:root {
  --bg: #f5f6f8;
  --card: #ffffff;
  --text: #1c2333;
  --muted: #6b7280;
  --border: #e3e6ea;
  --accent: #2f6f4f;
  --accent-dark: #234f39;
  --danger: #b3421f;
  --warn: #b8860b;
  --ok-bg: #e6f4ea;
  --ok-text: #1c6b34;
  --pend-bg: #fdecea;
  --pend-text: #a3341b;
  font-family: -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
}

[hidden] { display: none !important; }

button {
  cursor: pointer;
  font-family: inherit;
}

input, select {
  font-family: inherit;
  font-size: 0.95rem;
}

/* Login */
#login-screen {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 16px;
}

.login-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 32px;
  width: 100%;
  max-width: 360px;
  box-shadow: 0 2px 12px rgba(0,0,0,0.06);
}

.login-card h1 {
  font-size: 1.3rem;
  margin: 0 0 4px;
  color: var(--accent-dark);
}

.login-card p.sub {
  margin: 0 0 24px;
  color: var(--muted);
  font-size: 0.9rem;
}

.field {
  margin-bottom: 14px;
}

.field label {
  display: block;
  font-size: 0.82rem;
  color: var(--muted);
  margin-bottom: 4px;
}

.field input, .field select, .field textarea {
  width: 100%;
  padding: 9px 10px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: #fff;
  color: var(--text);
}

.btn {
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: 8px;
  padding: 10px 16px;
  font-size: 0.92rem;
  font-weight: 600;
}
.btn:hover { background: var(--accent-dark); }
.btn.secondary {
  background: #fff;
  color: var(--accent-dark);
  border: 1px solid var(--accent);
}
.btn.danger { background: var(--danger); }
.btn:disabled { opacity: 0.5; cursor: default; }

.error-msg {
  color: var(--danger);
  font-size: 0.85rem;
  margin-top: 10px;
  min-height: 1em;
}

/* App shell */
#app-screen {
  display: flex;
  min-height: 100vh;
}

.sidebar {
  width: 220px;
  background: var(--accent-dark);
  color: #fff;
  padding: 20px 14px;
  flex-shrink: 0;
}

.sidebar h2 {
  font-size: 1.05rem;
  margin: 0 0 2px;
}
.sidebar .who {
  font-size: 0.78rem;
  opacity: 0.75;
  margin-bottom: 22px;
}

.nav-item {
  display: block;
  width: 100%;
  text-align: left;
  background: transparent;
  border: none;
  color: #fff;
  padding: 10px 12px;
  border-radius: 8px;
  font-size: 0.9rem;
  margin-bottom: 4px;
  opacity: 0.85;
}
.nav-item:hover { background: rgba(255,255,255,0.08); }
.nav-item.active { background: rgba(255,255,255,0.18); opacity: 1; font-weight: 600; }

.logout-btn {
  margin-top: 24px;
  background: transparent;
  border: 1px solid rgba(255,255,255,0.35);
  color: #fff;
  border-radius: 8px;
  padding: 8px 12px;
  font-size: 0.82rem;
  width: 100%;
}

main {
  flex: 1;
  padding: 28px 32px;
  max-width: 1100px;
}

main h1 {
  font-size: 1.4rem;
  margin: 0 0 20px;
}

.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 14px;
  margin-bottom: 26px;
}

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 16px 18px;
}
.card .label { font-size: 0.78rem; color: var(--muted); margin-bottom: 6px; }
.card .value { font-size: 1.5rem; font-weight: 700; }
.card.balance-pos .value { color: var(--ok-text); }
.card.balance-neg .value { color: var(--pend-text); }

.section {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 18px 20px;
  margin-bottom: 20px;
}
.section h3 { margin: 0 0 12px; font-size: 1rem; }

.toolbar {
  display: flex;
  gap: 10px;
  align-items: center;
  margin-bottom: 16px;
  flex-wrap: wrap;
}

#dashboard-cards, #pendientes-table, #corriente-table, #pagos-table, #alumnos-table, #gastos-table {
  overflow-x: auto;
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.88rem;
}
th, td {
  text-align: left;
  padding: 8px 10px;
  border-bottom: 1px solid var(--border);
}
th { color: var(--muted); font-weight: 600; font-size: 0.78rem; text-transform: uppercase; }

.badge {
  display: inline-block;
  padding: 3px 9px;
  border-radius: 999px;
  font-size: 0.75rem;
  font-weight: 600;
}
.badge.ok { background: var(--ok-bg); color: var(--ok-text); }
.badge.pend { background: var(--pend-bg); color: var(--pend-text); }

.modal-backdrop {
  position: fixed; inset: 0;
  background: rgba(0,0,0,0.4);
  display: flex; align-items: center; justify-content: center;
  z-index: 50;
  padding: 16px;
}
.modal {
  background: #fff;
  border-radius: 12px;
  padding: 24px;
  width: 100%;
  max-width: 420px;
  max-height: 90vh;
  overflow-y: auto;
}
.modal h3 { margin-top: 0; }
.modal-actions {
  display: flex;
  gap: 10px;
  justify-content: flex-end;
  margin-top: 18px;
}

.link-btn {
  background: none;
  border: none;
  color: var(--accent-dark);
  text-decoration: underline;
  font-size: 0.85rem;
  padding: 0;
}

.empty {
  color: var(--muted);
  font-size: 0.88rem;
  padding: 10px 0;
}

.toast {
  position: fixed;
  bottom: 20px;
  right: 20px;
  background: var(--accent-dark);
  color: #fff;
  padding: 10px 16px;
  border-radius: 8px;
  font-size: 0.85rem;
  z-index: 100;
}
.toast.err { background: var(--danger); }

@media (max-width: 720px) {
  #app-screen { flex-direction: column; }
  .sidebar { width: 100%; }
  main { padding: 18px; }
}