/* ============================================================
   TEKS ARGUMENTASI — Stylesheet
   Tema: Oranye & Hitam  |  Container gelap -> teks putih
                            Container cerah -> teks hitam
   BAGIAN 1 : Variabel, reset, layout, navbar, tombol, hero 3D
   ============================================================ */

/* ---------- 1. Variabel ---------- */
:root{
  --orange:        #ff7a18;
  --orange-light:  #ffa53d;
  --orange-deep:   #e85d04;
  --orange-soft:   #fff1e3;

  --black:         #0a0a0b;
  --black-2:       #121214;
  --black-3:       #1b1b1f;
  --line-dark:     rgba(255,255,255,.10);

  --white:         #ffffff;
  --cream:         #fffaf5;
  --line-light:    rgba(10,10,11,.10);

  --txt-dark:      #0a0a0b;
  --txt-dark-soft: #4a4a52;
  --txt-light:     #ffffff;
  --txt-light-soft:#b7b7c0;

  --radius:   18px;
  --radius-l: 26px;
  --shadow:   0 20px 45px rgba(0,0,0,.35);
  --shadow-l: 0 18px 40px rgba(232,93,4,.14);
  --ease:     cubic-bezier(.22,.61,.36,1);

  --font-body: 'Plus Jakarta Sans', system-ui, -apple-system, sans-serif;
  --font-head: 'Outfit', system-ui, sans-serif;
}

/* ---------- 2. Reset ---------- */
*,*::before,*::after{ margin:0; padding:0; box-sizing:border-box; }

html{ scroll-behavior:smooth; scroll-padding-top:90px; }

body{
  font-family:var(--font-body);
  background:var(--black);
  color:var(--txt-light);
  line-height:1.75;
  overflow-x:hidden;
  -webkit-font-smoothing:antialiased;
}

img{ max-width:100%; display:block; }
a{ color:inherit; text-decoration:none; }
ul{ list-style:none; }
button{ font-family:inherit; cursor:pointer; border:none; background:none; color:inherit; }

::selection{ background:var(--orange); color:#fff; }

::-webkit-scrollbar{ width:11px; }
::-webkit-scrollbar-track{ background:var(--black-2); }
::-webkit-scrollbar-thumb{
  background:linear-gradient(var(--orange),var(--orange-deep));
  border-radius:99px; border:3px solid var(--black-2);
}

/* ---------- 3. Layout dasar ---------- */
.container{ width:min(1180px, 100% - 2.6rem); margin-inline:auto; }
.container--narrow{ width:min(760px, 100% - 2.6rem); }

.section{ padding:clamp(4.5rem,9vw,7.5rem) 0; position:relative; }
.section--dark{   background:var(--black);   color:var(--txt-light); }
.section--light{  background:var(--cream);   color:var(--txt-dark);  }
.section--accent{
  background:linear-gradient(135deg,var(--orange) 0%, var(--orange-deep) 100%);
  color:var(--txt-dark); overflow:hidden;
}
.section--dark + .section--dark{ border-top:1px solid var(--line-dark); }

/* utilitas kedalaman untuk elemen di dalam kartu tilt */
.depth-12{ transform:translateZ(12px); }
.depth-16{ transform:translateZ(16px); }
.depth-24{ transform:translateZ(24px); }
.depth-30{ transform:translateZ(30px); }
.depth-50{ transform:translateZ(50px); }

/* ---------- 4. Progress bar ---------- */
.progress-bar{
  position:fixed; inset:0 0 auto 0; height:3px; z-index:1000;
  background:transparent; pointer-events:none;
}
.progress-bar span{
  display:block; height:100%; width:0%;
  background:linear-gradient(90deg,var(--orange-light),var(--orange),var(--orange-deep));
  box-shadow:0 0 14px rgba(255,122,24,.8);
  transition:width .1s linear;
}

/* ---------- 5. Kubus logo di navbar ---------- */
.brand__cube{
  --s:40px;
  position:relative; width:var(--s); height:var(--s); flex:none;
  transform-style:preserve-3d; animation:spinCube 9s linear infinite;
}
.brand__cube--sm{ --s:34px; }
.brand__cube .f{
  position:absolute; inset:0; display:grid; place-items:center;
  font-family:var(--font-head); font-weight:900; font-size:calc(var(--s)*.34);
  color:#1a0d00; border-radius:8px;
  background:linear-gradient(140deg,var(--orange-light),var(--orange-deep));
  border:1px solid rgba(255,255,255,.25);
  backface-visibility:visible;
}
.brand__cube .f--front { transform:translateZ(calc(var(--s)/2)); }
.brand__cube .f--back  { transform:rotateY(180deg) translateZ(calc(var(--s)/2)); }
.brand__cube .f--right { transform:rotateY(90deg)  translateZ(calc(var(--s)/2)); }
.brand__cube .f--left  { transform:rotateY(-90deg) translateZ(calc(var(--s)/2)); }
.brand__cube .f--top   { transform:rotateX(90deg)  translateZ(calc(var(--s)/2)); }
.brand__cube .f--bottom{ transform:rotateX(-90deg) translateZ(calc(var(--s)/2)); }
@keyframes spinCube{ from{ transform:rotateX(-18deg) rotateY(0); } to{ transform:rotateX(-18deg) rotateY(360deg); } }

/* ---------- 6. Navbar ---------- */
.nav{
  position:fixed; top:3px; left:0; right:0; z-index:900;
  transition:background .35s var(--ease), backdrop-filter .35s, border-color .35s;
  border-bottom:1px solid transparent; perspective:600px;
}
.nav__inner{
  width:min(1180px,100% - 2.6rem); margin-inline:auto;
  display:flex; align-items:center; justify-content:space-between;
  padding:1.15rem 0; transition:padding .35s var(--ease);
}
.nav.is-scrolled{
  background:rgba(10,10,11,.82); backdrop-filter:blur(16px);
  border-bottom-color:var(--line-dark);
}
.nav.is-scrolled .nav__inner{ padding:.7rem 0; }

.brand{ display:flex; align-items:center; gap:.85rem; perspective:500px; }
.brand__text{
  font-family:var(--font-head); font-weight:800; font-size:1.05rem;
  letter-spacing:-.02em; color:#fff; line-height:1.15;
}
.brand__text em{
  display:block; font-style:normal; font-size:.72rem; font-weight:600;
  letter-spacing:.22em; text-transform:uppercase; color:var(--orange);
}

.nav__links{ display:flex; align-items:center; gap:.35rem; }
.nav__links a{
  padding:.5rem .8rem; border-radius:99px; font-size:.87rem; font-weight:600;
  color:var(--txt-light-soft); transition:color .25s, background .25s;
}
.nav__links a:hover{ color:#fff; background:rgba(255,255,255,.07); }
.nav__links a.is-active{ color:var(--orange); background:rgba(255,122,24,.12); }
.nav__links a.nav__cta{
  background:linear-gradient(135deg,var(--orange),var(--orange-deep));
  color:#1a0d00; font-weight:800; margin-left:.5rem; padding:.55rem 1.15rem;
  box-shadow:0 8px 20px rgba(255,122,24,.3);
}
.nav__links a.nav__cta:hover{ color:#1a0d00; filter:brightness(1.08); }

.burger{
  display:none; width:44px; height:44px; border-radius:12px;
  background:rgba(255,255,255,.07); place-items:center; gap:5px;
}
.burger span{
  display:block; width:20px; height:2px; background:#fff; border-radius:2px;
  transition:transform .3s var(--ease), opacity .25s;
}
.burger.is-open span:nth-child(1){ transform:translateY(7px) rotate(45deg); }
.burger.is-open span:nth-child(2){ opacity:0; }
.burger.is-open span:nth-child(3){ transform:translateY(-7px) rotate(-45deg); }

/* ---------- 7. Tombol ---------- */
.btn{
  display:inline-flex; align-items:center; justify-content:center; gap:.5rem;
  padding:.95rem 1.9rem; border-radius:99px; font-weight:700; font-size:.95rem;
  transform-style:preserve-3d;
  transition:transform .3s var(--ease), box-shadow .3s, background .28s, color .28s, filter .28s;
}
.btn--primary{
  background:linear-gradient(135deg,var(--orange-light),var(--orange-deep));
  color:#1a0d00;
  box-shadow:0 6px 0 #a63f00, 0 16px 34px rgba(255,122,24,.38);
}
.btn--primary:hover{
  transform:translateY(-4px) rotateX(12deg);
  box-shadow:0 10px 0 #a63f00, 0 24px 44px rgba(255,122,24,.5);
}
.btn--primary:active{ transform:translateY(2px); box-shadow:0 2px 0 #a63f00, 0 8px 18px rgba(255,122,24,.35); }
.btn--primary:disabled{ opacity:.35; cursor:not-allowed; transform:none; box-shadow:none; }

.btn--ghost{
  border:1.5px solid rgba(255,255,255,.25); color:#fff; background:rgba(255,255,255,.03);
}
.btn--ghost:hover{ border-color:var(--orange); color:var(--orange); transform:translateY(-4px) rotateX(10deg); }

.btn-mini{
  margin-left:auto; padding:.4rem 1rem; border-radius:99px; font-size:.75rem; font-weight:700;
  background:var(--black); color:#fff; border:1px solid rgba(255,255,255,.16);
  transition:background .25s, color .25s, transform .25s;
}
.btn-mini:hover{ background:var(--orange); color:#1a0d00; transform:translateY(-2px); }
.btn-mini.is-on{ background:var(--orange); color:#1a0d00; }

/* ---------- 8. Hero ---------- */
.hero{
  position:relative; min-height:100svh; display:grid; place-items:center;
  padding:8rem 0 5rem; overflow:hidden; text-align:center;
  background:radial-gradient(120% 80% at 50% -10%, #22120a 0%, var(--black) 55%);
  perspective:1000px;
}
.hero__canvas{ position:absolute; inset:0; width:100%; height:100%; z-index:1; opacity:.85; }
.hero__glow{
  position:absolute; width:820px; height:820px; top:-38%; left:50%;
  transform:translateX(-50%); z-index:0;
  background:radial-gradient(circle, rgba(255,122,24,.30) 0%, transparent 62%);
  filter:blur(30px); animation:pulse 7s ease-in-out infinite; pointer-events:none;
}
@keyframes pulse{
  0%,100%{ opacity:.75; transform:translateX(-50%) scale(1); }
  50%    { opacity:1;   transform:translateX(-50%) scale(1.1); }
}
.hero__grid-lines{
  position:absolute; inset:0; pointer-events:none; opacity:.3; z-index:0;
  background-image:
    linear-gradient(var(--line-dark) 1px, transparent 1px),
    linear-gradient(90deg, var(--line-dark) 1px, transparent 1px);
  background-size:64px 64px;
  mask-image:radial-gradient(ellipse 75% 60% at 50% 40%, #000 20%, transparent 75%);
  -webkit-mask-image:radial-gradient(ellipse 75% 60% at 50% 40%, #000 20%, transparent 75%);
}
.hero__inner{ position:relative; z-index:3; transform-style:preserve-3d; }

/* ---------- 9. Objek 3D melayang ---------- */
.floaters{ position:absolute; inset:0; z-index:2; pointer-events:none; perspective:900px; }

.cube3d, .pyr3d{ position:absolute; transform-style:preserve-3d; }

.cube3d{ width:var(--s); height:var(--s); }
.cube3d .f{
  position:absolute; inset:0; border-radius:6px;
  border:1.5px solid rgba(255,122,24,.55);
  background:rgba(255,122,24,.07);
  box-shadow:inset 0 0 24px rgba(255,122,24,.22);
}
.cube3d .f--front { transform:translateZ(calc(var(--s)/2)); }
.cube3d .f--back  { transform:rotateY(180deg) translateZ(calc(var(--s)/2)); }
.cube3d .f--right { transform:rotateY(90deg)  translateZ(calc(var(--s)/2)); }
.cube3d .f--left  { transform:rotateY(-90deg) translateZ(calc(var(--s)/2)); }
.cube3d .f--top   { transform:rotateX(90deg)  translateZ(calc(var(--s)/2)); }
.cube3d .f--bottom{ transform:rotateX(-90deg) translateZ(calc(var(--s)/2)); }

.cube3d--a{ top:18%; left:9%;  animation:float3d 15s ease-in-out infinite; }
.cube3d--b{ top:66%; right:11%; animation:float3d 12s ease-in-out infinite reverse; }
@keyframes float3d{
  0%,100%{ transform:translateY(0)     rotateX(-18deg) rotateY(0deg)   rotateZ(0deg); }
  50%    { transform:translateY(-34px) rotateX(200deg) rotateY(190deg) rotateZ(12deg); }
}

/* piramida */
.pyr3d{ width:var(--s); height:var(--s); top:30%; right:16%; animation:float3d 18s linear infinite; }
.pyr3d .p{
  position:absolute; left:0; bottom:0; width:0; height:0;
  border-left:calc(var(--s)/2) solid transparent;
  border-right:calc(var(--s)/2) solid transparent;
  border-bottom:var(--s) solid rgba(255,165,61,.16);
  transform-origin:bottom center;
}
.pyr3d .p--1{ transform:translateX(0) rotateY(0deg)   rotateX(20deg); }
.pyr3d .p--2{ transform:translateX(0) rotateY(90deg)  rotateX(20deg); }
.pyr3d .p--3{ transform:translateX(0) rotateY(180deg) rotateX(20deg); }
.pyr3d .p--4{ transform:translateX(0) rotateY(270deg) rotateX(20deg); }

/* cincin orbit */
.ring-deco{
  position:absolute; border-radius:50%;
  border:1.5px solid rgba(255,122,24,.22);
  box-shadow:0 0 40px rgba(255,122,24,.12) inset;
}
.ring-deco--a{
  width:520px; height:520px; top:50%; left:50%;
  transform:translate(-50%,-50%) rotateX(74deg);
  animation:ringSpin 26s linear infinite;
}
.ring-deco--b{
  width:740px; height:740px; top:50%; left:50%;
  transform:translate(-50%,-50%) rotateX(74deg) rotateZ(40deg);
  animation:ringSpin 40s linear infinite reverse;
  border-style:dashed; opacity:.6;
}
@keyframes ringSpin{
  from{ transform:translate(-50%,-50%) rotateX(74deg) rotateZ(0deg); }
  to  { transform:translate(-50%,-50%) rotateX(74deg) rotateZ(360deg); }
}

/* ---------- 10. Isi hero ---------- */
.pill{
  display:inline-block; padding:.45rem 1.15rem; border-radius:99px;
  font-size:.78rem; font-weight:700; letter-spacing:.16em; text-transform:uppercase;
  color:var(--orange); background:rgba(255,122,24,.10);
  border:1px solid rgba(255,122,24,.32);
  backdrop-filter:blur(6px);
}

.hero__title{
  font-family:var(--font-head); font-weight:900; letter-spacing:-.035em;
  font-size:clamp(3rem, 11vw, 7.5rem); line-height:.95; margin:1.6rem 0 1.2rem;
  color:#fff; transform-style:preserve-3d;
}
.hero__title .extrude{ display:inline-block; }
/* efek huruf ter-ekstrusi */
.extrude{
  text-shadow:
    1px 1px 0 #d1d1d6, 2px 2px 0 #b9b9c0, 3px 3px 0 #9d9da6,
    4px 4px 0 #7e7e88, 5px 5px 0 #5f5f69,
    6px 8px 14px rgba(0,0,0,.55);
}
.grad{
  background:linear-gradient(115deg,var(--orange-light) 10%, var(--orange) 45%, var(--orange-deep) 90%);
  -webkit-background-clip:text; background-clip:text; color:transparent;
  display:inline-block;
}
.extrude--grad{
  text-shadow:none;
  filter:drop-shadow(2px 2px 0 #c24a03) drop-shadow(4px 4px 0 #8f3702)
         drop-shadow(6px 9px 16px rgba(0,0,0,.6));
}

.hero__sub{
  max-width:640px; margin-inline:auto; font-size:clamp(1rem,2.2vw,1.2rem);
  color:var(--txt-light-soft);
}
.hero__sub b{ color:#fff; }
.hero__sub i{ color:var(--orange); font-style:italic; }

.hero__actions{ display:flex; gap:.9rem; justify-content:center; flex-wrap:wrap; margin-top:2.2rem; perspective:600px; }

.hero__stats{
  display:flex; gap:clamp(1.5rem,5vw,4rem); justify-content:center; flex-wrap:wrap;
  margin-top:3.8rem; padding-top:2.4rem; border-top:1px solid var(--line-dark);
}
.stat{ text-align:center; }
.stat b{
  display:block; font-family:var(--font-head); font-weight:900;
  font-size:clamp(1.8rem,4.5vw,2.6rem); color:var(--orange); line-height:1;
  text-shadow:0 2px 0 #a63f00, 0 8px 22px rgba(255,122,24,.5);
}
.stat span{ font-size:.78rem; letter-spacing:.13em; text-transform:uppercase; color:var(--txt-light-soft); }

.scroll-hint{
  position:absolute; bottom:2rem; left:50%; transform:translateX(-50%);
  width:24px; height:40px; border:2px solid rgba(255,255,255,.25); border-radius:99px;
  display:grid; justify-items:center; padding-top:7px; z-index:3;
}
.scroll-hint span{
  width:3px; height:8px; border-radius:2px; background:var(--orange);
  animation:wheel 1.8s ease-in-out infinite;
}
@keyframes wheel{
  0%  { transform:translateY(0);    opacity:1; }
  70% { transform:translateY(14px); opacity:0; }
  100%{ opacity:0; }
}

/* ---------- 11. Section header ---------- */
.sec-head{ max-width:660px; margin-bottom:3.2rem; }
.sec-num{
  font-family:var(--font-head); font-weight:800; font-size:.85rem; letter-spacing:.3em;
  color:var(--orange); display:block; margin-bottom:.7rem;
}
.sec-head h2{
  font-family:var(--font-head); font-weight:800; letter-spacing:-.03em;
  font-size:clamp(2rem,5.2vw,3.1rem); line-height:1.1; margin-bottom:.75rem;
}
.section--dark .sec-head h2{ text-shadow:0 2px 0 rgba(255,122,24,.22), 0 10px 30px rgba(0,0,0,.6); }
.sec-head h2::after{
  content:''; display:block; width:66px; height:4px; border-radius:99px; margin-top:1rem;
  background:linear-gradient(90deg,var(--orange),var(--orange-deep));
}
.sec-desc{ font-size:1.03rem; }
.section--dark  .sec-desc{ color:var(--txt-light-soft); }
.section--light .sec-desc{ color:var(--txt-dark-soft); }
.section--accent .sec-desc{ color:rgba(26,13,0,.72); }
.section--accent .sec-head h2::after{ background:var(--black); }
.hint{ color:var(--orange); font-weight:700; }
.section--light .hint{ color:var(--orange-deep); }

/* ---------- 12. Grid & tilt ---------- */
.grid{ display:grid; gap:1.3rem; }
.grid--3{ grid-template-columns:repeat(auto-fit,minmax(255px,1fr)); }
.grid--4{ grid-template-columns:repeat(auto-fit,minmax(240px,1fr)); }
.grid--5{ grid-template-columns:repeat(auto-fit,minmax(215px,1fr)); }

.tilt-wrap{ perspective:900px; }
[data-tilt]{
  transform-style:preserve-3d;
  transition:transform .45s var(--ease), box-shadow .45s;
  will-change:transform;
}
[data-tilt] > *{ transform-style:preserve-3d; }

/* ============================================================
   BAGIAN 2 : Pengertian, ciri-ciri, jenis (flip), struktur (iso)
   ============================================================ */

/* ---------- 13. Pengertian ---------- */
.quote-card{
  position:relative; padding:clamp(2rem,5vw,3.4rem); border-radius:var(--radius-l);
  background:linear-gradient(150deg, var(--black-3) 0%, var(--black-2) 100%);
  border:1px solid var(--line-dark);
  box-shadow:var(--shadow), inset 0 1px 0 rgba(255,255,255,.06);
  overflow:hidden;
}
.quote-card::before{
  content:''; position:absolute; inset:0 auto 0 0; width:5px;
  background:linear-gradient(var(--orange-light),var(--orange-deep));
}
.quote-card::after{
  content:''; position:absolute; inset:0; pointer-events:none; opacity:0;
  background:radial-gradient(420px circle at var(--mx,50%) var(--my,50%), rgba(255,122,24,.14), transparent 60%);
  transition:opacity .4s;
}
.quote-card:hover::after{ opacity:1; }
.quote-card p{
  position:relative; z-index:1;
  font-size:clamp(1.05rem,2.4vw,1.42rem); line-height:1.8; color:#fff; font-weight:500;
}
.quote-card b{ color:var(--orange); font-weight:800; }
.quote-card mark{
  background:rgba(255,122,24,.16); color:var(--orange-light);
  padding:.1em .35em; border-radius:6px; font-weight:600;
}
.quote-mark{
  position:absolute; top:-1.4rem; right:1.6rem; font-family:var(--font-head);
  font-size:11rem; line-height:1; color:rgba(255,122,24,.09); pointer-events:none;
  transform:translateZ(10px);
}

/* balok 3D pada rumus */
.formula{
  display:flex; align-items:center; justify-content:center; gap:1.4rem;
  flex-wrap:wrap; margin-top:3rem; perspective:1000px;
}
.formula__op{ font-style:normal; font-size:1.7rem; font-weight:800; color:var(--orange); }

.block3d{
  --d:16px;
  position:relative; transform-style:preserve-3d;
  transform:rotateX(12deg) rotateY(-16deg);
  transition:transform .5s var(--ease);
}
.block3d:hover{ transform:rotateX(6deg) rotateY(10deg) translateY(-8px); }
.block3d__face{
  display:flex; flex-direction:column; align-items:center; gap:.45rem;
  padding:1.3rem 1.7rem; border-radius:16px; min-width:150px;
  background:linear-gradient(150deg,var(--black-3),var(--black-2));
  border:1px solid var(--line-dark);
  box-shadow:
    var(--d) var(--d) 0 -2px rgba(255,122,24,.18),
    calc(var(--d) + 6px) calc(var(--d) + 6px) 24px rgba(0,0,0,.5);
}
.block3d__face span{ font-size:1.8rem; filter:drop-shadow(0 4px 6px rgba(0,0,0,.5)); }
.block3d__face b{ font-size:.9rem; color:#fff; }
.block3d--accent .block3d__face{
  background:linear-gradient(150deg,var(--orange-light),var(--orange-deep));
  border-color:rgba(255,255,255,.28);
  box-shadow:
    var(--d) var(--d) 0 -2px #8f3702,
    calc(var(--d) + 6px) calc(var(--d) + 6px) 28px rgba(232,93,4,.5);
}
.block3d--accent .block3d__face b{ color:#1a0d00; }

/* ---------- 14. Card terang (ciri-ciri) ---------- */
.card-light{
  background:var(--white); border:1px solid var(--line-light); border-radius:var(--radius);
  padding:1.9rem 1.6rem; color:var(--txt-dark); position:relative; overflow:hidden;
  height:100%;
  box-shadow:0 10px 24px rgba(10,10,11,.07);
}
.card-light::after{
  content:''; position:absolute; top:0; left:0; right:0; height:4px;
  background:linear-gradient(90deg,var(--orange),var(--orange-deep));
  transform:scaleX(0); transform-origin:left; transition:transform .45s var(--ease);
}
.card-light:hover{ box-shadow:0 26px 50px rgba(232,93,4,.20); border-color:rgba(255,122,24,.4); }
.card-light:hover::after{ transform:scaleX(1); }
.card-light__ico{
  width:56px; height:56px; border-radius:16px; display:grid; place-items:center;
  font-size:1.6rem; background:var(--orange-soft); margin-bottom:1.1rem;
  box-shadow:0 8px 16px rgba(232,93,4,.18);
}
.card-light h3{
  font-family:var(--font-head); font-size:1.08rem; font-weight:800;
  margin-bottom:.45rem; color:var(--txt-dark);
}
.card-light p{ font-size:.92rem; color:var(--txt-dark-soft); line-height:1.7; }

/* ---------- 15. Kartu balik 3D (jenis) ---------- */
.flip3d{
  perspective:1200px; height:270px; cursor:pointer; outline:none;
}
.flip3d__inner{
  position:relative; width:100%; height:100%; transform-style:preserve-3d;
  transition:transform .8s var(--ease);
}
.flip3d:hover .flip3d__inner,
.flip3d:focus-visible .flip3d__inner,
.flip3d.is-flipped .flip3d__inner{ transform:rotateY(180deg); }

.flip3d__face{
  position:absolute; inset:0; border-radius:var(--radius);
  backface-visibility:hidden; -webkit-backface-visibility:hidden;
  display:flex; flex-direction:column; justify-content:center;
  padding:1.8rem 1.6rem; overflow:hidden;
}
.flip3d__front{
  background:linear-gradient(155deg,var(--black-3),var(--black-2));
  border:1px solid var(--line-dark);
  box-shadow:var(--shadow); align-items:flex-start;
}
.flip3d__front::before{
  content:''; position:absolute; inset:0;
  background:radial-gradient(circle at 50% 0%, rgba(255,122,24,.16), transparent 65%);
}
.flip3d__front > *{ position:relative; z-index:1; }
.flip3d__tag{
  position:absolute; top:0; right:0; z-index:2;
  display:grid; place-items:center; width:42px; height:42px; border-radius:12px;
  font-family:var(--font-head); font-weight:900; font-size:.9rem;
  background:rgba(255,122,24,.13); color:var(--orange);
  border:1px solid rgba(255,122,24,.28);
}
.flip3d__ico{
  font-size:2.4rem; margin-bottom:.7rem;
  filter:drop-shadow(0 8px 12px rgba(0,0,0,.6));
}
.flip3d__front h3{
  font-family:var(--font-head); font-size:1.25rem; font-weight:800; color:#fff; line-height:1.25;
}
.ttl-sub{ font-size:.85rem; font-weight:600; color:var(--orange); }
.flip3d__front small{
  margin-top:.8rem; font-size:.75rem; letter-spacing:.12em; text-transform:uppercase;
  color:var(--orange); font-weight:700;
}
.flip3d__back{
  transform:rotateY(180deg);
  background:linear-gradient(155deg,var(--orange) 0%, var(--orange-deep) 100%);
  border:1px solid rgba(255,255,255,.25);
  box-shadow:0 22px 45px rgba(232,93,4,.35);
  color:#1a0d00;
}
.flip3d__back p{ font-size:.95rem; line-height:1.7; font-weight:500; color:#26150a; }
.flow3d{
  display:flex; align-items:center; gap:.5rem; flex-wrap:wrap;
  margin-top:1.2rem; padding-top:1rem; border-top:1px dashed rgba(26,13,0,.3);
}
.flow3d span{
  font-size:.76rem; font-weight:800; padding:.32rem .8rem; border-radius:99px;
  background:var(--black); color:#fff;
  box-shadow:0 3px 0 rgba(0,0,0,.35);
}
.flow3d i{ font-style:normal; color:#1a0d00; font-weight:900; font-size:1.05rem; }

/* ---------- 16. Struktur isometrik ---------- */
.iso-wrap{
  display:grid; grid-template-columns:1fr 1fr; gap:clamp(1.5rem,4vw,3.5rem);
  align-items:center;
}
.iso{ perspective:1200px; }
.iso__stage{
  position:relative; height:420px;
  transform-style:preserve-3d;
  transform:rotateX(58deg) rotateZ(-42deg);
  display:grid; place-items:center;
}
.slab{
  position:absolute; width:250px; height:250px; border-radius:20px;
  transform-style:preserve-3d;
  transform:translateZ(var(--z));
  transition:transform .55s var(--ease), filter .4s;
  cursor:pointer;
}
.slab__face{
  position:absolute; inset:0; border-radius:20px;
  display:flex; flex-direction:column; align-items:center; justify-content:center; gap:.2rem;
  background:linear-gradient(140deg, #ffffff, #fff3e6);
  border:1px solid rgba(232,93,4,.28);
  box-shadow:
    0 0 0 1px rgba(255,255,255,.7) inset,
    0 24px 40px rgba(10,10,11,.18);
  transform:rotateZ(42deg) rotateX(0deg);
}
.slab__face b{
  font-family:var(--font-head); font-size:2.6rem; font-weight:900; line-height:1;
  color:var(--orange-deep); text-shadow:0 3px 0 rgba(232,93,4,.2);
}
.slab__face em{
  font-style:normal; font-weight:800; font-size:.9rem; letter-spacing:.06em;
  color:var(--txt-dark); text-transform:uppercase;
}
.slab:hover{ transform:translateZ(calc(var(--z) + 26px)); }
.slab.is-active{ transform:translateZ(calc(var(--z) + 46px)); }
.slab.is-active .slab__face{
  background:linear-gradient(140deg,var(--orange-light),var(--orange-deep));
  border-color:rgba(255,255,255,.5);
  box-shadow:0 0 0 1px rgba(255,255,255,.4) inset, 0 34px 55px rgba(232,93,4,.42);
}
.slab.is-active .slab__face b{ color:#1a0d00; text-shadow:0 3px 0 rgba(255,255,255,.35); }
.slab.is-active .slab__face em{ color:#26150a; }

.iso__shadow{
  position:absolute; width:250px; height:250px; border-radius:20px;
  transform:translateZ(-90px);
  background:radial-gradient(closest-side, rgba(10,10,11,.30), transparent 78%);
  filter:blur(14px);
}

.iso-detail{ position:relative; min-height:230px; }
.iso-panel{
  position:absolute; inset:0; opacity:0; visibility:hidden;
  transform:translateY(22px) rotateX(-8deg);
  transform-origin:top center;
  transition:opacity .45s var(--ease), transform .45s var(--ease), visibility .45s;
  background:var(--white); border:1px solid var(--line-light); border-radius:var(--radius);
  padding:1.9rem 1.8rem; color:var(--txt-dark);
  box-shadow:0 22px 45px rgba(10,10,11,.10);
}
.iso-panel.is-active{ opacity:1; visibility:visible; transform:none; }
.iso-panel__num{
  display:inline-block; font-size:.72rem; font-weight:800; letter-spacing:.16em;
  text-transform:uppercase; color:#fff; background:var(--orange-deep);
  padding:.28rem .8rem; border-radius:99px; margin-bottom:.85rem;
}
.iso-panel h3{ font-family:var(--font-head); font-size:1.3rem; font-weight:800; margin-bottom:.5rem; }
.iso-panel h3 small{ font-weight:600; font-size:.86rem; color:var(--orange-deep); }
.iso-panel p{ font-size:.98rem; color:var(--txt-dark-soft); }

.iso-nav{ position:absolute; bottom:-3.6rem; left:0; display:flex; gap:.55rem; }
.iso-nav__btn{
  width:42px; height:42px; border-radius:13px;
  font-family:var(--font-head); font-weight:900; font-size:.95rem;
  background:var(--white); color:var(--txt-dark);
  border:1px solid var(--line-light);
  box-shadow:0 5px 0 rgba(10,10,11,.10);
  transition:transform .25s var(--ease), background .25s, color .25s, box-shadow .25s;
}
.iso-nav__btn:hover{ transform:translateY(-3px); box-shadow:0 8px 0 rgba(10,10,11,.12); }
.iso-nav__btn.is-active{
  background:linear-gradient(140deg,var(--orange-light),var(--orange-deep)); color:#1a0d00;
  box-shadow:0 5px 0 #a63f00, 0 12px 24px rgba(232,93,4,.35);
}

/* ============================================================
   BAGIAN 3 : Tabs, ring 3D, tahapan, accordion, contoh
   ============================================================ */

/* ---------- 17. Tabs (kaidah) ---------- */
.tabs{
  border-radius:var(--radius-l); background:var(--black-2);
  border:1px solid var(--line-dark); overflow:hidden;
  box-shadow:var(--shadow), inset 0 1px 0 rgba(255,255,255,.05);
}
.tabs__nav{ display:flex; gap:.4rem; padding:.6rem; background:rgba(255,255,255,.03); flex-wrap:wrap; }
.tab{
  flex:1 1 180px; padding:.8rem 1.2rem; border-radius:12px; font-weight:700; font-size:.92rem;
  color:var(--txt-light-soft); transition:background .28s, color .28s, transform .28s, box-shadow .28s;
}
.tab:hover{ color:#fff; background:rgba(255,255,255,.05); }
.tab.is-active{
  background:linear-gradient(135deg,var(--orange),var(--orange-deep)); color:#1a0d00;
  transform:translateY(-2px);
  box-shadow:0 4px 0 #a63f00, 0 12px 24px rgba(255,122,24,.3);
}
.tabs__panel{ display:none; padding:2rem clamp(1.2rem,3vw,2.2rem); perspective:900px; }
.tabs__panel.is-active{ display:block; animation:flipIn .5s var(--ease); }
@keyframes flipIn{
  from{ opacity:0; transform:translateY(14px) rotateX(-12deg); }
  to  { opacity:1; transform:none; }
}

.check-list li{
  position:relative; padding:.85rem 0 .85rem 2.6rem; font-size:.98rem;
  color:var(--txt-light-soft); border-bottom:1px dashed var(--line-dark);
  transition:transform .3s var(--ease), color .3s;
}
.check-list li:last-child{ border-bottom:none; }
.check-list li:hover{ transform:translateX(8px); color:#fff; }
.check-list li::before{
  content:'✓'; position:absolute; left:0; top:.85rem;
  width:24px; height:24px; border-radius:50%; display:grid; place-items:center;
  font-size:.72rem; font-weight:800; color:#1a0d00;
  background:linear-gradient(140deg,var(--orange-light),var(--orange-deep));
  box-shadow:0 3px 0 #a63f00, 0 6px 12px rgba(255,122,24,.35);
}
.check-list b{ color:#fff; }
.check-list em{ color:var(--orange); font-style:italic; }

/* ---------- 18. Ring carousel 3D ---------- */
.word-bank{ margin-top:2.6rem; text-align:center; }
.word-bank__label{
  font-size:.85rem; letter-spacing:.14em; text-transform:uppercase;
  color:var(--txt-light-soft); margin-bottom:1.2rem;
}
.word-bank__hint{ font-size:.8rem; color:#6e6e78; margin-top:.6rem; }

.ring3d{
  position:relative; height:190px; perspective:1200px;
  display:grid; place-items:center; overflow:hidden;
}
.ring3d__inner{
  position:relative; width:190px; height:60px;
  transform-style:preserve-3d;
  animation:ringRotate 26s linear infinite;
}
.ring3d:hover .ring3d__inner{ animation-play-state:paused; }
@keyframes ringRotate{
  from{ transform:rotateX(-9deg) rotateY(0deg); }
  to  { transform:rotateX(-9deg) rotateY(360deg); }
}
.ring3d__item{
  position:absolute; inset:0;
  display:grid; place-items:center;
  padding:.5rem .9rem; border-radius:99px;
  font-size:.9rem; font-weight:700; white-space:nowrap;
  background:rgba(255,255,255,.06); border:1px solid var(--line-dark); color:#fff;
  backdrop-filter:blur(4px);
  /* 9 item -> 40deg per item, radius 260px */
  transform:rotateY(calc(var(--i) * 40deg)) translateZ(260px);
  box-shadow:0 10px 24px rgba(0,0,0,.45);
}
.ring3d__item--accent{
  background:linear-gradient(140deg,var(--orange),var(--orange-deep));
  border-color:rgba(255,255,255,.3); color:#1a0d00;
  box-shadow:0 10px 26px rgba(232,93,4,.45);
}

/* ---------- 19. Steps (tahapan) ---------- */
.steps{ display:grid; grid-template-columns:repeat(auto-fit,minmax(250px,1fr)); gap:1.6rem 1.2rem; }
.steps .tilt-wrap{ perspective:900px; }
.step{
  position:relative; height:100%;
  padding:2.5rem 1.6rem 1.7rem; border-radius:var(--radius);
  background:var(--white); border:1px solid var(--line-light); color:var(--txt-dark);
  box-shadow:0 10px 24px rgba(10,10,11,.07);
  transition:box-shadow .4s, border-color .4s;
}
.step:hover{ box-shadow:0 28px 52px rgba(232,93,4,.2); border-color:rgba(255,122,24,.4); }
.step__num{
  position:absolute; top:-16px; left:1.5rem;
  display:grid; place-items:center; width:46px; height:46px; border-radius:14px;
  font-family:var(--font-head); font-weight:900; font-size:.95rem; color:#1a0d00;
  background:linear-gradient(140deg,var(--orange-light),var(--orange-deep));
  box-shadow:0 5px 0 #a63f00, 0 14px 26px rgba(255,122,24,.35);
}
.step h3{ font-family:var(--font-head); font-size:1.05rem; font-weight:800; margin-bottom:.35rem; }
.step p{ font-size:.9rem; color:var(--txt-dark-soft); line-height:1.7; }

/* ---------- 20. Accordion (tujuan) ---------- */
.accordion{ display:grid; gap:.75rem; perspective:1100px; }
.acc-item{
  border-radius:var(--radius); background:var(--black-2);
  border:1px solid var(--line-dark); overflow:hidden;
  transform-style:preserve-3d;
  transition:border-color .3s, background .3s, transform .45s var(--ease), box-shadow .45s;
}
.acc-item:hover{ transform:translateZ(14px) rotateX(1.5deg); box-shadow:0 18px 36px rgba(0,0,0,.4); }
.acc-item.is-open{
  border-color:rgba(255,122,24,.45); background:var(--black-3);
  transform:translateZ(24px);
  box-shadow:0 24px 48px rgba(0,0,0,.5), 0 0 0 1px rgba(255,122,24,.16);
}
.acc-head{
  width:100%; display:flex; align-items:center; justify-content:space-between; gap:1rem;
  padding:1.25rem 1.5rem; font-family:var(--font-head); font-weight:700; font-size:1.02rem;
  color:#fff; text-align:left; transition:color .25s;
}
.acc-head:hover{ color:var(--orange); }
.acc-item.is-open .acc-head{ color:var(--orange); }
.acc-head i{
  flex:none; position:relative; width:28px; height:28px; border-radius:50%;
  background:rgba(255,122,24,.14); border:1px solid rgba(255,122,24,.32);
  transition:transform .4s var(--ease);
}
.acc-item.is-open .acc-head i{ transform:rotate(180deg); }
.acc-head i::before,.acc-head i::after{
  content:''; position:absolute; top:50%; left:50%; transform:translate(-50%,-50%);
  background:var(--orange); border-radius:2px; transition:transform .3s var(--ease);
}
.acc-head i::before{ width:11px; height:2px; }
.acc-head i::after{ width:2px; height:11px; }
.acc-item.is-open .acc-head i::after{ transform:translate(-50%,-50%) scaleY(0); }

.acc-body{ max-height:0; overflow:hidden; transition:max-height .4s var(--ease); }
.acc-body p{ padding:0 1.5rem 1.35rem; color:var(--txt-light-soft); font-size:.96rem; }

/* ---------- 21. Contoh (paper 3D) ---------- */
.paper-scene{ perspective:1600px; }
.paper{
  border-radius:var(--radius-l); overflow:hidden; background:var(--white);
  border:1px solid var(--line-light);
  transform-style:preserve-3d;
  transform:rotateX(6deg) rotateY(-3deg);
  transition:transform .7s var(--ease), box-shadow .7s;
  box-shadow:
    0 30px 60px rgba(10,10,11,.18),
    0 90px 120px -40px rgba(232,93,4,.22);
}
.paper-scene:hover .paper{ transform:rotateX(0deg) rotateY(0deg); }
.paper__bar{
  display:flex; align-items:center; gap:.5rem;
  padding:.85rem 1.2rem; background:var(--black); color:#fff;
  transform:translateZ(30px);
}
.paper__bar .dot{ width:11px; height:11px; border-radius:50%; background:#3a3a42; }
.paper__bar .dot:first-child{ background:var(--orange); box-shadow:0 0 10px rgba(255,122,24,.7); }
.paper__bar p{ margin-left:.7rem; font-size:.8rem; color:var(--txt-light-soft); font-family:ui-monospace,monospace; }

.paper__body{ padding:clamp(1.7rem,4vw,3rem); color:var(--txt-dark); transform-style:preserve-3d; }
.paper__title{
  font-family:var(--font-head); font-weight:800; letter-spacing:-.02em;
  font-size:clamp(1.4rem,3.5vw,1.9rem); text-align:center; margin-bottom:1.8rem;
  color:var(--txt-dark); transform:translateZ(24px);
  text-shadow:0 2px 0 rgba(232,93,4,.14);
}
.paper__body p{
  font-size:1.02rem; line-height:1.95; color:#22222a; text-align:justify;
  border-radius:12px;
  transition:background .45s, padding .45s, box-shadow .45s, transform .45s var(--ease);
}
.paper__body p + p{ margin-top:1.1rem; }

.paper__body.show-struktur p.mark-part{
  position:relative; padding:1.5rem 1.3rem 1rem;
  background:var(--orange-soft);
  box-shadow:inset 4px 0 0 var(--orange), 0 14px 30px rgba(232,93,4,.18);
}
.paper__body.show-struktur p.mark-part:nth-of-type(1){ transform:translateZ(16px); }
.paper__body.show-struktur p.mark-part:nth-of-type(2){ transform:translateZ(30px); }
.paper__body.show-struktur p.mark-part:nth-of-type(3){ transform:translateZ(44px); }
.paper__body.show-struktur p.mark-part::before{
  content:attr(data-part); position:absolute; top:0; left:1.2rem;
  transform:translateY(-50%) translateZ(12px);
  font-size:.7rem; font-weight:800; letter-spacing:.1em; text-transform:uppercase;
  padding:.3rem .85rem; border-radius:99px; color:#fff; background:var(--black);
  box-shadow:0 6px 14px rgba(0,0,0,.3);
}
.paper__body.show-struktur p + p{ margin-top:2.1rem; }

/* ============================================================
   BAGIAN 4 : Kuis, rangkuman kubus 3D, footer, responsive
   ============================================================ */

/* ---------- 22. Kuis ---------- */
.quiz-scene{ perspective:1200px; }
.quiz{
  padding:clamp(1.6rem,4vw,2.5rem); border-radius:var(--radius-l);
  background:linear-gradient(155deg,var(--black-3),var(--black-2));
  border:1px solid var(--line-dark);
  box-shadow:var(--shadow), inset 0 1px 0 rgba(255,255,255,.05);
  transform-style:preserve-3d;
  transition:transform .5s var(--ease);
}
.quiz:hover{ transform:translateZ(14px) rotateX(2deg); }
.quiz__top{ display:flex; align-items:center; gap:1rem; margin-bottom:1.4rem; }
.quiz__top span{
  font-size:.8rem; font-weight:700; letter-spacing:.1em;
  text-transform:uppercase; color:var(--orange); white-space:nowrap;
}
.quiz__bar{
  flex:1; height:6px; border-radius:99px; background:rgba(255,255,255,.08); overflow:hidden;
  box-shadow:inset 0 2px 4px rgba(0,0,0,.4);
}
.quiz__bar i{
  display:block; height:100%; width:0%;
  background:linear-gradient(90deg,var(--orange-light),var(--orange-deep));
  box-shadow:0 0 12px rgba(255,122,24,.6);
  transition:width .5s var(--ease);
}

.quiz__q{
  font-family:var(--font-head); font-weight:800;
  font-size:clamp(1.1rem,2.8vw,1.42rem);
  line-height:1.45; color:#fff; margin-bottom:1.4rem;
  transform:translateZ(10px);
}
.quiz__options{ display:grid; gap:.65rem; }
.opt{
  display:flex; align-items:center; gap:.9rem; text-align:left; width:100%;
  padding:1rem 1.2rem; border-radius:14px; font-size:.96rem; font-weight:500; color:#fff;
  background:rgba(255,255,255,.04); border:1.5px solid var(--line-dark);
  transform-style:preserve-3d;
  transition:transform .3s var(--ease), background .25s, border-color .25s, box-shadow .25s;
}
.opt:hover:not(:disabled){
  background:rgba(255,122,24,.1); border-color:rgba(255,122,24,.5);
  transform:translateX(8px) translateZ(6px);
  box-shadow:0 12px 26px rgba(0,0,0,.35);
}
.opt__key{
  flex:none; width:32px; height:32px; border-radius:10px; display:grid; place-items:center;
  font-family:var(--font-head); font-weight:800; font-size:.85rem;
  background:rgba(255,255,255,.08); color:var(--orange);
  box-shadow:0 2px 0 rgba(255,122,24,.2);
}
.opt:disabled{ cursor:default; }
.opt.is-correct{
  background:rgba(46,204,113,.14); border-color:#2ecc71;
  box-shadow:0 0 22px rgba(46,204,113,.25);
}
.opt.is-correct .opt__key{
  background:#2ecc71; color:#04220f;
  box-shadow:0 2px 0 #1e8c4a, 0 8px 14px rgba(46,204,113,.4);
}
.opt.is-wrong{
  background:rgba(231,76,60,.14); border-color:#e74c3c;
  box-shadow:0 0 18px rgba(231,76,60,.2);
}
.opt.is-wrong .opt__key{
  background:#e74c3c; color:#fff;
  box-shadow:0 2px 0 #a8322c, 0 8px 14px rgba(231,76,60,.35);
}

.quiz__foot{ display:flex; align-items:center; gap:1rem; margin-top:1.5rem; flex-wrap:wrap; }
.quiz__feedback{ flex:1; min-width:190px; font-size:.9rem; font-weight:600; color:var(--txt-light-soft); }
.quiz__feedback.ok{ color:#2ecc71; }
.quiz__feedback.no{ color:#e74c3c; }

.quiz-result{
  text-align:center; padding:clamp(2rem,5vw,3.2rem); border-radius:var(--radius-l);
  background:linear-gradient(150deg,var(--orange),var(--orange-deep)); color:var(--txt-dark);
  box-shadow:
    0 30px 60px rgba(232,93,4,.4),
    0 70px 100px -30px rgba(232,93,4,.25);
  animation:fadeUp .5s var(--ease);
  transform-style:preserve-3d;
}
.quiz-result__score{ font-family:var(--font-head); font-weight:900; line-height:1; margin-bottom:.8rem; }
.quiz-result__score b{
  font-size:clamp(3.2rem,10vw,4.6rem); color:#1a0d00;
  text-shadow:0 4px 0 rgba(255,255,255,.3);
}
.quiz-result__score span{ font-size:1.5rem; color:rgba(26,13,0,.6); }
.quiz-result h3{ font-family:var(--font-head); font-size:1.5rem; font-weight:800; margin-bottom:.4rem; color:#1a0d00; }
.quiz-result p{ color:rgba(26,13,0,.78); margin-bottom:1.6rem; }
.quiz-result .btn--ghost{
  border-color:rgba(26,13,0,.35); color:#1a0d00; background:rgba(255,255,255,.28);
}
.quiz-result .btn--ghost:hover{ background:var(--black); color:#fff; border-color:var(--black); transform:translateY(-4px); }

/* ---------- 23. Rangkuman — kubus 3D interaktif ---------- */
.cube-wrap{
  display:grid; grid-template-columns:1fr 1fr; gap:clamp(1.5rem,5vw,3.5rem); align-items:center;
}
.cube-scene{
  perspective:1200px; width:300px; height:300px; margin-inline:auto;
}
.cube{
  width:100%; height:100%; position:relative; transform-style:preserve-3d;
  transition:transform .8s var(--ease);
}
.cube__face{
  position:absolute; inset:0; border-radius:var(--radius);
  background:var(--black); color:#fff;
  display:flex; flex-direction:column; align-items:center; justify-content:center;
  padding:1.6rem; text-align:center;
  border:2px solid rgba(255,122,24,.35);
  box-shadow:0 0 0 1px rgba(255,255,255,.08) inset;
  backface-visibility:visible;
}
.cube__face span{
  display:inline-block; font-family:var(--font-head); font-weight:900; font-size:1.35rem;
  color:var(--orange); margin-bottom:.8rem;
  text-shadow:0 2px 0 rgba(255,122,24,.3);
}
.cube__face p{ font-size:.88rem; color:var(--txt-light-soft); line-height:1.7; }

/* posisi tiap sisi — kubus 300px */
.cube__face--front  { transform:translateZ(150px); }
.cube__face--back   { transform:rotateY(180deg) translateZ(150px); }
.cube__face--right  { transform:rotateY(90deg)  translateZ(150px); }
.cube__face--left   { transform:rotateY(-90deg) translateZ(150px); }
.cube__face--top    { transform:rotateX(90deg)  translateZ(150px); }
.cube__face--bottom { transform:rotateX(-90deg) translateZ(150px); }

.cube-ctrl{ display:flex; flex-wrap:wrap; gap:.5rem; }
.cube-ctrl button{
  flex:1 1 calc(50% - .5rem); padding:.7rem .5rem; border-radius:12px;
  font-weight:700; font-size:.85rem; color:var(--txt-dark);
  background:rgba(255,255,255,.55); border:1px solid rgba(26,13,0,.16);
  backdrop-filter:blur(4px);
  box-shadow:0 3px 0 rgba(10,10,11,.12);
  transition:transform .25s var(--ease), background .25s, box-shadow .25s, color .25s;
}
.cube-ctrl button:hover{
  transform:translateY(-3px);
  background:var(--black); color:#fff;
  box-shadow:0 7px 0 rgba(10,10,11,.18), 0 14px 24px rgba(0,0,0,.2);
}
.cube-ctrl button.is-active{
  background:linear-gradient(140deg,var(--orange-light),var(--orange-deep));
  color:#1a0d00; box-shadow:0 5px 0 #a63f00, 0 12px 22px rgba(232,93,4,.35);
}

/* ---------- 24. Footer ---------- */
.footer{
  background:var(--black); border-top:1px solid var(--line-dark);
  padding:3.2rem 0 2.2rem;
}
.footer__inner{ display:flex; flex-wrap:wrap; align-items:center; justify-content:space-between; gap:1.6rem; }
.footer__brand{ display:flex; align-items:center; gap:.85rem; perspective:500px; }
.footer__brand p{ font-size:.95rem; color:#fff; line-height:1.4; }
.footer__brand b{ color:var(--orange); }
.footer__brand small{ color:var(--txt-light-soft); font-size:.8rem; }
.footer__links{ display:flex; gap:1.3rem; flex-wrap:wrap; }
.footer__links a{ font-size:.88rem; color:var(--txt-light-soft); transition:color .25s; }
.footer__links a:hover{ color:var(--orange); }
.footer__copy{
  width:100%; padding-top:1.5rem; border-top:1px solid var(--line-dark);
  font-size:.82rem; color:#6e6e78; text-align:center;
}

/* ---------- 25. To top ---------- */
.to-top{
  position:fixed; right:1.4rem; bottom:1.4rem; z-index:800;
  width:48px; height:48px; border-radius:50%; font-size:1.2rem; font-weight:800; color:#1a0d00;
  background:linear-gradient(140deg,var(--orange-light),var(--orange-deep));
  box-shadow:0 5px 0 #a63f00, 0 16px 32px rgba(255,122,24,.45);
  opacity:0; visibility:hidden; transform:translateY(14px) rotateX(-40deg);
  transition:opacity .35s, transform .4s var(--ease), visibility .35s;
}
.to-top.is-show{ opacity:1; visibility:visible; transform:none; }
.to-top:hover{ transform:translateY(-5px) rotateX(10deg); box-shadow:0 9px 0 #a63f00, 0 20px 38px rgba(255,122,24,.5); }

/* ---------- 26. Reveal on scroll ---------- */
.reveal{ opacity:0; transform:translateY(32px) rotateX(4deg); transition:opacity .75s var(--ease), transform .75s var(--ease); }
.reveal.is-visible{ opacity:1; transform:none; }

.reveal[data-delay="1"]{ transition-delay:.08s; }
.reveal[data-delay="2"]{ transition-delay:.16s; }
.reveal[data-delay="3"]{ transition-delay:.24s; }
.reveal[data-delay="4"]{ transition-delay:.32s; }
.reveal[data-delay="5"]{ transition-delay:.40s; }
.reveal[data-delay="6"]{ transition-delay:.48s; }

/* ---------- 27. Responsive ---------- */
@media (max-width:1024px){
  .iso-wrap{ grid-template-columns:1fr; }
  .iso__stage{ height:340px; }
  .slab{ width:200px; height:200px; }
  .cube-wrap{ grid-template-columns:1fr; }
  .cube-scene{ width:240px; height:240px; }
  .cube__face--front  { transform:translateZ(120px); }
  .cube__face--back   { transform:rotateY(180deg) translateZ(120px); }
  .cube__face--right  { transform:rotateY(90deg)  translateZ(120px); }
  .cube__face--left   { transform:rotateY(-90deg) translateZ(120px); }
  .cube__face--top    { transform:rotateX(90deg)  translateZ(120px); }
  .cube__face--bottom { transform:rotateX(-90deg) translateZ(120px); }
}

@media (max-width:900px){
  .burger{ display:grid; }
  .nav__links{
    position:fixed; inset:0 0 auto 0; top:0; padding:6rem 1.6rem 2rem;
    flex-direction:column; align-items:stretch; gap:.3rem;
    background:rgba(10,10,11,.97); backdrop-filter:blur(18px);
    border-bottom:1px solid var(--line-dark);
    transform:translateY(-110%); transition:transform .42s var(--ease);
    max-height:100svh; overflow-y:auto;
  }
  .nav__links.is-open{ transform:none; }
  .nav__links a{ padding:.9rem 1rem; font-size:1rem; border-radius:12px; }
  .nav__links a.nav__cta{ margin:.5rem 0 0; text-align:center; }
  .brand{ position:relative; z-index:2; }
  .burger{ position:relative; z-index:2; }

  .formula__op{ display:none; }
  .block3d{ transform:rotateX(6deg) rotateY(-10deg); }
  .block3d__face{ min-width:0; padding:1rem 1.2rem; }
  .flip3d{ height:240px; }
  .ring3d__item{ transform:rotateY(calc(var(--i) * 40deg)) translateZ(160px); font-size:.78rem; }

  .hero__canvas{ opacity:.55; }
}

@media (max-width:560px){
  .hero__actions .btn{ width:100%; }
  .hero__stats{ gap:1.6rem 2.2rem; }
  .quote-mark{ font-size:7rem; right:.8rem; }
  .paper__body p{ text-align:left; }
  .quiz__foot .btn{ width:100%; }
  .footer__inner{ flex-direction:column; align-items:flex-start; }
  .flip3d{ height:220px; }
  .iso__stage{ height:260px; }
  .slab{ width:160px; height:160px; }
  .cube-scene{ width:200px; height:200px; }
  .cube__face--front  { transform:translateZ(100px); }
  .cube__face--back   { transform:rotateY(180deg) translateZ(100px); }
  .cube__face--right  { transform:rotateY(90deg)  translateZ(100px); }
  .cube__face--left   { transform:rotateY(-90deg) translateZ(100px); }
  .cube__face--top    { transform:rotateX(90deg)  translateZ(100px); }
  .cube__face--bottom { transform:rotateX(-90deg) translateZ(100px); }
  .floaters{ display:none; }
}

/* ---------- 28. Aksesibilitas & print ---------- */
@media (prefers-reduced-motion:reduce){
  *,*::before,*::after{ animation-duration:.01ms !important; transition-duration:.01ms !important; }
  html{ scroll-behavior:auto; }
  .reveal{ opacity:1; transform:none; }
  .brand__cube{ animation:none; }
  .ring3d__inner{ animation:none; }
}

:focus-visible{ outline:3px solid var(--orange); outline-offset:3px; border-radius:6px; }

@media print{
  .nav,.to-top,.progress-bar,.scroll-hint,.quiz,.quiz-result,.floaters,.ring-deco,.hero__canvas{ display:none !important; }
  body{ background:#fff; color:#000; }
  .reveal{ opacity:1; transform:none; }
  .section--accent{ background:#fff; color:#000; }
}

/* ---------- 29. Keyframe pendukung ---------- */
@keyframes fadeUp{
  from{ opacity:0; transform:translateY(18px) scale(.97); }
  to  { opacity:1; transform:none; }
}

/* ============================================================
   BAGIAN 5 : Perbaikan & penyempurnaan 3D
   ============================================================ */

/* ---------- Pemusatan slab isometrik ---------- */
.iso__stage{ display:block; }
.slab{
  top:50%; left:50%;
  transform:translate(-50%,-50%) translateZ(var(--z));
}
.slab:hover{ transform:translate(-50%,-50%) translateZ(calc(var(--z) + 26px)); }
.slab.is-active{ transform:translate(-50%,-50%) translateZ(calc(var(--z) + 46px)); }
.iso__shadow{
  top:50%; left:50%;
  transform:translate(-50%,-50%) translateZ(-90px);
}

/* ---------- Tata letak panel struktur ---------- */
.iso-detail{ min-height:250px; padding-bottom:5rem; }
.iso-panel{ inset:0 0 auto 0; }
.iso-nav{ bottom:0; }

/* ---------- Ring 3D: sembunyikan item yang membelakangi ---------- */
.ring3d__item{
  backface-visibility:hidden; -webkit-backface-visibility:hidden;
}

/* ---------- Kubus: kursor grab ---------- */
.cube-scene{ cursor:grab; user-select:none; -webkit-user-select:none; touch-action:pan-y; }
.cube-scene:active{ cursor:grabbing; }

/* ---------- Reduced motion: matikan efek 3D berat ---------- */
@media (prefers-reduced-motion:reduce){
  .paper{ transform:none !important; }
  .block3d{ transform:none !important; }
  .cube3d, .pyr3d, .ring-deco{ display:none; }
  #trailCanvas{ display:none !important; }
  .flip3d:hover .flip3d__inner{ transform:none; }
}