/* Student portal: one narrow reading column, phone first; follows the device's light or dark setting. */
:root{--bg:#f3f7f9;--card:#ffffff;--ink:#14232e;--muted:#5a6f80;--line:#d6e2e9;--accent:#066b79;--accent-ink:#ffffff;--soft:#dff0f1;--ok:#13683b;--ok-soft:#dcf3e5;--warn:#8a5a00;--warn-soft:#fbf0d9;color-scheme:light}
@media (prefers-color-scheme:dark){:root{--bg:#0d151b;--card:#152129;--ink:#e4eef3;--muted:#9bb1c0;--line:#2a3c49;--accent:#6cdce2;--accent-ink:#06222e;--soft:#12363b;--ok:#7fe0a7;--ok-soft:#173b28;--warn:#f0c46a;--warn-soft:#3a2d12;color-scheme:dark}}
*{box-sizing:border-box}
[hidden]{display:none!important}
body{margin:0;background:var(--bg);color:var(--ink);font:16px/1.5 system-ui,-apple-system,'Segoe UI',Roboto,sans-serif}
a{color:var(--accent)}
button,input{font:inherit}
.pt-top{position:sticky;top:0;z-index:5;display:flex;align-items:center;justify-content:space-between;gap:12px;padding:calc(10px + env(safe-area-inset-top,0px)) 16px 10px;background:var(--card);border-bottom:1px solid var(--line)}
.pt-home{display:flex;align-items:center;gap:10px;text-decoration:none;color:var(--ink)}
.pt-home img{width:96px;height:auto;box-sizing:content-box;padding:6px 10px;border-radius:8px;background:#0d151b}
.pt-home span{font-size:12px;font-weight:800;letter-spacing:.14em;color:var(--accent)}
main{max-width:760px;margin:0 auto;padding:20px 16px calc(40px + env(safe-area-inset-bottom,0px));display:grid;gap:16px;outline:none}
main>*{min-width:0}
h1{font-size:clamp(24px,6vw,32px);line-height:1.15;margin:0;text-wrap:balance}
h2{font-size:20px;line-height:1.2;margin:0}
h3{font-size:16px;margin:0}
p{margin:0}
.pt-muted{color:var(--muted)}
.pt-card{background:var(--card);border:1px solid var(--line);border-radius:14px;padding:18px;display:grid;gap:12px}
.pt-form{display:grid;gap:14px}
.pt-form label{display:grid;gap:6px;font-weight:600;font-size:14px}
.pt-form input{width:100%;padding:12px 14px;border-radius:10px;border:1px solid var(--line);background:var(--bg);color:var(--ink);min-height:48px}
.pt-btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;min-height:46px;padding:10px 18px;border-radius:10px;border:0;background:var(--accent);color:var(--accent-ink);font-weight:700;cursor:pointer;text-decoration:none}
.pt-btn.secondary{background:var(--soft);color:var(--ink)}
.pt-btn[disabled]{opacity:.6;cursor:wait}
.pt-link{background:none;border:0;color:var(--accent);font-weight:700;cursor:pointer;padding:8px}
:is(.pt-btn,.pt-link,input,a):focus-visible{outline:3px solid var(--accent);outline-offset:2px}
.pt-error{color:#c0392b;font-weight:600;min-height:1.2em}
@media (prefers-color-scheme:dark){.pt-error{color:#ff8a7a}}
.pt-tag{font-size:12px;font-weight:800;letter-spacing:.08em;text-transform:uppercase;color:var(--accent)}
.pt-progress{display:grid;gap:6px}
.pt-bar{height:10px;border-radius:99px;background:var(--soft);overflow:hidden}
.pt-bar>i{display:block;height:100%;width:0;background:var(--accent);border-radius:99px;transition:width .4s ease}
.pt-alert{padding:12px 14px;border-radius:10px;background:var(--warn-soft);color:var(--warn);font-weight:600}
.pt-okbox{padding:12px 14px;border-radius:10px;background:var(--ok-soft);color:var(--ok);font-weight:600}
.pt-module{display:grid;gap:8px}
.pt-module>p{font-size:14px}
.pt-class{display:flex;align-items:center;gap:12px;width:100%;text-align:left;padding:12px 14px;border:1px solid var(--line);border-radius:12px;background:var(--card);color:var(--ink);cursor:pointer;min-height:56px}
.pt-class:hover{border-color:var(--accent)}
.pt-check{flex:none;width:26px;height:26px;border-radius:50%;border:2px solid var(--line);display:grid;place-items:center;font-size:14px;font-weight:800}
.pt-class.done .pt-check{background:var(--ok);border-color:var(--ok);color:var(--card)}
.pt-class span:last-child{min-width:0}
.pt-class small{display:block;color:var(--muted)}
.pt-video{position:relative;aspect-ratio:var(--ratio,16/9);width:100%;max-width:100%;border-radius:12px;overflow:hidden;background:#000}
/* Vertical videos: as tall as the screen allows, centered, with their own width. */
.pt-video.vertical{width:min(100%,calc(78vh * var(--ratio)));margin-inline:auto}
.pt-video iframe{position:absolute;inset:0;width:100%;height:100%;border:0}
.pt-novideo{aspect-ratio:16/9;display:grid;place-items:center;text-align:center;padding:20px;border-radius:12px;background:var(--soft);color:var(--muted)}
.pt-actions{display:flex;flex-wrap:wrap;gap:10px}
.pt-list{margin:0;padding-left:20px;display:grid;gap:4px}
.pt-back{justify-self:start}
/* Home: "continue where you left off" card with the video thumbnail */
.pt-continue{display:flex;align-items:center;gap:16px;padding:14px;border-radius:16px;background:var(--card);border:1px solid var(--line);color:var(--ink);text-decoration:none;box-shadow:0 8px 24px #0000001a}
.pt-continue:hover{border-color:var(--accent)}
.pt-thumb{position:relative;flex:none;width:132px;aspect-ratio:16/10;border-radius:10px;overflow:hidden;background:var(--soft);display:grid;place-items:center}
.pt-thumb img{position:absolute;inset:0;width:100%;height:100%;object-fit:cover}
.pt-thumb>span{position:relative;z-index:1;width:40px;height:40px;border-radius:50%;display:grid;place-items:center;background:var(--accent);color:var(--accent-ink);font-size:16px;box-shadow:0 4px 12px #0006}
.pt-continue-text{display:grid;gap:4px;min-width:0}
.pt-continue-text b{font-size:18px;line-height:1.25}
.pt-install{display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:12px}
.pt-help{justify-self:start;display:inline-flex;align-items:center;gap:8px;padding:10px 16px;border-radius:99px;border:1px solid var(--line);background:var(--card);color:var(--ink);font-weight:700;text-decoration:none}
.pt-help:hover{border-color:var(--accent)}
/* Lesson: video and tabs, with the course outline beside it on wide screens */
main.pt-wide{max-width:1180px}
.pt-lesson-main{display:grid;gap:14px;min-width:0;align-content:start}
.pt-outline details{background:var(--card);border:1px solid var(--line);border-radius:14px;padding:6px 14px 14px}
.pt-outline summary{display:flex;justify-content:space-between;align-items:baseline;gap:10px;padding:10px 0;cursor:pointer}
.pt-outline .pt-module{margin-top:12px}
.pt-outline .pt-module h3{font-size:13px;color:var(--muted);text-transform:uppercase;letter-spacing:.05em}
.pt-outline .pt-class{min-height:48px;padding:9px 10px}
.pt-outline-full{display:grid;gap:16px}
.pt-class.current{border-color:var(--accent);background:var(--soft)}
.pt-lesson-nav{align-items:center}
.pt-tabs{display:flex;gap:4px;overflow-x:auto;border-bottom:1px solid var(--line);scrollbar-width:none}
.pt-tabs button{flex:none;background:none;border:0;border-bottom:3px solid transparent;color:var(--muted);font-weight:700;padding:10px 12px;cursor:pointer;min-height:44px}
.pt-tabs button[aria-selected=true]{color:var(--ink);border-bottom-color:var(--accent)}
.pt-tabpanel{display:grid;gap:10px;line-height:1.6}
@media (min-width:960px){
 main.pt-lesson{grid-template-columns:minmax(0,1fr) 340px;align-items:start;column-gap:28px}
 .pt-outline{position:sticky;top:76px;max-height:calc(100vh - 96px);overflow:auto}
}
@media (max-width:520px){.pt-thumb{width:96px}.pt-continue-text b{font-size:16px}}
/* Visual guide under each video */
.pt-guide{display:grid;gap:14px;padding:18px;border-radius:16px;background:var(--card);border:1px solid var(--line)}
.pt-diagram{margin:0;display:grid;gap:8px;justify-items:center}
.pt-diagram svg{display:block;width:100%;max-width:520px;height:auto;font-family:inherit}
.pt-diagram figcaption{font-size:13px;font-weight:700;color:var(--accent);text-align:center}
.pt-guide-cols{display:grid;gap:12px;grid-template-columns:repeat(auto-fit,minmax(240px,1fr))}
.pt-tips{padding:14px;border-radius:12px;display:grid;gap:8px;align-content:start}
.pt-tips h3{display:flex;align-items:center;gap:8px}
.pt-tips h3 span{display:grid;place-items:center;width:22px;height:22px;border-radius:50%;font-size:13px}
.pt-tips ul{margin:0;padding-left:18px;display:grid;gap:6px;line-height:1.45}
.pt-tips.ok{background:var(--ok-soft)}.pt-tips.ok h3 span{background:var(--ok);color:var(--card)}
.pt-tips.warn{background:var(--warn-soft)}.pt-tips.warn h3 span{background:var(--warn);color:var(--card)}
.pt-network{display:grid;gap:10px;padding:14px;border-radius:12px;border:1px dashed var(--accent)}
.pt-net-inputs{display:grid;gap:10px;grid-template-columns:repeat(auto-fit,minmax(200px,1fr))}
.pt-net-inputs label{display:grid;gap:4px;font-weight:600;font-size:14px}
.pt-net-inputs small{font-weight:400;color:var(--muted)}
.pt-net-inputs input{padding:10px 12px;border-radius:10px;border:1px solid var(--line);background:var(--bg);color:var(--ink);min-height:44px;max-width:140px}
.pt-net-result{display:grid;gap:6px}
.pt-net-meter{height:10px;border-radius:99px;background:var(--soft);overflow:hidden}
.pt-net-meter>i{display:block;height:100%;border-radius:99px}
.pt-net-meter.ok>i{background:var(--ok)}.pt-net-meter.warn>i{background:var(--warn)}.pt-net-meter.alert>i{background:#e5533d}
/* Product card */
.pt-product{display:grid;grid-template-columns:72px minmax(0,1fr);gap:12px 14px;padding:14px;border-radius:12px;background:var(--soft)}
.pt-product-icon svg{width:72px;height:72px;display:block}
.pt-product-info{display:grid;gap:4px;align-content:start}
.pt-specs{margin:4px 0 0;padding-left:18px;display:grid;gap:3px;font-size:14px}
.pt-example{grid-column:1/-1;margin:0;padding:10px 12px;border-radius:10px;background:var(--card);border-left:4px solid var(--accent);line-height:1.5}
.pt-product-photo{width:72px;height:72px;border-radius:12px;overflow:hidden;background:#fff;display:grid;place-items:center}
.pt-product-photo img{width:100%;height:100%;object-fit:contain}
.pt-photo-strip{grid-column:1/-1;display:grid;grid-template-columns:repeat(5,1fr);gap:6px}
.pt-photo-strip img{width:100%;aspect-ratio:1;object-fit:contain;background:#fff;border-radius:8px}
.pt-sheet{grid-column:1/-1;display:flex;align-items:center;gap:12px;padding:10px;border-radius:10px;background:var(--card);border:1px solid var(--line);color:var(--ink);text-decoration:none}
.pt-sheet:hover{border-color:var(--accent)}
.pt-sheet img{flex:none;width:64px;height:90px;object-fit:cover;object-position:top;border-radius:6px;background:#fff}
.pt-sheet span{display:grid;gap:2px;min-width:0}
.pt-sheet small{color:var(--muted)}
/* Diagram drawing */
.dg-node rect,.dg-node circle{fill:var(--card);stroke:var(--line);stroke-width:1.5}
.dg-node.acc rect,.dg-node.acc circle{fill:var(--soft);stroke:var(--accent)}
.dg-node.warn rect{fill:var(--warn-soft);stroke:var(--warn)}
.dg-t{fill:var(--ink);font-size:13px;font-weight:700}
.dg-s{fill:var(--muted);font-size:12px}
.dg-l{fill:var(--muted);font-size:12px}
.dg-line{stroke:var(--muted);stroke-width:1.5;fill:none}
.dg-line.dash{stroke-dasharray:5 4}
.dg-head{fill:var(--muted)}
.dg-bulb circle{fill:var(--soft);stroke:var(--accent);stroke-width:2}
.dg-room{fill:none;stroke:var(--line);stroke-width:2}
.dg-cone{fill:var(--accent);opacity:.14}
.dg-tri{fill:var(--soft);stroke:var(--accent);stroke-width:2;stroke-dasharray:6 5}
/* Infographics (reading classes) */
.pt-infos{display:grid;gap:12px}
.pt-info{display:grid;gap:6px;text-decoration:none;color:var(--ink)}
.pt-info img{width:100%;height:auto;border-radius:12px;border:1px solid var(--line);background:#fff}
.pt-info span{font-size:13px;color:var(--muted)}
/* Student tools */
.pt-tools{display:grid;gap:10px;grid-template-columns:repeat(auto-fit,minmax(220px,1fr))}
.pt-tool{display:grid;gap:4px;padding:14px;border-radius:12px;border:1px solid var(--line);background:var(--soft);color:var(--ink);text-decoration:none}
.pt-tool:hover{border-color:var(--accent)}.pt-tool small{color:var(--muted)}
.pt-quiz{display:grid;gap:12px}
.pt-question{border:1px solid var(--line)}.pt-question legend{display:grid;gap:6px;font-weight:700;line-height:1.4;padding:0;margin-bottom:6px}
.pt-option{display:flex;gap:10px;align-items:flex-start;padding:10px 12px;border-radius:10px;border:1px solid var(--line);cursor:pointer;line-height:1.4}
.pt-option:has(input:checked){border-color:var(--accent);background:var(--soft)}.pt-option input{margin-top:3px;flex:none;width:18px;height:18px;accent-color:var(--accent)}
.pt-result.ok{border-color:var(--ok)}.pt-result.warn{border-color:var(--warn)}
.pt-review.ok{border-left:4px solid var(--ok)}.pt-review.bad{border-left:4px solid #e5533d}.pt-why{padding:10px 12px;border-radius:10px;background:var(--soft)}
.pt-rates{width:100%;border-collapse:collapse;font-size:15px}.pt-rates td,.pt-rates th{text-align:left;padding:10px 6px;border-bottom:1px solid var(--line);vertical-align:top}.pt-rates td:last-child,.pt-rates th:last-child{text-align:right;white-space:nowrap}.pt-rates small{display:block;color:var(--muted);font-size:12.5px}
.pt-total td{font-weight:800;font-size:18px;color:var(--accent);border-bottom:0}
.pt-quote{display:grid;gap:14px}
.pt-grid{display:grid;gap:12px;grid-template-columns:repeat(auto-fit,minmax(200px,1fr))}
.pt-quote label{display:grid;gap:4px;font-weight:600;font-size:14px}
.pt-quote input,.pt-quote select,.pt-quote textarea{width:100%;padding:10px 12px;border-radius:10px;border:1px solid var(--line);background:var(--bg);color:var(--ink);min-height:44px;font:inherit}
.pt-check{display:flex!important;align-items:center;gap:10px;font-weight:600}.pt-check input{width:20px!important;min-height:0!important;accent-color:var(--accent)}
.pt-room{display:grid;gap:10px;padding:12px;border-radius:12px;border:1px solid var(--line);margin-bottom:10px}
.pt-room-head{display:flex;gap:10px;align-items:center}.pt-room-head input{font-weight:700}
.pt-devgrid{display:grid;gap:8px;grid-template-columns:repeat(auto-fill,minmax(110px,1fr))}.pt-devgrid label{font-size:12.5px;font-weight:600}
.pt-price{display:grid;gap:8px;grid-template-columns:minmax(0,1.4fr) 1fr 1fr;align-items:end;padding:10px 0;border-bottom:1px solid var(--line)}.pt-price small{color:var(--muted)}
.pt-recs{list-style:none;margin:0;padding:0;display:grid;gap:8px}.pt-recs li{padding:10px 12px;border-radius:10px;background:var(--soft);line-height:1.45}.pt-recs li b{display:block;font-size:12px;text-transform:uppercase;letter-spacing:.05em;color:var(--accent)}
.pt-recs li.warn,.pt-recs li.alert{background:var(--warn-soft)}.pt-recs li.warn b,.pt-recs li.alert b{color:var(--warn)}
@media (max-width:520px){.pt-price{grid-template-columns:1fr 1fr}.pt-price>b{grid-column:1/-1}}
#pt-toast{position:fixed;left:50%;bottom:calc(18px + env(safe-area-inset-bottom,0px));transform:translateX(-50%);max-width:calc(100% - 32px);padding:10px 18px;border-radius:99px;background:var(--ink);color:var(--bg);font-weight:600;z-index:10}
@media (prefers-reduced-motion:reduce){.pt-bar>i{transition:none}}

.pt-help-row{display:flex;flex-wrap:wrap;gap:10px}.pt-help-row:empty{display:none}
.pt-help-call{border-color:var(--accent);color:var(--accent)}
.pt-call{display:grid;gap:6px;padding:14px 0;border-top:1px solid var(--line)}.pt-call:first-of-type{border-top:0}.pt-call p{margin:0}
.pt-call .pt-tag{justify-self:start}.pt-call.scheduled .pt-tag{background:var(--ok-soft);color:var(--ok);padding:2px 8px;border-radius:6px}.pt-call.cancelled{opacity:.7}.pt-form select,.pt-form textarea{width:100%;padding:12px 14px;border-radius:10px;border:1px solid var(--line);background:var(--bg);color:var(--ink);min-height:48px;font:inherit}

/* Accessibility: visible focus on every control and touch targets of at least 44px. */
:is(button,select,textarea,summary):focus-visible,.pt-option:focus-within{outline:3px solid var(--accent);outline-offset:2px}
.pt-link,.pt-back,.pt-top .pt-link{min-height:44px;display:inline-flex;align-items:center}