/* ============================================================
   nslabs — Core Principles (Section 5)
   Interactive vertical "operating system" stack.
   Theme tokens expected with fallbacks.
   ============================================================ */
.ns-principles{
  --pr-accent: var(--accent, #4f7df5);
  --pr-accent-2: var(--accent-2, #22d3a7);
  --pr-bg: var(--bg-deep, #0a0e1a);
  --pr-surface: var(--bg-surface, #111728);
  --pr-elevated: var(--bg-elevated, #161d33);
  --pr-elevated-2: var(--bg-elevated-2, #1a2342);
  --pr-text: var(--text-primary, #e8ecf4);
  --pr-text-2: var(--text-secondary, #8a93ad);
  --pr-text-3: var(--text-dim, #5b6480);
  --pr-border: var(--border, rgba(140,160,220,.10));
  --pr-border-2: var(--border-strong, rgba(140,160,220,.18));

  position: relative;
  padding: 180px 24px 200px;
  background:
    radial-gradient(900px 600px at 80% 0%, rgba(34,211,167,.06), transparent 65%),
    radial-gradient(1100px 700px at -10% 100%, rgba(79,125,245,.10), transparent 60%),
    radial-gradient(circle at top, #0e1428, #070a12);
  overflow: hidden;
  isolation: isolate;
}

/* Architectural backdrop: dot field + crosshair */
.ns-principles::before{
  content:""; position:absolute; inset:0; pointer-events:none; z-index:0;
  background-image: radial-gradient(rgba(140,160,220,.18) 1px, transparent 1.2px);
  background-size: 28px 28px;
  mask-image: radial-gradient(ellipse at center, black 25%, transparent 75%);
  opacity:.5;
}
.ns-principles::after{
  content:""; position:absolute; left:50%; top:0; bottom:0; width:1px;
  background: linear-gradient(180deg, transparent, rgba(79,125,245,.18), rgba(34,211,167,.10), transparent);
  pointer-events:none; z-index:0;
}

.ns-principles__wrap{
  position: relative; z-index: 1;
  max-width: 1240px; margin: 0 auto;
}

/* ============ HEADER ============ */
.pr-eyebrow{
  display:inline-flex; align-items:center; gap: 10px;
  padding: 7px 14px;
  background: linear-gradient(135deg, rgba(79,125,245,.12), rgba(34,211,167,.08));
  border: 1px solid rgba(79,125,245,.28);
  color: var(--pr-text-2);
  border-radius: 999px;
  font-size: .74rem; letter-spacing: .2em; text-transform: uppercase; font-weight: 600;
}
.pr-eyebrow code{
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  color: var(--pr-accent-2);
}

.ns-principles__head{
  text-align:center; max-width: 820px; margin: 0 auto 90px;
}
.ns-principles__head h2{
  margin: 24px 0 18px;
  font-size: clamp(2.4rem, 5.4vw, 3.8rem);
  line-height: 1.06; letter-spacing: -.02em; font-weight: 680;
  color: var(--pr-text);
}
.ns-principles__head h2 .grad{
  background: linear-gradient(110deg, var(--pr-accent), var(--pr-accent-2) 70%, #b9c7ff);
  -webkit-background-clip: text; background-clip: text; color: transparent;
}
.ns-principles__head p{
  margin: 0 auto; max-width: 620px;
  color: var(--pr-text-2);
  font-size: 1.1rem; line-height: 1.7;
}

/* ============ STACK LAYOUT ============ */
.pr-stack{
  display:grid;
  grid-template-columns: 240px 1fr;
  gap: 60px;
  align-items: flex-start;
}

/* LEFT — sticky index */
.pr-index{
  position: sticky; top: 100px;
  display:flex; flex-direction:column; gap: 4px;
  padding: 18px;
  background: linear-gradient(180deg, rgba(255,255,255,.03), rgba(255,255,255,.01));
  border: 1px solid var(--pr-border);
  border-radius: 18px;
  backdrop-filter: blur(10px);
}
.pr-index__title{
  font-size: .68rem; letter-spacing: .22em; text-transform: uppercase;
  color: var(--pr-text-3); padding: 6px 8px 12px;
}
.pr-idx{
  display:flex; align-items:center; gap: 12px;
  padding: 10px 12px;
  border-radius: 10px;
  color: var(--pr-text-2);
  cursor:pointer; text-align:left;
  background: transparent; border:1px solid transparent;
  font-size: .92rem;
  transition: background .25s, color .25s, border-color .25s, transform .25s;
}
.pr-idx:hover{ color: var(--pr-text); background: rgba(79,125,245,.06); transform: translateX(2px); }
.pr-idx .num{
  font-family: ui-monospace, monospace;
  font-size: .72rem; color: var(--pr-text-3); letter-spacing: .1em;
}
.pr-idx.is-active{
  color: var(--pr-text);
  background: linear-gradient(90deg, rgba(79,125,245,.18), rgba(34,211,167,.06));
  border-color: rgba(79,125,245,.35);
}
.pr-idx.is-active .num{ color: var(--pr-accent-2); }
.pr-idx .bar{
  flex: 1; height: 1px;
  background: linear-gradient(90deg, transparent, var(--pr-border-2), transparent);
}
.pr-idx.is-active .bar{
  background: linear-gradient(90deg, transparent, var(--pr-accent-2), transparent);
}

/* RIGHT — principle cards */
.pr-list{
  display:flex; flex-direction:column; gap: 22px;
}

.pr-card{
  --i: 0;
  position: relative;
  display: grid;
  grid-template-columns: 88px 1fr auto;
  gap: 28px;
  align-items: center;
  padding: 32px 36px;
  background: linear-gradient(180deg, rgba(255,255,255,.035), rgba(255,255,255,.015));
  border: 1px solid var(--pr-border);
  border-radius: 22px;
  backdrop-filter: blur(10px);
  cursor: pointer;
  transition: transform .5s cubic-bezier(.2,.8,.2,1), border-color .35s, background .35s, box-shadow .5s;
  overflow: hidden;
}
.pr-card::before{
  content:""; position:absolute; inset:0; pointer-events:none;
  background: radial-gradient(420px 220px at var(--mx,50%) var(--my,50%), rgba(79,125,245,.18), transparent 60%);
  opacity: 0; transition: opacity .35s;
}
.pr-card:hover::before{ opacity: 1; }
.pr-card:hover{ transform: translateY(-4px); border-color: rgba(79,125,245,.30); }

.pr-card.is-active{
  background: linear-gradient(135deg, rgba(79,125,245,.10), rgba(34,211,167,.05));
  border-color: transparent;
  box-shadow:
    0 20px 50px rgba(0,0,0,.35),
    0 0 0 1px rgba(79,125,245,.45),
    0 8px 28px rgba(79,125,245,.20);
}
.pr-card.is-active::after{
  content:""; position:absolute; left:0; top:18px; bottom:18px; width: 3px;
  border-radius: 0 4px 4px 0;
  background: linear-gradient(180deg, var(--pr-accent), var(--pr-accent-2));
  box-shadow: 0 0 16px rgba(79,125,245,.5);
}

/* Big number + icon */
.pr-card__head{
  position: relative;
  width: 88px; height: 88px;
}
.pr-card__num{
  position:absolute; inset:0;
  display:grid; place-items:center;
  font-family: ui-monospace, monospace;
  font-size: 2.4rem; font-weight: 700;
  color: transparent;
  -webkit-text-stroke: 1.5px rgba(140,160,220,.45);
  letter-spacing: -.02em;
  transition: -webkit-text-stroke-color .35s, color .35s, transform .5s;
}
.pr-card.is-active .pr-card__num{
  color: var(--pr-text);
  -webkit-text-stroke-color: transparent;
  transform: scale(.92) translateY(-4px);
}
.pr-card__icon{
  position:absolute; inset:0;
  display:grid; place-items:center;
  opacity: 0;
  transform: scale(.6);
  transition: opacity .35s, transform .5s cubic-bezier(.2,.8,.2,1);
  color: var(--pr-accent-2);
}
.pr-card__icon svg{ width: 36px; height: 36px; }
.pr-card.is-active .pr-card__icon{
  opacity: 1; transform: scale(1) translateY(8px);
}

/* Body */
.pr-card__body h3{
  margin: 0 0 8px;
  font-size: 1.45rem; font-weight: 620;
  color: var(--pr-text); letter-spacing: -.01em;
}
.pr-card__body p{
  margin: 0;
  color: var(--pr-text-2);
  font-size: 1rem; line-height: 1.65;
  max-width: 520px;
}

/* meta tag */
.pr-card__meta{
  display:flex; flex-direction:column; align-items:flex-end; gap: 8px;
}
.pr-card__tag{
  font-family: ui-monospace, monospace;
  font-size: .68rem; letter-spacing: .14em; text-transform: uppercase;
  color: var(--pr-text-3);
  padding: 5px 10px;
  border: 1px solid var(--pr-border-2);
  border-radius: 999px;
  white-space: nowrap;
}
.pr-card.is-active .pr-card__tag{
  color: var(--pr-accent-2);
  border-color: rgba(34,211,167,.4);
  background: rgba(34,211,167,.08);
}
.pr-card__chev{
  width: 28px; height: 28px; border-radius: 50%;
  display:grid; place-items:center;
  color: var(--pr-text-3);
  border: 1px solid var(--pr-border-2);
  transition: transform .35s, color .35s, border-color .35s, background .35s;
}
.pr-card__chev svg{ width: 12px; height: 12px; }
.pr-card.is-active .pr-card__chev{
  color: #fff; background: var(--pr-accent); border-color: var(--pr-accent);
  transform: rotate(90deg);
}

/* ============ FOOTER ============ */
.ns-principles__foot{
  margin-top: 130px;
  text-align: center;
  position: relative;
}
.pr-divider{
  width: 60px; height: 1px; margin: 0 auto 28px;
  background: linear-gradient(90deg, transparent, var(--pr-accent), transparent);
}
.ns-principles__foot p{
  margin: 0 auto; max-width: 640px;
  font-size: clamp(1.1rem, 1.7vw, 1.35rem);
  line-height: 1.55;
  color: var(--pr-text);
  font-weight: 480; letter-spacing: -.005em;
}
.ns-principles__foot p .accent{ color: var(--pr-accent-2); font-weight: 600; }
.ns-principles__foot .signature{
  margin-top: 18px;
  font-family: ui-monospace, monospace;
  font-size: .72rem; letter-spacing: .22em; text-transform: uppercase;
  color: var(--pr-text-3);
}

/* ============ RESPONSIVE ============ */
@media (max-width: 980px){
  .pr-stack{ grid-template-columns: 1fr; gap: 28px; }
  .pr-index{
    position: static;
    flex-direction: row; flex-wrap: wrap; gap: 6px;
    padding: 12px;
  }
  .pr-index__title{ width: 100%; padding: 4px 8px 4px; }
  .pr-idx{ flex: 1 1 auto; padding: 8px 12px; }
  .pr-idx .bar{ display:none; }
}
@media (max-width: 720px){
  .ns-principles{ padding: 120px 18px 140px; }
  .pr-card{ grid-template-columns: 64px 1fr; gap: 20px; padding: 24px 22px; }
  .pr-card__head{ width: 64px; height: 64px; }
  .pr-card__num{ font-size: 1.8rem; }
  .pr-card__icon svg{ width: 26px; height: 26px; }
  .pr-card__meta{ display: none; }
}