:root {
  --brand-primary: #1fb6ff;
  --brand-accent:  #22c55e;
  --brand-danger:  #f97373;

  --bg-body:      #050816;
  --bg-surface:   rgba(9, 20, 40, 0.96);
  --bg-surface-soft: rgba(15, 28, 52, 0.9);
  --border-subtle: rgba(255, 255, 255, 0.06);

  --text-main:    #e5edf7;
  --text-muted:   #a0b3ce;
  --text-soft:    #7c8aa5;

  --nav-bg:       #020817;
  --nav-border:   rgba(255, 255, 255, 0.06);
  --card-radius:  16px;
  --card-shadow:  0 18px 40px rgba(0,0,0,0.65);

  --table-header-bg: rgba(255, 255, 255, 0.03);
  --table-row-alt:   rgba(255, 255, 255, 0.01);

  --timeline-line:   rgba(173, 216, 255, 0.35);
  --timeline-dot:    #38bdf8;

  --chat-parent-bg:  #0f172a;
  --chat-student-bg: #16a34a;
  --chat-student-text:#04110a;

  --badge-task:      #64748b;
  --badge-log:       #22c55e;

  --font-sans: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

/* Light theme override */
html[data-theme="light"] {
  --bg-body:      #f8fafc;
  --bg-surface:   #ffffff;
  --bg-surface-soft: #f1f5f9;
  --border-subtle: rgba(15,23,42,0.08);

  --text-main:    #020617;
  --text-muted:   #4b5563;
  --text-soft:    #6b7280;

  --nav-bg:       #0f172a;
  --nav-border:   rgba(15,23,42,0.45);

  --chat-parent-bg:  #0f172a;
  --chat-student-bg: #e0fbea;
  --chat-student-text:#052e16;
}

body {
  min-height: 100vh;
  margin: 0;
  padding-bottom: 24px;
  font-family: var(--font-sans);
  background: radial-gradient(circle at top, #0f172a 0, var(--bg-body) 45%, #020617 100%);
  color: var(--text-main);
}

.navbar {
  background: linear-gradient(90deg, var(--nav-bg), #02091e);
  border-bottom: 1px solid var(--nav-border);
  box-shadow: 0 12px 35px rgba(0,0,0,0.7);
}

.navbar-brand {
  font-weight: 700;
  letter-spacing: 0.02em;
}

.navbar .nav-link {
  font-size: 0.9rem;
  color: var(--text-soft);
}

.navbar .nav-link:hover {
  color: var(--text-main);
}

.container {
  max-width: 1180px;
}

.card {
  background: var(--bg-surface);
  border-radius: var(--card-radius);
  border: 1px solid var(--border-subtle);
  box-shadow: var(--card-shadow);
  backdrop-filter: blur(14px);
}

.card-header {
  border-bottom-color: rgba(255,255,255,0.04);
  background: linear-gradient(90deg, rgba(15,23,42,0.95), rgba(15,23,42,0.8));
  font-weight: 600;
}

.table {
  color: var(--text-main);
  font-size: 0.86rem;
}
.table thead {
  background: var(--table-header-bg);
}
.table tbody tr:nth-child(2n) {
  background: var(--table-row-alt);
}
.table td,
.table th {
  border-color: rgba(255,255,255,0.06);
}

.btn-primary {
  background: linear-gradient(135deg, #0284c7, #22c55e);
  border: 0;
  box-shadow: 0 0 0 1px rgba(56,189,248,0.35), 0 14px 30px rgba(8,47,73,0.8);
}
.btn-primary:hover {
  filter: brightness(1.05);
}

.btn-success {
  background: linear-gradient(135deg, #16a34a, #22c55e);
  border: 0;
  box-shadow: 0 0 0 1px rgba(34,197,94,0.4), 0 14px 30px rgba(5,46,22,0.8);
}

.badge.bg-secondary {
  background-color: var(--badge-task) !important;
}
.badge.bg-success {
  background-color: var(--badge-log) !important;
}

.alert-info {
  background: rgba(37, 99, 235, 0.14);
  border-color: rgba(37, 99, 235, 0.35);
  color: #dbeafe;
}

.timeline {
  position: relative;
  padding-left: 20px;
}
.timeline::before {
  content: "";
  position: absolute;
  top: 2px;
  bottom: 0;
  left: 8px;
  width: 2px;
  background: linear-gradient(to bottom, transparent, var(--timeline-line), transparent);
}
.timeline li {
  position: relative;
  padding-left: 16px;
}
.timeline li::before {
  content: "";
  position: absolute;
  left: 3px;
  top: 4px;
  width: 10px;
  height: 10px;
  border-radius: 999px;
  background: var(--timeline-dot);
  box-shadow: 0 0 0 4px rgba(56,189,248,0.28);
}

/* WhatsApp-style chat ------------------------------------------------ */
.chat-row-left {
  display: flex;
  justify-content: flex-start;
}
.chat-row-right {
  display: flex;
  justify-content: flex-end;
}

.chat-bubble-parent,
.chat-bubble-student {
  max-width: 70%;
  padding: 6px 10px;
  border-radius: 18px;
  position: relative;
  font-size: 0.84rem;
}

.chat-bubble-parent {
  background: var(--chat-parent-bg);
  color: var(--text-main);
}
.chat-bubble-student {
  background: var(--chat-student-bg);
  color: var(--chat-student-text);
}

.chat-meta {
  font-size: 0.7rem;
  opacity: 0.8;
  margin-bottom: 2px;
}

/* Inputs -------------------------------------------------------------- */
.form-control,
.form-select {
  background: #020617;
  border-color: rgba(148, 163, 184, 0.4);
  color: var(--text-main);
  font-size: 0.85rem;
}
html[data-theme="light"] .form-control,
html[data-theme="light"] .form-select {
  background: #ffffff;
  color: var(--text-main);
}
.form-control:focus,
.form-select:focus {
  background: #020617;
  border-color: var(--brand-primary);
  box-shadow: 0 0 0 1px rgba(59,130,246,0.8);
  color: var(--text-main);
}

.small {
  color: var(--text-muted);
}
.text-muted {
  color: var(--text-soft) !important;
}