:root {
  color-scheme: light;
  --bg: #f5f7fb;
  --panel: #ffffff;
  --ink: #172033;
  --muted: #667085;
  --brand: #2563eb;
  --brand-dark: #1d4ed8;
  --ok: #047857;
  --warn: #b45309;
  --danger: #b91c1c;
  --line: #d9e2f2;
  --shadow: 0 18px 45px rgba(15, 23, 42, 0.08);
}

* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: radial-gradient(circle at top left, #dbeafe 0, transparent 34rem), var(--bg);
  color: var(--ink);
}
button, input, select, textarea { font: inherit; }
button {
  border: 0;
  border-radius: 0.75rem;
  padding: 0.7rem 1rem;
  background: var(--brand);
  color: white;
  cursor: pointer;
  font-weight: 700;
  transition: transform .12s ease, background .12s ease, opacity .12s ease;
}
button:hover { background: var(--brand-dark); transform: translateY(-1px); }
button:disabled { opacity: .5; cursor: not-allowed; transform: none; }
button.secondary { background: #edf2ff; color: #1e40af; }
button.secondary:hover { background: #dbeafe; }
button.ghost { background: transparent; color: var(--brand); }
button.danger { background: #fee2e2; color: var(--danger); }
input, select, textarea {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: .75rem;
  padding: .7rem .8rem;
  background: white;
  color: var(--ink);
}
textarea { min-height: 7rem; resize: vertical; }
label { display: grid; gap: .35rem; color: #344054; font-weight: 650; }
small { color: var(--muted); }

.app-shell { min-height: 100vh; display: grid; grid-template-rows: auto 1fr; }
.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 1rem clamp(1rem, 3vw, 2rem);
  background: rgba(255,255,255,.78);
  backdrop-filter: blur(18px);
  border-bottom: 1px solid rgba(217,226,242,.75);
  position: sticky;
  top: 0;
  z-index: 10;
}
.brand { display: flex; align-items: center; gap: .75rem; font-weight: 900; font-size: 1.1rem; }
.brand-mark {
  width: 2.35rem; height: 2.35rem; border-radius: .85rem;
  display: grid; place-items: center; color: white; background: linear-gradient(135deg, #2563eb, #7c3aed);
  box-shadow: 0 8px 20px rgba(37,99,235,.25);
}
.user-chip { display: flex; align-items: center; gap: .7rem; color: var(--muted); }
.layout { display: grid; grid-template-columns: 16rem minmax(0,1fr); gap: 1.2rem; padding: 1.2rem clamp(1rem,3vw,2rem) 2rem; }
.sidebar {
  align-self: start;
  position: sticky;
  top: 5rem;
  background: rgba(255,255,255,.9);
  border: 1px solid var(--line);
  border-radius: 1.2rem;
  padding: .75rem;
  box-shadow: var(--shadow);
}
.nav-link {
  display: flex;
  gap: .65rem;
  align-items: center;
  width: 100%;
  padding: .8rem .9rem;
  border-radius: .85rem;
  color: #344054;
  text-decoration: none;
  font-weight: 750;
}
.nav-link:hover, .nav-link.active { background: #eff6ff; color: #1d4ed8; }
.main { min-width: 0; }

.auth-wrap { min-height: 100vh; display: grid; place-items: center; padding: 2rem; }
.auth-card {
  width: min(100%, 28rem);
  background: rgba(255,255,255,.92);
  border: 1px solid var(--line);
  border-radius: 1.4rem;
  padding: 1.5rem;
  box-shadow: var(--shadow);
}
.auth-card h1 { margin: .2rem 0 .5rem; font-size: 1.75rem; }
.stack { display: grid; gap: 1rem; }
.grid { display: grid; gap: 1rem; }
.grid.two { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid.three { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid.four { grid-template-columns: repeat(4, minmax(0, 1fr)); }
.card {
  background: rgba(255,255,255,.92);
  border: 1px solid var(--line);
  border-radius: 1.2rem;
  padding: 1.1rem;
  box-shadow: var(--shadow);
}
.card h2, .card h3 { margin-top: 0; }
.kpi {
  display: grid;
  gap: .3rem;
  padding: 1rem;
  border-radius: 1rem;
  background: linear-gradient(135deg, #eff6ff, #f5f3ff);
  border: 1px solid #dbeafe;
}
.kpi strong { font-size: 1.7rem; }
.toolbar { display: flex; flex-wrap: wrap; gap: .7rem; align-items: end; }
.table-wrap { overflow-x: auto; border: 1px solid var(--line); border-radius: 1rem; }
table { width: 100%; border-collapse: collapse; background: white; }
th, td { padding: .75rem; border-bottom: 1px solid var(--line); text-align: left; vertical-align: top; }
th { background: #f8fafc; color: #475467; font-size: .9rem; }
tr:last-child td { border-bottom: 0; }
.badge { display: inline-flex; align-items: center; gap: .35rem; padding: .28rem .55rem; border-radius: 999px; background: #eef2ff; color: #3730a3; font-size: .8rem; font-weight: 800; }
.badge.ok { background: #dcfce7; color: var(--ok); }
.badge.warn { background: #fef3c7; color: var(--warn); }
.badge.danger { background: #fee2e2; color: var(--danger); }
.notice { padding: .8rem 1rem; border-radius: .9rem; background: #eff6ff; color: #1e40af; border: 1px solid #bfdbfe; }
.notice.error { background: #fef2f2; color: var(--danger); border-color: #fecaca; }
.notice.ok { background: #ecfdf5; color: var(--ok); border-color: #bbf7d0; }
.flash-card {
  min-height: 16rem;
  display: grid;
  place-items: center;
  text-align: center;
  border: 1px dashed #93c5fd;
  border-radius: 1.2rem;
  background: linear-gradient(135deg, #eff6ff, #fff);
  padding: 2rem;
}
.flash-card .front { font-size: clamp(2rem, 6vw, 4rem); font-weight: 900; }
.flash-card .back { margin-top: 1rem; color: var(--muted); font-size: 1.25rem; }
.word-list { display: flex; flex-wrap: wrap; gap: .5rem; }
.word-pill { padding: .45rem .65rem; background: #f8fafc; border: 1px solid var(--line); border-radius: 999px; }
.hidden { display: none !important; }
.loading { opacity: .7; pointer-events: none; }

@media (max-width: 900px) {
  .layout { grid-template-columns: 1fr; }
  .sidebar { position: static; display: flex; overflow-x: auto; }
  .nav-link { white-space: nowrap; }
  .grid.two, .grid.three, .grid.four { grid-template-columns: 1fr; }
  .topbar { align-items: start; flex-direction: column; }
}