/* ===== Reset & Base ===== */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --bg: #0f172a;
  --bg-card: #1e293b;
  --bg-hover: #334155;
  --text: #f1f5f9;
  --text-muted: #94a3b8;
  --accent: #6366f1;
  --accent-hover: #818cf8;
  --accent-glow: rgba(99, 102, 241, 0.25);
  --success: #22c55e;
  --border: #334155;
  --radius: 16px;
  --radius-sm: 10px;
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans SC", sans-serif;
}

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  min-height: 100dvh;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

/* ===== Layout ===== */
.container {
  max-width: 480px;
  margin: 0 auto;
  padding: 20px 16px 40px;
}

header {
  text-align: center;
  padding: 24px 0 8px;
}

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

.subtitle {
  color: var(--text-muted);
  font-size: 0.85rem;
  margin-top: 4px;
}

/* ===== Card ===== */
.card {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 24px 20px;
  margin-top: 20px;
  animation: fadeUp 0.3s ease;
}

@keyframes fadeUp {
  from { opacity: 0; transform: translateY(12px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ===== Upload ===== */
.upload-area {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 12px;
  padding: 48px 24px;
  border: 2px dashed var(--border);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: border-color 0.2s, background 0.2s;
  -webkit-tap-highlight-color: transparent;
}

.upload-area:active,
.upload-area.dragover {
  border-color: var(--accent);
  background: var(--accent-glow);
}

.upload-icon {
  color: var(--accent);
}

.upload-text {
  font-size: 1.1rem;
  font-weight: 600;
}

.upload-hint {
  color: var(--text-muted);
  font-size: 0.8rem;
}

/* ===== Preview ===== */
.image-preview-wrapper {
  width: 100%;
  max-height: 240px;
  border-radius: var(--radius-sm);
  overflow: hidden;
  margin-bottom: 20px;
  background: var(--bg);
  display: flex;
  align-items: center;
  justify-content: center;
}

.image-preview-wrapper img {
  max-width: 100%;
  max-height: 240px;
  object-fit: contain;
}

/* ===== Info Grid ===== */
.info-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
}

.info-item {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.info-item:last-child:nth-child(odd) {
  grid-column: 1 / -1;
}

.info-label {
  font-size: 0.75rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.info-value {
  font-size: 0.95rem;
  font-weight: 500;
  word-break: break-all;
}

/* ===== Divider ===== */
.divider {
  height: 1px;
  background: var(--border);
  margin: 24px 0;
}

h2 {
  font-size: 1.15rem;
  font-weight: 600;
  margin-bottom: 16px;
}

/* ===== Mode Toggle ===== */
.mode-toggle {
  display: flex;
  gap: 0;
  background: var(--bg);
  border-radius: var(--radius-sm);
  padding: 4px;
  margin-bottom: 20px;
}

.mode-btn {
  flex: 1;
  padding: 10px 0;
  font-size: 0.9rem;
  font-weight: 500;
  border: none;
  background: transparent;
  color: var(--text-muted);
  border-radius: 8px;
  cursor: pointer;
  transition: background 0.2s, color 0.2s;
  font-family: var(--font);
  -webkit-tap-highlight-color: transparent;
}

.mode-btn.active {
  background: var(--accent);
  color: #fff;
}

/* ===== Mode Panels ===== */
.mode-panel {
  margin-bottom: 20px;
}

.field-label {
  display: flex;
  align-items: baseline;
  gap: 8px;
  font-size: 0.9rem;
  font-weight: 500;
  margin-bottom: 10px;
}

.field-hint {
  font-size: 0.8rem;
  color: var(--text-muted);
  font-weight: 400;
}

/* ===== Range Slider ===== */
input[type="range"] {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 6px;
  border-radius: 3px;
  background: var(--bg);
  outline: none;
}

input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: var(--accent);
  border: 3px solid var(--bg-card);
  box-shadow: 0 2px 8px rgba(0,0,0,0.3);
  cursor: pointer;
}

input[type="range"]::-moz-range-thumb {
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: var(--accent);
  border: 3px solid var(--bg-card);
  box-shadow: 0 2px 8px rgba(0,0,0,0.3);
  cursor: pointer;
}

.range-labels {
  display: flex;
  justify-content: space-between;
  margin-top: 6px;
  font-size: 0.75rem;
  color: var(--text-muted);
}

/* ===== Number Input ===== */
.input-row {
  display: flex;
  align-items: center;
  gap: 8px;
}

.input-row input[type="number"] {
  flex: 1;
  padding: 12px 16px;
  font-size: 1rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  outline: none;
  transition: border-color 0.2s;
}

.input-row input[type="number"]:focus {
  border-color: var(--accent);
}

.input-unit {
  font-size: 0.9rem;
  color: var(--text-muted);
  font-weight: 500;
}

/* ===== Output Format ===== */
.output-format-row {
  margin-bottom: 24px;
}

.output-format-row .field-label {
  margin-bottom: 10px;
}

.format-chips {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.chip {
  padding: 8px 16px;
  font-size: 0.85rem;
  font-weight: 500;
  border: 1px solid var(--border);
  border-radius: 20px;
  background: transparent;
  color: var(--text-muted);
  cursor: pointer;
  transition: all 0.2s;
  font-family: var(--font);
  -webkit-tap-highlight-color: transparent;
}

.chip.active {
  border-color: var(--accent);
  background: var(--accent-glow);
  color: var(--accent-hover);
}

/* ===== Buttons ===== */
.primary-btn {
  width: 100%;
  padding: 14px;
  font-size: 1rem;
  font-weight: 600;
  border: none;
  border-radius: var(--radius-sm);
  background: var(--accent);
  color: #fff;
  cursor: pointer;
  transition: background 0.2s, transform 0.1s;
  font-family: var(--font);
  -webkit-tap-highlight-color: transparent;
}

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

.primary-btn:hover {
  background: var(--accent-hover);
}

.primary-btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.primary-btn.outline {
  background: transparent;
  border: 1.5px solid var(--accent);
  color: var(--accent-hover);
}

.primary-btn.outline:hover {
  background: var(--accent-glow);
}

.btn-row {
  display: flex;
  gap: 10px;
}

.btn-row .primary-btn {
  flex: 1;
}

.secondary-btn {
  width: 100%;
  padding: 12px;
  margin-top: 12px;
  font-size: 0.9rem;
  font-weight: 500;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--text-muted);
  cursor: pointer;
  transition: background 0.2s;
  font-family: var(--font);
  -webkit-tap-highlight-color: transparent;
}

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

/* ===== Result ===== */
.result-compare {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 16px;
  flex-wrap: wrap;
  margin-bottom: 16px;
}

.result-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
}

.result-label {
  font-size: 0.75rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.result-value {
  font-size: 1.1rem;
  font-weight: 600;
}

.result-highlight {
  color: var(--success);
}

.result-arrow {
  font-size: 1.2rem;
  color: var(--text-muted);
}

.result-details {
  display: flex;
  justify-content: center;
  gap: 16px;
  margin-bottom: 20px;
  font-size: 0.85rem;
  color: var(--text-muted);
}

.result-preview-wrapper {
  margin-bottom: 20px;
  text-align: center;
}

.result-preview-wrapper img {
  max-width: 100%;
  max-height: 300px;
  border-radius: var(--radius-sm);
  object-fit: contain;
}

.save-hint {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-bottom: 10px;
}

/* ===== Progress Overlay ===== */
.overlay {
  position: fixed;
  inset: 0;
  background: rgba(15, 23, 42, 0.85);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 16px;
  z-index: 100;
  backdrop-filter: blur(4px);
}

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

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

/* ===== Utilities ===== */
[hidden] {
  display: none !important;
}

/* ===== Desktop ===== */
@media (min-width: 600px) {
  .container {
    padding-top: 48px;
  }

  .upload-area:hover {
    border-color: var(--accent);
    background: var(--accent-glow);
  }
}