:root {
  --bg: #0f172a;
  --bg-alt: #1e293b;
  --card: #ffffff;
  --primary: #2dd4bf;
  --primary-dark: #0d9488;
  --accent: #818cf8;
  --text: #1e293b;
  --text-muted: #64748b;
  --border: #e2e8f0;
  --radius: 12px;
  --shadow: 0 10px 30px rgba(0, 0, 0, 0.25);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Segoe UI", system-ui, -apple-system, Roboto, Helvetica, Arial, sans-serif;
  background: linear-gradient(135deg, #0f172a 0%, #1e293b 100%);
  color: var(--text);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.app-header {
  background: rgba(15, 23, 42, 0.85);
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
}

.header-inner {
  max-width: 1200px;
  margin: 0 auto;
  padding: 18px 24px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 14px;
}

.brand-icon {
  font-size: 34px;
  color: var(--primary);
}

.brand h1 {
  margin: 0;
  font-size: 22px;
  color: #f8fafc;
  letter-spacing: 0.3px;
}

.brand p {
  margin: 2px 0 0;
  font-size: 13px;
  color: #94a3b8;
}

.app-main {
  max-width: 1200px;
  margin: 0 auto;
  padding: 28px 24px;
  display: grid;
  grid-template-columns: 420px 1fr;
  gap: 24px;
  align-items: start;
  flex: 1;
  width: 100%;
}

.controls-panel,
.output-panel {
  background: var(--card);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 24px;
}

.panel-title {
  margin: 0 0 18px;
  font-size: 16px;
  text-transform: uppercase;
  letter-spacing: 0.8px;
  color: var(--primary-dark);
  border-bottom: 2px solid var(--border);
  padding-bottom: 10px;
}

.field-group {
  margin-bottom: 18px;
}

.field-group label {
  display: block;
  font-size: 13px;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 6px;
}

.field-group select,
.field-group textarea {
  width: 100%;
  padding: 10px 12px;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 14px;
  font-family: inherit;
  background: #f8fafc;
  color: var(--text);
  transition: border-color 0.15s ease, box-shadow 0.15s ease;
}

.field-group select:focus,
.field-group textarea:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(45, 212, 191, 0.18);
  background: #ffffff;
}

.field-group textarea {
  resize: vertical;
  min-height: 60px;
}

.field-group input[type="range"] {
  width: 100%;
  accent-color: var(--primary-dark);
  cursor: pointer;
}

.checkbox-list {
  display: flex;
  flex-direction: column;
  gap: 7px;
}

.checkbox-item {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13.5px;
  font-weight: 400;
  cursor: pointer;
  color: var(--text);
}

.checkbox-item input[type="checkbox"] {
  accent-color: var(--primary-dark);
  width: 15px;
  height: 15px;
  cursor: pointer;
}

.checkbox-item.disabled {
  opacity: 0.45;
  pointer-events: none;
}

.muted {
  color: var(--text-muted);
  font-weight: 400;
  font-size: 12.5px;
}

.actions {
  display: flex;
  gap: 10px;
  margin-top: 20px;
}

.btn {
  flex: 1;
  padding: 11px 14px;
  border: none;
  border-radius: 8px;
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  transition: transform 0.1s ease, box-shadow 0.15s ease, opacity 0.15s ease;
  font-family: inherit;
}

.btn:active {
  transform: scale(0.98);
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: #042f2e;
}

.btn-primary:hover {
  box-shadow: 0 4px 16px rgba(45, 212, 191, 0.4);
}

.btn-secondary {
  background: #f1f5f9;
  color: var(--text);
  border: 1px solid var(--border);
}

.btn-secondary:hover {
  background: #e2e8f0;
}

.output-toolbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.output-toolbar .panel-title {
  margin-bottom: 14px;
}

#prompt-output {
  width: 100%;
  min-height: 420px;
  padding: 14px;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-family: "Cascadia Code", "Fira Code", "JetBrains Mono", Consolas, monospace;
  font-size: 13px;
  line-height: 1.6;
  background: #0f172a;
  color: #d1e7e6;
  resize: vertical;
}

.hint {
  margin: 10px 0 0;
  font-size: 12.5px;
}

.app-footer {
  text-align: center;
  padding: 16px;
  color: #94a3b8;
  font-size: 12.5px;
}

#toast {
  position: fixed;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%) translateY(20px);
  background: #042f2e;
  color: #5eead4;
  padding: 10px 18px;
  border-radius: 8px;
  font-size: 13.5px;
  font-weight: 500;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.25s ease, transform 0.25s ease;
  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.35);
  z-index: 50;
}

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

@media (max-width: 900px) {
  .app-main {
    grid-template-columns: 1fr;
    padding: 16px;
  }
}