* { box-sizing: border-box; margin: 0; padding: 0; }
body {
  font-family: -apple-system, 'Segoe UI', Roboto, Arial, sans-serif;
  background: linear-gradient(160deg, #e8f5e9 0%, #e3f2fd 100%);
  color: #1b3a2f;
  font-size: 20px;
  min-height: 100vh;
}
.container { max-width: 520px; margin: 0 auto; padding: 20px; }
header { text-align: center; margin-bottom: 18px; }
h1 { color: #1b5e20; font-size: 30px; }
.sub { color: #2e7d32; font-size: 18px; }
.card {
  background: #fff; border-radius: 16px; padding: 22px;
  box-shadow: 0 4px 14px rgba(27,94,32,.12); margin-bottom: 16px;
}
h2 { color: #1565c0; margin-bottom: 14px; font-size: 24px; }
input, textarea {
  width: 100%; padding: 18px; font-size: 22px; margin-bottom: 14px;
  border: 2px solid #b0bec5; border-radius: 12px;
}
button.big {
  width: 100%; padding: 20px; font-size: 22px; font-weight: 600;
  border: none; border-radius: 14px; background: #1565c0; color: #fff;
  cursor: pointer; margin-bottom: 12px;
}
button.big.green { background: #2e7d32; }
button.ghost {
  width: 100%; padding: 16px; font-size: 20px;
  border: 2px solid #90a4ae; border-radius: 14px; background: #fff;
  color: #455a64; cursor: pointer;
}
.banner { padding: 18px; border-radius: 14px; font-size: 24px; font-weight: 700; text-align: center; margin-bottom: 16px; }
.banner.paid { background: #c8e6c9; color: #1b5e20; }
.banner.debt { background: #ffcdd2; color: #b71c1c; }
.balanceBox { background: #fff; border-radius: 16px; padding: 22px; text-align: center; margin-bottom: 16px; box-shadow: 0 4px 14px rgba(21,101,192,.12); }
.label { color: #546e7a; font-size: 18px; }
.balance { font-size: 44px; font-weight: 800; color: #1b5e20; margin: 6px 0; }
.err { color: #c62828; margin-top: 10px; }
.result { margin-top: 14px; padding: 14px; background: #e8f5e9; border-radius: 12px; font-size: 20px; }
.hint { color: #607d8b; font-size: 16px; margin-bottom: 10px; }
.hidden { display: none; }
table { width: 100%; border-collapse: collapse; font-size: 18px; }
th, td { padding: 10px; text-align: left; border-bottom: 1px solid #e0e0e0; }
.debt-row td { color: #c62828; font-weight: 700; }
.item { padding: 12px 0; border-bottom: 1px solid #e0e0e0; }