:root{
  --bg:#101214; --panel:#17191C; --panel2:#202328; --line:#2E3238; --text:#E8E6E1; --muted:#9AA0A6;
  --wire:#454B53; --on:#34D17A; --on-glow:rgba(34,197,94,.35); --amber:#F5B301; --red:#E5484D; --cyan:#F5B301;
  --mono:'JetBrains Mono',ui-monospace,Consolas,monospace;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;background:var(--bg);color:var(--text);font:15px/1.55 'Archivo',system-ui,Segoe UI,sans-serif}
code{font-family:var(--mono);font-size:.88em;background:#202328;padding:1px 5px;border-radius:4px;color:#E8E6E1}
a{color:var(--cyan)}
button{font:inherit;cursor:pointer}

.topbar{position:sticky;top:0;z-index:20;display:flex;align-items:center;justify-content:space-between;gap:16px;
  padding:10px 24px;background:rgba(236,233,225,.94);backdrop-filter:blur(8px);border-bottom:1px solid var(--line);flex-wrap:wrap}
.brand{font-weight:700;letter-spacing:.3px;display:flex;align-items:center;gap:10px}
.brand-dot{width:12px;height:12px;border-radius:50%;background:var(--on);box-shadow:0 0 10px var(--on)}
.topbar nav{display:flex;gap:4px;flex-wrap:wrap}
.topbar nav a{color:var(--muted);text-decoration:none;padding:6px 10px;border-radius:6px;font-size:14px}
.topbar nav a:hover{color:var(--text);background:var(--panel2)}

main{max-width:1320px;margin:0 auto;padding:0 16px}
.hero{padding:40px 0 8px}
.hero h1{font-size:clamp(26px,4vw,40px);margin:0 0 10px;line-height:1.15}
.hero p{color:var(--muted);max-width:780px;margin:0}
.section{padding:36px 0 12px}
.section-head h2{margin:0 0 6px;font-size:24px}
.section-head p{color:var(--muted);margin:0 0 18px;max-width:900px}

.panel{background:var(--panel);border:1px solid var(--line);border-radius:12px;padding:14px;min-width:0}
.panel-title{font-size:12px;text-transform:uppercase;letter-spacing:1px;color:var(--muted);margin-bottom:10px;font-weight:600}
.panel-title.small{margin:14px 0 8px}

/* ---- simulator layout ---- */
.sim-grid{display:grid;grid-template-columns:minmax(0,1fr) 320px;gap:14px}
.sim-grid2{display:grid;grid-template-columns:minmax(0,420px) minmax(0,1fr);gap:14px;margin-top:14px}
@media (max-width:1000px){.sim-grid,.sim-grid2{grid-template-columns:minmax(0,1fr)}}
.plant-panel{padding:8px}
#plant{width:100%;aspect-ratio:1000/460;display:block;border-radius:8px;background:#0c0e10;cursor:pointer}
.info-box{margin-top:8px;padding:10px 12px;background:var(--panel2);border-radius:8px;font-size:14px;color:#CFCFCB;min-height:48px}
.info-box h4{margin:0 0 4px;color:var(--text)}

.hmi{display:flex;flex-direction:column;gap:14px}
.hmi-title{font-weight:600}
.pb-row{display:flex;align-items:center;gap:12px;justify-content:space-between}
.pb{width:78px;height:78px;border-radius:50%;border:4px solid #0003;color:#fff;font-weight:700;font-size:13px;
  box-shadow:inset 0 -6px 0 #0004,0 4px 10px #0006;transition:transform .05s;user-select:none;touch-action:none}
.pb:active,.pb.pressed{transform:translateY(3px);box-shadow:inset 0 -2px 0 #0004,0 1px 4px #0006}
.pb-green{background:radial-gradient(circle at 35% 30%,#4ade80,#15803d)}
.pb-red{background:radial-gradient(circle at 35% 30%,#f87171,#991b1b)}
.estop{width:96px;height:96px;border-radius:50%;border:none;background:#facc15;display:grid;place-items:center;padding:0;
  box-shadow:0 4px 10px #0006}
.estop span{width:74px;height:74px;border-radius:50%;display:grid;place-items:center;color:#fff;font-weight:800;font-size:12px;
  background:radial-gradient(circle at 35% 30%,#f87171,#b91c1c);box-shadow:0 6px 0 #7a1519,0 8px 12px #0008;transition:.1s}
.estop.active span{box-shadow:0 1px 0 #7a1519,0 2px 4px #0008;transform:translateY(5px);background:radial-gradient(circle at 35% 30%,#E5484D,#7a1519)}

.ctl label{display:flex;justify-content:space-between;font-size:14px}
.ctl output{font-family:var(--mono);color:var(--cyan)}
.ctl small{display:block;color:var(--muted);font-size:12px;margin-top:4px}
input[type=range]{width:100%;accent-color:var(--cyan)}
.chk{display:flex;gap:8px;align-items:center;font-size:14px;cursor:pointer}
.add-parts{display:flex;flex-wrap:wrap;gap:6px;margin-top:8px}
.add-parts button,.btn-row button{background:var(--panel2);border:1px solid var(--line);color:var(--text);border-radius:6px;padding:5px 9px;font-size:13px}
.add-parts button:hover,.btn-row button:hover{border-color:var(--cyan)}
.btn-row{display:flex;gap:8px}
.counters{display:grid;grid-template-columns:repeat(3,1fr);gap:8px}
.counters div{background:#101214;border:1px solid var(--line);border-radius:8px;padding:8px;text-align:center}
.counters span{display:block;font-family:var(--mono);font-size:24px;color:var(--on)}
.counters span.err{color:var(--amber)}
.counters small{color:var(--muted);font-size:11px}
.faults summary{cursor:pointer;color:var(--amber);font-weight:600;font-size:14px}
.faults .chk{margin-top:8px}

/* ---- I/O table ---- */
.io-cols{display:grid;grid-template-columns:1fr 1fr;gap:10px}
@media (max-width:520px){.io-cols{grid-template-columns:1fr}}
table.io{width:100%;border-collapse:collapse;font-size:12.5px}
table.io th{text-align:left;color:var(--muted);font-weight:600;padding:3px 4px;border-bottom:1px solid var(--line)}
table.io td{padding:3px 4px;border-bottom:1px solid #22262b}
table.io td.addr{font-family:var(--mono);color:#D9D6CE;width:44px}
.led{display:inline-block;width:11px;height:11px;border-radius:50%;background:#2a2e34;border:1px solid #0006;vertical-align:middle}
.led.on{background:var(--on);box-shadow:0 0 8px var(--on)}
.led.on.o{background:var(--amber);box-shadow:0 0 8px var(--amber)}
.fifo{display:flex;gap:4px;min-height:34px;flex-wrap:wrap}
.fifo .slot{width:32px;height:32px;border-radius:6px;display:grid;place-items:center;font-family:var(--mono);font-weight:600;background:#101214;border:1px solid var(--line)}
.fifo .slot.m{background:#334155;color:#fff;border-color:#94a3b8}
.fifo .empty{color:var(--muted);font-size:13px;align-self:center}
.scan-stat{margin-top:12px;font-family:var(--mono);font-size:12px;color:var(--muted)}

/* ---- ladder ---- */
.ladder{max-height:680px;overflow:auto;padding-right:4px}
.rung{display:grid;grid-template-columns:30px minmax(0,1fr);gap:6px;margin-bottom:10px}
.rung-no{font-family:var(--mono);font-size:12px;color:var(--muted);padding-top:24px;text-align:right}
.rung-body{min-width:0}
.rung-cmt{font-size:12px;color:#9AA0A6;font-style:italic;margin-bottom:2px}
.rung-line{display:flex;align-items:stretch;border-left:3px solid var(--on);border-right:3px solid var(--wire);min-height:58px;overflow-x:auto}
.seq{display:flex;align-items:center;flex:1;min-width:max-content;background:linear-gradient(var(--wire),var(--wire)) left center/100% 2px no-repeat}
.seq>.fill,.brow>.fill{flex:1;min-width:12px;align-self:stretch}
.el{display:flex;flex-direction:column;align-items:center;padding:0 6px;background:var(--panel);font-family:var(--mono);font-size:11px;line-height:1.2;min-width:62px}
.el .nm{color:var(--muted);font-size:10px;white-space:nowrap}
.el .ad{color:#D9D6CE;white-space:nowrap}
.el svg{width:44px;height:22px;display:block;margin:2px 0}
.el svg .s{stroke:#9AA0A6;fill:none;stroke-width:2.5}
.el.on svg .s{stroke:var(--on);filter:drop-shadow(0 0 3px var(--on-glow))}
.el.on .ad{color:var(--on)}
.el svg text{fill:#9AA0A6;font:bold 11px var(--mono)}
.el.on svg text{fill:var(--on)}
.box{border:2px solid #9AA0A6;border-radius:4px;padding:3px 7px;font-family:var(--mono);font-size:11px;background:var(--panel);margin:4px 6px;min-width:96px;line-height:1.35}
.box b{display:block;color:var(--text);font-size:11.5px}
.box span{color:var(--muted);display:block;white-space:nowrap}
.box.on{border-color:var(--on);box-shadow:0 0 8px var(--on-glow)}
.box.on b{color:var(--on)}
.branch{display:flex;flex-direction:column;align-self:stretch;justify-content:center}
.brow{position:relative;display:flex;align-items:center;padding:0 10px;min-height:54px;
  background:linear-gradient(var(--wire),var(--wire)) left center/100% 2px no-repeat}
.brow::before,.brow::after{content:"";position:absolute;top:0;bottom:0;border-left:2px solid var(--wire)}
.brow::before{left:0}.brow::after{right:0}
.brow:first-child::before,.brow:first-child::after{top:50%}
.brow:last-child::before,.brow:last-child::after{bottom:50%}

/* ---- lab ---- */
.lab-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(min(100%,520px),1fr));gap:14px}
.lab-card h3{margin:2px 0 10px}
.lab-card p{color:#B9BBB8;font-size:14px;margin:10px 0 0}
.labcv{width:100%;height:auto;aspect-ratio:520/220;background:#0c0e10;border-radius:8px;display:block}
.lab-ctl{display:flex;gap:14px;flex-wrap:wrap;margin-top:10px}
.lab-ctl label{display:flex;flex-direction:column;gap:4px;font-size:13px;color:var(--muted);flex:1;min-width:150px}
.lab-ctl output{color:var(--cyan);font-family:var(--mono)}
select{background:var(--panel2);color:var(--text);border:1px solid var(--line);border-radius:6px;padding:6px;font:inherit;font-size:14px}
.readout{margin-top:10px;font-family:var(--mono);font-size:13px;background:#101214;border:1px solid var(--line);border-radius:8px;padding:8px 10px;color:#E8E6E1}
.readout .ok{color:var(--on)} .readout .off{color:var(--muted)} .readout .warn{color:var(--amber)}

/* ---- wiring ---- */
.wiring-ctl{display:flex;gap:12px;flex-wrap:wrap;align-items:center;margin-bottom:10px}
.seg{display:inline-flex;border:1px solid var(--line);border-radius:8px;overflow:hidden}
.seg button{background:var(--panel2);border:none;color:var(--muted);padding:8px 14px}
.seg button.active{background:var(--cyan);color:#141619;font-weight:600}
.toggle{background:var(--panel2);border:1px solid var(--line);color:var(--text);padding:8px 14px;border-radius:8px}
.toggle.on{border-color:var(--on);color:var(--on)}
#wiringSvg{width:100%;max-width:900px;display:block;margin:0 auto}

/* ---- equipment ---- */
.eq-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(min(100%,290px),1fr));gap:12px}
.eq{background:var(--panel);border:1px solid var(--line);border-radius:12px;padding:14px}
.eq .ico{width:44px;height:44px;border-radius:10px;background:var(--panel2);display:grid;place-items:center;margin-bottom:8px}
.eq .ico svg{width:28px;height:28px;stroke:var(--cyan);fill:none;stroke-width:1.8;stroke-linecap:round;stroke-linejoin:round}
.eq h4{margin:0 0 4px}
.eq .io-tag{font-family:var(--mono);font-size:11px;color:var(--amber)}
.eq p{margin:6px 0 0;color:#B9BBB8;font-size:14px}

/* ---- scan ---- */
.scan-panel{display:grid;grid-template-columns:340px 1fr;gap:20px;align-items:center}
@media (max-width:800px){.scan-panel{grid-template-columns:1fr}}
#scanSvg{width:100%;max-width:340px;margin:0 auto;display:block}
.scan-steps{margin:0;padding-left:20px}
.scan-steps li{margin-bottom:10px;color:#B9BBB8;padding:6px 8px;border-radius:8px;transition:background .15s}
.scan-steps li.act{background:rgba(245,179,1,.14);color:var(--text)}
.lang-panel{margin-top:14px;overflow-x:auto}
.lang-panel h3{margin:0 0 10px}
table.lang{border-collapse:collapse;width:100%;font-size:14px}
table.lang th,table.lang td{text-align:left;padding:7px 10px;border-bottom:1px solid var(--line)}
table.lang th{color:var(--muted);font-weight:600}
table.lang td:first-child{white-space:nowrap}

.foot{text-align:center;color:var(--muted);font-size:13px;padding:40px 16px}.rung-line.live{border-right-color:var(--on)}
.topbar nav a.nav-cta{color:#141619;background:var(--cyan);font-weight:600}
.cta{display:inline-block;margin-top:16px;background:var(--cyan);color:#141619;font-weight:700;padding:10px 16px;border-radius:10px;text-decoration:none}
.cta:hover{filter:brightness(1.1)}

/* ==== PLC Sim Lab design theme: paper + ink page, graphite machine panels, amber accent ==== */
:root{--paper:#ECE9E1;--paper2:#F6F4EE;--paper3:#E2DED3;--rule:#CFCABD;--ink:#141619;--ink2:#2c2f33;--ink3:#4A4E54;--gold:#8a6400;
  --sans:'Archivo',system-ui,Segoe UI,sans-serif}
h1,h2,h3,h4{font-family:var(--sans)}
.btn,.tool,button{font-family:var(--sans)}
/* home page: paper background, ink text; .panel keeps the dark graphite machine look */
body:not(.pg){background:var(--paper);color:var(--ink)}
body:not(.pg) a{color:var(--ink)}
body:not(.pg) a:hover{color:var(--gold)}
body:not(.pg) main>section>.section-head p,body:not(.pg) .hero p{color:var(--ink2)}
body:not(.pg) code{background:var(--paper3);color:var(--ink)}
.panel{color:var(--text)} .panel a{color:var(--cyan)}
.panel code{background:#202328;color:#E8E6E1}
.topbar{background:rgba(236,233,225,.94);border-bottom:1px solid var(--rule);padding:0 32px;height:64px;flex-wrap:nowrap}
.brand{font-weight:800;font-stretch:80%;font-size:20px;letter-spacing:-.01em;color:var(--ink)}
.topbar .brand-dot{width:30px;height:30px;border-radius:4px;background:var(--ink) radial-gradient(circle,#34D17A 0 4.5px,transparent 5.5px);box-shadow:none}
.topbar nav{gap:22px;align-items:center}
.topbar nav a{color:var(--ink3);padding:4px 0;border-radius:0;font-weight:500;border-bottom:2px solid transparent}
.topbar nav a:hover{color:var(--ink);background:none;border-bottom-color:#F5B301}
.topbar nav a.nav-cta{order:9;margin-left:12px;background:var(--ink);color:var(--paper);padding:10px 16px;border-radius:4px;border:none}
.topbar nav a.nav-cta:hover{background:#2a2e34;color:var(--paper)}
.topbar nav a.nav-cta::after{content:" \2192";color:#F5B301}
@media (max-width:900px){.topbar{height:auto;padding:10px 16px;flex-wrap:wrap}.topbar nav{gap:12px}}
main{max-width:1440px;padding:0 48px}
@media (max-width:700px){main{padding:0 16px}}
.hero{padding:72px 0 40px;border-bottom:1px solid var(--rule)}
.hero::before{content:"EDU";display:inline-block;font:700 12px var(--mono);letter-spacing:.1em;background:#F5B301;color:var(--ink);padding:3px 8px;border-radius:2px;margin-bottom:22px}
.hero h1{font-weight:850;font-stretch:72%;font-size:clamp(48px,8vw,104px);line-height:.9;letter-spacing:-.025em;max-width:1000px;margin:0 0 26px}
.hero p{font-size:19px;line-height:1.5;max-width:760px}
.cta{background:#F5B301;color:var(--ink)!important;border-radius:4px;padding:14px 20px;box-shadow:inset 0 -3px 0 rgba(0,0,0,.18);margin-top:26px}
.cta:hover{background:#ffc21a;filter:none}
body:not(.pg) .section{padding:72px 0 16px;border-top:1px solid var(--rule)}
body:not(.pg) .hero+.section{border-top:none}
.section-head{counter-increment:sec}
main{counter-reset:sec}
.section-head h2{font-weight:850;font-stretch:72%;font-size:clamp(36px,5vw,64px);line-height:.95;letter-spacing:-.02em;margin:0 0 14px;color:var(--ink)}
.section-head h2::before{content:counter(sec,decimal-leading-zero);display:block;font:700 18px var(--mono);color:var(--gold);margin-bottom:12px;letter-spacing:0}
.section-head p{font-size:16px;line-height:1.55;margin-bottom:28px}
.panel{background:#17191C;border:1px solid #2E3238;border-radius:10px;box-shadow:0 20px 50px -24px rgba(20,22,25,.5)}
.panel-title{font:400 11px var(--mono);letter-spacing:.1em;color:#9AA0A6}
/* light cards (sensor lab, equipment, languages): paper surface, dark visual stage */
.lab-card,.eq,.lang-panel{--panel:var(--paper2);--panel2:#fff;--line:var(--rule);--text:var(--ink);--muted:var(--ink3);--cyan:var(--gold);
  background:var(--paper2);border-color:var(--rule);color:var(--ink);box-shadow:none}
.lab-card h3{font-size:20px;font-weight:800;font-stretch:85%}
.lab-card p,.eq p{color:var(--ink2)}
.lab-card code,.lang-panel code{background:var(--paper3);color:var(--ink)}
.lab-card select{background:#fff;color:var(--ink);border-color:var(--rule)}
.eq-grid{gap:0;border-top:1px solid var(--ink);border-left:1px solid var(--rule)}
.eq{border-radius:0;border-width:0 1px 1px 0;border-style:solid}
.eq:hover{background:#F9F7F2}
.eq h4{font-weight:800;font-size:17px;font-stretch:88%}
.eq .ico{background:var(--ink)} .eq .ico svg{stroke:#F5B301}
.eq .io-tag{color:var(--gold);font-weight:700}
.seg{border-color:var(--rule);background:var(--paper3);padding:3px;border-radius:5px;gap:2px}
.seg button{background:none;color:var(--ink);border-radius:3px}
.seg button.active{background:var(--ink);color:var(--paper)}
.toggle{background:#fff;border-color:var(--rule);color:var(--ink)}
.toggle.on{border-color:#1f7a47;color:#1f7a47}
.pb-green{background:radial-gradient(circle at 35% 30%,#3fbf78,#1f7a47)}
.pb-red{background:radial-gradient(circle at 35% 30%,#ff6b6f,#b3262b)}
.estop{background:#F5B301}
input[type=range]{accent-color:#F5B301}
.lab-card input[type=range]{accent-color:var(--ink)}
.foot{background:var(--ink);color:#9AA0A6;margin-top:48px;text-align:left;padding:24px 48px}

/* ---- ad spaces: height is reserved so the page never jumps when an ad loads; removed when ads are off ---- */
.ad-slot{display:block;min-height:120px;margin:40px 0 8px;padding-top:18px;position:relative;border-top:1px solid var(--rule)}
.ad-slot::before{content:"ADVERTISEMENT";position:absolute;top:4px;left:0;font:600 9.5px var(--mono);letter-spacing:.12em;color:var(--ink3)}
body .foot a{color:#ECE9E1;text-decoration:underline;text-underline-offset:3px;text-decoration-color:#F5B301}
body .foot a:hover{color:#F5B301}

/* ---- FAQ ---- */
.faq{border-top:1px solid var(--ink);max-width:980px}
.faq-item{border-bottom:1px solid var(--rule)}
.faq-item summary{list-style:none;cursor:pointer;display:flex;justify-content:space-between;align-items:center;gap:16px;padding:18px 4px;font-weight:700;font-size:18px;font-stretch:92%}
.faq-item summary::-webkit-details-marker{display:none}
.faq-item summary::after{content:"+";flex:none;width:28px;height:28px;display:grid;place-items:center;border-radius:4px;background:var(--paper3);font:700 18px var(--mono);color:var(--ink)}
.faq-item[open] summary::after{content:"\2212";background:#F5B301}
.faq-item summary:hover{color:var(--gold)}
.faq-item p{margin:0 0 20px;padding:0 48px 0 4px;font-size:15.5px;line-height:1.6;color:var(--ink2);max-width:820px}