:root {
  --fancy-bg1: #12002f;
  --fancy-bg2: #1d3557;
  --fancy-bg3: #2a9d8f;
}

body {
  background: linear-gradient(135deg, var(--fancy-bg1), var(--fancy-bg2), var(--fancy-bg3));
  background-size: 300% 300%;
  animation: aiHubBgShift 14s ease infinite;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  opacity: 0.25;
  background-image:
    radial-gradient(circle at 20% 20%, rgba(255,255,255,0.55) 1px, transparent 2px),
    radial-gradient(circle at 80% 30%, rgba(255,255,255,0.45) 1px, transparent 2px),
    radial-gradient(circle at 40% 70%, rgba(255,255,255,0.45) 1px, transparent 2px);
  background-size: 180px 180px;
  animation: aiHubTwinkle 8s linear infinite;
  z-index: 0;
}

@keyframes aiHubBgShift {
  0% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
  100% { background-position: 0% 50%; }
}

@keyframes aiHubTwinkle {
  0% { transform: translateY(0); }
  50% { transform: translateY(-8px); }
  100% { transform: translateY(0); }
}

.ai-hub-wrap {
  position: relative;
  z-index: 1;
  padding-top: 1.4rem;
  font-family: "Inter", "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}
.hub-hero {
  background: linear-gradient(135deg, rgba(255,77,157,.28), rgba(6,214,240,.2));
  border: 1px solid rgba(255,255,255,.25);
  border-radius: 16px;
  padding: 1.2rem;
  backdrop-filter: blur(10px);
  box-shadow: 0 16px 34px rgba(0,0,0,.28);
}
.kicker { margin: 0; font-size: .75rem; letter-spacing: .12em; color: #a5b4fc; }
.hub-hero h1 { margin: .25rem 0 .4rem; }
.hub-hero h1 {
  font-size: 2.4rem;
  line-height: 1.08;
}
.hub-hero p { margin: 0; color: var(--muted); }
.track-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: .9rem;
  margin-top: 1rem;
}
.track-card {
  background: rgba(18, 24, 43, .7);
  border: 1px solid rgba(255,255,255,.2);
  border-radius: 14px;
  padding: .9rem;
  backdrop-filter: blur(10px);
}
.track-card h3 { margin: 0 0 .4rem; font-size: 1.04rem; }
.track-card p { margin: 0 0 .65rem; color: var(--muted); font-size: .92rem; }
.track-card .btn { margin-top: .3rem; }
.hub-note {
  margin-top: 1rem;
  border: 1px dashed #3a4879;
  border-radius: 12px;
  padding: .8rem;
  color: var(--muted);
}
.back-link {
  display: inline-block;
  margin-bottom: .8rem;
  color: #8df5d1;
  font-weight: 800;
  text-decoration: none;
  border-bottom: 1px solid currentColor;
}
.quiz-header {
  background: rgba(18, 24, 43, .72);
  border: 1px solid rgba(255,255,255,.2);
  border-radius: 14px;
  padding: 1rem;
  backdrop-filter: blur(10px);
}
.quiz-header h1 { margin: 0 0 .35rem; }
.quiz-header h1 { font-size: 2.35rem; line-height: 1.08; }
.quiz-header p { margin: 0; color: var(--muted); }
.progress-wrap {
  margin-top: .8rem;
  height: 9px;
  background: #0f1426;
  border-radius: 999px;
  overflow: hidden;
  border: 1px solid #2d385f;
}
.progress-bar { height: 100%; width: 0%; background: linear-gradient(90deg, #7c9cff, #38bdf8); transition: width .25s ease; }
.quiz-card {
  margin-top: .9rem;
  background: rgba(18, 24, 43, .72);
  border: 1px solid rgba(255,255,255,.2);
  border-radius: 14px;
  padding: 1rem;
  backdrop-filter: blur(10px);
  box-shadow: 0 12px 30px rgba(0,0,0,.24);
}
.quiz-card h2 { margin-top: 0; font-size: 1.55rem; line-height: 1.18; }
.difficulty-tag {
  display: inline-block;
  margin: -.2rem 0 .45rem;
  padding: .22rem .55rem;
  border-radius: 999px;
  border: 1px solid #3f4f88;
  font-size: .8rem;
  font-weight: 700;
  color: #dbe6ff;
  background: #121a33;
}
.difficulty-beginner { border-color: #ef5e7a; color: #ffd6de; }
.difficulty-intermediate { border-color: #f0c05f; color: #ffefc2; }
.difficulty-advanced { border-color: #41d28f; color: #d7ffe9; }
.options { display: grid; gap: .55rem; margin-top: .8rem; }
.option {
  border: 1px solid #30417f;
  border-radius: 10px;
  padding: .72rem .8rem;
  cursor: pointer;
  background: #12182b;
  color: #e8edff;
  font-size: 1rem;
  font-weight: 500;
  line-height: 1.35;
  text-align: left;
}
.option:hover { border-color: #5a71ce; }
.option.selected { border-color: #7c9cff; background: #1a2340; color: #f2f5ff; }
.option.correct { border-color: #41d28f; background: #133326; color: #dcffe9; }
.option.wrong { border-color: #ef5e7a; background: #3b1520; color: #ffdce3; }
.quiz-actions { margin-top: .85rem; display: flex; gap: .6rem; }
.feedback { margin-top: .7rem; padding: .55rem .65rem; border-radius: 10px; border: 1px solid #3d4e8f; background: #11172b; }
.feedback.good { border-color: #41d28f; }
.feedback.bad { border-color: #ef5e7a; }
.table-wrap { overflow: auto; margin-top: .8rem; }
.table-wrap table { width:100%; border-collapse: collapse; }
.table-wrap th, .table-wrap td { border: 1px solid #324173; padding: .45rem .55rem; }
.table-wrap th { background: #1e2a4d; }
.grade-pill {
  display: inline-block;
  margin: .2rem 0 0;
  padding: .35rem .6rem;
  border-radius: 999px;
  font-weight: 700;
  border: 1px solid #3f4f88;
  background: #121a33;
}
.grade-beginner { border-color: #ef5e7a; color: #ffd6de; }
.grade-intermediate { border-color: #f0c05f; color: #ffefc2; }
.grade-advanced { border-color: #41d28f; color: #d7ffe9; }
.muted { color: var(--muted); margin-top: .45rem; }

/* ── TIMER ── */
.quiz-header-top {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}
.timer-wrap {
  display: flex;
  align-items: center;
  gap: .45rem;
  background: rgba(12, 18, 40, .7);
  border: 1px solid #2d3d6e;
  border-radius: 10px;
  padding: .45rem .85rem;
  flex-shrink: 0;
  backdrop-filter: blur(8px);
}
.timer-icon { font-size: 1rem; }
.timer-display {
  font-size: 1.3rem;
  font-weight: 800;
  font-variant-numeric: tabular-nums;
  color: #7dd3fc;
  letter-spacing: .04em;
  min-width: 4ch;
}
.timer-label { font-size: .75rem; color: #6b7db8; }
.timer-wrap.warn .timer-display { color: #fbbf24; }
.timer-wrap.danger .timer-display {
  color: #f87171;
  animation: timerPulse .7s ease-in-out infinite;
}
@keyframes timerPulse {
  0%,100% { opacity: 1; }
  50% { opacity: .55; }
}

/* ── CERT MODAL ── */
.cert-modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(4, 8, 22, .82);
  backdrop-filter: blur(6px);
  z-index: 200;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1rem;
  opacity: 0;
  pointer-events: none;
  transition: opacity .22s ease;
}
.cert-modal-overlay.open {
  opacity: 1;
  pointer-events: all;
}
.cert-modal {
  background: #0e1628;
  border: 1px solid rgba(255,255,255,.22);
  border-radius: 16px;
  padding: 1.8rem 2rem;
  max-width: 480px;
  width: 100%;
  box-shadow: 0 24px 60px rgba(0,0,0,.5);
  transform: translateY(12px);
  transition: transform .22s ease;
}
.cert-modal-overlay.open .cert-modal { transform: none; }
.cert-modal-header { margin-bottom: 1.2rem; }
.cert-modal-icon { font-size: 2.2rem; display: block; margin-bottom: .5rem; }
.cert-modal-header h2 { margin: 0 0 .35rem; font-size: 1.35rem; }
.cert-modal-header p { margin: 0; color: #8899cc; font-size: .92rem; }
.cert-form { display: grid; gap: .7rem; margin-bottom: 1.3rem; }
.cert-form label {
  font-size: .85rem;
  font-weight: 600;
  color: #a5b4d8;
  margin-bottom: .15rem;
  display: block;
}
.required { color: #f87171; }
.cert-optional { color: #5a6e9a; font-weight: 400; }
.cert-form input {
  width: 100%;
  background: #121c36;
  border: 1px solid #2d3d6e;
  border-radius: 8px;
  padding: .65rem .85rem;
  font-size: .97rem;
  color: #e8edff;
  font-family: inherit;
  transition: border-color .2s;
}
.cert-form input:focus { outline: none; border-color: #7c9cff; }
.cert-modal-actions { display: flex; gap: .7rem; flex-wrap: wrap; }
.btn-ghost {
  background: transparent;
  border: 1px solid #2d3d6e;
  color: #8899cc;
}
.btn-ghost:hover { border-color: #5a71ce; color: #c0cef0; }