/* ── Reset & Tokens ──────────────────────────────────────────────────────── */

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

:root {
  --clr-bg: #f4f5f7;
  --clr-surface: #ffffff;
  --clr-border: #e2e4e9;
  --clr-text: #1a1d23;
  --clr-text-muted: #6b7280;
  --clr-primary: #4f46e5;
  --clr-primary-hover: #4338ca;
  --clr-primary-light: #eef2ff;
  --clr-success: #16a34a;
  --clr-danger: #dc2626;
  --radius: 10px;
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.06);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.08);
  --transition: 0.2s ease;
}

html {
  font-size: 16px;
}

body {
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  background: var(--clr-bg);
  color: var(--clr-text);
  line-height: 1.6;
  min-height: 100vh;
}

/* ── Layout ──────────────────────────────────────────────────────────────── */

.container {
  max-width: 640px;
  margin: 0 auto;
  padding: 2rem 1rem 4rem;
}

header {
  text-align: center;
  margin-bottom: 2rem;
}

header h1 {
  font-size: 1.75rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.subtitle {
  color: var(--clr-text-muted);
  font-size: 0.95rem;
  margin-top: 0.25rem;
}

.card {
  background: var(--clr-surface);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius);
  padding: 1.5rem;
  margin-bottom: 1rem;
  box-shadow: var(--shadow-sm);
}

.card h2 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 1rem;
}

/* ── Drop Zone ───────────────────────────────────────────────────────────── */

.drop-zone {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  border: 2px dashed var(--clr-border);
  border-radius: var(--radius);
  padding: 2.5rem 1rem;
  cursor: pointer;
  transition: border-color var(--transition), background var(--transition);
  color: var(--clr-text-muted);
}

.drop-zone:hover,
.drop-zone.drag-over {
  border-color: var(--clr-primary);
  background: var(--clr-primary-light);
}

.drop-zone p {
  font-size: 0.95rem;
}

.drop-zone__or {
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.file-name {
  margin-top: 0.75rem;
  font-size: 0.85rem;
  color: var(--clr-primary);
  font-weight: 500;
  min-height: 1.2em;
}

/* ── Buttons ─────────────────────────────────────────────────────────────── */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  padding: 0.6rem 1.25rem;
  border-radius: 8px;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  border: none;
  transition: background var(--transition), opacity var(--transition);
  text-decoration: none;
}

.btn--primary {
  background: var(--clr-primary);
  color: #fff;
  width: 100%;
}

.btn--primary:hover:not(:disabled) {
  background: var(--clr-primary-hover);
}

.btn--primary:disabled {
  opacity: 0.45;
  cursor: not-allowed;
}

.btn--outline {
  background: transparent;
  border: 1px solid var(--clr-border);
  color: var(--clr-text);
}

.btn--outline:hover {
  border-color: var(--clr-primary);
  color: var(--clr-primary);
}

/* ── Option Cards ────────────────────────────────────────────────────────── */

.options-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0.6rem;
  margin-bottom: 1.25rem;
}

@media (min-width: 480px) {
  .options-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

.option-card {
  cursor: pointer;
}

.option-card input[type="radio"] {
  display: none;
}

.option-card__inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: 0.35rem;
  padding: 1rem 0.5rem;
  border: 1.5px solid var(--clr-border);
  border-radius: var(--radius);
  transition: border-color var(--transition), background var(--transition);
}

.option-card__inner strong {
  font-size: 0.85rem;
}

.option-card__inner span {
  font-size: 0.72rem;
  color: var(--clr-text-muted);
  line-height: 1.3;
}

.option-card input:checked + .option-card__inner {
  border-color: var(--clr-primary);
  background: var(--clr-primary-light);
}

/* ── Scale Slider ────────────────────────────────────────────────────────── */

.scale-control {
  margin-bottom: 1.25rem;
  display: none;
}

.scale-control.visible {
  display: block;
}

.scale-control label {
  display: block;
  font-size: 0.85rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
}

.scale-control input[type="range"] {
  width: 100%;
  accent-color: var(--clr-primary);
}

.scale-labels {
  display: flex;
  justify-content: space-between;
  font-size: 0.75rem;
  color: var(--clr-text-muted);
  margin-top: 0.2rem;
}

/* ── Result ──────────────────────────────────────────────────────────────── */

.result-card {
  border-color: var(--clr-success);
}

.result-stats {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: 0.5rem;
  margin-bottom: 1rem;
}

.stat {
  text-align: center;
}

.stat__label {
  font-size: 0.7rem;
  color: var(--clr-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.stat__value {
  font-size: 1.1rem;
  font-weight: 700;
}

.stat__value--success {
  color: var(--clr-success);
}

/* ── Loader ──────────────────────────────────────────────────────────────── */

.loader-overlay {
  position: fixed;
  inset: 0;
  background: rgba(255, 255, 255, 0.85);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 1rem;
  z-index: 100;
  backdrop-filter: blur(4px);
}

.loader-overlay[hidden],
.result-card[hidden] {
  display: none;
}

.loader-spinner {
  width: 40px;
  height: 40px;
  border: 3px solid var(--clr-border);
  border-top-color: var(--clr-primary);
  border-radius: 50%;
  animation: spin 0.7s linear infinite;
}

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

.loader-overlay p {
  font-size: 0.9rem;
  color: var(--clr-text-muted);
  font-weight: 500;
}

/* ── History ─────────────────────────────────────────────────────────────── */

.history-list {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.history-empty {
  text-align: center;
  color: var(--clr-text-muted);
  font-size: 0.85rem;
  padding: 1rem 0;
}

.history-item {
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: center;
  gap: 0.75rem;
  padding: 0.75rem;
  border: 1px solid var(--clr-border);
  border-radius: 8px;
  font-size: 0.83rem;
  transition: background var(--transition);
}

.history-item:hover {
  background: var(--clr-primary-light);
}

.history-item__name {
  font-weight: 600;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.history-item__meta {
  color: var(--clr-text-muted);
  font-size: 0.75rem;
  margin-top: 0.15rem;
}

.history-item__badge {
  display: inline-block;
  padding: 0.15rem 0.5rem;
  border-radius: 99px;
  font-size: 0.7rem;
  font-weight: 600;
  background: var(--clr-primary-light);
  color: var(--clr-primary);
  text-transform: uppercase;
  white-space: nowrap;
}

.history-item__download {
  color: var(--clr-primary);
  text-decoration: none;
  font-weight: 600;
  font-size: 0.8rem;
  white-space: nowrap;
}

.history-item__download:hover {
  text-decoration: underline;
}

/* ── Responsive ──────────────────────────────────────────────────────────── */

@media (max-width: 480px) {
  .container {
    padding: 1.25rem 0.75rem 3rem;
  }

  header h1 {
    font-size: 1.4rem;
  }

  .card {
    padding: 1.15rem;
  }

  .result-stats {
    grid-template-columns: 1fr;
    gap: 0.3rem;
  }

  .stat {
    display: flex;
    justify-content: space-between;
    text-align: left;
  }
}