/* Palmway Pool School, shared design system.
   Palette and type ported from the v1 prototype. */

:root{
  --deck:#E7EDEB; --deck-2:#F3F7F6;
  --ink:#0C2426;  --ink-2:#153A3D;
  --tile:#1C6E7E; --tile-lt:#3E97A8;
  --chlor:#F2C037; --chlor-dk:#C08F13;
  --ph:#C1402B; --alk:#4F8F72; --hard:#7A5C9E;
  --line:rgba(12,36,38,.14); --line-2:rgba(12,36,38,.08);
  --paper:#fff;
  --shadow:0 1px 0 rgba(12,36,38,.06), 0 8px 24px -12px rgba(12,36,38,.28);
  --display:'Archivo',system-ui,sans-serif;
  --util:'Barlow Condensed',system-ui,sans-serif;
  --body:'IBM Plex Sans',system-ui,sans-serif;
  --wrap:720px;
}
@media (prefers-color-scheme:dark){
  :root{
    --deck:#0E1B1D; --deck-2:#132528; --paper:#16292C;
    --ink:#E9F1F0; --ink-2:#B9CFCE;
    --tile:#54AEBF; --tile-lt:#7FC9D6;
    --line:rgba(233,241,240,.18); --line-2:rgba(233,241,240,.10);
    --shadow:0 1px 0 rgba(0,0,0,.3), 0 8px 24px -12px rgba(0,0,0,.6);
  }
}
*{box-sizing:border-box}
html,body{margin:0;padding:0}
body{
  background:var(--deck); color:var(--ink);
  font:17px/1.65 var(--body); -webkit-text-size-adjust:100%;
}
.wrap{max-width:var(--wrap);margin:0 auto;padding:24px 20px 96px}

/* type */
h1,h2,h3{font-family:var(--display);line-height:1.2;letter-spacing:-.015em;margin:0}
h1{font-size:clamp(1.7rem,5vw,2.4rem);margin:0 0 6px}
h2{font-size:clamp(1.25rem,3.4vw,1.55rem);margin:40px 0 12px}
h3{font-size:1.08rem;margin:26px 0 8px}
p{margin:0 0 14px}
.kicker{font-family:var(--util);text-transform:uppercase;letter-spacing:.09em;
  font-size:.82rem;color:var(--tile);font-weight:600;margin:0 0 4px}
.lede{font-size:1.08rem;color:var(--ink-2);margin:0 0 8px}

/* blocks */
.card{background:var(--paper);border:1px solid var(--line);border-radius:12px;
  padding:18px 20px;margin:18px 0;box-shadow:var(--shadow)}
.say{border-left:3px solid var(--tile);background:var(--deck-2);
  border-radius:0 10px 10px 0;padding:14px 18px;margin:18px 0}
.say .lbl{font-family:var(--util);text-transform:uppercase;letter-spacing:.08em;
  font-size:.76rem;color:var(--tile);font-weight:600;display:block;margin-bottom:4px}
.warn{border-left:3px solid var(--ph);background:var(--deck-2);
  border-radius:0 10px 10px 0;padding:14px 18px;margin:18px 0}
.warn .lbl{font-family:var(--util);text-transform:uppercase;letter-spacing:.08em;
  font-size:.76rem;color:var(--ph);font-weight:600;display:block;margin-bottom:4px}
.todo{border:1px dashed var(--chlor-dk);background:rgba(242,192,55,.10);
  border-radius:10px;padding:12px 16px;margin:18px 0;font-size:.94rem}
.todo .lbl{font-family:var(--util);text-transform:uppercase;letter-spacing:.08em;
  font-size:.76rem;color:var(--chlor-dk);font-weight:700;display:block;margin-bottom:4px}

/* tables */
.tbl{width:100%;overflow-x:auto;margin:18px 0}
table{border-collapse:collapse;width:100%;font-size:.95rem;min-width:460px}
th,td{text-align:left;padding:10px 12px;border-bottom:1px solid var(--line-2);vertical-align:top}
th{font-family:var(--util);text-transform:uppercase;letter-spacing:.06em;
  font-size:.8rem;color:var(--tile);border-bottom:1px solid var(--line)}

/* nav */
.topbar{background:var(--paper);border-bottom:1px solid var(--line);position:sticky;top:0;z-index:20}
.topbar .in{max-width:var(--wrap);margin:0 auto;padding:10px 20px;
  display:flex;align-items:center;gap:12px;justify-content:space-between}
.brand{font-family:var(--display);font-weight:700;font-size:.98rem;
  color:var(--ink);text-decoration:none;letter-spacing:-.01em}
.prog{flex:1;height:5px;background:var(--line-2);border-radius:99px;overflow:hidden;max-width:160px}
.prog i{display:block;height:100%;background:var(--tile);width:0}
.step{font-family:var(--util);font-size:.85rem;color:var(--ink-2);letter-spacing:.04em;white-space:nowrap}

.btn{display:inline-block;background:var(--tile);color:#fff;border:0;
  font:600 1rem/1 var(--body);padding:14px 22px;border-radius:9px;
  cursor:pointer;text-decoration:none;transition:background .15s}
.btn:hover{background:var(--ink-2)}
.btn.ghost{background:transparent;color:var(--tile);border:1px solid var(--tile)}
.btn.ghost:hover{background:var(--deck-2)}
.btn[disabled]{opacity:.45;cursor:not-allowed}
.nav-foot{display:flex;gap:12px;align-items:center;justify-content:space-between;
  margin-top:40px;padding-top:22px;border-top:1px solid var(--line)}

a{color:var(--tile)}
a:focus-visible,.btn:focus-visible,button:focus-visible,input:focus-visible,select:focus-visible{
  outline:3px solid var(--chlor-dk);outline-offset:2px;border-radius:4px}

/* forms */
label{display:block;font-family:var(--util);text-transform:uppercase;
  letter-spacing:.07em;font-size:.82rem;color:var(--ink-2);margin:16px 0 5px;font-weight:600}
input[type=text],input[type=email],select{
  width:100%;font:1rem var(--body);padding:12px 14px;border:1px solid var(--line);
  border-radius:9px;background:var(--paper);color:var(--ink)}
.choice{display:grid;gap:10px;grid-template-columns:1fr 1fr}
@media(max-width:520px){.choice{grid-template-columns:1fr}}
.choice button{background:var(--paper);border:1px solid var(--line);border-radius:10px;
  padding:14px;text-align:left;cursor:pointer;font:1rem var(--body);color:var(--ink)}
.choice button[aria-pressed=true]{border-color:var(--tile);background:var(--deck-2);
  box-shadow:inset 0 0 0 1px var(--tile)}
.choice small{display:block;color:var(--ink-2);font-size:.86rem;margin-top:3px}

/* quiz */
.q{margin:22px 0;padding:18px 20px;background:var(--paper);
  border:1px solid var(--line);border-radius:12px}
.q .stem{font-weight:600;margin-bottom:12px}
.opt{display:block;width:100%;text-align:left;background:var(--deck-2);
  border:1px solid var(--line);border-radius:9px;padding:12px 14px;margin:8px 0;
  cursor:pointer;font:1rem var(--body);color:var(--ink)}
.opt:hover{border-color:var(--tile)}
.opt.right{border-color:var(--alk);background:rgba(79,143,114,.14)}
.opt.wrong{border-color:var(--ph);background:rgba(193,64,43,.12)}
.why{display:none;margin-top:10px;padding:12px 14px;border-radius:9px;
  background:var(--deck-2);border-left:3px solid var(--tile);font-size:.95rem}
.why.show{display:block}

@media (prefers-reduced-motion:reduce){
  *,*::before,*::after{animation:none!important;transition:none!important;scroll-behavior:auto!important}
}

/* ============================================================
   Diagrams and interactives
   ============================================================ */

.fig{background:var(--paper);border:1px solid var(--line);border-radius:14px;
  padding:16px;margin:24px 0;box-shadow:var(--shadow)}
.fig figcaption{font-family:var(--util);text-transform:uppercase;letter-spacing:.08em;
  font-size:.78rem;color:var(--tile);font-weight:600;margin:0 0 10px}
.fig svg{display:block;width:100%;height:auto;overflow:visible}
.fig .hint{font-size:.86rem;color:var(--ink-2);margin:10px 0 0}

/* clickable diagram parts */
.part{cursor:pointer}
.part .hit{fill:transparent}
.part .body{transition:fill .15s, stroke .15s}
.part:hover .body,.part[aria-pressed=true] .body{fill:var(--tile-lt);stroke:var(--tile)}
.part:focus-visible{outline:none}
.part:focus-visible .body{stroke:var(--chlor-dk);stroke-width:3}
.part text{font-family:var(--util);font-size:13px;fill:var(--ink);
  text-transform:uppercase;letter-spacing:.05em;pointer-events:none}
.part[aria-pressed=true] text{font-weight:600}

/* animated water flow */
.flow{fill:none;stroke:var(--tile-lt);stroke-width:3;stroke-linecap:round;
  stroke-dasharray:9 13;animation:drift 1.6s linear infinite}
@keyframes drift{to{stroke-dashoffset:-44}}
.pipe{fill:none;stroke:var(--line);stroke-width:9;stroke-linecap:round}

/* detail panel under a diagram */
.detail{margin-top:14px;border-left:3px solid var(--tile);background:var(--deck-2);
  border-radius:0 10px 10px 0;padding:14px 16px;min-height:96px}
.detail h4{font-family:var(--display);margin:0 0 6px;font-size:1.05rem}
.detail .row{margin:0 0 8px;font-size:.94rem}
.detail .row:last-child{margin-bottom:0}
.detail .tag{font-family:var(--util);text-transform:uppercase;letter-spacing:.07em;
  font-size:.72rem;font-weight:700;color:var(--tile);display:block}
.detail .quote{font-style:italic;color:var(--ink-2)}
.detail .empty{color:var(--ink-2);font-size:.94rem;margin:0}

/* pH effectiveness slider */
.slider-wrap{margin:18px 0}
.slider-wrap input[type=range]{width:100%;accent-color:var(--tile);height:32px}
.ph-readout{display:flex;gap:14px;flex-wrap:wrap;align-items:baseline;margin:8px 0 4px}
.ph-num{font-family:var(--display);font-size:2rem;font-weight:700;line-height:1}
.ph-state{font-family:var(--util);text-transform:uppercase;letter-spacing:.07em;
  font-size:.86rem;font-weight:600}
.bar-track{height:26px;border-radius:99px;background:var(--line-2);overflow:hidden;margin:6px 0}
.bar-fill{height:100%;border-radius:99px;transition:width .25s, background .25s}
.ph-note{font-size:.93rem;color:var(--ink-2);margin:8px 0 0;min-height:2.6em}

@media (prefers-reduced-motion:reduce){
  .flow{animation:none}
  .bar-fill{transition:none}
}