:root {
  --red: #E8131E;
  --red-light: #fde8e9;
  --green: #0F6E56;
  --green-light: #e1f5ee;
  --text-primary: #171717;   /* Carbon — не чистый чёрный */
  --text-secondary: #555;
  --text-tertiary: #737373;  /* контраст ≥4.5:1, не «тонкий серый» */
  --text-inverse: #FFFAFA;   /* Snow — не чистый белый */
  --bg: #f5f5f5;
  --card: #FCFCFC;           /* off-white вместо #fff */
  --border: #e5e5e5;
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-full: 999px;
  --font: system-ui, -apple-system, sans-serif;
  --transition: 300ms ease;
}

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

html, body { height: 100%; background: var(--bg); font-family: var(--font); color: var(--text-primary); -webkit-tap-highlight-color: transparent; }

#app { height: 100%; display: flex; flex-direction: column; max-width: 480px; margin: 0 auto; }

#screen-container { flex: 1; position: relative; overflow: hidden; }

/* Screen transitions */
.screen { position: absolute; inset: 0; background: var(--bg); padding: 20px 16px 32px; overflow-y: auto; transition: transform var(--transition); display: flex; flex-direction: column; gap: 16px; }
.screen.enter-right { transform: translateX(100%); }
.screen.enter-left  { transform: translateX(-100%); }
.screen.active      { transform: translateX(0); }
.screen.exit-left   { transform: translateX(-100%); }
.screen.exit-right  { transform: translateX(100%); }

/* Typography */
.screen-title { font-size: 22px; font-weight: 700; color: var(--text-primary); }
.label { font-size: 13px; color: var(--text-secondary); }
.amount-big { font-size: 36px; font-weight: 700; color: var(--text-primary); }
.amount-note { font-size: 13px; color: var(--text-tertiary); }

/* Card */
.card { background: var(--card); border-radius: var(--radius-lg); padding: 16px; }

/* Focus — клавиатурная доступность (состояние Focused) */
button:focus-visible, [role="button"]:focus-visible, .scan-area:focus-visible { outline: 2px solid var(--red); outline-offset: 2px; }

/* Button */
.btn-primary { width: 100%; padding: 16px; background: var(--red); color: var(--text-inverse); border: none; border-radius: var(--radius-md); font-size: 16px; font-weight: 600; cursor: pointer; transition: opacity var(--transition); margin-top: auto; }
.btn-primary:active { opacity: 0.85; }
.btn-primary:disabled { opacity: 0.4; cursor: not-allowed; }

/* Back button — тач-зона ≥44px */
.btn-back { background: none; border: none; color: var(--red); font-size: 15px; cursor: pointer; padding: 8px 4px; min-height: 44px; display: flex; align-items: center; gap: 4px; align-self: flex-start; }

/* Input */
input[type="text"], input[type="number"], input[type="tel"] {
  width: 100%; padding: 12px 14px; border: 1px solid var(--border); border-radius: var(--radius-sm);
  font-size: 16px; font-family: var(--font); color: var(--text-primary); background: var(--card);
  outline: none; transition: border-color var(--transition);
}
input:focus { border-color: var(--red); }

/* Avatar */
.avatar { width: 36px; height: 36px; border-radius: 50%; display: flex; align-items: center; justify-content: center; font-size: 14px; font-weight: 600; flex-shrink: 0; }

/* Progress bar */
.progress-track { height: 6px; background: var(--border); border-radius: var(--radius-full); overflow: hidden; }
.progress-fill  { height: 100%; background: var(--red); border-radius: var(--radius-full); transition: width 600ms cubic-bezier(0.34,1.56,0.64,1); }

/* Participant card */
.participant-card { display: flex; align-items: center; gap: 12px; background: var(--card); border-radius: var(--radius-md); padding: 14px; cursor: pointer; transition: background var(--transition); }
.participant-card:active { background: #fafafa; }
.participant-card.paid .progress-fill { background: var(--green); }
.participant-info { flex: 1; min-width: 0; }
.participant-name { font-size: 15px; font-weight: 500; }
.participant-amount { font-size: 13px; color: var(--text-secondary); }
.participant-status { font-size: 13px; font-weight: 600; color: var(--green); white-space: nowrap; }
.participant-status.pending { color: var(--text-tertiary); }

/* Divider */
.divider { display: flex; align-items: center; gap: 8px; }
.divider::before, .divider::after { content: ''; flex: 1; height: 1px; background: var(--border); }
.divider span { font-size: 12px; color: var(--text-tertiary); }

/* Counter — тач-зоны ≥44px */
.counter { display: flex; align-items: center; gap: 16px; }
.counter-btn { width: 44px; height: 44px; border-radius: 50%; border: 1px solid var(--border); background: var(--card); font-size: 22px; cursor: pointer; display: flex; align-items: center; justify-content: center; transition: background var(--transition); }
.counter-btn.inc { background: var(--red); color: var(--text-inverse); border-color: var(--red); }
.counter-btn:active { opacity: 0.8; }
.counter-value { font-size: 28px; font-weight: 700; min-width: 40px; text-align: center; }

/* Items list */
.items-list { display: flex; flex-direction: column; gap: 8px; }
.item-row { display: flex; align-items: center; gap: 8px; }
.item-row input[type="text"] { flex: 1; }
.item-row input[type="number"] { width: 100px; }
.item-row .btn-remove { background: none; border: none; color: var(--text-tertiary); font-size: 20px; cursor: pointer; min-width: 44px; min-height: 44px; display: flex; align-items: center; justify-content: center; flex-shrink: 0; }

/* Scan area */
.scan-area { border: 2px dashed var(--border); border-radius: var(--radius-lg); padding: 24px; display: flex; flex-direction: column; align-items: center; gap: 12px; cursor: pointer; transition: border-color var(--transition); }
.scan-area:active { border-color: var(--red); }
.scan-icon { font-size: 40px; }
.scan-label { font-size: 15px; color: var(--text-secondary); text-align: center; }
.scan-hint { font-size: 12px; color: var(--text-tertiary); text-align: center; }

/* OCR status */
.ocr-status { font-size: 13px; color: var(--text-secondary); text-align: center; padding: 8px; }

/* Total summary */
.total-card { background: var(--card); border-radius: var(--radius-lg); padding: 20px; text-align: center; }
.total-header { font-size: 13px; color: var(--text-secondary); margin-bottom: 4px; }
.total-subtext { font-size: 13px; color: var(--text-tertiary); margin-top: 4px; }

/* Collection header */
.collection-header { display: flex; align-items: center; justify-content: space-between; }
.btn-share { background: none; border: none; color: var(--red); font-size: 24px; cursor: pointer; min-width: 44px; min-height: 44px; display: flex; align-items: center; justify-content: center; }

/* Confetti canvas */
#confetti-canvas { position: fixed; inset: 0; pointer-events: none; z-index: 100; }

/* Participant row (screen 2) */
.participant-row { display: flex; align-items: flex-start; gap: 8px; flex-wrap: wrap; }
.participant-fields { flex: 1; display: flex; flex-direction: column; gap: 8px; min-width: 0; }
.participant-fields .p-phone { font-size: 14px; padding: 8px 12px; }
.btn-friends { background: none; border: none; font-size: 22px; cursor: pointer; min-width: 44px; min-height: 44px; display: flex; align-items: center; justify-content: center; line-height: 1; flex-shrink: 0; }

/* Friends picker */
.friend-picker { flex-basis: 100%; width: 100%; display: flex; flex-wrap: wrap; gap: 8px; margin-top: 4px; }
.friend-chip { background: var(--red-light); color: var(--red); border: none; border-radius: var(--radius-full); padding: 6px 12px; font-size: 13px; cursor: pointer; }
.friend-chip:active { opacity: 0.7; }
.friend-empty { font-size: 13px; color: var(--text-tertiary); }

/* Reminder button + menu (screen 4) */
.participant-info { position: relative; }
.btn-remind { margin-top: 8px; background: var(--red-light); color: var(--red); border: none; border-radius: var(--radius-full); padding: 5px 12px; font-size: 12px; font-weight: 600; cursor: pointer; }
.btn-remind:active { opacity: 0.7; }
.reminder-menu { position: absolute; left: 0; top: 100%; margin-top: 4px; background: var(--card); border: 1px solid var(--border); border-radius: var(--radius-md); box-shadow: 0 6px 24px rgba(0,0,0,0.12); z-index: 50; display: flex; flex-direction: column; min-width: 160px; overflow: hidden; }
.reminder-item { background: none; border: none; text-align: left; padding: 14px 16px; font-size: 14px; min-height: 44px; cursor: pointer; }
.reminder-item:active { background: var(--bg); }
.reminder-item + .reminder-item { border-top: 1px solid var(--border); }

/* Screen 1 header + history */
.screen1-header { display: flex; align-items: center; justify-content: space-between; gap: 8px; }
.btn-history { background: none; border: none; color: var(--red); font-size: 14px; font-weight: 600; cursor: pointer; padding: 8px; min-height: 44px; white-space: nowrap; }
.history-row { display: grid; grid-template-columns: auto 1fr auto; align-items: center; gap: 12px; background: var(--card); border: none; border-radius: var(--radius-md); padding: 16px; min-height: 44px; text-align: left; cursor: pointer; }
.history-row:active { background: #f0f0f0; }
.history-date { font-size: 13px; color: var(--text-tertiary); }
.history-total { font-size: 15px; font-weight: 600; }
.history-status { font-size: 13px; font-weight: 600; white-space: nowrap; }
.history-status.done { color: var(--green); }
.history-status.pending { color: var(--text-tertiary); }
.history-empty { font-size: 14px; color: var(--text-tertiary); text-align: center; padding: 32px 0; }