/* Seston — deep navy, glass panels and a real waveform. The palette follows the logo:
   the shell and its trace are blue, so the site is blue. */
:root{
  --bg:#06101c;
  --bg-2:#0a1626;
  --panel:linear-gradient(160deg,rgba(13,28,47,.86),rgba(9,20,34,.86));
  --line:rgba(180,220,255,.14);
  --line-2:rgba(180,220,255,.22);
  --text:#f5f9ff;
  --muted:#93a9c4;
  --blue:#3ea7ff;
  --cyan:#54e0ff;
  --green:#69e4bd;
  --amber:#ffc86e;
  /* tints built from the accent, so they move with the theme instead of being written
     out once in a colour that only works on one background */
  --tint:rgba(84,224,255,.09);
  --tint-edge:rgba(84,224,255,.22);
  --shadow:0 30px 80px rgba(0,0,0,.38);
  --radius:26px;
  --radius-sm:18px;
  --max:1180px;
}

html[data-theme="light"]{
  --bg:#eef4f8; --bg-2:#f7fafc;
  --panel:linear-gradient(160deg,rgba(255,255,255,.94),rgba(238,245,249,.94));
  --line:rgba(32,76,115,.13); --line-2:rgba(32,76,115,.2);
  --text:#102033; --muted:#60758b;
  --shadow:0 28px 70px rgba(34,66,96,.13);

  /* The accents have to change with the theme, not just the background. Cyan that reads
     as bright on navy reads as nothing at all on near-white - which is what happened to
     every keyboard key in the handbook. */
  --blue:#1462bd;
  --cyan:#0b6f95;
  --green:#12805f;
  --amber:#a86a00;
  --tint:rgba(11,111,149,.09);
  --tint-edge:rgba(11,111,149,.24);
  --code-bg:rgba(16,50,80,.06);
  --code-line:rgba(16,50,80,.16);
  --note-edge:rgba(168,106,0,.30);
  --note-bg:rgba(255,196,92,.10);
}

:root{
  --code-bg:rgba(180,220,255,.08);
  --code-line:var(--line-2);
  --note-edge:rgba(255,200,110,.24);
  --note-bg:rgba(255,200,110,.06);
}

*{box-sizing:border-box}
html{scroll-behavior:smooth}

body{
  margin:0;
  color:var(--text);
  font:16px/1.68 -apple-system,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;
  -webkit-font-smoothing:antialiased;
  background:
    radial-gradient(circle at 18% 14%, rgba(42,123,255,.16), transparent 38%),
    radial-gradient(circle at 84% 8%,  rgba(73,224,255,.13), transparent 34%),
    linear-gradient(180deg,var(--bg) 0%,var(--bg-2) 46%,var(--bg) 100%);
  background-attachment:fixed;
}
html[data-theme="light"] body{
  background:
    radial-gradient(circle at 18% 14%, rgba(42,123,255,.10), transparent 34%),
    radial-gradient(circle at 84% 8%,  rgba(73,224,255,.09), transparent 30%),
    linear-gradient(180deg,#f8fbfd 0%,#edf4f8 44%,#f7fafc 100%);
}

/* the faint grid that stops the gradients looking like a screensaver */
body:before{
  content:"";
  position:fixed; inset:0; z-index:-1; pointer-events:none;
  background-image:
    linear-gradient(rgba(180,220,255,.030) 1px, transparent 1px),
    linear-gradient(90deg, rgba(180,220,255,.024) 1px, transparent 1px);
  background-size:64px 64px;
  mask-image:radial-gradient(circle at 50% 22%, #000 0%, transparent 72%);
}
html[data-theme="light"] body:before{
  background-image:
    linear-gradient(rgba(16,32,51,.035) 1px, transparent 1px),
    linear-gradient(90deg, rgba(16,32,51,.028) 1px, transparent 1px);
}

a{color:var(--cyan); text-decoration:none}
a:hover{text-decoration:underline}
.wrap{max-width:var(--max); margin:0 auto; padding:0 26px}

/* ---------- nav ---------- */

.nav-wrap{
  position:sticky; top:0; z-index:30;
  backdrop-filter:blur(14px);
  background:linear-gradient(180deg,rgba(6,16,28,.92),rgba(6,16,28,.62));
  border-bottom:1px solid var(--line);
}
html[data-theme="light"] .nav-wrap{
  background:linear-gradient(180deg,rgba(248,251,253,.94),rgba(248,251,253,.72));
}
.nav{display:flex; align-items:center; gap:22px; height:66px}
.brand{display:flex; align-items:center; gap:11px; font-weight:750; letter-spacing:.02em; color:var(--text)}
.brand img{width:30px; height:30px}
.nav-links{margin-left:auto; display:flex; gap:24px; font-size:14.5px; color:var(--muted)}
/* Last in the row on a phone, whatever order the markup happens to be in. */
.nav-menu{display:none; order:3}
.nav-menu summary{
  list-style:none; cursor:pointer;
  display:inline-flex; align-items:center; justify-content:center;
  width:38px; height:38px; border-radius:12px; font-size:17px;
  background:var(--panel); border:1px solid var(--line); color:var(--text);
}
.nav-menu summary::-webkit-details-marker{display:none}
.nav-menu[open] summary{border-color:var(--cyan)}
.nav-menu .sheet{
  position:absolute; inset-inline:12px; top:70px; z-index:35;
  background:var(--panel); border:1px solid var(--line-2);
  border-radius:var(--radius-sm); box-shadow:var(--shadow);
  padding:10px; display:flex; flex-direction:column;
  backdrop-filter:blur(14px);
}
.nav-menu .sheet a{
  padding:12px 14px; border-radius:11px; color:var(--text); font-size:16px;
}
.nav-menu .sheet a:hover{background:var(--code-bg); text-decoration:none}
.nav-links a{color:inherit}
.nav-links a{
  position:relative; padding:6px 0;
  border-bottom:2px solid transparent; transition:color .18s ease, border-color .18s ease;
}
.nav-links a:hover{color:var(--text); text-decoration:none; border-bottom-color:var(--line-2)}
.nav-links a.active{color:var(--text); border-bottom-color:var(--cyan)}

/* The header is sticky, so an anchor would otherwise land with its heading underneath it. */
section{scroll-margin-top:86px}

/* Keyboard users get to see where they are. */
a:focus-visible, button:focus-visible, select:focus-visible{
  outline:2px solid var(--cyan); outline-offset:3px; border-radius:8px;
}

.to-top{
  position:fixed; inset-inline-end:24px; bottom:24px; z-index:40;
  width:46px; height:46px; border-radius:14px; cursor:pointer;
  background:var(--panel); border:1px solid var(--line-2); color:var(--text);
  font-size:19px; line-height:1; box-shadow:var(--shadow);
  opacity:0; transform:translateY(10px); pointer-events:none;
  transition:opacity .22s ease, transform .22s ease, border-color .18s ease;
}
.to-top.shown{opacity:1; transform:none; pointer-events:auto}
.to-top:hover{border-color:var(--cyan)}

@media (prefers-reduced-motion: reduce){
  html{scroll-behavior:auto}
  .to-top{transition:none}
}
.icon-btn{
  display:inline-flex; align-items:center; justify-content:center;
  width:38px; height:38px; border-radius:12px; cursor:pointer;
  background:var(--panel); border:1px solid var(--line); color:var(--text);
  font-size:15px;
}
.icon-btn:hover{border-color:var(--line-2)}

.lang{display:inline-flex}
.lang select{
  appearance:none; -webkit-appearance:none;
  height:38px; padding:0 30px 0 13px; border-radius:12px; cursor:pointer;
  background:var(--panel); border:1px solid var(--line); color:var(--text);
  font:14.5px/1 inherit; font-family:inherit;
  background-image:linear-gradient(45deg,transparent 50%,currentColor 50%),
                   linear-gradient(135deg,currentColor 50%,transparent 50%);
  background-position:calc(100% - 16px) 17px, calc(100% - 11px) 17px;
  background-size:5px 5px, 5px 5px;
  background-repeat:no-repeat;
}
.lang select:hover{border-color:var(--line-2)}
.lang select option{background:#0a1626; color:#f5f9ff}
html[data-theme="light"] .lang select option{background:#fff; color:#102033}

.visually-hidden{
  position:absolute; width:1px; height:1px; overflow:hidden;
  clip:rect(0 0 0 0); clip-path:inset(50%); white-space:nowrap;
}

/* Arabic reads the other way; the layout follows without a second stylesheet. */
[dir="rtl"] .nav-links{margin-left:0; margin-right:auto}
[dir="rtl"] .toc{text-align:right}
[dir="rtl"] ol, [dir="rtl"] ul.steps{padding-left:0; padding-right:22px}
[dir="rtl"] .note{border-left:0; border-right:1px solid var(--note-edge)}

/* ---------- buttons ---------- */

.btn{
  display:inline-flex; align-items:center; justify-content:center; gap:10px;
  min-height:52px; padding:0 26px; border-radius:15px;
  border:1px solid rgba(255,255,255,.10);
  font-weight:680; font-size:16px; transition:.22s ease; cursor:pointer;
}
.btn:hover{text-decoration:none; transform:translateY(-1px)}
.btn.primary{
  color:#04111d;
  background:linear-gradient(135deg,#9fe8ff,#5bc9ff 47%,#64e1bb);
  box-shadow:0 18px 50px rgba(62,167,255,.24);
}
.btn.primary:hover{box-shadow:0 22px 60px rgba(62,167,255,.34)}
.btn.secondary{background:var(--panel); border-color:var(--line); color:var(--text)}
.btn.secondary:hover{border-color:var(--line-2)}

/* ---------- hero ---------- */

.hero{position:relative; padding:70px 0 40px; overflow:hidden}
/* Behind the words, not in front of them. Low enough that the headline stays the loudest
   thing on the page - a background that competes with the title is decoration, not design. */
.hero-wave{
  position:absolute; left:0; right:0; top:50%; transform:translateY(-50%);
  height:300px; z-index:0; opacity:.30; pointer-events:none;
  mask-image:linear-gradient(90deg,transparent,#000 14%,#000 86%,transparent);
  -webkit-mask-image:linear-gradient(90deg,transparent,#000 14%,#000 86%,transparent);
}
html[data-theme="light"] .hero-wave{opacity:.42}
.hero-wave svg{width:100%; height:100%; display:block}
.hero .wrap{position:relative; z-index:1}

.hero-grid{display:grid; grid-template-columns:minmax(0,1fr) minmax(0,1.12fr); gap:44px; align-items:center}
/* Grid and flex children default to min-width:auto and refuse to shrink past their content.
   Everything that lays out in a track gets told it may. */
.hero-grid > *, .grid > *, .steps > *, .dl > *, footer > *{min-width:0}

.pill{
  display:inline-flex; align-items:center; gap:9px;
  padding:7px 15px; border-radius:999px; font-size:13px; letter-spacing:.04em;
  color:var(--cyan); background:var(--tint);
  border:1px solid var(--tint-edge);
}
.hero h1{
  margin:20px 0 14px; font-size:clamp(36px,5.4vw,58px); line-height:1.06;
  letter-spacing:-.028em; font-weight:760;
}
.hero h1 .soft{color:var(--muted); font-weight:600; display:block; font-size:.62em; letter-spacing:-.01em; margin-top:10px}
.hero-copy{color:var(--muted); font-size:18px; max-width:56ch; margin:0 0 30px}
.get{display:flex; flex-wrap:wrap; gap:14px; align-items:center}
.fineprint{margin:16px 0 0; font-size:13.5px; color:var(--muted)}

/* The logo is a cut-out with a real alpha channel, so it needs neither a card nor a mask -
   it simply sits on the page. Earlier attempts put it in a panel (a box inside a box) and
   then faded its edges with a radial mask, which read as a bad crop. A glow behind it does
   the work instead. */
.logo-card{text-align:center; position:relative; padding:0; overflow:visible}
.logo-card:before{
  content:""; position:absolute; inset:-8% -6% 16%;
  background:radial-gradient(ellipse at 50% 44%, rgba(84,224,255,.30), transparent 64%);
  filter:blur(58px); z-index:0; pointer-events:none;
}
.logo-card img{
  position:relative; z-index:1;
  width:118%; max-width:760px; height:auto; display:block;
  margin-inline:auto; margin-block:-4% -2%;
  filter:drop-shadow(0 22px 56px rgba(4,20,38,.6));
}
/* On a light page the artwork is bright-on-nothing, so it gets a soft dark disc to sit on
   rather than floating on white with no contrast under it. */
/* A dark disc under the logo on a white page looked like a smudge. The artwork is bright
   and already carries its own outline, so it gets light instead: a cool wash that lifts it
   off the background without putting a hole in it. */
html[data-theme="light"] .logo-card:before{
  background:
    radial-gradient(ellipse at 50% 42%, rgba(62,167,255,.20), transparent 62%),
    radial-gradient(ellipse at 50% 52%, rgba(105,228,189,.14), transparent 58%);
  filter:blur(44px);
}
html[data-theme="light"] .logo-card img{
  filter:drop-shadow(0 10px 26px rgba(20,60,100,.28));
}
html[data-theme="light"] .logo-card img{filter:none}

.tags{display:flex; flex-wrap:wrap; gap:8px; justify-content:center; margin-top:20px; position:relative; z-index:1}
.tag{
  font-size:12.5px; padding:6px 12px; border-radius:999px;
  color:var(--muted); border:1px solid var(--line); background:var(--code-bg);
}

/* ---------- sections ---------- */

section{padding:78px 0; position:relative}
/* Two columns on a wide screen: the heading on the left, the sentence that explains it on
   the right. One column left half the page empty and read as an unfinished layout. */
.section-head{
  display:grid; grid-template-columns:minmax(0,1fr) minmax(0,1fr);
  gap:14px 48px; margin-bottom:36px; align-items:end;
}
.section-head .kicker{grid-column:1; grid-row:1; align-self:end}
.section-head h2{grid-column:1; grid-row:2; margin-bottom:0}
.section-head p:not(.kicker){grid-column:2; grid-row:1 / span 2; align-self:end; margin:0}
@media (max-width:820px){
  .section-head{grid-template-columns:1fr; gap:10px}
  .section-head .kicker, .section-head h2,
  .section-head p:not(.kicker){grid-column:1; grid-row:auto}
}
.kicker{
  margin:0 0 10px; font-size:12.5px; letter-spacing:.14em; text-transform:uppercase;
  color:var(--blue); font-weight:700;
}
h2{margin:0 0 12px; font-size:clamp(26px,3.4vw,38px); line-height:1.14; letter-spacing:-.022em; font-weight:740}
.section-head p{margin:0; color:var(--muted); font-size:17px}
p.body{color:var(--muted); margin:0 0 16px; font-size:16.5px; max-width:82ch}

.panel{
  background:var(--panel); border:1px solid var(--line);
  border-radius:var(--radius); box-shadow:var(--shadow);
}

.shot{overflow:hidden; margin:30px 0 0}
.shot img{display:block; width:100%; height:auto}
.shot figcaption{padding:14px 20px; font-size:13.5px; color:var(--muted); border-top:1px solid var(--line)}

.grid{display:grid; gap:18px; grid-template-columns:repeat(auto-fit,minmax(258px,1fr)); margin-top:30px}
.feature{padding:26px 26px 28px}
.feature .mark{
  display:inline-flex; align-items:center; justify-content:center;
  width:42px; height:42px; border-radius:13px; margin-bottom:14px; font-size:19px;
  background:var(--tint); border:1px solid var(--tint-edge); color:var(--cyan);
}
.feature h3{margin:0 0 8px; font-size:17px; font-weight:700}
.feature p{margin:0; color:var(--muted); font-size:14.8px}

.steps{display:grid; gap:18px; grid-template-columns:repeat(auto-fit,minmax(240px,1fr)); margin-top:30px}
.step{padding:26px}
.step .num{font-size:12.5px; letter-spacing:.14em; color:var(--blue); font-weight:700; margin-bottom:10px}
.step h3{margin:0 0 8px; font-size:17px}
.step p{margin:0; color:var(--muted); font-size:14.8px}

.note{
  margin-top:26px; padding:20px 24px; border-radius:var(--radius-sm);
  border:1px solid var(--note-edge); background:var(--note-bg);
  color:var(--muted); font-size:15.2px;
}
.note strong{color:var(--text)}

/* ---------- downloads ---------- */

.dl{display:grid; gap:16px; grid-template-columns:repeat(auto-fit,minmax(268px,1fr)); margin-top:30px}
.dl a{padding:24px; display:block; color:inherit}
.dl a:hover{text-decoration:none; border-color:var(--line-2)}
.dl .name{font-weight:700; font-size:16px; margin-bottom:6px; color:var(--text)}
.dl .name .best{
  margin-left:8px; font-size:11px; letter-spacing:.08em; text-transform:uppercase;
  color:#04111d; background:linear-gradient(135deg,#9fe8ff,#64e1bb);
  padding:3px 8px; border-radius:999px; font-weight:800;
}
.dl .desc{color:var(--muted); font-size:14.5px; margin-bottom:12px}
.dl .size{font:12.5px/1 Consolas,monospace; color:var(--blue)}

/* ---------- release notes ---------- */

.release{padding:30px 34px; max-width:820px}
.release-head{display:flex; flex-wrap:wrap; align-items:baseline; gap:14px; margin-bottom:6px}
.release-head .ver{font-size:22px; font-weight:740}
.release-head .when{color:var(--muted); font-size:14px}
.release-body{
  margin-top:16px; padding-top:18px; border-top:1px solid var(--line);
  color:var(--muted); font-size:15.2px;
}
.release-body strong{color:var(--text)}
.release-body p{margin:0 0 12px}
.release-body code{
  font:13px/1.5 Consolas,monospace; padding:2px 6px; border-radius:6px;
  background:var(--code-bg); color:var(--cyan);
}

footer{
  padding:52px 0 70px; color:var(--muted); font-size:14px; border-top:1px solid var(--line);
  display:grid; grid-template-columns:minmax(0,1.6fr) minmax(0,1fr); gap:16px 56px;
}
footer p{margin:0 0 10px; max-width:66ch}
footer .sep{opacity:.5; margin:0 8px}

/* The right-hand column used to be empty. It carries the mark now, which is what belongs
   at the bottom of a page anyway. */
.foot-brand{
  grid-column:2; grid-row:1 / span 4; align-self:start; justify-self:end;
  max-width:320px; text-align:center;
}
.foot-brand img{width:100%; max-width:280px; height:auto; display:block; margin:0 auto 12px}
.foot-brand p{margin:0; font-size:13px; opacity:.72; max-width:none}
html[data-theme="light"] .foot-brand img{filter:drop-shadow(0 8px 20px rgba(20,60,100,.22))}

@media (max-width:820px){
  footer{grid-template-columns:1fr}
  .foot-brand{grid-column:1; grid-row:auto; justify-self:center; margin-top:22px}
}

@media (max-width:880px){
  .hero-grid{grid-template-columns:1fr; gap:26px}
  .nav-links{display:none}
  .nav-menu{display:block}      /* the links do not vanish, they move into a menu */
  .nav{gap:8px}
  .lang{order:1; margin-inline-start:auto}
  .lang select{max-width:132px}
  .icon-btn{order:2}
  section{padding:56px 0}
  .wrap{padding:0 18px}

  /* 118% of a narrow column overflows, and margin:auto cannot centre something wider than
     its container - which is why the logo sat off to one side on a phone. */
  .logo-card img{width:100%; max-width:420px; margin-inline:auto; margin-block:0}
  .logo-card:before{inset:-4% 0 12%}
  .hero{padding:44px 0 30px}
  .hero h1{font-size:clamp(30px,8vw,40px)}
  .to-top{inset-inline-end:16px; bottom:16px}
}