:root {
  --qt-ink: #0f172a;
  --qt-muted: #5f6b7a;
  --qt-body: #334155;

  --qt-line: #e7ebf3;
  --qt-line-strong: #d7e1f6;

  --qt-accent: #4067D9;
  --qt-accent-2: #6f8cff;
  --qt-accent-soft: #eef3ff;
  --qt-accent-glow: rgba(64, 103, 217, 0.12);

  --qt-ring: #dfe6f2;
  --qt-card: rgba(255, 255, 255, 0.86);
  --qt-card-solid: #ffffff;

  --qt-radius-lg: 26px;
  --qt-radius-md: 18px;

  --qt-shadow-sm: 0 10px 24px rgba(17, 24, 39, 0.06);
  --qt-shadow-md: 0 18px 40px rgba(17, 24, 39, 0.08);
  --qt-shadow-lg: 0 30px 72px rgba(17, 24, 39, 0.12);
}

/* section */
#quant-research.quant-section {
  position: relative;
  overflow: clip;
  padding: clamp(48px, 6vw, 92px) 0;
  background:
    radial-gradient(circle at 12% 10%, rgba(64, 103, 217, 0.04), transparent 24%),
    radial-gradient(circle at 88% 18%, rgba(64, 103, 217, 0.05), transparent 22%);
}

/* shell */
#quant-research .quant-shell {
  max-width: 1180px;
  margin: 0 auto;
  padding: 0 clamp(20px, 4vw, 32px);
  display: grid;
  gap: 28px;
}

/* header */
#quant-research .quant-header {
  display: grid;
  gap: 12px;
  max-width: 760px;
  animation: quantIntroUp 0.72s cubic-bezier(.2,.7,.2,1) both;
}

#quant-research .quant-header-main {
  display: grid;
  gap: 10px;
}

#quant-research .quant-kicker {
  margin: 0;
  width: fit-content;
  padding: 8px 12px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.78);
  border: 1px solid rgba(64, 103, 217, 0.12);
  box-shadow: 0 8px 18px rgba(17, 24, 39, 0.04);
  font-size: 12px;
  line-height: 1.2;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--qt-accent);
  font-weight: 800;
}

#quant-research .quant-header h2 {
  margin: 0;
  font-size: clamp(30px, 4vw, 46px);
  line-height: 1.06;
  letter-spacing: -0.03em;
  font-weight: 800;
  color: var(--qt-ink);
  max-width: 14ch;
  text-wrap: balance;
}

#quant-research .quant-sub {
  margin: 0;
  font-size: 16px;
  line-height: 1.8;
  color: var(--qt-muted);
  max-width: 62ch;
}

/* list */
#quant-research .quant-list {
  display: grid;
  gap: 18px;
}

/* item */
#quant-research .quant-item {
  position: relative;
  overflow: hidden;
  isolation: isolate;
  display: grid;
  grid-template-columns: minmax(0, 1fr) 240px;
  gap: clamp(20px, 4vw, 56px);
  align-items: center;
  background: var(--qt-card);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid var(--qt-line);
  border-radius: var(--qt-radius-lg);
  padding: clamp(20px, 3vw, 28px);
  box-shadow: var(--qt-shadow-sm);
  transition:
    transform 0.28s cubic-bezier(.2,.7,.2,1),
    box-shadow 0.28s cubic-bezier(.2,.7,.2,1),
    border-color 0.28s ease,
    background 0.28s ease;
}

#quant-research .quant-item::before {
  content: "";
  position: absolute;
  inset: 0;
  background:
    radial-gradient(circle at top right, rgba(64, 103, 217, 0.1), transparent 34%);
  opacity: 0;
  transition: opacity 0.28s ease;
  z-index: -1;
}

#quant-research .quant-item::after {
  content: "";
  position: absolute;
  left: 0;
  top: 18px;
  bottom: 18px;
  width: 3px;
  border-radius: 999px;
  background: linear-gradient(180deg, var(--qt-accent), var(--qt-accent-2));
  transform: scaleY(0.24);
  transform-origin: top;
  opacity: 0.35;
  transition: transform 0.3s ease, opacity 0.3s ease;
}

#quant-research .quant-item:hover {
  transform: translateY(-6px);
  box-shadow: var(--qt-shadow-lg);
  border-color: var(--qt-line-strong);
  background: var(--qt-card-solid);
}

#quant-research .quant-item:hover::before {
  opacity: 1;
}

#quant-research .quant-item:hover::after {
  transform: scaleY(1);
  opacity: 1;
}

#quant-research .quant-item--reverse {
  grid-template-columns: 240px minmax(0, 1fr);
}

/* copy */
#quant-research .quant-copy {
  display: grid;
  gap: 10px;
}

#quant-research .quant-copy h3 {
  margin: 0;
  font-size: clamp(22px, 2.8vw, 34px);
  line-height: 1.12;
  letter-spacing: -0.02em;
  font-weight: 800;
  color: var(--qt-ink);
  max-width: 18ch;
  transition: color 0.28s ease, transform 0.28s ease;
}

#quant-research .quant-copy p {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: var(--qt-body);
  max-width: 60ch;
  transition: color 0.28s ease, transform 0.28s ease;
}

#quant-research .quant-item:hover .quant-copy h3 {
  color: var(--qt-accent);
  transform: translateY(-1px);
}

#quant-research .quant-item:hover .quant-copy p {
  color: #22314d;
  transform: translateY(-1px);
}

/* chart */
#quant-research .quant-chart {
  position: relative;
  width: 212px;
  max-width: 100%;
  margin: 0 auto;
  display: grid;
  place-items: center;
  transition: transform 0.28s cubic-bezier(.2,.7,.2,1);
}

#quant-research .quant-chart::before {
  content: "";
  position: absolute;
  inset: 12px;
  border-radius: 50%;
  background:
    radial-gradient(circle at center, rgba(64, 103, 217, 0.08), rgba(64, 103, 217, 0) 72%);
  filter: blur(6px);
  opacity: 0.8;
  transition: opacity 0.28s ease, transform 0.28s ease;
}

#quant-research .quant-donut {
  width: 100%;
  height: auto;
  display: block;
  transform: rotate(-90deg);
  position: relative;
  z-index: 1;
}

#quant-research .quant-ring {
  fill: none;
  stroke: var(--qt-ring);
  stroke-width: 18;
}

#quant-research .quant-slice {
  fill: none;
  stroke: var(--qt-accent);
  stroke-width: 18;
  stroke-linecap: round;
  filter: drop-shadow(0 6px 10px rgba(64, 103, 217, 0.12));
  transition: stroke 0.28s ease, transform 0.28s ease;
  transform-origin: 60px 60px;
}

#quant-research .quant-center {
  position: absolute;
  inset: 50% auto auto 50%;
  transform: translate(-50%, -50%);
  width: 110px;
  height: 110px;
  border-radius: 50%;
  background: linear-gradient(180deg, #ffffff 0%, #f8fbff 100%);
  border: 1px solid #e3eaf8;
  display: grid;
  place-items: center;
  box-shadow:
    inset 0 1px 0 rgba(255,255,255,0.8),
    0 10px 24px rgba(17, 24, 39, 0.05);
  z-index: 2;
}

#quant-research .quant-pill {
  margin: 0;
  text-align: center;
  display: grid;
  gap: 4px;
}

#quant-research .quant-pill strong {
  display: block;
  font-size: 28px;
  line-height: 1;
  letter-spacing: -0.04em;
  font-weight: 800;
  color: var(--qt-ink);
}

#quant-research .quant-pill span {
  display: block;
  font-size: 11px;
  line-height: 1;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  font-weight: 700;
  color: var(--qt-accent);
}

/* chart hover */
#quant-research .quant-item:hover .quant-chart {
  transform: scale(1.03);
}

#quant-research .quant-item:hover .quant-chart::before {
  opacity: 1;
  transform: scale(1.04);
}

#quant-research .quant-item:hover .quant-slice {
  stroke: #365dd0;
}

/* motion */
@media (prefers-reduced-motion: no-preference) {
  #quant-research .quant-item {
    animation: quantCardIn 0.58s cubic-bezier(.2,.7,.2,1) both;
  }

  #quant-research .quant-item:nth-child(1) {
    animation-delay: 0.05s;
  }

  #quant-research .quant-item:nth-child(2) {
    animation-delay: 0.12s;
  }

  #quant-research .quant-item:nth-child(3) {
    animation-delay: 0.19s;
  }
}

@keyframes quantIntroUp {
  from {
    opacity: 0;
    transform: translateY(14px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes quantCardIn {
  from {
    opacity: 0;
    transform: translateY(14px) scale(0.985);
  }
  to {
    opacity: 1;
    transform: translateY(0) scale(1);
  }
}

@media (prefers-reduced-motion: reduce) {
  #quant-research .quant-header,
  #quant-research .quant-item,
  #quant-research .quant-item::before,
  #quant-research .quant-item::after,
  #quant-research .quant-copy h3,
  #quant-research .quant-copy p,
  #quant-research .quant-chart,
  #quant-research .quant-chart::before,
  #quant-research .quant-slice {
    animation: none !important;
    transition: none !important;
    transform: none !important;
  }
}

/* responsive */
@media (max-width: 900px) {
  #quant-research .quant-item,
  #quant-research .quant-item--reverse {
    grid-template-columns: 1fr;
    gap: 18px;
    text-align: center;
  }

  #quant-research .quant-item--reverse .quant-chart {
    order: -1;
  }

  #quant-research .quant-copy {
    justify-items: center;
  }

  #quant-research .quant-copy h3,
  #quant-research .quant-copy p {
    max-width: none;
  }
}

@media (max-width: 640px) {
  #quant-research.quant-section {
    padding: 34px 0 58px;
  }

  #quant-research .quant-shell {
    gap: 22px;
    padding: 0 20px;
  }

  #quant-research .quant-header h2 {
    font-size: 32px;
    line-height: 1.1;
  }

  #quant-research .quant-sub {
    font-size: 15px;
    line-height: 1.72;
  }

  #quant-research .quant-item {
    padding: 18px 16px;
    border-radius: 22px;
  }

  #quant-research .quant-copy h3 {
    font-size: 24px;
  }

  #quant-research .quant-copy p {
    font-size: 14px;
    line-height: 1.7;
  }

  #quant-research .quant-chart {
    width: 180px;
  }

  #quant-research .quant-center {
    width: 96px;
    height: 96px;
  }

  #quant-research .quant-pill strong {
    font-size: 24px;
  }
}