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

:root {
  --primary: #6366f1;
  --primary-hover: #4f46e5;
  --secondary: #64748b;
  --secondary-hover: #475569;
  --background: #0f172a;
  --surface: #1e293b;
  --surface-hover: #334155;
  --text: #f1f5f9;
  --text-secondary: #94a3b8;
  --border: #334155;
  --success: #22c55e;
  --error: #ef4444;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
  background: var(--background);
  color: var(--text);
  min-height: 100vh;
  line-height: 1.6;
}

.container {
  max-width: 1000px;
  margin: 0 auto;
  padding: 2rem 1.5rem;
}

header {
  text-align: center;
  margin-bottom: 2.5rem;
}

h1 {
  font-size: 2.5rem;
  font-weight: 700;
  background: linear-gradient(135deg, #6366f1, #a855f7, #ec4899);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 0.5rem;
}

.subtitle {
  color: var(--text-secondary);
  font-size: 1.1rem;
}

main {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.input-section,
.output-section {
  background: var(--surface);
  border-radius: 16px;
  padding: 1.5rem;
  border: 1px solid var(--border);
}

label {
  display: block;
  font-weight: 600;
  margin-bottom: 0.75rem;
  font-size: 1rem;
  color: var(--text);
}

textarea {
  width: 100%;
  background: var(--background);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1rem;
  font-size: 1rem;
  color: var(--text);
  resize: vertical;
  font-family: inherit;
  transition: border-color 0.2s, box-shadow 0.2s;
}

textarea:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.2);
}

textarea::placeholder {
  color: var(--text-secondary);
  opacity: 0.7;
}

textarea[readonly] {
  background: var(--surface-hover);
  cursor: default;
}

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

.btn {
  padding: 0.75rem 1.5rem;
  border-radius: 10px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  border: none;
  transition: all 0.2s;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  min-width: 120px;
}

.btn.primary {
  background: var(--primary);
  color: white;
}

.btn.primary:hover:not(:disabled) {
  background: var(--primary-hover);
  transform: translateY(-1px);
}

.btn.primary:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

.btn.secondary {
  background: var(--surface-hover);
  color: var(--text);
  border: 1px solid var(--border);
}

.btn.secondary:hover {
  background: var(--border);
}

.output-section .btn {
  margin-top: 1rem;
  width: 100%;
}

footer {
  text-align: center;
  margin-top: 2rem;
  color: var(--text-secondary);
  font-size: 0.875rem;
}

/* 加载动画 */
.loading .btn-text {
  display: none;
}

.loading .btn-loading {
  display: inline !important;
}

.spinner {
  width: 16px;
  height: 16px;
  border: 2px solid transparent;
  border-top-color: currentColor;
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* Toast 提示 */
.toast {
  position: fixed;
  bottom: 2rem;
  left: 50%;
  transform: translateX(-50%) translateY(100px);
  background: var(--surface);
  color: var(--text);
  padding: 0.875rem 1.5rem;
  border-radius: 10px;
  font-weight: 500;
  opacity: 0;
  transition: all 0.3s ease;
  border: 1px solid var(--border);
  z-index: 1000;
}

.toast.show {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

.toast.success {
  border-color: var(--success);
}

.toast.error {
  border-color: var(--error);
}

/* 响应式 */
@media (max-width: 640px) {
  .container {
    padding: 1rem;
  }

  h1 {
    font-size: 1.75rem;
  }

  .subtitle {
    font-size: 0.95rem;
  }

  .button-group {
    flex-direction: column;
  }

  .btn {
    width: 100%;
  }
}