:root {
  --color-bg: #eef4f5;
  --color-surface: #ffffff;
  --color-primary: #0a6e77;
  --color-primary-dark: #074e55;
  --color-primary-light: #e2f2f1;
  --color-accent: #ff7a45;
  --color-accent-dark: #e0611f;
  --color-text: #16232a;
  --color-muted: #5b7079;
  --color-border: #dbe6e6;
  --color-danger: #c0392b;
  --color-danger-bg: #fdecea;
  --color-warning-bg: #fff3cd;
  --color-warning-text: #7a5b00;
  --color-success: #1f8a5f;
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --shadow-sm: 0 1px 3px rgba(15, 40, 45, 0.08);
  --shadow-md: 0 8px 24px rgba(15, 40, 45, 0.12);
  --font-sans: -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: var(--font-sans);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.55;
}

.app-header {
  background: linear-gradient(135deg, var(--color-primary-dark), var(--color-primary) 65%);
  color: #ffffff;
  padding: 28px 16px 22px;
  text-align: center;
  border-radius: 0 0 var(--radius-lg) var(--radius-lg);
  box-shadow: var(--shadow-md);
}
.app-header h1 {
  margin: 0;
  font-size: 1.5rem;
  font-weight: 700;
  letter-spacing: -0.01em;
}
.subtitle {
  color: rgba(255, 255, 255, 0.82);
  margin: 6px 0 0;
  font-size: 0.88rem;
}

#app { max-width: 640px; margin: 0 auto; padding: 20px 16px 40px; }

.stepper {
  display: flex;
  list-style: none;
  padding: 0;
  margin: 0 0 26px;
  gap: 4px;
  font-size: 0.72rem;
  color: var(--color-muted);
  counter-reset: step;
}
.stepper li {
  flex: 1;
  text-align: center;
  padding-top: 34px;
  position: relative;
  font-weight: 500;
}
.stepper li::before {
  counter-increment: step;
  content: counter(step);
  position: absolute;
  top: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 24px;
  height: 24px;
  line-height: 24px;
  border-radius: 50%;
  background: var(--color-surface);
  border: 2px solid var(--color-border);
  color: var(--color-muted);
  font-weight: 700;
  font-size: 0.75rem;
}
.stepper li::after {
  content: '';
  position: absolute;
  top: 11px;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--color-border);
  z-index: -1;
}
.stepper li:first-child::after { left: 50%; }
.stepper li:last-child::after { right: 50%; }
.stepper li.active {
  color: var(--color-primary-dark);
}
.stepper li.active::before {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: #ffffff;
}

.step { display: none; }
.step.active { display: block; animation: fadeIn 0.2s ease; }

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(4px); }
  to { opacity: 1; transform: translateY(0); }
}

h2 { font-size: 1.15rem; font-weight: 700; margin: 4px 0 2px; }

.card-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-top: 14px;
}
@media (max-width: 420px) {
  .card-grid { grid-template-columns: 1fr; }
}

.card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 18px 16px;
  text-align: left;
  cursor: pointer;
  box-shadow: var(--shadow-sm);
  transition: box-shadow 0.15s, transform 0.15s, border-color 0.15s;
}
.card:hover:not([disabled]), .card:focus-visible:not([disabled]) {
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
  border-color: var(--color-primary);
}
.card .card-icon {
  font-size: 1.6rem;
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 12px;
  background: var(--color-primary-light);
  margin-bottom: 8px;
}
.card .card-title { font-weight: 700; margin: 2px 0 4px; font-size: 0.95rem; }
.card .card-desc { font-size: 0.8rem; color: var(--color-muted); }
.card[disabled], .card.disabled {
  opacity: 0.5;
  cursor: not-allowed;
}
.card .badge {
  display: inline-block;
  margin-top: 8px;
  font-size: 0.68rem;
  font-weight: 600;
  padding: 3px 10px;
  border-radius: 999px;
  background: #eef3f1;
  color: var(--color-muted);
}
.card .badge.local { background: var(--color-warning-bg); color: var(--color-warning-text); }
.card .badge.cloud { background: var(--color-primary-light); color: var(--color-primary-dark); }

.hint { color: var(--color-muted); font-size: 0.85rem; }
.upload-hint { margin-top: -4px; margin-bottom: 12px; }

.reference-inputs { margin: 14px 0; display: flex; flex-direction: column; gap: 12px; }
.field { display: flex; flex-direction: column; gap: 3px; }
.field label { font-size: 0.85rem; font-weight: 600; }
.field input {
  padding: 11px 14px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  font-size: 1rem;
  background: var(--color-surface);
  transition: border-color 0.15s, box-shadow 0.15s;
}
.field input:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px var(--color-primary-light);
}
.field-help { color: var(--color-muted); font-size: 0.75rem; }

.camera-area { margin: 14px 0; }
.camera-preview, .capture-preview video, .capture-preview img {
  width: 100%;
  max-height: 360px;
  object-fit: contain;
  background: #0c1618;
  border-radius: var(--radius-md);
  display: block;
  box-shadow: var(--shadow-sm);
}
.camera-preview:not([srcObject]) { display: none; }

.capture-controls {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 14px 0 6px;
}

.btn {
  padding: 11px 18px;
  border-radius: 999px;
  border: 1px solid var(--color-border);
  background: var(--color-surface);
  color: var(--color-text);
  font-size: 0.88rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s, box-shadow 0.15s, border-color 0.15s;
}
.btn:hover:not(:disabled) { border-color: var(--color-primary); background: var(--color-primary-light); }
.btn-primary {
  background: var(--color-primary);
  color: #fff;
  border-color: var(--color-primary);
}
.btn-primary:hover:not(:disabled) { background: var(--color-primary-dark); border-color: var(--color-primary-dark); color: #fff; }
.btn-analyze {
  display: block;
  width: 100%;
  margin-top: 10px;
  padding: 15px;
  font-size: 1rem;
  font-weight: 700;
  background: linear-gradient(135deg, var(--color-primary), var(--color-primary-dark));
  color: #fff;
  border: none;
  box-shadow: var(--shadow-sm);
}
.btn-analyze:hover:not(:disabled) { box-shadow: var(--shadow-md); }
.btn-analyze:disabled { background: #b9c9c4; cursor: not-allowed; box-shadow: none; }
.btn-link { background: none; border: none; color: var(--color-primary-dark); text-decoration: underline; padding: 6px 0; font-weight: 600; }
.btn-back { display: block; margin-bottom: 10px; }

/* Khoi ma xac nhan (anti-bot friction) */
.verify-box {
  margin: 18px 0;
  padding: 16px;
  border: 1px dashed var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-primary-light);
}
.verify-box label {
  display: block;
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--color-primary-dark);
  margin-bottom: 8px;
}
.verify-code-row {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
}
.verify-code-display {
  font-family: "SF Mono", Consolas, monospace;
  font-size: 1.6rem;
  font-weight: 700;
  letter-spacing: 0.35em;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  padding: 8px 14px;
  color: var(--color-primary-dark);
  min-width: 110px;
  text-align: center;
}
.verify-code-input {
  flex: 1;
  min-width: 120px;
  padding: 10px 14px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  font-size: 1.1rem;
  letter-spacing: 0.2em;
  text-align: center;
  font-weight: 700;
}
.verify-code-input:focus { outline: none; border-color: var(--color-primary); box-shadow: 0 0 0 3px rgba(10,110,119,0.15); }
.verify-hint { margin-top: 8px; margin-bottom: 0; font-size: 0.75rem; }

.cooldown-banner {
  margin: 14px 0;
  padding: 12px 14px;
  border-radius: var(--radius-sm);
  background: var(--color-warning-bg);
  color: var(--color-warning-text);
  font-size: 0.85rem;
  font-weight: 600;
}

.loading { text-align: center; padding: 28px; color: var(--color-muted); font-weight: 600; }

.result-table { width: 100%; border-collapse: collapse; margin-top: 14px; background: var(--color-surface); border-radius: var(--radius-md); overflow: hidden; box-shadow: var(--shadow-sm); }
.result-table td { padding: 12px 14px; border-bottom: 1px solid var(--color-border); }
.result-table tr:last-child td { border-bottom: none; }
.result-label { color: var(--color-muted); font-size: 0.88rem; }
.result-value { text-align: right; font-weight: 700; color: var(--color-primary-dark); }
.result-formula { font-size: 0.8rem; color: var(--color-muted); margin-top: 12px; }
.result-notes { font-size: 0.85rem; margin-top: 10px; }
.result-disclaimer {
  font-size: 0.8rem;
  background: var(--color-warning-bg);
  color: var(--color-warning-text);
  padding: 12px 14px;
  border-radius: var(--radius-sm);
  margin-top: 16px;
}
.result-error {
  background: var(--color-danger-bg);
  color: var(--color-danger);
  padding: 14px;
  border-radius: var(--radius-sm);
  margin-bottom: 14px;
  font-weight: 600;
}
.result-actions { display: flex; flex-direction: column; gap: 10px; margin-top: 20px; }

.app-footer {
  text-align: center;
  font-size: 0.75rem;
  color: var(--color-muted);
  padding: 20px 16px;
}