18px;
}

.spb__label {
  display: block;
  margin-bottom: 8px;
  font-weight: 600;
  font-size: 0.93rem;
}

.spb__select,
.spb__input,
.spb__textarea {
  width: 100%;
  border: 1px solid #cbd5e1;
  border-radius: 10px;
  padding: 10px 12px;
  font-size: 0.95rem;
  box-sizing: border-box;
  background: #fff;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.spb__select:focus,
.spb__input:focus,
.spb__textarea:focus {
  outline: none;
  border-color: var(--spb-accent);
  box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.15);
}

.spb__textarea {
  min-height: 120px;
  resize: vertical;
}

.spb__field {
  margin-top: 14px;
}

.spb__preview-column {
  background: #fcfdff;
}

.spb__preview-title {
  margin: 0 0 10px;
  font-size: 1rem;
}

.spb__preview {
  background: var(--spb-code-bg);
  border: 1px solid #dbe4ff;
  border-radius: 10px;
  padding: 14px;
  min-height: 240px;
  white-space: pre-wrap;
  word-break: break-word;
  margin: 0;
  font-size: 0.92rem;
  line-height: 1.6;
}

.spb__copy,
.spb__reset {
  margin-top: 14px;
  border: 0;
  border-radius: 10px;
  padding: 10px 14px;
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: transform 0.08s ease, box-shadow 0.2s ease, background-color 0.2s ease;
}

.spb__copy:hover,
.spb__reset:hover {
  transform: translateY(-1px);
}

.spb__copy {
  background: linear-gradient(135deg, var(--spb-accent) 0%, var(--spb-accent-strong) 100%);
  color: #fff;
  box-shadow: 0 10px 18px rgba(79, 70, 229, 0.25);
}

.spb__copy:disabled {
  opacity: 0.75;
  cursor: default;
  transform: none;
}

.spb__reset {
  background: #eef2ff;
  color: #1e293b;
}

@media (max-width: 640px) {
  .spb {
    margin: 1rem auto;
  }

  .spb__card {
    padding: 18px;
    border-radius: 14px;
  }

  .spb__input-column,
  .spb__preview-column {
    padding: 14px;
  }
}