@import url('https://fonts.googleapis.com/css2?family=JetBrains+Mono:wght@300;400;600;700&family=Syne:wght@400;600;700;800&display=swap');

:root {
  --bg:       #07090f;
  --bg2:      #0c1018;
  --bg3:      #111722;
  --panel:    #131b28;
  --panel2:   #18233a;
  --border:   #1e2d44;
  --border2:  #263550;
  --accent:   #00c8ff;
  --accent2:  #0077aa;
  --green:    #00e5a0;
  --orange:   #ff7b35;
  --purple:   #a855f7;
  --red:      #ff4d6d;
  --yellow:   #ffd166;
  --text:     #dde6f0;
  --text2:    #7a90ab;
  --text3:    #3d5068;
  --glow:     rgba(0,200,255,.12);
  --glow2:    rgba(0,229,160,.08);
  --wire:     #1e3a5f;
  --cur:      #3b82f6;
  --cur2:     #60a5fa;
}

*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}

body {
  background: var(--bg);
  color: var(--text);
  font-family: 'Syne', sans-serif;
  font-size: 15px;
  line-height: 1.7;
  min-height: 100vh;
  overflow-x: hidden;
}

/* subtle grid texture */
body::before {
  content:'';
  position:fixed;inset:0;
  background-image:
    linear-gradient(rgba(0,200,255,.025) 1px,transparent 1px),
    linear-gradient(90deg,rgba(0,200,255,.025) 1px,transparent 1px);
  background-size:40px 40px;
  pointer-events:none;z-index:0;
}
body::after {
  content:'';
  position:fixed;inset:0;
  background:
    radial-gradient(ellipse 70% 45% at 50% 0%,rgba(0,200,255,.07),transparent),
    radial-gradient(ellipse 40% 30% at 90% 85%,rgba(168,85,247,.06),transparent);
  pointer-events:none;z-index:0;
}

/* ── TOP BAR ── */
#topbar {
  position:sticky;top:0;z-index:200;
  background:rgba(7,9,15,.95);
  backdrop-filter:blur(20px);
  border-bottom:1px solid var(--border);
  display:flex;align-items:center;gap:0;
  height:56px;padding:0 1.5rem;
  box-shadow:0 4px 24px rgba(0,0,0,.4);
}

.logo {
  font-family:'JetBrains Mono',monospace;
  font-size:.95rem;font-weight:700;
  color:var(--accent);
  text-shadow:0 0 18px rgba(0,200,255,.5);
  white-space:nowrap;
  margin-right:1.5rem;
  flex-shrink:0;
  letter-spacing:.04em;
}
.logo span{color:var(--text3);font-weight:300}

/* ── TAB STRIP ── */
#tab-strip {
  display:flex;align-items:stretch;
  gap:0;overflow-x:auto;flex:1;
  scrollbar-width:none;height:56px;
}
#tab-strip::-webkit-scrollbar{display:none}

.tab-btn {
  background:none;border:none;
  color:var(--text3);
  font-family:'JetBrains Mono',monospace;
  font-size:.7rem;font-weight:600;
  letter-spacing:.06em;
  padding:0 1rem;
  cursor:pointer;
  white-space:nowrap;
  border-bottom:2px solid transparent;
  transition:color .2s,border-color .2s,background .2s;
  display:flex;align-items:center;gap:.4rem;
  height:100%;
  position:relative;
}
.tab-btn:hover{color:var(--text);background:rgba(0,200,255,.04)}
.tab-btn.active{color:var(--accent);border-bottom-color:var(--accent)}
.tab-btn .num {
  font-size:.6rem;color:var(--text3);
  background:var(--bg3);
  padding:.1rem .35rem;border-radius:3px;
}
.tab-btn.active .num{background:rgba(0,200,255,.12);color:var(--accent)}

/* ── MAIN ── */
main {
  position:relative;z-index:1;
  max-width:1200px;margin:0 auto;
  padding:2rem 1.5rem 5rem;
}

/* ── TAB PANELS ── */
.panel{display:none}
.panel.active{display:block}

/* ── PAGE HERO ── */
.hero {
  display:flex;align-items:flex-start;
  gap:1.5rem;margin-bottom:2rem;
  padding-bottom:1.5rem;
  border-bottom:1px solid var(--border);
}
.hero-num {
  font-family:'JetBrains Mono',monospace;
  font-size:3.5rem;font-weight:700;
  color:var(--border2);line-height:1;
  flex-shrink:0;user-select:none;
  letter-spacing:-.03em;
}
.hero-text h1 {
  font-family:'Syne',sans-serif;
  font-size:clamp(1.3rem,3vw,2rem);
  font-weight:800;line-height:1.15;
  color:var(--text);margin-bottom:.4rem;
}
.hero-text h1 em{font-style:normal;color:var(--accent)}
.hero-text p{color:var(--text2);font-size:.9rem;font-family:'Syne',sans-serif}

/* ── GRID ── */
.grid2{display:grid;grid-template-columns:1fr 1fr;gap:1.25rem;margin-bottom:1.25rem}
.grid3{display:grid;grid-template-columns:1fr 1fr 1fr;gap:1.25rem;margin-bottom:1.25rem}
.grid-full{display:grid;grid-template-columns:1fr;gap:1.25rem;margin-bottom:1.25rem}
@media(max-width:768px){.grid2,.grid3{grid-template-columns:1fr}}

/* ── CARD ── */
.card {
  background:var(--panel);
  border:1px solid var(--border);
  border-radius:10px;padding:1.25rem;
  position:relative;overflow:hidden;
  transition:border-color .25s;
}
.card:hover{border-color:var(--border2)}
.card-top-line {
  position:absolute;top:0;left:0;right:0;height:1px;
  background:linear-gradient(90deg,transparent,var(--accent),transparent);
  opacity:0;transition:opacity .3s;
}
.card:hover .card-top-line{opacity:.5}

.card-label {
  font-family:'JetBrains Mono',monospace;
  font-size:.65rem;text-transform:uppercase;
  letter-spacing:.14em;color:var(--accent);
  margin-bottom:.9rem;
  display:flex;align-items:center;gap:.5rem;
}
.card-label::before{
  content:'';width:3px;height:12px;
  background:var(--accent);border-radius:2px;
  box-shadow:0 0 6px var(--accent);
}

/* ── THEORY ── */
.theory{color:var(--text2);font-size:.9rem;line-height:1.8}
.theory p+p{margin-top:.7rem}
.theory strong{color:var(--text)}

/* ── FORMULAS ── */
.fbox {
  background:var(--bg2);
  border:1px solid var(--border);
  border-radius:7px;
  padding:1rem 1.2rem;
  text-align:center;
  margin:.8rem 0;
}
.fbox .f {
  font-family:'JetBrains Mono',monospace;
  font-size:1.2rem;font-weight:600;
  color:var(--accent);display:block;
  text-shadow:0 0 12px rgba(0,200,255,.35);
  margin-bottom:.35rem;
}
.fbox .fl{font-size:.75rem;color:var(--text3);display:block}

.flist{list-style:none;display:flex;flex-direction:column;gap:.45rem;margin-top:.75rem}
.flist li {
  display:flex;align-items:flex-start;gap:.6rem;
  font-family:'JetBrains Mono',monospace;
  font-size:.8rem;color:var(--text2);
  padding:.45rem .7rem;
  background:var(--bg3);
  border-radius:5px;
  border-left:2px solid var(--accent);
}
.flist li .sym{color:var(--accent);min-width:110px;flex-shrink:0}

/* ── CALCULATOR ── */
.calc-grid{display:grid;grid-template-columns:1fr 1fr;gap:.7rem;margin-bottom:.8rem}
.igroup{display:flex;flex-direction:column;gap:.25rem}
.igroup label{font-family:'JetBrains Mono',monospace;font-size:.68rem;color:var(--text3);text-transform:uppercase;letter-spacing:.05em}
.igroup input,.igroup select{
  background:var(--bg2);
  border:1px solid var(--border);
  border-radius:5px;color:var(--text);
  padding:.55rem .7rem;
  font-size:.88rem;font-family:'JetBrains Mono',monospace;
  width:100%;transition:border-color .2s,box-shadow .2s;
}
.igroup input:focus,.igroup select:focus{
  outline:none;border-color:var(--accent);
  box-shadow:0 0 0 2px rgba(0,200,255,.1);
}

.btn {
  display:flex;align-items:center;justify-content:center;gap:.45rem;
  background:linear-gradient(135deg,var(--accent2),var(--accent));
  color:var(--bg);border:none;border-radius:7px;
  padding:.6rem 1.2rem;
  font-size:.78rem;font-weight:700;
  font-family:'JetBrains Mono',monospace;
  cursor:pointer;transition:all .2s;
  text-transform:uppercase;letter-spacing:.06em;width:100%;
}
.btn:hover{transform:translateY(-1px);box-shadow:0 4px 18px rgba(0,200,255,.28)}
.btn:active{transform:translateY(0)}
.btn.green{background:linear-gradient(135deg,#00a870,var(--green))}
.btn.orange{background:linear-gradient(135deg,#cc4400,var(--orange))}

.rbox{
  background:var(--bg2);
  border:1px solid rgba(0,200,255,.18);
  border-radius:7px;padding:.9rem 1rem;
  margin-top:.8rem;display:none;
}
.rbox.show{display:block}
.rlabel{font-size:.68rem;color:var(--text3);font-family:'JetBrains Mono',monospace;text-transform:uppercase;margin-bottom:.3rem}
.rval{font-family:'JetBrains Mono',monospace;font-size:1.5rem;font-weight:700;color:var(--green);text-shadow:0 0 12px rgba(0,229,160,.4)}
.runit{font-size:.85rem;color:var(--text2);margin-left:.35rem}
.rdetail{font-size:.78rem;color:var(--text2);margin-top:.4rem;font-family:'JetBrains Mono',monospace}

/* ── SLIDER ── */
.sl-group{display:flex;flex-direction:column;gap:.35rem;margin-bottom:.75rem}
.sl-head{display:flex;justify-content:space-between;align-items:center}
.sl-lbl{font-family:'JetBrains Mono',monospace;font-size:.7rem;color:var(--text3);text-transform:uppercase;letter-spacing:.05em}
.sl-val{font-family:'JetBrains Mono',monospace;font-size:.82rem;color:var(--accent)}
input[type=range]{-webkit-appearance:none;width:100%;height:3px;background:var(--border);border-radius:2px;outline:none}
input[type=range]::-webkit-slider-thumb{-webkit-appearance:none;width:14px;height:14px;border-radius:50%;background:var(--accent);cursor:pointer;box-shadow:0 0 6px rgba(0,200,255,.5)}

/* ── VISUAL / CANVAS areas ── */
.viz{
  background:var(--bg2);border:1px solid var(--border);
  border-radius:7px;overflow:hidden;position:relative;
  display:flex;align-items:center;justify-content:center;
}
.viz canvas,.viz svg{display:block;width:100%;max-width:100%}

/* ── CHIP ── */
.chip{
  display:inline-flex;align-items:center;gap:.35rem;
  background:rgba(0,200,255,.06);
  border:1px solid rgba(0,200,255,.14);
  border-radius:20px;padding:.22rem .65rem;
  font-size:.74rem;color:var(--text2);
  font-family:'JetBrains Mono',monospace;
}
.chip b{color:var(--accent)}
.chips{display:flex;flex-wrap:wrap;gap:.4rem;margin-top:.6rem}

/* ── INNER TABS ── */
.itabs{display:flex;gap:.3rem;margin-bottom:1rem;border-bottom:1px solid var(--border);padding-bottom:0}
.itab{
  background:none;border:none;color:var(--text3);
  font-family:'JetBrains Mono',monospace;font-size:.7rem;
  text-transform:uppercase;letter-spacing:.08em;
  padding:.5rem .85rem;cursor:pointer;
  border-bottom:2px solid transparent;margin-bottom:-1px;
  transition:all .2s;
}
.itab.active{color:var(--accent);border-bottom-color:var(--accent)}
.itab:hover:not(.active){color:var(--text2)}
.ipanel{display:none}.ipanel.active{display:block}

/* ── RESULT GRID ── */
.res-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:.7rem;margin-top:.8rem}
.res-cell{
  background:var(--bg2);border:1px solid var(--border);
  border-radius:7px;padding:.7rem;text-align:center;
}
.res-cell-top{border-top-width:2px}
.rc-lbl{font-size:.65rem;color:var(--text3);font-family:'JetBrains Mono',monospace;margin-bottom:.25rem}
.rc-val{font-size:1.1rem;font-weight:700;font-family:'JetBrains Mono',monospace}
.rc-unit{font-size:.7rem;color:var(--text2)}

/* ── SPECTRUM ── */
.spectrum{
  width:100%;height:44px;border-radius:6px;overflow:hidden;margin:1rem 0;
  background:linear-gradient(90deg,#7c3aed,#3b82f6,#06b6d4,#22c55e,#eab308,#f97316,#ef4444);
  position:relative;box-shadow:0 0 20px rgba(255,255,255,.05);
}
.spectrum-labels{
  display:grid;font-family:'JetBrains Mono',monospace;
  font-size:.6rem;color:var(--text3);
  grid-template-columns:repeat(7,1fr);text-align:center;
  margin-top:.3rem;
}

/* ── CIRCUIT ANIMATIONS ── */
@keyframes flowR{0%{stroke-dashoffset:80}100%{stroke-dashoffset:0}}
@keyframes flowL{0%{stroke-dashoffset:0}100%{stroke-dashoffset:80}}
@keyframes glowPulse{0%,100%{opacity:.5}50%{opacity:1}}
@keyframes needleSwing{0%,100%{transform:rotate(-25deg) translateY(0)}50%{transform:rotate(25deg) translateY(0)}}
@keyframes coilMove{0%,100%{transform:translateX(0)}50%{transform:translateX(55px)}}
@keyframes lcOscE{0%,100%{opacity:1;stroke-width:3}50%{opacity:.2;stroke-width:1}}
@keyframes lcOscB{0%,100%{opacity:.2;r:3}50%{opacity:1;r:5}}

.flow{stroke-dasharray:10 7;animation:flowR .7s linear infinite}
.flow-slow{stroke-dasharray:10 7;animation:flowR 1.4s linear infinite}
.flow-rev{stroke-dasharray:10 7;animation:flowL 1s linear infinite}
.needle{transform-origin:50% 88%;animation:needleSwing 2.5s ease-in-out infinite}
.coil-moving{animation:coilMove 2.8s ease-in-out infinite}

/* ── SCROLLBAR ── */
::-webkit-scrollbar{width:5px}
::-webkit-scrollbar-track{background:var(--bg)}
::-webkit-scrollbar-thumb{background:var(--border);border-radius:3px}

/* ── MAXWELL BLOCK ── */
.maxwell-grid{display:grid;grid-template-columns:1fr 1fr;gap:1rem;margin:1rem 0}
.maxwell-eq{
  background:var(--bg3);border:1px solid var(--border);
  border-radius:8px;padding:1rem;
  border-left:3px solid var(--accent);
}
.maxwell-eq .f{font-family:'JetBrains Mono',monospace;font-size:.95rem;color:var(--accent);margin-bottom:.5rem;display:block}
.maxwell-eq p{font-size:.82rem;color:var(--text2)}

/* ── TABLE ── */
.ftable{width:100%;border-collapse:collapse;font-size:.83rem}
.ftable th{text-align:left;padding:.6rem .8rem;color:var(--accent);font-family:'JetBrains Mono',monospace;font-size:.72rem;letter-spacing:.06em;border-bottom:1px solid var(--border);font-weight:600}
.ftable td{padding:.6rem .8rem;color:var(--text2);border-bottom:1px solid rgba(30,45,68,.6);font-family:'JetBrains Mono',monospace;font-size:.8rem}
.ftable tr:hover td{background:var(--bg3)}
.ftable td:first-child{color:var(--text)}
.ftable td:nth-child(2){color:var(--green)}