:root {
  --bg: #f4f5f7;
  --card: #ffffff;
  --border: #e3e5ea;
  --text: #1c1e21;
  --text-secondary: #666b73;
  --primary: #3a6df0;
  --primary-contrast: #ffffff;
  --positive: #1f9254;
  --negative: #d1453b;
  --chip-bg: #eef1f6;
  --radius: 12px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #14161a;
    --card: #1e2126;
    --border: #2c3038;
    --text: #f0f1f3;
    --text-secondary: #9aa0aa;
    --primary: #6f93ff;
    --primary-contrast: #0c1220;
    --positive: #4cc785;
    --negative: #ff6b62;
    --chip-bg: #262a31;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
}

.hidden { display: none !important; }

.screen {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
}

header {
  width: 100%;
  max-width: 640px;
  padding: 24px 16px 8px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

header h1 { margin: 0; font-size: 24px; }

.header-right {
  display: flex;
  align-items: center;
  gap: 10px;
}

.back-btn {
  padding: 6px 4px;
  font-size: 15px;
}

main {
  width: 100%;
  max-width: 640px;
  padding: 8px 16px 64px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px;
}

.card h2 {
  margin: 0 0 12px;
  font-size: 16px;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.card h3 {
  margin: 16px 0 8px;
  font-size: 13px;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.login-card {
  margin-top: 12vh;
  width: 100%;
  max-width: 340px;
  text-align: center;
}

.form-title {
  margin: 8px 0 12px;
  font-size: 15px;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  text-align: left;
}

.switch-line { margin-top: 4px; }
.switch-line a { color: var(--primary); text-decoration: none; }

.muted { color: var(--text-secondary); font-size: 14px; }

.groups-list {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-bottom: 12px;
}

.group-row {
  width: 100%;
  text-align: left;
  padding: 14px 16px;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--chip-bg);
  color: var(--text);
  font-size: 16px;
  font-weight: 600;
}

input[type="text"],
input[type="password"],
input[type="number"],
select {
  width: 100%;
  padding: 11px 12px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--bg);
  color: var(--text);
  font-size: 15px;
  margin-bottom: 10px;
}

.field-label {
  display: block;
  font-size: 13px;
  color: var(--text-secondary);
  margin: 4px 0 6px;
}

button {
  font-size: 15px;
  padding: 11px 16px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--chip-bg);
  color: var(--text);
  cursor: pointer;
}

button.primary {
  width: 100%;
  background: var(--primary);
  color: var(--primary-contrast);
  border: none;
  font-weight: 600;
  margin-top: 8px;
}

button.link-btn {
  background: none;
  border: none;
  color: var(--primary);
  padding: 4px 8px;
  font-size: 13px;
}

.inline-form {
  display: flex;
  gap: 8px;
  margin-top: 10px;
}
.inline-form input { margin-bottom: 0; flex: 1; }

.error {
  color: var(--negative);
  font-size: 14px;
  margin-top: 8px;
}

.chip-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.chip {
  display: flex;
  align-items: center;
  gap: 6px;
  background: var(--chip-bg);
  border-radius: 999px;
  padding: 6px 8px 6px 14px;
  font-size: 14px;
}

.chip button {
  border: none;
  background: none;
  color: var(--text-secondary);
  padding: 2px 6px;
  font-size: 13px;
  border-radius: 999px;
}

.checkbox-list {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 12px;
}

.checkbox-chip {
  display: flex;
  align-items: center;
  gap: 6px;
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 8px 14px;
  font-size: 14px;
  cursor: pointer;
  user-select: none;
}

.checkbox-chip input { margin: 0; width: auto; }

.checkbox-chip.checked {
  background: var(--primary);
  color: var(--primary-contrast);
  border-color: var(--primary);
}

.split-actions {
  display: flex;
  gap: 4px;
  margin-bottom: 4px;
}

.balances-list, .settlements-list, .expenses-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.balance-row, .settlement-row, .expense-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 10px 0;
  border-bottom: 1px solid var(--border);
}
.balance-row:last-child, .settlement-row:last-child, .expense-row:last-child {
  border-bottom: none;
  padding-bottom: 0;
}

.balance-amount.positive { color: var(--positive); font-weight: 600; }
.balance-amount.negative { color: var(--negative); font-weight: 600; }
.balance-amount.zero { color: var(--text-secondary); }

.settlement-row { font-size: 14px; }

.expense-row {
  align-items: flex-start;
}

.expense-main { flex: 1; }
.expense-desc { font-weight: 600; }
.expense-meta { font-size: 13px; color: var(--text-secondary); margin-top: 2px; }
.expense-amount { font-weight: 600; white-space: nowrap; margin-left: 12px; }

.delete-btn {
  background: none;
  border: none;
  color: var(--text-secondary);
  font-size: 16px;
  padding: 2px 6px;
  margin-left: 8px;
}

.empty-note { color: var(--text-secondary); font-size: 14px; }