/* The one-screen resource layout (RESOURCE-LAYOUT.md): the header bar, the title bar with its
   toggles and dialog buttons, the stage, the dialogs and the challenge questions. Shared by the
   resource pages that use resource_header() in includes/site.php. Theme tokens only. */

*{box-sizing:border-box}
body.rp{
  margin:0;min-height:100vh;min-height:100dvh;display:flex;flex-direction:column;
  background:var(--paper);color:var(--ink);font-family:var(--font-body);font-size:16px;line-height:1.55;-webkit-font-smoothing:antialiased;
}

/* ---------- buttons ---------- */
.btn{
  font-family:var(--font-display);font-weight:600;font-size:13px;border-radius:4px;line-height:1.2;
  padding:8px 14px;cursor:pointer;border:1px solid transparent;transition:transform .05s ease;text-decoration:none;
  display:inline-flex;align-items:center;gap:6px;white-space:nowrap;
}
.btn:active{transform:translateY(1px)}
.btn:focus-visible{outline:2px solid var(--focus);outline-offset:2px}
.btn:disabled{opacity:.45;cursor:default;transform:none}
.btn-primary{background:var(--accent);color:var(--on-accent)}
.btn-primary:hover:not(:disabled){background:var(--accent-deep)}
.btn-ghost{background:transparent;border-color:var(--line-strong);color:var(--ink-soft)}
.btn-ghost:hover:not(:disabled){border-color:var(--accent);color:var(--accent)}
.btn-sm{padding:4px 8px;font-size:12px}

/* ---------- the header bar ---------- */
.rp-header{position:sticky;top:0;z-index:30;background:var(--paper);border-bottom:2px solid var(--accent-deep)}
.rp-header-in{max-width:1600px;margin:0 auto;padding:8px 20px;display:flex;align-items:center;justify-content:space-between;gap:16px}
.rp-brand{display:flex;align-items:center;text-decoration:none;flex:none}
.rp-logo{height:46px;width:auto;display:block;border-radius:5px;background:var(--logo-plate);padding:var(--logo-pad);box-sizing:content-box}
.rp-nav{display:flex;align-items:center;gap:12px}
.rp-nav .account-link{font:600 13px/1.2 var(--font-display);padding:7px 12px;border-radius:999px;border:1px solid var(--line-strong);color:var(--ink-soft);text-decoration:none}
.rp-nav .account-link:hover{border-color:var(--accent);color:var(--accent)}
.rp-nav .subscribe-link{padding:7px 14px}

/* ---------- the title bar: name, toggles, then the dialog buttons on the right ---------- */
.rp-titlebar{max-width:1600px;width:100%;margin:0 auto;padding:14px 20px 0;display:flex;align-items:center;gap:14px 26px;flex-wrap:wrap}
.rp-name{display:flex;flex-direction:column;gap:3px;min-width:0}
.rp-name .school{font-family:var(--font-mono);font-size:10.5px;letter-spacing:.14em;text-transform:uppercase;color:var(--brand-grey)}
.rp-name h1{font-family:var(--font-display);font-weight:700;font-size:clamp(22px,2.6vw,30px);line-height:1.05;letter-spacing:-.02em;margin:0;color:var(--accent-deep)}
.rp-controls{display:flex;align-items:center;gap:12px;flex-wrap:wrap}
.rp-actions{margin-left:auto;display:flex;gap:8px;flex-wrap:wrap}

/* a toggle: buttons on one track, with a thumb that slides to the chosen one (js/resource.js) */
.seg-toggle{position:relative;display:inline-flex;padding:3px;border-radius:999px;background:var(--panel-2);border:1px solid var(--line-strong);isolation:isolate}
.seg-toggle button{position:relative;z-index:1;font:600 14px/1 var(--font-display);padding:9px 16px;border:0;border-radius:999px;background:transparent;color:var(--ink-soft);cursor:pointer;display:inline-flex;align-items:center;gap:7px;white-space:nowrap;transition:color .2s}
.seg-toggle button:hover{color:var(--ink)}
.seg-toggle button[aria-selected="true"]{color:var(--on-accent)}
.seg-toggle button:focus-visible{outline:2px solid var(--focus);outline-offset:1px}
.seg-toggle .seg-thumb{position:absolute;z-index:0;top:3px;bottom:3px;left:0;width:0;border-radius:999px;background:var(--accent);box-shadow:var(--shadow)}
.seg-toggle.ready .seg-thumb{transition:transform .28s cubic-bezier(.3,.7,.2,1),width .28s cubic-bezier(.3,.7,.2,1)}
.seg-toggle button .ic{font-family:var(--font-mono);font-size:13px;opacity:.85}
.seg-toggle.seg-quiet{background:transparent}
.seg-toggle.seg-quiet button{font-size:13px;padding:7px 13px}
.seg-toggle.seg-quiet .seg-thumb{background:var(--accent-deep)}
@media (prefers-reduced-motion:reduce){.seg-toggle .seg-thumb,.seg-toggle button{transition:none}}

/* ---------- the stage: everything the resource shows, in one screen ---------- */
.rp-main{flex:1;max-width:1600px;width:100%;margin:0 auto;padding:14px 20px 12px;display:flex;flex-direction:column;gap:12px;min-height:0}
.panel{background:var(--panel);border:1px solid var(--line);border-radius:6px;box-shadow:var(--shadow)}
.small{font-size:13px;color:var(--muted)}
.num{font-family:var(--font-mono);font-variant-numeric:tabular-nums}
[hidden]{display:none !important}

/* ---------- dialogs ---------- */
dialog{border:1px solid var(--line-strong);border-radius:8px;padding:0;max-width:820px;width:94vw;background:var(--panel);color:var(--ink);box-shadow:var(--shadow)}
dialog::backdrop{background:rgba(15,21,29,.55)}
.dialog-head{display:flex;align-items:center;justify-content:space-between;padding:14px 18px;border-bottom:1px solid var(--line)}
.dialog-head h3{margin:0;font-size:16px;font-family:var(--font-display)}
.dialog-body{padding:16px 18px 18px;max-height:68vh;overflow:auto}
.dialog-foot{padding:12px 18px;display:flex;justify-content:flex-end;border-top:1px solid var(--line)}
.close-x{border:0;background:transparent;color:var(--muted);font-size:22px;line-height:1;cursor:pointer;padding:4px}
.close-x:hover{color:var(--ink)}
.objective{font-size:15px;color:var(--ink-soft)}
.objective p{margin:0 0 10px}
.objective strong{color:var(--ink)}
.objective ul{margin:0 0 10px;padding-left:20px}
.objective li{margin-bottom:6px}
.tablewrap{overflow-x:auto}
table{border-collapse:collapse;width:100%;font-size:13.5px}
th,td{text-align:left;padding:7px 10px;border-bottom:1px solid var(--line);vertical-align:top}
th{font-family:var(--font-display);font-size:11px;letter-spacing:.06em;text-transform:uppercase;color:var(--muted)}
td.mi .gap,td .gap{color:var(--muted);font-style:italic;font-size:12.5px}
.tnote{font-size:12px;color:var(--muted);margin-top:14px}
.tnote a{color:var(--muted)}

/* ---------- challenge questions (js/challenges.js) ---------- */
.cq{display:grid;grid-template-columns:minmax(0,1fr) 240px;gap:18px;height:100%;min-height:0}
.cq-card{display:flex;flex-direction:column;gap:14px;padding:20px 22px;min-height:0;overflow:auto}
.cq-meta{display:flex;align-items:center;gap:10px;font:600 12px/1 var(--font-mono);letter-spacing:.06em;text-transform:uppercase;color:var(--muted)}
.cq-level{display:inline-flex;gap:3px}
.cq-level i{width:8px;height:8px;border-radius:50%;background:var(--line-strong)}
.cq-level i.on{background:var(--accent-b)}
.cq-q{margin:0;font:600 clamp(17px,1.6vw,21px)/1.4 var(--font-display);color:var(--ink);text-wrap:pretty}
.cq-q .unit-note{display:block;margin-top:4px;font:500 13.5px/1.4 var(--font-body);color:var(--muted)}
.cq-opts{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px}
.cq-opt{text-align:left;font:600 16px/1.3 var(--font-body);padding:13px 16px;border-radius:8px;border:1.5px solid var(--line-strong);background:var(--panel);color:var(--ink);cursor:pointer;display:flex;flex-direction:column;gap:6px;transition:border-color .15s,background .15s}
.cq-opt:hover:not(:disabled){border-color:var(--accent);background:var(--accent-tint)}
.cq-opt:focus-visible{outline:2px solid var(--focus);outline-offset:2px}
.cq-opt .why{font:500 13px/1.4 var(--font-body);color:var(--ink-soft)}
.cq-opt.wrong{border-color:var(--bad);background:var(--bad-tint);cursor:default;animation:cq-shake .35s}
.cq-opt.right{border-color:var(--ok);background:var(--ok-tint);cursor:default}
.cq-opt.right::before{content:"✓ Correct";font:700 11px/1 var(--font-mono);letter-spacing:.06em;text-transform:uppercase;color:var(--ok)}
.cq-opt.wrong::before{content:"✗ Not quite";font:700 11px/1 var(--font-mono);letter-spacing:.06em;text-transform:uppercase;color:var(--bad)}
.cq-opt:disabled:not(.right):not(.wrong){opacity:.55;cursor:default}
.cq-working{border-left:3px solid var(--ok);background:var(--panel-2);border-radius:0 6px 6px 0;padding:12px 16px;animation:cq-in .35s ease both}
.cq-working h4{margin:0 0 6px;font:700 13px/1 var(--font-display);letter-spacing:.04em;text-transform:uppercase;color:var(--ok)}
.cq-working ol{margin:0;padding-left:20px;font-size:15px;color:var(--ink-soft)}
.cq-working li{margin:3px 0}
.cq-working b{color:var(--ink)}
.cq-nav{display:flex;align-items:center;gap:10px;margin-top:auto}
.cq-nav .cq-score{margin-left:auto;font-size:13.5px;color:var(--muted)}
.cq-side{padding:16px;display:flex;flex-direction:column;gap:12px;min-height:0;overflow:auto}
.cq-side h3{margin:0;font:700 14px/1.2 var(--font-display);color:var(--ink)}
.cq-dots{display:grid;grid-template-columns:repeat(4,1fr);gap:6px}
.cq-dot{font:600 13px/1 var(--font-mono);padding:8px 0;border-radius:6px;border:1px solid var(--line-strong);background:var(--panel);color:var(--ink-soft);cursor:pointer}
.cq-dot.current{outline:2px solid var(--accent);outline-offset:1px}
.cq-dot.first{background:var(--ok);border-color:var(--ok);color:#fff}
.cq-dot.later{background:var(--ok-tint);border-color:var(--ok);color:var(--ink)}
.cq-key{margin:0;padding:0;list-style:none;font-size:12.5px;color:var(--muted);display:flex;flex-direction:column;gap:4px}
.cq-key i{display:inline-block;width:11px;height:11px;border-radius:3px;vertical-align:-1px;margin-right:6px;border:1px solid var(--ok)}
.cq-done{font-size:14px;color:var(--ink);background:var(--ok-tint);border-radius:6px;padding:10px 12px}
@keyframes cq-shake{0%,100%{transform:none}25%{transform:translateX(-4px)}75%{transform:translateX(4px)}}
@keyframes cq-in{from{opacity:0;transform:translateY(6px)}to{opacity:1;transform:none}}
@media (prefers-reduced-motion:reduce){.cq-opt.wrong,.cq-working{animation:none}}

/* ---------- footer ---------- */
.rp .site-footer{max-width:1600px;width:100%;margin:0 auto;padding:10px 20px 14px;display:flex;flex-wrap:wrap;gap:4px 18px;font-size:12px;color:var(--muted);border-top:1px solid var(--line)}
.rp .site-footer a{color:var(--muted)}
.rp .site-footer a:hover{color:var(--accent)}

/* ---------- smaller screens: the title bar wraps, and the page may scroll (the phone pass is issue #4) ---------- */
@media (max-width:900px){
  .rp-actions{margin-left:0}
  .cq{grid-template-columns:1fr}
}
@media (max-width:640px){
  .rp-header-in,.rp-titlebar,.rp-main{padding-left:14px;padding-right:14px}
  .rp-back span{display:none}
  .cq-opts{grid-template-columns:1fr}
  .seg-toggle button{padding:8px 11px;font-size:13px}
}

/* ---------- pages that fit one screen (body.rp-fit): the main area takes the height that's left ---------- */
@media (min-width:901px) and (min-height:560px){
  body.rp-fit{height:100vh;height:100dvh}
}

/* ---------- the title bar as a banner, over the subject's video (banner_video(), js/banner-video.js) ----------
   Laptops and desktops only; on smaller screens it's the plain title bar above. White text, a darkened
   video, and see-through controls. */
.rp-banner .banner-video,.rp-banner .banner-shade{display:none}
@media (min-width:901px){
  .rp-banner.banner-video-on{position:relative;overflow:hidden;isolation:isolate;border-bottom:1px solid rgba(0,0,0,.25)}
  .rp-banner.banner-video-on .banner-video{display:block;position:absolute;inset:0;width:100%;height:100%;object-fit:cover;object-position:center 70%;z-index:-2}
  .rp-banner.banner-video-on .banner-shade{display:block;position:absolute;inset:0;z-index:-1;background:linear-gradient(90deg,rgba(6,12,22,.86) 0%,rgba(6,12,22,.62) 45%,rgba(6,12,22,.32) 100%)}
  .rp-banner.banner-video-on .rp-titlebar{padding-bottom:12px;padding-top:12px}
  .rp-banner.banner-video-on .rp-name .school{color:rgba(255,255,255,.72)}
  .rp-banner.banner-video-on .rp-name h1{color:#fff}
  .rp-banner.banner-video-on .seg-toggle{background:rgba(255,255,255,.1);border-color:rgba(255,255,255,.28)}
  .rp-banner.banner-video-on .seg-toggle button{color:rgba(255,255,255,.86)}
  .rp-banner.banner-video-on .seg-toggle button:hover{color:#fff}
  .rp-banner.banner-video-on .seg-toggle button[aria-selected="true"]{color:#fff}
  .rp-banner.banner-video-on .seg-toggle.seg-quiet .seg-thumb{background:rgba(255,255,255,.22)}
  .rp-banner.banner-video-on .btn-ghost{color:#fff;border-color:rgba(255,255,255,.55);background:rgba(255,255,255,.06)}
  .rp-banner.banner-video-on .btn-ghost:hover:not(:disabled){color:#fff;border-color:#fff;background:rgba(255,255,255,.14)}
}