:root{
    --bg:#07090e;--surface:#0f1520;--surface2:#1a2035;
    --orange:#fb923c;--gold:#facc15;--green:#34d399;--purple:#818cf8;--pink:#f472b6;
    --text:#f1f5f9;--muted:#64748b;--border:rgba(255,255,255,0.06);
}
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
body{font-family:'Outfit',sans-serif;background:var(--bg);color:var(--text);height:100vh;overflow:hidden}
#bgCanvas{position:fixed;inset:0;z-index:0;pointer-events:none}

#phet-stage {
    position: absolute; top: 0; left: 0;
    width: 1280px; height: 720px;
    background: var(--bg);
    display: flex; flex-direction: column;
    overflow: hidden; transform-origin: 0 0;
    box-shadow: 0 0 50px rgba(0, 0, 0, 0.4);
    touch-action: none;
}

.rp-nav{position:absolute;top:0;left:0;right:0;height:58px;display:flex;align-items:center;justify-content:space-between;padding:0 2rem;background:rgba(7,9,14,0.93);backdrop-filter:blur(20px);border-bottom:1px solid var(--border);z-index:200}
.nav-logo a{text-decoration:none;font-weight:800;font-size:1.15rem;color:var(--text);display:flex;align-items:center;gap:0.4rem}
.nav-logo em{color:var(--orange);font-style:normal}
.nav-center{font-size:0.82rem;color:var(--muted);letter-spacing:0.5px;font-weight:500}
.nav-back{display:flex;align-items:center;gap:0.4rem;padding:0.45rem 1.1rem;border-radius:50px;border:1px solid var(--border);background:transparent;color:var(--text);font-size:0.82rem;text-decoration:none;transition:0.2s}
.nav-back:hover{border-color:var(--orange);color:var(--orange)}

.app-shell{position:absolute;top:58px;bottom:0;left:0;right:0;display:grid;grid-template-columns:520px 1fr;z-index:1;overflow:hidden}

/* Story Panel */
.story-panel{display:flex;flex-direction:column;background:var(--surface);border-right:1px solid var(--border);overflow:hidden}
.progress-bar-wrap{height:4px;background:var(--surface2);flex-shrink:0}
.progress-bar-fill{height:100%;background:linear-gradient(90deg,var(--orange),var(--gold));width:0%;transition:width 0.5s ease;border-radius:0 4px 4px 0}
.story-content{flex:1;overflow-y:auto;padding:2.2rem 2.5rem 1rem;scroll-behavior:smooth}
.story-content::-webkit-scrollbar{width:4px}
.story-content::-webkit-scrollbar-thumb{background:var(--surface2);border-radius:4px}
.step-block{display:none;flex-direction:column;gap:1.2rem;animation:fadeUp 0.4s ease}
.step-block.active{display:flex}
@keyframes fadeUp{from{opacity:0;transform:translateY(14px)}to{opacity:1;transform:translateY(0)}}

.step-kicker{display:inline-flex;align-items:center;gap:0.5rem;background:rgba(251,146,60,0.1);border:1px solid rgba(251,146,60,0.25);border-radius:50px;padding:0.28rem 1rem;font-size:0.74rem;font-weight:700;text-transform:uppercase;letter-spacing:1px;color:var(--orange);width:fit-content}
.step-block h2{font-size:1.65rem;font-weight:900;line-height:1.2;color:white}
.step-block h2 span{color:var(--orange)}
.step-block p{color:#94a3b8;line-height:1.82;font-size:0.97rem}
.step-block p strong{color:white;font-weight:700}
.hl{color:var(--gold);font-family:'JetBrains Mono';font-weight:700;background:rgba(250,204,21,0.08);padding:0.1em 0.3em;border-radius:4px}
.or{color:var(--orange);font-weight:700}
.gn{color:var(--green);font-weight:700}
.pu{color:var(--purple);font-weight:700}
.pk{color:var(--pink);font-weight:700}

.eq{background:var(--surface2);border:1px solid var(--border);border-radius:14px;padding:1.1rem 1.5rem;font-family:'JetBrains Mono',monospace;font-size:1.05rem;color:white;line-height:2}
.eq.center{text-align:center}
.eq.gold{border-color:rgba(250,204,21,0.4);background:rgba(250,204,21,0.06);color:var(--gold);text-align:center;font-size:1.15rem}
.eq.orange{border-color:rgba(251,146,60,0.4);background:rgba(251,146,60,0.06);color:var(--orange);text-align:center}
.eq.green-box{border-color:rgba(52,211,153,0.4);background:rgba(52,211,153,0.06);color:var(--green);text-align:center}
.eq small{display:block;font-family:'Outfit';font-size:0.74rem;color:var(--muted);margin-top:0.4rem;font-style:italic}

.color-legend{display:flex;flex-direction:column;gap:0.6rem}
.cl-item{display:flex;align-items:flex-start;gap:0.8rem;font-size:0.9rem;color:#94a3b8}
.cl-dot{width:12px;height:12px;border-radius:50%;flex-shrink:0;margin-top:3px}
.notation-grid{display:grid;grid-template-columns:1fr 1fr;gap:0.7rem}
.notebox{background:var(--surface2);border:1px solid var(--border);border-radius:12px;padding:0.7rem 1rem;font-size:0.88rem;color:#94a3b8}
.notebox span{display:block;font-family:'JetBrains Mono';font-size:1rem;font-weight:700;margin-bottom:0.2rem;color:var(--orange)}
.hint{background:rgba(251,146,60,0.06);border:1px dashed rgba(251,146,60,0.3);border-radius:12px;padding:0.9rem 1.2rem;font-size:0.88rem;color:var(--orange);display:flex;gap:0.7rem;align-items:flex-start;line-height:1.7}
.hint i{margin-top:2px;flex-shrink:0}

.story-footer{display:flex;align-items:center;gap:1rem;padding:1.1rem 2.5rem 3.5rem;border-top:1px solid var(--border);flex-shrink:0}
.step-pips{display:flex;gap:6px;flex:1;justify-content:center}
.pip{width:7px;height:7px;border-radius:50%;background:var(--muted);cursor:pointer;transition:0.3s;border:none;padding:0}
.pip.active{background:var(--orange);transform:scale(1.5)}
.pip:hover{background:var(--gold)}
.nav-btn{display:flex;align-items:center;gap:0.5rem;padding:0.65rem 1.4rem;border-radius:50px;font-family:'Outfit';font-weight:700;font-size:0.9rem;cursor:pointer;transition:0.2s;border:none}
.nav-btn.ghost{background:transparent;border:1px solid var(--border);color:var(--text)}
.nav-btn.ghost:hover:not(:disabled){border-color:rgba(255,255,255,0.3);background:rgba(255,255,255,0.05)}
.nav-btn.primary{background:var(--orange);color:white;box-shadow:0 0 18px rgba(251,146,60,0.35)}
.nav-btn.primary:hover{background:#ea7c2b}
.nav-btn.gold-btn{background:var(--gold);color:#000}
.nav-btn:disabled{opacity:0.3;cursor:default}

/* Visual panel */
.visual-shell{display:flex;flex-direction:column;align-items:center;justify-content:center;padding:1.2rem;gap:0.9rem;background:var(--bg);overflow:hidden}
#mainCanvas{border-radius:18px;border:1px solid var(--border);background:var(--surface);max-width:100%;max-height:calc(100% - 140px)}
.canvas-caption{font-size:0.82rem;color:var(--muted);text-align:center;max-width:480px;line-height:1.6;min-height:2.2em;transition:opacity 0.3s}

/* Controls */
.controls-row{display:flex;align-items:center;gap:1rem;width:100%;max-width:480px;flex-wrap:wrap;justify-content:center}
.ctrl-group{display:flex;flex-direction:column;align-items:center;gap:0.3rem;min-width:120px}
.ctrl-group label{font-size:0.75rem;color:var(--muted);text-transform:uppercase;letter-spacing:0.5px;font-weight:600}
.rp-slider{-webkit-appearance:none;appearance:none;width:120px;height:5px;border-radius:5px;background:var(--surface2);outline:none;cursor:pointer}
.rp-slider::-webkit-slider-thumb{-webkit-appearance:none;appearance:none;width:18px;height:18px;border-radius:50%;background:var(--orange);cursor:pointer;box-shadow:0 0 8px rgba(251,146,60,0.5)}
.ctrl-val{font-family:'JetBrains Mono';font-size:1.4rem;font-weight:700;color:var(--orange)}
.ctrl-sep{font-family:'JetBrains Mono';font-size:2rem;font-weight:900;color:var(--muted);align-self:flex-end;margin-bottom:10px}

/* Chips */
.chip-row{display:flex;gap:0.7rem;flex-wrap:wrap;justify-content:center;max-width:500px}
.chip{background:var(--surface);border:1px solid var(--border);border-radius:12px;padding:0.5rem 1rem;font-size:0.82rem;display:flex;flex-direction:column;gap:0.2rem;align-items:center;min-width:100px}
.chip-label{color:var(--muted);font-size:0.72rem;text-transform:uppercase;letter-spacing:0.5px;font-weight:600}
.chip-val{font-family:'JetBrains Mono';font-size:0.95rem;font-weight:700;color:white;text-align:center}
.chip.orange-chip{border-color:rgba(251,146,60,0.4);background:rgba(251,146,60,0.07)}
.chip.orange-chip .chip-val{color:var(--orange)}
.chip.gold-chip{border-color:rgba(250,204,21,0.4);background:rgba(250,204,21,0.07)}
.chip.gold-chip .chip-val{color:var(--gold)}
.chip.green-chip{border-color:rgba(52,211,153,0.4);background:rgba(52,211,153,0.07)}
.chip.green-chip .chip-val{color:var(--green)}

/* Finale */
.finale-overlay{position:absolute;inset:0;background:rgba(0,0,0,0.88);z-index:500;display:flex;align-items:center;justify-content:center;opacity:0;pointer-events:none;transition:opacity 0.6s;backdrop-filter:blur(12px)}
.finale-overlay.show{opacity:1;pointer-events:all}
.finale-card{position:relative;background:var(--surface);border:1px solid rgba(251,146,60,0.3);border-radius:28px;padding:3rem 3.5rem;text-align:center;max-width:520px;overflow:hidden;animation:popUp 0.6s cubic-bezier(0.34,1.56,0.64,1) both}
@keyframes popUp{from{transform:scale(0.7);opacity:0}to{transform:scale(1);opacity:1}}
.ring{position:absolute;border-radius:50%;border:1px solid;top:50%;left:50%;transform:translate(-50%,-50%);animation:expand 3s ease-in-out infinite}
.ring1{width:220px;height:220px;border-color:rgba(251,146,60,0.15);animation-delay:0s}
.ring2{width:360px;height:360px;border-color:rgba(251,146,60,0.07);animation-delay:1s}
@keyframes expand{0%,100%{transform:translate(-50%,-50%) scale(1);opacity:0.8}50%{transform:translate(-50%,-50%) scale(1.05);opacity:0.3}}
.finale-kicker{font-size:0.78rem;color:var(--muted);text-transform:uppercase;letter-spacing:2px;margin-bottom:1rem;position:relative}
.finale-eq{font-family:'JetBrains Mono';font-size:2.5rem;font-weight:900;color:var(--orange);margin-bottom:1.2rem;position:relative}
.finale-facts{display:flex;flex-direction:column;gap:0.6rem;margin-bottom:2rem;position:relative;text-align:left}
.ff{display:flex;align-items:center;gap:0.7rem;font-size:0.9rem;color:#94a3b8}
.finale-btn{display:inline-flex;align-items:center;gap:0.6rem;padding:0.85rem 2.2rem;border-radius:50px;border:2px solid var(--orange);background:transparent;color:var(--orange);font-family:'Outfit';font-weight:700;font-size:1rem;cursor:pointer;transition:0.3s;position:relative}
.finale-btn:hover{background:var(--orange);color:#000}

sup,sub{line-height:0}

/* Media Query to keep footer compact on mobile */
@media screen and (max-width: 899px) {
    .story-footer {
        padding: 1.1rem 2.5rem !important;
    }
}