.security {
  position: relative;
  height: 420vh;
  background: var(--bg);
}

.security__sticky {
  position: sticky;
  top: 0;
  height: 100vh;
  display: grid;
  grid-template-columns: minmax(300px, 0.85fr) 1.15fr;
  gap: clamp(40px, 6vw, 90px);
  align-items: center;
  max-width: var(--container-max);
  margin-inline: auto;
  padding-inline: var(--container-pad);
  overflow: hidden;
}

.security__intro {
  position: relative;
  z-index: 2;
}

.security__title {
  font-size: var(--fs-4xl);
  font-weight: 800;
  line-height: var(--lh-tight);
  margin-bottom: 48px;
}

.security__progress {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.security__dot {
  position: relative;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--border-strong);
  transition: background 0.5s ease, transform 0.5s var(--ease-out), box-shadow 0.5s ease;
}

.security__dot.is-active {
  background: var(--accent);
  transform: scale(1.6);
  box-shadow: 0 0 14px rgba(36, 137, 253, 0.6);
}

.security__stages {
  position: relative;
  height: min(520px, 72vh);
}

.sec-item {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: 44px 48px;
  border-radius: var(--radius-lg);
  border: 1px solid var(--border);
  box-shadow: var(--shadow-lg);
  opacity: 0;
  transform: translateY(36px) scale(0.985);
  pointer-events: none;
  transition: opacity 0.7s var(--ease-out), transform 0.7s var(--ease-out);
  overflow: hidden;
}

.sec-item::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  z-index: 1;
  background: var(--accent);
  opacity: 0.7;
}

.sec-item.is-active {
  opacity: 1;
  transform: translateY(0) scale(1);
  pointer-events: auto;
}

.sec-item__num {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  letter-spacing: 0.28em;
  color: var(--accent);
  margin-bottom: 18px;
}

.sec-item__title {
  font-size: clamp(1.7rem, 1.4rem + 1.2vw, 2.4rem);
  font-weight: 800;
  margin-bottom: 18px;
}

.sec-item__desc {
  color: var(--text-2);
  font-size: var(--fs-base);
  line-height: var(--lh-relaxed);
  max-width: 520px;
}

.sec-item__feats {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-top: 26px;
}

.sec-item__feats li {
  position: relative;
  padding-left: 22px;
  font-family: var(--font-mono);
  font-size: 0.86rem;
  color: var(--text-2);
}

.sec-item__feats li::before {
  content: '▸';
  position: absolute;
  left: 0;
  color: var(--accent);
}