:root {
  --classes-blue: #2563eb;
  --classes-blue-2: #60a5fa;
  --classes-ink: #0f172a;
  --classes-muted: #64748b;
  --classes-card: rgba(255, 255, 255, .92);
  --classes-border: rgba(148, 163, 184, .25);
  --classes-shadow: 0 24px 80px rgba(15, 23, 42, .12);
}

.universe-page-classes {
  min-height: 100vh;
}

.universe-page-classes .universe-page-stage {
  padding: clamp(1rem, 2vw, 2rem) 0 clamp(3rem, 5vw, 5rem);
}

.universe-page-classes .universe-page-stage-inner {
  width: min(1840px, calc(100vw - 1rem));
  max-width: none;
  margin: 0 auto;
}

.classes-shell {
  width: 100%;
  color: var(--classes-ink);
  font-family: 'DM Sans', sans-serif;
}

.classes-shell h1,
.classes-shell h2 {
  font-family: 'Bebas Neue', 'Rajdhani', sans-serif;
  font-weight: 400;
  letter-spacing: .025em;
}

.classes-kicker,
.classes-pill,
.classes-button,
.classes-login-button,
.classes-back,
.classes-topic-meta,
.classes-channel,
.classes-question-card h3 {
  font-family: 'Rajdhani', sans-serif;
}

.classes-hero,
.classes-panel,
.classes-topic-video,
.classes-questions-panel,
.classes-course-card,
.classes-topic-card {
  background: var(--classes-card);
  border: 1px solid var(--classes-border);
  border-radius: 28px;
  box-shadow: var(--classes-shadow);
  backdrop-filter: blur(18px);
}

.classes-hero {
  padding: clamp(1.2rem, 3vw, 2.4rem);
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 1rem;
  align-items: center;
  margin-bottom: 1rem;
}

.classes-topic-topbar {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 1rem;
  align-items: center;
  margin-bottom: .75rem;
  padding: .95rem 1.1rem;
  border: 1px solid var(--classes-border);
  border-radius: 24px;
  background: var(--classes-card);
  box-shadow: 0 18px 55px rgba(15, 23, 42, .08);
  backdrop-filter: blur(18px);
}

.classes-topic-topbar h1 {
  margin: .15rem 0 0;
  font-size: clamp(1.75rem, 3vw, 3.6rem);
  line-height: .95;
  letter-spacing: -.055em;
}

.classes-topic-topbar p {
  color: var(--classes-muted);
  margin: .45rem 0 0;
  line-height: 1.45;
}

.classes-kicker {
  color: var(--classes-blue);
  font-size: .78rem;
  font-weight: 900;
  letter-spacing: .18em;
  text-transform: uppercase;
  margin-bottom: .6rem;
}

.classes-hero h1 {
  font-size: clamp(2rem, 4.5vw, 5rem);
  line-height: .95;
  letter-spacing: -.06em;
  margin: 0;
}

.classes-hero p {
  max-width: 760px;
  color: var(--classes-muted);
  font-size: clamp(1rem, 1.2vw, 1.18rem);
  line-height: 1.7;
  margin: .9rem 0 0;
}

.classes-pill-row {
  display: flex;
  flex-wrap: wrap;
  gap: .55rem;
  margin-top: 1.1rem;
}

.classes-pill {
  border: 1px solid rgba(37, 99, 235, .18);
  background: rgba(37, 99, 235, .08);
  color: #1d4ed8;
  border-radius: 999px;
  padding: .55rem .8rem;
  font-size: .82rem;
  font-weight: 800;
}

.classes-button,
.classes-login-button,
.classes-back {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: .45rem;
  border: 0;
  border-radius: 999px;
  background: linear-gradient(135deg, var(--classes-blue), #7c3aed);
  color: #fff;
  font-weight: 900;
  text-decoration: none;
  padding: .82rem 1.05rem;
  box-shadow: 0 16px 40px rgba(37, 99, 235, .22);
  cursor: pointer;
}

.classes-back {
  background: rgba(15, 23, 42, .06);
  color: var(--classes-ink);
  box-shadow: none;
  border: 1px solid var(--classes-border);
}

.classes-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1rem;
}

.classes-explorer {
  display: grid;
  gap: 1rem;
}

.classes-bank-banner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 1rem;
  padding: clamp(1rem, 2vw, 1.4rem);
  border: 1px solid rgba(37, 99, 235, .25);
  border-radius: 24px;
  color: var(--classes-ink);
  background: linear-gradient(125deg, rgba(219, 234, 254, .96), rgba(238, 242, 255, .94));
  box-shadow: 0 18px 55px rgba(37, 99, 235, .1);
  text-decoration: none;
}

.classes-bank-banner span,
.classes-bank-banner strong {
  font-family: 'Rajdhani', sans-serif;
  color: var(--classes-blue);
  font-weight: 900;
  letter-spacing: .08em;
  text-transform: uppercase;
}

.classes-bank-banner h2 {
  margin: .18rem 0 .25rem;
  font-size: clamp(1.45rem, 2.5vw, 2.4rem);
}

.classes-bank-banner p {
  margin: 0;
  color: var(--classes-muted);
}

.classes-bank-panel {
  width: min(1080px, 100%);
  margin: 0 auto;
}

.classes-explorer-controls {
  display: grid;
  grid-template-columns: minmax(260px, 1fr) minmax(210px, 320px) auto;
  gap: .8rem;
  align-items: end;
  padding: 1rem;
  border: 1px solid var(--classes-border);
  border-radius: 22px;
  background: var(--classes-card);
  box-shadow: var(--classes-shadow);
}

.classes-explorer-controls label {
  display: grid;
  gap: .4rem;
  color: var(--classes-muted);
  font: 800 .82rem/1 'Rajdhani', sans-serif;
  letter-spacing: .08em;
  text-transform: uppercase;
}

.classes-explorer-controls input,
.classes-explorer-controls select {
  width: 100%;
  min-height: 46px;
  border: 1px solid var(--classes-border);
  border-radius: 14px;
  background: rgba(255, 255, 255, .9);
  color: var(--classes-ink);
  padding: 0 .9rem;
  font: 500 .96rem/1 'DM Sans', sans-serif;
  outline: none;
}

.classes-explorer-controls input:focus,
.classes-explorer-controls select:focus {
  border-color: var(--classes-blue);
  box-shadow: 0 0 0 4px rgba(37, 99, 235, .1);
}

.classes-explorer-controls strong {
  min-height: 46px;
  display: grid;
  place-items: center;
  color: var(--classes-blue);
  font: 900 .9rem/1 'Rajdhani', sans-serif;
}

.classes-course-card,
.classes-topic-card {
  min-height: 220px;
  padding: 1.25rem;
  color: inherit;
  text-decoration: none;
  position: relative;
  overflow: hidden;
  transform: translateZ(0);
  transition: transform .18s ease, box-shadow .18s ease, border-color .18s ease;
}

.classes-course-card::after,
.classes-topic-card::after {
  content: "";
  position: absolute;
  inset: auto -15% -35% 40%;
  height: 170px;
  background: radial-gradient(circle, rgba(96, 165, 250, .38), transparent 65%);
  pointer-events: none;
}

.classes-course-card:hover,
.classes-topic-card:hover {
  transform: translateY(-4px);
  border-color: rgba(37, 99, 235, .42);
  box-shadow: 0 28px 95px rgba(37, 99, 235, .2);
}

.classes-card-icon {
  width: 58px;
  height: 58px;
  display: grid;
  place-items: center;
  border-radius: 20px;
  color: #fff;
  background: linear-gradient(135deg, var(--classes-blue), var(--classes-blue-2));
  font-size: 1.6rem;
  font-weight: 900;
  box-shadow: 0 16px 40px rgba(37, 99, 235, .25);
}

.classes-course-card h2,
.classes-topic-card h2 {
  margin: 1rem 0 .45rem;
  font-size: clamp(1.3rem, 1.9vw, 2rem);
  line-height: 1.05;
}

.classes-course-card p,
.classes-topic-card p {
  color: var(--classes-muted);
  line-height: 1.55;
  margin: 0;
}

.classes-topic-meta {
  display: flex;
  flex-wrap: wrap;
  gap: .45rem;
  margin-top: 1rem;
}

.classes-topic-meta span {
  border-radius: 999px;
  padding: .42rem .65rem;
  background: rgba(15, 23, 42, .05);
  border: 1px solid var(--classes-border);
  color: var(--classes-muted);
  font-size: .78rem;
  font-weight: 800;
}

.classes-video-grid {
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
}

.classes-video-grid .classes-topic-card {
  min-height: 0;
  padding: .8rem;
}

.classes-video-grid .classes-topic-card h2 {
  margin: .75rem .2rem .45rem;
  font-family: 'Rajdhani', sans-serif;
  font-size: 1.08rem;
  font-weight: 800;
  letter-spacing: .01em;
  line-height: 1.25;
  text-transform: none;
}

.classes-video-thumb {
  position: relative;
  overflow: hidden;
  aspect-ratio: 16 / 9;
  border-radius: 16px;
  background: #020617;
}

.classes-video-thumb img {
  width: 100%;
  height: 100%;
  display: block;
  object-fit: cover;
  transition: transform .25s ease;
}

.classes-topic-card:hover .classes-video-thumb img {
  transform: scale(1.035);
}

.classes-load-more {
  justify-self: center;
  min-width: 220px;
}

.classes-topic-layout {
  display: grid;
  grid-template-columns: minmax(0, 3fr) minmax(340px, 1fr);
  gap: 1rem;
  align-items: start;
  min-height: calc(100svh - 170px);
}

.classes-topic-video,
.classes-questions-panel {
  padding: clamp(1rem, 1.5vw, 1.4rem);
}

.classes-topic-video {
  position: sticky;
  top: 88px;
}

.classes-video-frame {
  width: 100%;
  height: min(78vh, 920px);
  min-height: 620px;
  aspect-ratio: auto;
  border: 0;
  border-radius: 24px;
  background: #020617;
  box-shadow: 0 22px 70px rgba(15, 23, 42, .22);
}

.classes-video-title {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: .8rem;
  margin: 1rem 0 0;
}

.classes-video-title h2 {
  margin: 0;
  font-size: clamp(1.45rem, 2vw, 2.4rem);
  letter-spacing: -.04em;
}

.classes-channel {
  color: var(--classes-blue);
  font-weight: 900;
  white-space: nowrap;
}

.classes-questions-panel {
  min-height: min(760px, calc(100vh - 118px));
  max-height: calc(100vh - 112px);
  overflow: auto;
}

.classes-questions-head {
  display: flex;
  gap: .8rem;
  align-items: flex-start;
  justify-content: space-between;
  border-bottom: 1px solid var(--classes-border);
  padding-bottom: .9rem;
  margin-bottom: 1rem;
}

.classes-questions-head h2 {
  margin: 0;
  font-size: clamp(1.35rem, 2vw, 2rem);
  letter-spacing: -.035em;
}

.classes-private-note {
  color: var(--classes-muted);
  line-height: 1.55;
  margin: .4rem 0 0;
}

.classes-login-box,
.classes-empty,
.classes-error {
  border: 1px dashed rgba(37, 99, 235, .32);
  border-radius: 24px;
  background: rgba(37, 99, 235, .06);
  padding: 1.1rem;
}

.classes-login-box h3,
.classes-empty h3,
.classes-error h3 {
  margin: 0 0 .45rem;
}

.classes-login-box p,
.classes-empty p,
.classes-error p {
  margin: 0 0 .9rem;
  color: var(--classes-muted);
  line-height: 1.6;
}

.classes-question-list {
  display: grid;
  gap: .85rem;
}

.classes-question-card {
  border: 1px solid var(--classes-border);
  border-radius: 22px;
  background: rgba(255, 255, 255, .72);
  padding: 1rem;
}

.classes-question-card h3 {
  margin: 0 0 .75rem;
  color: var(--classes-blue);
  font-size: .95rem;
  letter-spacing: .06em;
  text-transform: uppercase;
}

.classes-question-stem {
  white-space: pre-wrap;
  color: var(--classes-ink);
  font-weight: 650;
  line-height: 1.62;
}

.classes-choice-list {
  list-style: none;
  padding: 0;
  margin: .9rem 0 0;
  display: grid;
  gap: .5rem;
}

.classes-choice-list li {
  display: grid;
  grid-template-columns: 34px 1fr;
  gap: .65rem;
  align-items: start;
  color: var(--classes-ink);
}

.classes-choice-label {
  width: 34px;
  height: 34px;
  border-radius: 12px;
  display: grid;
  place-items: center;
  background: rgba(37, 99, 235, .1);
  color: #1d4ed8;
  font-weight: 950;
}

.classes-question-image {
  display: block;
  width: 100%;
  max-height: 420px;
  object-fit: contain;
  border-radius: 16px;
  margin: .85rem 0 0;
  border: 1px solid var(--classes-border);
  background: #fff;
}

.classes-loading {
  padding: 2rem;
  text-align: center;
  color: var(--classes-muted);
  font-weight: 900;
}

.theme-dark .classes-shell,
html[data-universe-theme="dark"] .classes-shell,
html[data-theme="dark"] .classes-shell,
body.dark-mode .classes-shell {
  --classes-ink: #e5edf9;
  --classes-muted: #a8b5c8;
  --classes-card: rgba(2, 6, 23, .82);
  --classes-border: rgba(148, 163, 184, .18);
  --classes-shadow: 0 24px 90px rgba(0, 0, 0, .45);
}

.theme-dark .classes-back,
html[data-universe-theme="dark"] .classes-back,
html[data-theme="dark"] .classes-back,
body.dark-mode .classes-back,
.theme-dark .classes-topic-meta span,
html[data-universe-theme="dark"] .classes-topic-meta span,
html[data-theme="dark"] .classes-topic-meta span,
body.dark-mode .classes-topic-meta span {
  background: rgba(255, 255, 255, .06);
  color: #e5edf9;
}

.theme-dark .classes-question-card,
html[data-universe-theme="dark"] .classes-question-card,
html[data-theme="dark"] .classes-question-card,
body.dark-mode .classes-question-card {
  background: rgba(15, 23, 42, .7);
}

.theme-dark .classes-bank-banner,
html[data-universe-theme="dark"] .classes-bank-banner,
html[data-theme="dark"] .classes-bank-banner,
body.dark-mode .classes-bank-banner {
  background: linear-gradient(125deg, rgba(15, 23, 42, .95), rgba(30, 41, 59, .92));
  color: #f8fafc;
}

html[data-universe-theme="dark"] .classes-explorer-controls input,
html[data-universe-theme="dark"] .classes-explorer-controls select {
  background: #071426;
  color: #f8fafc;
}

.theme-dark .classes-login-box,
html[data-universe-theme="dark"] .classes-login-box,
html[data-theme="dark"] .classes-login-box,
body.dark-mode .classes-login-box,
.theme-dark .classes-empty,
html[data-universe-theme="dark"] .classes-empty,
html[data-theme="dark"] .classes-empty,
body.dark-mode .classes-empty,
.theme-dark .classes-error,
html[data-universe-theme="dark"] .classes-error,
html[data-theme="dark"] .classes-error,
body.dark-mode .classes-error {
  background: rgba(37, 99, 235, .12);
}

@media (max-width: 1180px) {
  .classes-topic-layout {
    grid-template-columns: 1fr;
  }

  .classes-topic-video {
    position: static;
  }

  .classes-questions-panel {
    min-height: auto;
    max-height: none;
  }

  .classes-video-frame {
    height: auto;
    min-height: 0;
    aspect-ratio: 16 / 9;
  }
}

@media (max-width: 720px) {
  .universe-page-classes .universe-page-stage-inner {
    width: min(100%, calc(100vw - .7rem));
  }

  .classes-hero {
    grid-template-columns: 1fr;
    border-radius: 22px;
  }

  .classes-topic-topbar {
    grid-template-columns: 1fr;
    border-radius: 20px;
    padding: .9rem;
  }

  .classes-grid {
    grid-template-columns: 1fr;
  }

  .classes-explorer-controls {
    grid-template-columns: 1fr;
  }

  .classes-bank-banner {
    align-items: flex-start;
    flex-direction: column;
  }

  .classes-course-card,
  .classes-topic-card {
    min-height: 190px;
    border-radius: 22px;
  }

  .classes-video-title,
  .classes-questions-head {
    display: block;
  }

  .classes-channel {
    display: inline-block;
    margin-top: .45rem;
  }
}