/* =========================================================
   CSS VARIABLES
   ========================================================= */
:root {
  --bg:         hsl(222,47%,6%);
  --fg:         hsl(210,20%,95%);
  --card:       hsl(222,40%,9%);
  --card-fg:    hsl(210,20%,95%);
  --primary:    hsl(192,91%,42%);
  --primary-fg: #fff;
  --secondary:  hsl(222,30%,16%);
  --muted:      hsl(222,30%,16%);
  --muted-fg:   hsl(215,16%,57%);
  --accent:     hsl(222,30%,16%);
  --accent-fg:  hsl(192,91%,56%);
  --border:     hsl(222,25%,18%);
  --destructive:hsl(0,62.8%,40%);
  --radius:     0.625rem;
  --cyan:       #22d3ee;
  --teal:       #4ecdc4;
  --amber:      #f59e0b;
  --blue:       #3b82f6;
  --orange:     #f97316;
  --green:      #22c55e;
  --red:        #ef4444;
  --purple:     #a855f7;
  --copper:     #cd7f32;
}
.light {
  --bg:         hsl(210,20%,98%);
  --fg:         hsl(222,47%,11%);
  --card:       #fff;
  --card-fg:    hsl(222,47%,11%);
  --primary:    hsl(192,91%,36%);
  --primary-fg: #fff;
  --secondary:  hsl(210,16%,93%);
  --muted:      hsl(210,16%,93%);
  --muted-fg:   hsl(215,16%,47%);
  --accent:     hsl(192,91%,95%);
  --accent-fg:  hsl(192,91%,26%);
  --border:     hsl(214,20%,88%);
  --destructive:hsl(0,84.2%,60.2%);
}

/* =========================================================
   RESET & BASE
   ========================================================= */
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0;border-color:var(--border)}
html{scroll-behavior:smooth;font-size:16px}
body{background:var(--bg);color:var(--fg);font-family:ui-sans-serif,system-ui,-apple-system,sans-serif;-webkit-font-smoothing:antialiased;line-height:1.6;min-height:100vh}
a{color:var(--primary);text-decoration:none}
a:hover{text-decoration:underline}
img{max-width:100%;height:auto;display:block}
pre{overflow-x:auto}
table{border-collapse:collapse;width:100%}
button{cursor:pointer;font-family:inherit;background:none;border:none;color:inherit}
input[type=range]{width:100%;cursor:pointer;accent-color:var(--primary)}

/* =========================================================
   SCROLLBAR
   ========================================================= */
::-webkit-scrollbar{width:6px;height:6px}
::-webkit-scrollbar-track{background:transparent}
::-webkit-scrollbar-thumb{background:var(--border);border-radius:9999px}

/* =========================================================
   LAYOUT UTILITIES
   ========================================================= */
.container{max-width:1280px;margin:0 auto;padding:0 1.5rem}
.flex{display:flex}.flex-col{flex-direction:column}.flex-wrap{flex-wrap:wrap}
.items-center{align-items:center}.items-start{align-items:flex-start}
.justify-between{justify-content:space-between}.justify-center{justify-content:center}
.gap-1{gap:.25rem}.gap-2{gap:.5rem}.gap-3{gap:.75rem}.gap-4{gap:1rem}
.gap-6{gap:1.5rem}.gap-8{gap:2rem}
.grid{display:grid}.grid-2{grid-template-columns:repeat(2,1fr)}.grid-3{grid-template-columns:repeat(3,1fr)}.grid-4{grid-template-columns:repeat(4,1fr)}
@media(max-width:900px){.grid-4{grid-template-columns:repeat(2,1fr)}.grid-3{grid-template-columns:repeat(2,1fr)}}
@media(max-width:640px){.grid-2,.grid-3,.grid-4{grid-template-columns:1fr}}
.w-full{width:100%}
.h-full{height:100%}
.overflow-hidden{overflow:hidden}
.overflow-x-auto{overflow-x:auto}
.relative{position:relative}
.text-center{text-align:center}
.text-left{text-align:left}
.hidden{display:none}
.block{display:block}

/* =========================================================
   TYPOGRAPHY
   ========================================================= */
.font-display{font-family:ui-serif,Georgia,serif}
.font-mono{font-family:ui-monospace,monospace}
h1{font-size:clamp(2rem,5vw,3.5rem);line-height:1.1;font-weight:800;letter-spacing:-.03em}
h2{font-size:clamp(1.6rem,3vw,2.2rem);line-height:1.2;font-weight:700;letter-spacing:-.02em}
h3{font-size:1.4rem;font-weight:700;letter-spacing:-.01em}
h4{font-size:1.1rem;font-weight:600}
.text-sm{font-size:.875rem}.text-xs{font-size:.75rem}.text-lg{font-size:1.125rem}.text-xl{font-size:1.25rem}
.font-bold{font-weight:700}.font-semibold{font-weight:600}.font-medium{font-weight:500}
.text-primary{color:var(--primary)}
.text-muted{color:var(--muted-fg)}
.text-destructive{color:var(--destructive)}
.text-cyan{color:var(--cyan)}
.text-amber{color:var(--amber)}
.text-blue{color:var(--blue)}
.text-orange{color:var(--orange)}
.text-green{color:var(--green)}
.text-red{color:var(--red)}
.text-purple{color:var(--purple)}
.leading-relaxed{line-height:1.7}

/* =========================================================
   COMPONENTS
   ========================================================= */
/* Card */
.card{background:var(--card);color:var(--card-fg);border:1px solid var(--border);border-radius:var(--radius);box-shadow:0 1px 3px rgba(0,0,0,.15)}
.card-content{padding:1.5rem}
.card-content-sm{padding:1rem}
.card-header{padding:1.5rem 1.5rem .5rem}
.card-title{font-size:1.1rem;font-weight:600}

/* Badge */
.badge{display:inline-flex;align-items:center;gap:.375rem;padding:.375rem .875rem;border-radius:9999px;font-size:.75rem;font-weight:600;border:1px solid var(--border);background:transparent;color:var(--muted-fg)}
.badge-primary{background:var(--primary);color:var(--primary-fg);border-color:var(--primary)}
.badge-secondary{background:var(--secondary);color:var(--fg);border-color:var(--secondary)}

/* Button */
.btn{display:inline-flex;align-items:center;gap:.5rem;padding:.5rem 1rem;border-radius:var(--radius);font-size:.875rem;font-weight:500;transition:opacity .15s,background .15s;border:1px solid transparent}
.btn-primary{background:var(--primary);color:var(--primary-fg)}
.btn-primary:hover{opacity:.9}
.btn-ghost{background:transparent;border-color:var(--border)}
.btn-ghost:hover{background:var(--accent)}
.btn-icon{padding:.5rem;border-radius:var(--radius)}

/* Section divider */
.section-divider{padding:2rem 0}.section-divider hr{border:none;border-top:1px solid rgba(255,255,255,.07)}

/* Stat cards */
.stat-card{text-align:center;padding:1.5rem;background:var(--card);border:1px solid var(--border);border-radius:var(--radius)}
.stat-value{font-size:2.25rem;font-weight:800;color:var(--primary);font-family:ui-monospace,monospace;line-height:1}
.stat-label{font-size:.8rem;color:var(--muted-fg);margin-top:.5rem}

/* Hero gradient bg */
.hero-gradient{background:radial-gradient(ellipse 60% 50% at 50% -10%,hsl(192 91% 42% / .2),transparent),radial-gradient(ellipse 40% 40% at 80% 0%,hsl(200 80% 40% / .12),transparent),radial-gradient(ellipse 40% 30% at 20% 10%,hsl(210 80% 50% / .08),transparent)}

/* Code blocks */
.code-block{background:var(--muted);border-radius:var(--radius);padding:1rem;font-size:.8rem;font-family:ui-monospace,monospace;color:var(--muted-fg)}
.code-result{background:rgba(34,211,238,.07);border-radius:var(--radius);padding:.75rem;font-family:ui-monospace,monospace;font-size:.8rem}

/* =========================================================
   HEADER
   ========================================================= */
#site-header{position:sticky;top:0;z-index:50;width:100%;border-bottom:1px solid rgba(255,255,255,.08);background:rgba(10,14,26,.85);backdrop-filter:blur(16px);-webkit-backdrop-filter:blur(16px)}
.header-inner{display:flex;align-items:center;justify-content:space-between;height:4rem}
.logo{display:flex;align-items:center;gap:.5rem;font-weight:700;font-size:1.05rem;font-family:ui-serif,Georgia,serif;cursor:pointer}
.logo-icon{display:flex;align-items:center;justify-content:center;width:2rem;height:2rem;border-radius:.5rem;background:var(--primary);color:#fff;flex-shrink:0}
.nav-desktop{display:flex;align-items:center;gap:.25rem}
@media(max-width:900px){.nav-desktop{display:none}}
.nav-link{display:flex;align-items:center;gap:.375rem;padding:.5rem .75rem;border-radius:.5rem;font-size:.85rem;font-weight:500;color:var(--muted-fg);transition:background .15s,color .15s;cursor:pointer}
.nav-link:hover{background:var(--accent);color:var(--fg)}
.nav-link.active{background:rgba(34,211,238,.1);color:var(--primary)}
.header-actions{display:flex;align-items:center;gap:.5rem}
#theme-toggle{padding:.5rem;border-radius:.5rem;color:var(--muted-fg);transition:background .15s}
#theme-toggle:hover{background:var(--accent)}
#menu-toggle{display:none;padding:.5rem;border-radius:.5rem;color:var(--muted-fg)}
@media(max-width:900px){#menu-toggle{display:flex;align-items:center;justify-content:center}}
#mobile-nav{display:none;padding:1rem 0;border-top:1px solid rgba(255,255,255,.06)}
#mobile-nav.open{display:block}
.mobile-nav-link{display:flex;align-items:center;gap:.5rem;padding:.625rem .75rem;border-radius:.5rem;font-size:.9rem;font-weight:500;color:var(--muted-fg);width:100%;cursor:pointer;transition:background .15s,color .15s}
.mobile-nav-link:hover,.mobile-nav-link.active{background:var(--accent);color:var(--primary)}

/* =========================================================
   MAIN SECTIONS
   ========================================================= */
section{scroll-margin-top:4.5rem}
.section-badge{margin-bottom:1.5rem}
.section-intro{max-width:48rem;margin-bottom:3rem}
.section-intro p{font-size:1.1rem;color:var(--muted-fg);line-height:1.7;margin-top:.75rem}

/* =========================================================
   HERO IMAGE
   ========================================================= */
.hero-image-wrapper{position:relative;border-radius:calc(var(--radius) * 2);overflow:hidden;background:var(--muted);box-shadow:0 10px 40px rgba(0,0,0,.3);max-width:56rem;margin:0 auto 4rem}
.hero-image-wrapper img{width:100%;height:auto;display:block;aspect-ratio:16/9;object-fit:cover}

/* =========================================================
   FLOW DIAGRAM (simplified)
   ========================================================= */
.flow-diagram-wrapper{background:var(--card);border:1px solid var(--border);border-radius:calc(var(--radius)*2);padding:1.5rem;margin-bottom:3rem}
.flow-diagram-wrapper svg{width:100%;height:auto}

/* =========================================================
   TABS
   ========================================================= */
.tabs-list{display:flex;flex-wrap:wrap;gap:.25rem;margin-bottom:1.5rem;background:var(--muted);padding:.25rem;border-radius:.625rem}
.tab-btn{padding:.4rem .8rem;border-radius:.45rem;font-size:.82rem;font-weight:500;color:var(--muted-fg);transition:background .15s,color .15s;white-space:nowrap}
.tab-btn:hover{background:var(--accent);color:var(--fg)}
.tab-btn.active{background:var(--card);color:var(--fg);box-shadow:0 1px 3px rgba(0,0,0,.2)}
.tab-panel{display:none}
.tab-panel.active{display:block}

/* =========================================================
   ACCORDION
   ========================================================= */
.accordion-item{border-bottom:1px solid var(--border)}
.accordion-trigger{display:flex;align-items:center;justify-content:space-between;width:100%;padding:.875rem 0;font-weight:600;font-size:.95rem;cursor:pointer;text-align:left;gap:.5rem;font-family:ui-serif,Georgia,serif}
.accordion-trigger svg.chevron{transition:transform .25s;flex-shrink:0}
.accordion-item.open .accordion-trigger svg.chevron{transform:rotate(180deg)}
.accordion-content{display:none;padding:.5rem 0 1rem 1rem;font-size:.875rem;color:var(--muted-fg);line-height:1.7}
.accordion-item.open .accordion-content{display:block}

/* =========================================================
   SPEC CARD GRID
   ========================================================= */
.spec-card{background:var(--card);border:1px solid var(--border);border-radius:var(--radius);padding:1rem;transition:box-shadow .2s,transform .2s}
.spec-card:hover{box-shadow:0 4px 20px rgba(0,0,0,.2);transform:translateY(-2px)}
.spec-icon{display:flex;align-items:center;gap:.5rem;margin-bottom:.5rem;font-size:.75rem;color:var(--muted-fg)}
.spec-value{font-family:ui-monospace,monospace;font-size:.82rem;font-weight:700}

/* =========================================================
   COMPARISON TABLE
   ========================================================= */
.comp-table thead tr{border-bottom:1px solid var(--border)}
.comp-table th,.comp-table td{padding:.875rem 1rem;text-align:left}
.comp-table th{font-weight:600;font-size:.85rem;color:var(--muted-fg)}
.comp-table tbody tr{border-bottom:1px solid rgba(255,255,255,.05);transition:background .1s}
.comp-table tbody tr:hover{background:rgba(255,255,255,.03)}
.comp-table td{font-size:.85rem}
.comp-table td.mono{font-family:ui-monospace,monospace;font-size:.8rem}
.comp-table td.primary{color:var(--primary);font-family:ui-monospace,monospace;font-size:.8rem}

/* =========================================================
   SAFETY LAYER CARDS
   ========================================================= */
.safety-card{background:var(--card);border:1px solid var(--border);border-radius:var(--radius);padding:1.5rem;transition:box-shadow .2s,transform .2s;height:100%}
.safety-card:hover{box-shadow:0 4px 20px rgba(0,0,0,.2);transform:translateY(-2px)}

/* =========================================================
   OPERATING MODES TABLE
   ========================================================= */
.mode-row{padding:.75rem;border-radius:.5rem;background:rgba(255,255,255,.04);margin-bottom:.5rem}
.mode-header{display:flex;align-items:center;justify-content:space-between;margin-bottom:.25rem;flex-wrap:wrap;gap:.25rem}
.mode-name{font-size:.9rem;font-weight:600}
.mode-ratios{display:flex;gap:.75rem;font-size:.75rem;font-family:ui-monospace,monospace}
.mode-note{font-size:.75rem;color:var(--muted-fg)}

/* =========================================================
   CODE PSEUDOCODE
   ========================================================= */
.pseudo-code{background:var(--muted);border-radius:var(--radius);padding:1rem;font-family:ui-monospace,monospace;font-size:.78rem;color:var(--muted-fg);line-height:1.6;white-space:pre-wrap;word-break:break-word}

/* =========================================================
   INTERLOCK ITEMS
   ========================================================= */
.interlock-item{display:flex;align-items:flex-start;gap:.5rem;padding:.625rem .75rem;border-radius:.5rem;background:rgba(239,68,68,.06);font-size:.85rem;color:var(--muted-fg)}

/* =========================================================
   CHART — CSS bar chart
   ========================================================= */
.bar-chart{margin-top:.5rem}
.bar-row{display:flex;align-items:center;gap:.75rem;margin-bottom:.75rem;font-size:.8rem}
.bar-label{width:160px;flex-shrink:0;color:var(--muted-fg);text-align:right;font-size:.78rem}
.bar-track{flex:1;background:var(--muted);border-radius:9999px;height:10px;overflow:hidden;position:relative}
.bar-fill{height:100%;border-radius:9999px;transition:width 1s ease;background:var(--primary)}
.bar-value{width:60px;flex-shrink:0;font-family:ui-monospace,monospace;font-size:.75rem;color:var(--fg)}

@media(max-width:640px){.bar-label{width:100px}}

/* =========================================================
   H2 PRODUCTION TABLE
   ========================================================= */
.production-table{width:100%}
.production-table thead th{font-size:.78rem;font-weight:600;color:var(--muted-fg);padding:.5rem .75rem;text-align:left;border-bottom:1px solid var(--border)}
.production-table tbody td{padding:.5rem .75rem;font-size:.8rem;font-family:ui-monospace,monospace;border-bottom:1px solid rgba(255,255,255,.04)}
.production-table tbody tr:hover{background:rgba(255,255,255,.03)}

/* =========================================================
   SLIDER CALCULATOR
   ========================================================= */
.calc-result-row{display:flex;align-items:center;justify-content:space-between;padding:.75rem;border-radius:.5rem;background:rgba(255,255,255,.04);margin-bottom:.5rem}
.calc-result-label{font-size:.875rem;display:flex;align-items:center;gap:.5rem}
.calc-result-value{font-family:ui-monospace,monospace;font-size:.875rem;font-weight:700;color:var(--primary)}

/* =========================================================
   WATER RECOVERY TABLE
   ========================================================= */
.recovery-row{display:flex;justify-content:space-between;padding:.5rem 0;border-bottom:1px solid rgba(255,255,255,.06);font-size:.85rem}
.recovery-row:last-child{border-bottom:none}
.recovery-val{font-family:ui-monospace,monospace;font-weight:700;color:var(--blue)}

/* =========================================================
   TOOLTIP (TechTerm)
   ========================================================= */
.tech-term{color:var(--primary);cursor:help;border-bottom:1px dotted var(--primary);font-size:inherit}
.tech-term[title]{position:relative}

/* =========================================================
   PROPERTY GRID
   ========================================================= */
.prop-row{display:flex;justify-content:space-between;align-items:center;padding:.75rem;border-radius:.5rem;background:rgba(255,255,255,.04);margin-bottom:.375rem}
.prop-label{font-size:.85rem;color:var(--muted-fg)}
.prop-value{font-family:ui-monospace,monospace;font-size:.82rem;font-weight:700}

/* =========================================================
   SVG DIAGRAM BACKGROUNDS
   ========================================================= */
.diagram-bg{background:#0a0f1e;border-radius:calc(var(--radius)*2);padding:1rem;margin-bottom:3rem;max-width:56rem}
.diagram-bg-full{background:#0a0f1e;border-radius:calc(var(--radius)*2);padding:1rem;margin-bottom:3rem}

/* =========================================================
   HERO STATS
   ========================================================= */
.stats-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:1.5rem;max-width:48rem;margin:0 auto 4rem}
@media(max-width:640px){.stats-grid{grid-template-columns:repeat(2,1fr)}}

/* =========================================================
   WARN BOX
   ========================================================= */
.warn-box{display:flex;align-items:flex-start;gap:.75rem;padding:.875rem 1rem;border-radius:.5rem;background:rgba(239,68,68,.08);border:1px solid rgba(239,68,68,.2);margin-bottom:1.5rem}
.info-box{display:flex;align-items:flex-start;gap:.75rem;padding:.875rem 1rem;border-radius:.5rem;background:rgba(59,130,246,.08);border:1px solid rgba(59,130,246,.2);margin-bottom:1.5rem}

/* =========================================================
   FOOTER
   ========================================================= */
#site-footer{border-top:1px solid var(--border);background:rgba(0,0,0,.2)}
.footer-inner{display:flex;flex-direction:column;align-items:center;justify-content:space-between;gap:1rem;padding:2rem 0}
@media(min-width:640px){.footer-inner{flex-direction:row}}
.footer-inner span{font-size:.875rem;color:var(--muted-fg)}

/* =========================================================
   HOW-IT-WORKS CARDS
   ========================================================= */
.hiw-step{background:var(--card);border:1px solid var(--border);border-radius:var(--radius);padding:1.5rem;transition:box-shadow .2s,transform .2s}
.hiw-step:hover{box-shadow:0 4px 20px rgba(0,0,0,.2);transform:translateY(-2px)}
.hiw-icon-row{display:flex;align-items:center;gap:.75rem;margin-bottom:1rem}
.hiw-icon{width:2.5rem;height:2.5rem;border-radius:.5rem;background:rgba(34,211,238,.1);display:flex;align-items:center;justify-content:center;flex-shrink:0}

/* =========================================================
   SECTION PADDING
   ========================================================= */
.pt-hero{padding-top:5rem}
.pb-section{padding-bottom:4rem}

/* =========================================================
   SENSOR / ACTUATOR CARDS
   ========================================================= */
.sensor-card{background:var(--card);border:1px solid var(--border);border-radius:var(--radius);padding:1rem;height:100%;transition:box-shadow .15s,transform .15s}
.sensor-card:hover{box-shadow:0 4px 16px rgba(0,0,0,.2);transform:translateY(-2px)}
.sensor-title{font-size:.875rem;font-weight:600;margin-bottom:.25rem}
.sensor-purpose{font-size:.75rem;color:var(--muted-fg);line-height:1.5}

/* =========================================================
   THEME TOGGLE ICON
   ========================================================= */
.icon-sun,.icon-moon{width:1.1rem;height:1.1rem;fill:none;stroke:currentColor;stroke-width:2;stroke-linecap:round;stroke-linejoin:round}
.dark .icon-sun{display:block}
.dark .icon-moon{display:none}
.light .icon-sun{display:none}
.light .icon-moon{display:block}