/* base.css - Global styles and design tokens */

:root {
  --color-primary:        #3860B2;
  --color-primary-dark:   #195975;
  --color-primary-light:  #EBF0FA;
  --color-text:           #1A1A2E;
  --color-text-muted:     #5A6A85;
  --color-border:         #C8D5EC;
  --color-bg:             #F4F6FB;
  --color-surface:        #FFFFFF;
  --color-shadow:         rgba(56, 96, 178, 0.12);

  /* Schedule cell colours */
  --color-unavailable:    #F0C4BC;   /* red-ish — no availability */

  /* In-person pair: white (available) → grey (booked) */
  --color-avail-ip:       #FFFFFF;
  --color-booked-ip:      #94A3B8;

  /* Online pair: light green (available) → medium green (booked) */
  --color-avail-online:   #BBF7D0;
  --color-booked-online:  #4ADE80;

  /* Meeting: blue */
  --color-meeting:        #93C5FD;

  /* Admin: purple */
  --color-admin:          #C4B5FD;

  /* Hold / partial (kept for Day View use) */
  --color-hold:           #FEF08A;
  --color-booked-partial: #DBEAFE;

  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --transition: 150ms ease;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html, body {
  height: 100%;
  font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
  font-size: 14px;
  color: var(--color-text);
  background: var(--color-bg);
  -webkit-font-smoothing: antialiased;
}

/* ── Screens ─────────────────────────────────────────────────────────────── */

.screen { display: none; }
.screen.active { display: flex; flex-direction: column; height: 100%; }

/* ── Loading overlay ─────────────────────────────────────────────────────── */

#loading-overlay {
  position: fixed; inset: 0;
  background: rgba(255,255,255,0.85);
  display: flex; flex-direction: column;
  align-items: center; justify-content: center;
  gap: 12px;
  z-index: 1000;
  backdrop-filter: blur(2px);
}
#loading-overlay.hidden { display: none; }

.loading-spinner {
  width: 36px; height: 36px;
  border: 3px solid var(--color-border);
  border-top-color: var(--color-primary);
  border-radius: 50%;
  animation: spin 0.75s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

.loading-message { color: var(--color-text-muted); font-size: 13px; }

/* ── Buttons ─────────────────────────────────────────────────────────────── */

button { cursor: pointer; font-family: inherit; font-size: 14px; border: none; }

.btn-primary {
  background: var(--color-primary);
  color: #fff;
  padding: 10px 20px;
  border-radius: var(--radius-md);
  font-weight: 600;
  transition: background var(--transition);
}
.btn-primary:hover { background: var(--color-primary-dark); }

.btn-secondary {
  background: var(--color-surface);
  color: var(--color-primary);
  border: 1px solid var(--color-border);
  padding: 7px 14px;
  border-radius: var(--radius-md);
  transition: background var(--transition);
}
.btn-secondary:hover { background: var(--color-primary-light); }

.btn-text {
  background: none;
  color: var(--color-text-muted);
  padding: 4px 8px;
  border-radius: var(--radius-sm);
  transition: color var(--transition);
}
.btn-text:hover { color: var(--color-text); }

.btn-icon {
  background: none;
  color: var(--color-text-muted);
  width: 32px; height: 32px;
  border-radius: var(--radius-sm);
  display: flex; align-items: center; justify-content: center;
  font-size: 18px;
  transition: background var(--transition);
}
.btn-icon:hover { background: var(--color-primary-light); color: var(--color-primary); }

/* ── Teacher filter chips ────────────────────────────────────────────────── */

.filter-chip {
  background: var(--color-surface);
  color: var(--color-text-muted);
  border: 1px solid var(--color-border);
  padding: 4px 10px;
  border-radius: 20px;
  font-size: 12px;
  font-weight: 500;
  transition: all var(--transition);
  white-space: nowrap;
}
.filter-chip:hover { border-color: var(--color-primary); color: var(--color-primary); }
.filter-chip.active {
  background: var(--color-primary);
  color: #fff;
  border-color: var(--color-primary);
}

/* ── Toast ───────────────────────────────────────────────────────────────── */

.toast {
  position: fixed; bottom: 24px; left: 50%; transform: translateX(-50%) translateY(20px);
  background: var(--color-text);
  color: #fff;
  padding: 10px 20px;
  border-radius: var(--radius-md);
  font-size: 13px;
  z-index: 2000;
  opacity: 0;
  transition: opacity 0.2s, transform 0.2s;
  pointer-events: none;
}
.toast.toast-visible { opacity: 1; transform: translateX(-50%) translateY(0); }
.toast.toast-error   { background: #DC2626; }
.toast.toast-success { background: #16A34A; }

/* ── Button modifiers ────────────────────────────────────────────────────── */

.btn-sm { padding: 5px 12px; font-size: 12px; }
.btn-primary.btn-sm { padding: 6px 14px; }

.btn-danger         { color: #DC2626; }
.btn-danger:hover   { color: #991B1B; }

/* ── Utility ─────────────────────────────────────────────────────────────── */

.hidden { display: none !important; }

/* ── Login screen ────────────────────────────────────────────────────────── */

#screen-login {
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, var(--color-primary-dark) 0%, var(--color-primary) 100%);
}

.login-card {
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  padding: 48px 40px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 20px;
  box-shadow: 0 8px 40px rgba(0,0,0,0.2);
  min-width: 320px;
}

.login-logo { width: 80px; height: auto; }
.login-title { font-size: 22px; font-weight: 700; color: var(--color-text); }
.login-subtitle { font-size: 13px; color: var(--color-text-muted); text-align: center; }