/* CSS Variables */
:root {
  --bg: #f8fafc;
  --card: #ffffff;
  --muted: #64748b;
  --text: #0f172a;
  --primary: #3b82f6;
  --primary-600: #2563eb;
  --accent: #10b981;
  --danger: #ef4444;
  --warning: #f59e0b;
  --ring: rgba(59, 130, 246, .2);
  --border: #e2e8f0;
  --shadow: rgba(15, 23, 42, 0.08);
}

/* Reset & Base */
* {
  box-sizing: border-box;
}

html, body {
  height: 100%;
}

body {
  margin: 0;
  font-family: Inter, system-ui, -apple-system, Segoe UI, Roboto, Ubuntu, Cantarell, "Helvetica Neue", Arial, "Noto Sans", "Apple Color Emoji", "Segoe UI Emoji";
  background: linear-gradient(135deg, #f0f9ff 0%, #e0f2fe 100%);
  color: var(--text);
  line-height: 1.55;
}

a {
  color: var(--primary);
  text-decoration: none;
}

.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 24px;
}

.center {
  display: flex;
  align-items: center;
  justify-content: center;
}

/* Cards */
.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 18px;
  box-shadow: 0 4px 16px var(--shadow);
}

.card.pad {
  padding: 24px;
}

/* Header */
header {
  position: sticky;
  top: 0;
  z-index: 10;
  backdrop-filter: blur(10px);
  background: rgba(255, 255, 255, 0.9);
  border-bottom: 1px solid var(--border);
  box-shadow: 0 2px 8px var(--shadow);
}

header .row {
  display: flex;
  gap: 16px;
  align-items: center;
  justify-content: space-between;
  padding: 14px 0;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 800;
  letter-spacing: .3px;
  color: var(--text);
}

.logo .mark {
  width: 34px;
  height: 34px;
  border-radius: 9px;
  background: linear-gradient(135deg, var(--primary), #60a5fa);
  display: grid;
  place-items: center;
  color: white;
  font-weight: 900;
  box-shadow: 0 4px 12px rgba(59, 130, 246, 0.3);
}

/* Buttons */
.btn {
  -webkit-tap-highlight-color: transparent;
  appearance: none;
  border: 1px solid var(--border);
  padding: 10px 14px;
  border-radius: 12px;
  color: var(--text);
  background: var(--card);
  cursor: pointer;
  font-weight: 600;
  transition: all 0.2s ease;
}

.btn:hover {
  border-color: var(--muted);
  box-shadow: 0 2px 8px var(--shadow);
  transform: translateY(-1px);
}

.btn.primary {
  background: linear-gradient(135deg, var(--primary), var(--primary-600));
  border-color: transparent;
  color: white;
  box-shadow: 0 4px 12px rgba(59, 130, 246, 0.3);
}

.btn.primary:hover {
  box-shadow: 0 6px 16px rgba(59, 130, 246, 0.4);
}

.btn.ghost {
  background: transparent;
  border-color: transparent;
}

.btn.ghost:hover {
  background: var(--card);
  border-color: var(--border);
}

.btn.danger {
  background: linear-gradient(135deg, var(--danger), #dc2626);
  border-color: transparent;
  color: white;
}

.btn.success {
  background: linear-gradient(135deg, var(--accent), #059669);
  border-color: transparent;
  color: white;
}

.btn.small {
  padding: 8px 10px;
  font-size: .9rem;
  border-radius: 10px;
}

/* Forms */
.grid {
  display: grid;
  gap: 16px;
}

.grid.cols-2 {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.grid.cols-3 {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.field {
  display: grid;
  gap: 8px;
}

.field label {
  color: var(--muted);
  font-size: .9rem;
  font-weight: 500;
}

.input, select, textarea {
  width: 100%;
  padding: 12px 14px;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: var(--card);
  color: var(--text);
  transition: all 0.2s ease;
}

.input:focus, select:focus, textarea:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 4px var(--ring);
}

.row {
  display: flex;
  gap: 12px;
  align-items: center;
}

.right {
  margin-left: auto;
}

/* Tabs / sections */
.tabs {
  display: flex;
  gap: 8px;
  margin-bottom: 10px;
  flex-wrap: wrap;
}

.tab {
  padding: 10px 12px;
  border-radius: 11px;
  border: 1px solid var(--border);
  color: var(--muted);
  cursor: pointer;
  user-select: none;
  background: var(--card);
  transition: all 0.2s ease;
}

.tab:hover {
  border-color: var(--primary);
  color: var(--primary);
}

.tab.active {
  color: var(--primary);
  background: rgba(59, 130, 246, 0.1);
  border-color: var(--primary);
  font-weight: 600;
}

.hide {
  display: none !important;
}

/* Tables */
table {
  width: 100%;
  border-collapse: collapse;
  border-spacing: 0;
  overflow: hidden;
  border-radius: 14px;
  font-size: .95rem;
}

th, td {
  padding: 12px 12px;
  text-align: left;
  border-bottom: 1px solid var(--border);
}

thead th {
  position: sticky;
  top: 0;
  background: #f1f5f9;
  z-index: 1;
  font-weight: 600;
  color: var(--text);
}

tbody tr:hover td {
  background: #f8fafc;
}

/* Chips */
.chip {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 10px;
  border-radius: 999px;
  font-weight: 600;
  font-size: .85rem;
}

.chip.ok {
  background: #d1fae5;
  color: #047857;
  border: 1px solid #6ee7b7;
}

.chip.bad {
  background: #fee2e2;
  color: #b91c1c;
  border: 1px solid #fca5a5;
}

.chip.warn {
  background: #fef3c7;
  color: #92400e;
  border: 1px solid #fcd34d;
}

.chip.partial {
  background: #fef3c7;
  color: #92400e;
  border: 1px solid #fcd34d;
}

.chip.overdue {
  background: #fee2e2;
  color: #b91c1c;
  border: 1px solid #fca5a5;
}

.chip.paid {
  background: #d1fae5;
  color: #047857;
  border: 1px solid #6ee7b7;
}

/* Admin chip */
.chip.admin {
  background: linear-gradient(135deg, #dbeafe, #bfdbfe);
  color: #1d4ed8;
  border: 1px solid #93c5fd;
}

/* Bad text for overdue/negative amounts */
.bad {
  color: #ef4444 !important;
  font-weight: 600;
}

/* Auth page */
.auth-wrap {
  min-height: calc(100vh - 70px);
  display: grid;
  place-items: center;
  padding: 24px;
}

.auth {
  width: min(980px, 100%);
  display: grid;
  grid-template-columns: 1.2fr 1fr;
  gap: 18px;
}

.auth .illustration {
  background: linear-gradient(135deg, #dbeafe 0%, #bfdbfe 100%);
  border-radius: 18px;
  padding: 26px;
  border: 1px solid var(--border);
}

.auth h1 {
  margin: 0 0 10px 0;
  font-size: 2rem;
  color: var(--text);
}

.auth p {
  margin: 0;
  color: var(--muted);
}

/* Dashboard layout */
.dash {
  display: grid;
  grid-template-columns: 250px 1fr;
  gap: 18px;
  min-height: calc(100vh - 110px);
}

.side {
  position: sticky;
  top: 86px;
  height: fit-content;
}

.nav {
  display: grid;
  gap: 8px;
}

.nav .item {
  display: flex;
  gap: 10px;
  padding: 10px 12px;
  border-radius: 12px;
  cursor: pointer;
  color: var(--muted);
  border: 1px solid transparent;
  transition: all 0.2s ease;
}

.nav .item.active, .nav .item:hover {
  color: var(--primary);
  background: rgba(59, 130, 246, 0.1);
  border-color: rgba(59, 130, 246, 0.2);
  font-weight: 600;
}

.section {
  display: grid;
  gap: 16px;
}

/* Stats */
.stats {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 12px;
}

.stat {
  padding: 16px;
  border-radius: 14px;
  background: linear-gradient(135deg, #eff6ff 0%, #dbeafe 100%);
  border: 1px solid var(--border);
  transition: all 0.2s ease;
}

.stat:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px var(--shadow);
}

.stat .big {
  font-size: 1.6rem;
  font-weight: 800;
  color: var(--primary);
}

.pill {
  font-size: .8rem;
  color: var(--primary);
  border: 1px solid rgba(59, 130, 246, 0.3);
  padding: 6px 10px;
  border-radius: 999px;
  background: rgba(59, 130, 246, 0.1);
  font-weight: 600;
}

/* Admin pill variant */
.pill.admin-pill {
  background: linear-gradient(135deg, #dbeafe, #bfdbfe);
  color: #1d4ed8;
  border-color: #93c5fd;
}

/* Modal overlay */
.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.5);
  display: grid;
  place-items: center;
  z-index: 1000;
  padding: 20px;
}

/* Payment methods */
.payment-methods {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  margin: 16px 0;
}

.payment-method {
  border: 2px solid var(--border);
  border-radius: 12px;
  padding: 16px;
  text-align: center;
  cursor: pointer;
  transition: all 0.2s ease;
}

.payment-method:hover {
  border-color: var(--primary);
  transform: translateY(-2px);
}

.payment-method.selected {
  border-color: var(--primary);
  background: rgba(59, 130, 246, 0.1);
}

.payment-method i {
  font-size: 24px;
  margin-bottom: 8px;
}

/* Role selector buttons on login */
.role-selector {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 10px;
  margin-bottom: 4px;
}

.role-btn {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  padding: 14px 8px;
  border-radius: 14px;
  border: 2px solid var(--border);
  background: var(--card);
  cursor: pointer;
  transition: all 0.2s ease;
  font-family: inherit;
}

.role-btn:hover {
  border-color: var(--primary);
  background: rgba(59,130,246,0.05);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px var(--shadow);
}

.role-btn.active {
  border-color: var(--primary);
  background: rgba(59,130,246,0.08);
  box-shadow: 0 4px 12px rgba(59,130,246,0.15);
}

.role-btn[data-role="admin"].active {
  border-color: #7c3aed;
  background: rgba(124,58,237,0.08);
  box-shadow: 0 4px 12px rgba(124,58,237,0.15);
}

.role-btn[data-role="student"].active {
  border-color: var(--accent);
  background: rgba(16,185,129,0.08);
  box-shadow: 0 4px 12px rgba(16,185,129,0.15);
}

.role-icon {
  font-size: 1.6rem;
  line-height: 1;
}

.role-label {
  font-weight: 700;
  font-size: .95rem;
  color: var(--text);
}

.role-sub {
  font-size: .75rem;
  color: var(--muted);
}

/* Responsive */
@media (max-width: 1000px) {
  .auth {
    grid-template-columns: 1fr;
  }
  
  .dash {
    grid-template-columns: 1fr;
  }
  
  .side {
    position: relative;
    top: 0;
  }
  
  .stats {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  
  header .row {
    flex-wrap: wrap;
  }
  
  .payment-methods {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 600px) {
  .stats {
    grid-template-columns: 1fr;
  }
  
  .grid.cols-3, .grid.cols-2 {
    grid-template-columns: 1fr;
  }
  
  .payment-methods {
    grid-template-columns: 1fr;
  }
}