:root {
  --bg-primary: #0a0a0f;
  --bg-secondary: #14141f;
  --bg-tertiary: #1e1e2e;
  --bg-elevated: #252539;
  --text-primary: #ffffff;
  --text-secondary: #a0a0b0;
  --text-muted: #606070;
  --accent: #00d4ff;
  --accent-secondary: #00ff88;
  --danger: #ff4466;
  --focus-ring: #00d4ff;
  --focus-glow: rgba(0, 212, 255, 0.45);
  --radius-md: 12px;
  --radius-sm: 8px;
}

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

html, body {
  width: 600px;
  height: 600px;
  overflow: hidden;
  background: #000;
  color: var(--text-primary);
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  -webkit-font-smoothing: antialiased;
}

#app { width: 100%; height: 100%; position: relative; }

.screen {
  width: 100%;
  height: 100%;
  position: absolute;
  top: 0;
  left: 0;
  display: flex;
  flex-direction: column;
}
.screen.hidden { display: none; }

.focusable {
  transition: transform 0.15s ease, box-shadow 0.15s ease, border-color 0.15s ease, background 0.15s ease;
  border: 2px solid transparent;
  cursor: pointer;
  outline: none;
}
.focusable:focus {
  border-color: var(--focus-ring);
  box-shadow: 0 0 20px var(--focus-glow);
  transform: scale(1.05);
}
.hidden { display: none !important; }

/* Header */
.app-header {
  padding: 10px 18px;
  background: var(--bg-primary);
  border-bottom: 1px solid var(--bg-tertiary);
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex: 0 0 auto;
}
.header-left {
  display: flex;
  align-items: center;
  gap: 10px;
}
.header-icon {
  color: var(--accent-secondary);
  display: block;
}
.app-header h1 {
  font-size: 18px;
  font-weight: 700;
  color: var(--accent);
  letter-spacing: 2px;
  text-transform: uppercase;
}
.header-hint {
  font-size: 11px;
  color: var(--text-muted);
  letter-spacing: 1px;
  font-variant-numeric: tabular-nums;
}

/* Main */
.app-main {
  flex: 1;
  padding: 12px 16px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  overflow: hidden;
  min-height: 0;
}

/* Row */
.row {
  background: var(--bg-primary);
  border: 1px solid var(--bg-tertiary);
  border-radius: var(--radius-md);
  padding: 10px 12px;
  display: flex;
  align-items: center;
  gap: 10px;
  flex: 0 0 auto;
}
.row-info {
  flex: 0 0 130px;
  display: flex;
  flex-direction: column;
  gap: 2px;
}
.row-label {
  font-size: 10px;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 2px;
  font-weight: 700;
}
.row-value {
  font-size: 24px;
  font-weight: 800;
  color: var(--text-primary);
  font-variant-numeric: tabular-nums;
  line-height: 1.1;
}
.row-value.flash {
  color: var(--accent);
}
.row-controls {
  flex: 1;
  display: flex;
  gap: 6px;
  justify-content: flex-end;
  flex-wrap: nowrap;
}

/* Buttons */
.adj-btn,
.tip-btn,
.reset-btn {
  background: var(--bg-tertiary);
  color: var(--text-primary);
  border-radius: var(--radius-sm);
  font-family: inherit;
  font-weight: 700;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}
.adj-btn {
  min-width: 56px;
  height: 50px;
  font-size: 15px;
  padding: 0 4px;
}
.adj-btn.big {
  min-width: 64px;
}
.tip-btn {
  min-width: 60px;
  height: 50px;
  font-size: 14px;
  padding: 0 4px;
}
.tip-btn.active {
  background: var(--accent);
  color: #000;
}
.tip-btn.active:focus {
  box-shadow: 0 0 24px var(--focus-glow);
}
.split-controls {
  gap: 12px;
  justify-content: flex-end;
}
.split-btn {
  min-width: 78px;
  height: 50px;
  font-size: 24px;
  font-weight: 700;
}

/* Results */
.results {
  background: linear-gradient(180deg, var(--bg-primary) 0%, var(--bg-secondary) 100%);
  border: 1px solid var(--bg-tertiary);
  border-radius: var(--radius-md);
  padding: 12px 16px;
  display: flex;
  flex-direction: column;
  gap: 6px;
  flex: 0 0 auto;
}
.result-row {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
}
.result-label {
  font-size: 11px;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 1.5px;
  font-weight: 700;
}
.result-value {
  font-size: 18px;
  font-weight: 700;
  color: var(--text-primary);
  font-variant-numeric: tabular-nums;
}
.result-row.total-row .result-value {
  font-size: 20px;
  color: var(--accent);
}
.result-row.per-person {
  margin-top: 6px;
  padding-top: 8px;
  border-top: 1px solid var(--bg-tertiary);
  align-items: center;
}
.result-row.per-person .result-label {
  font-size: 12px;
  color: var(--text-primary);
}
.result-row.per-person .result-value {
  font-size: 28px;
  color: var(--accent-secondary);
  font-weight: 800;
}

/* Footer */
.footer-bar {
  flex: 0 0 auto;
  padding: 8px 16px 12px;
  display: flex;
  justify-content: center;
  background: var(--bg-primary);
  border-top: 1px solid var(--bg-tertiary);
}
.reset-btn {
  height: 46px;
  padding: 0 36px;
  font-size: 11px;
  letter-spacing: 2.5px;
  text-transform: uppercase;
  color: var(--text-secondary);
}
.reset-btn:focus {
  color: var(--accent);
}