:root {
  --bg: #e8eef3;
  --bg-soft: #f4f7fa;
  --card: #ffffff;
  --text: #1b2a36;
  --muted: #5e7386;
  --line: #d6e0e8;
  --primary: #1f4f7d;
  --primary-soft: #d9e7f3;
  --secondary: #2f699f;
  --danger: #8e3e4c;
  --success: #2d6a4f;
}

* { box-sizing: border-box; }
body {
  margin: 0;
  background: linear-gradient(180deg, #ecf2f7 0%, var(--bg) 60%, #dde7ef 100%);
  color: var(--text);
  font-family: "Avenir Next", "Segoe UI", sans-serif;
  min-height: 100vh;
}

#app {
  max-width: 720px;
  margin: 0 auto;
  padding: max(env(safe-area-inset-top), 12px) 12px calc(12px + env(safe-area-inset-bottom));
}

.topbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 10px;
}

h1, h2, h3 { margin: 0; }
h1 { font-size: 1.35rem; }
h2 { font-size: 1.1rem; }
h3 { font-size: 1rem; margin-bottom: 8px; }
p { margin: 6px 0; }
.title-wrap p { color: var(--muted); font-size: 0.86rem; }

.card {
  background: rgba(255, 255, 255, 0.93);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 12px;
  box-shadow: 0 4px 14px rgba(39, 66, 91, 0.07);
}

.view { display: block; }
.hidden { display: none !important; }

.stack {
  display: grid;
  gap: 10px;
  margin-top: 10px;
}

.compact { gap: 6px; }

.row {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 8px;
}

input, select {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 10px 12px;
  background: var(--bg-soft);
  color: var(--text);
  font-size: 0.98rem;
}

input[type="hidden"] {
  display: none !important;
}

button {
  border: 0;
  border-radius: 12px;
  padding: 10px 12px;
  font-size: 0.93rem;
  font-weight: 600;
}

.primary { background: var(--primary); color: #fff; }
.secondary { background: var(--secondary); color: #fff; }
.ghost { background: var(--primary-soft); color: var(--primary); }
.danger { background: #f1dfe3; color: var(--danger); }

.between { display: flex; justify-content: space-between; align-items: center; gap: 10px; }
.row-inline { display: flex; gap: 8px; }

.tab-menu {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: 8px;
  margin-top: 10px;
}

.tab-btn {
  background: var(--bg-soft);
  color: var(--muted);
  border: 1px solid var(--line);
}

.tab-btn.active {
  background: var(--primary);
  color: #fff;
  border-color: var(--primary);
}

.tab-panel {
  margin-top: 12px;
}

.expense-form {
  display: grid;
  grid-template-columns: 1.1fr 0.7fr 1fr;
  gap: 8px;
}

.split-mode-line {
  display: flex;
  align-items: center;
  gap: 12px;
  grid-column: 1 / -1;
  flex-wrap: wrap;
  padding: 6px 0;
}

.split-mode-line label {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 0.9rem;
  color: var(--muted);
}

.split-mode-line input[type="radio"] {
  width: auto;
}

.split-editor {
  grid-column: 1 / -1;
  display: grid;
  gap: 6px;
  padding: 8px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: #f7fbff;
}

.split-row {
  display: grid;
  grid-template-columns: auto 1fr 100px;
  align-items: center;
  gap: 8px;
}

.split-row input[type="checkbox"] { width: auto; }
.member-list { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 8px; }
.member-chip {
  font-size: 0.8rem;
  padding: 5px 8px;
  border-radius: 999px;
  background: #eaf2f9;
  border: 1px solid #d0deea;
}

.add-member-form { margin-top: 8px; }
.invite-row { margin-top: 8px; }
.group-tools { margin-top: 10px; }

.group-card {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 8px;
  cursor: pointer;
}

.group-card:active {
  transform: translateY(1px);
}

.group-card .group-main {
  flex: 1;
}

.group-delete-checkbox {
  width: auto;
  margin: 0;
}

.field-label {
  grid-column: 1 / -1;
  margin: 0;
  font-size: 0.76rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  color: var(--muted);
  text-transform: uppercase;
}

.payer-picker {
  grid-column: 1 / -1;
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.payer-option {
  border: 1px solid #c9d9e8;
  background: #edf5fc;
  color: var(--text);
  padding: 8px 10px;
  border-radius: 999px;
  font-size: 0.86rem;
  font-weight: 600;
  line-height: 1.1;
}

.payer-option.active {
  background: var(--primary);
  border-color: var(--primary);
  color: #fff;
}

.invite-output {
  margin-top: 8px;
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 8px;
}

.invite-output input {
  font-size: 0.86rem;
}

.modal-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(20, 32, 44, 0.45);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 12px;
  z-index: 200;
}

.modal-card {
  width: 100%;
  max-width: 440px;
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 14px;
  display: grid;
  gap: 10px;
}

.group-meta { color: var(--muted); font-size: 0.85rem; }

.expense-card {
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 10px;
  background: #f9fcff;
}

.expense-title {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 8px;
}

.expense-sub { color: var(--muted); font-size: 0.86rem; }

.expense-actions {
  display: flex;
  gap: 6px;
  margin-top: 8px;
}

.balance-row {
  display: flex;
  justify-content: space-between;
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 8px 10px;
  background: #f7fbff;
}

.positive { color: var(--success); }
.negative { color: var(--danger); }
.muted { color: var(--muted); font-size: 0.85rem; }
main { display: grid; gap: 10px; }

@media (max-width: 520px) {
  .tab-menu {
    grid-template-columns: 1fr;
  }

  .expense-form {
    grid-template-columns: 1fr 1fr;
  }
  .expense-form button { grid-column: 1 / -1; }
  .split-row {
    grid-template-columns: auto 1fr;
  }
  .split-row input[type="number"] { grid-column: 1 / -1; }
}