/* cOS — modern. Self-hosted Space Grotesk (display) + Inter (body); no external deps. */

@font-face { font-family: "Space Grotesk"; font-weight: 500; font-display: swap;
  src: url("assets/fonts/space-grotesk-latin-500-normal.woff2") format("woff2"); }
@font-face { font-family: "Space Grotesk"; font-weight: 600; font-display: swap;
  src: url("assets/fonts/space-grotesk-latin-600-normal.woff2") format("woff2"); }
@font-face { font-family: "Space Grotesk"; font-weight: 700; font-display: swap;
  src: url("assets/fonts/space-grotesk-latin-700-normal.woff2") format("woff2"); }
@font-face { font-family: "Inter"; font-weight: 400; font-display: swap;
  src: url("assets/fonts/inter-latin-400-normal.woff2") format("woff2"); }
@font-face { font-family: "Inter"; font-weight: 500; font-display: swap;
  src: url("assets/fonts/inter-latin-500-normal.woff2") format("woff2"); }
@font-face { font-family: "Inter"; font-weight: 600; font-display: swap;
  src: url("assets/fonts/inter-latin-600-normal.woff2") format("woff2"); }
@font-face { font-family: "Inter"; font-weight: 700; font-display: swap;
  src: url("assets/fonts/inter-latin-700-normal.woff2") format("woff2"); }

:root {
  --paper:      #f7f3ec;   /* warm ink-on-paper */
  --paper-2:    #f1ebe0;   /* faint band */
  --card:       #fffdf8;
  --ink:        #1b1a17;   /* near-black, warm */
  --ink-soft:   #55524b;   /* secondary text */
  --ink-faint:  #8b8779;
  --rule:       #ddd5c6;   /* hairline */
  --accent:     #1c3d5a;   /* deep navy */
  --accent-ink: #163049;
  --accent-on:  #fbfaf6;
  --tag-due:    #8a3324;   /* muted terracotta */
  --tag-prep:   #1c3d5a;
  --tag-open:   #5b4a1f;

  --display: "Space Grotesk", "Inter", system-ui, -apple-system, "Segoe UI", sans-serif;
  --sans:    "Inter", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --mono:    ui-monospace, "SF Mono", "SFMono-Regular", Menlo, Consolas, monospace;

  --wrap: 1080px;
  --gutter: clamp(20px, 5vw, 48px);
}

/* Dark palette — applied by the visitor's OS preference, unless they've forced light
   (?theme=light → data-theme). Forcing dark uses [data-theme="dark"]. */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) { color-scheme: dark;
    --paper: #15161a; --paper-2: #191b20; --card: #1d1f25;
    --ink: #edeae3; --ink-soft: #a8a49b; --ink-faint: #7c7870; --rule: #2c2e35;
    --accent: #8fb4d6; --accent-ink: #a8c6e2; --accent-on: #12131a;
    --tag-due: #d98a72; --tag-prep: #8fb4d6; --tag-open: #cbb583;
  }
}
:root[data-theme="dark"] { color-scheme: dark;
  --paper: #15161a; --paper-2: #191b20; --card: #1d1f25;
  --ink: #edeae3; --ink-soft: #a8a49b; --ink-faint: #7c7870; --rule: #2c2e35;
  --accent: #8fb4d6; --accent-ink: #a8c6e2; --accent-on: #12131a;
  --tag-due: #d98a72; --tag-prep: #8fb4d6; --tag-open: #cbb583;
}

* { box-sizing: border-box; }
html, body { overflow-x: hidden; }   /* safety net against any sub-pixel horizontal overflow */
html { scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

.wrap { max-width: var(--wrap); margin: 0 auto; padding-inline: var(--gutter); }

h1, h2, h3 { font-family: var(--display); font-weight: 600; color: var(--ink); letter-spacing: -0.01em; }
h1 { font-weight: 500; font-size: clamp(2.2rem, 4.6vw, 3.4rem); line-height: 1.12;
     letter-spacing: -0.02em; margin: 0 0 .55em; }
h2 { font-size: clamp(1.8rem, 3.6vw, 2.7rem); line-height: 1.12; margin: 0; }
h3 { font-size: 1.28rem; line-height: 1.25; margin: 0 0 .35em; }
p  { margin: 0 0 1em; }
a  { color: var(--accent); text-decoration-thickness: 1px; text-underline-offset: 3px; }
code { font-family: var(--mono); font-size: .9em; background: var(--paper-2); padding: .12em .4em; border-radius: 4px; }

.skip {
  position: absolute; left: -9999px; top: 0; background: var(--ink); color: var(--paper);
  padding: 10px 16px; z-index: 100;
}
.skip:focus { left: 12px; top: 12px; }

/* ---------- header ---------- */
.site {
  position: sticky; top: 0; z-index: 50;
  background: color-mix(in srgb, var(--paper) 88%, transparent);
  backdrop-filter: saturate(1.2) blur(8px);
  border-bottom: 1px solid var(--rule);
}
.bar { display: flex; align-items: center; gap: 24px; height: 64px; }
.mark { display: flex; align-items: center; text-decoration: none; margin-right: auto; }
.mono { font-family: var(--display); font-weight: 600; letter-spacing: .06em; font-size: 1.15rem; color: var(--ink); }
.nav { display: flex; gap: 26px; }
.nav a { color: var(--ink-soft); text-decoration: none; font-size: .95rem; }
.nav a:hover { color: var(--ink); }
@media (max-width: 760px) { .nav { display: none; } }

.btn {
  display: inline-block; font: inherit; font-size: .95rem; line-height: 1;
  padding: 11px 18px; border-radius: 8px; text-decoration: none; cursor: pointer;
  transition: transform .12s ease, background .15s ease, border-color .15s ease;
}
.btn-quiet { border: 1px solid var(--rule); color: var(--ink); background: transparent; }
.btn-quiet:hover { border-color: var(--ink-faint); }
.btn-solid { background: var(--accent); color: var(--accent-on); border: 1px solid var(--accent); }
.btn-solid:hover { background: var(--accent-ink); transform: translateY(-1px); }

.link-arrow { color: var(--ink); text-decoration: none; font-weight: 500; }
.link-arrow::after { content: " →"; color: var(--accent); }
.link-arrow:hover { color: var(--accent); }

/* ---------- hero ---------- */
.hero {
  display: grid; grid-template-columns: 1.15fr .85fr; gap: clamp(28px, 5vw, 72px);
  align-items: center; padding-top: clamp(56px, 9vw, 104px); padding-bottom: clamp(48px, 8vw, 88px);
}
.eyebrow {
  font-family: var(--sans); text-transform: uppercase; letter-spacing: .16em;
  font-size: .74rem; font-weight: 600; color: var(--accent); margin: 0 0 1.1em;
}
.lede { font-size: 1.22rem; color: var(--ink-soft); max-width: 34ch; margin: .2em 0 1.8em; }
.cta-row { display: flex; align-items: center; gap: 22px; flex-wrap: wrap; }
.cta-row.center { justify-content: center; }
@media (max-width: 860px) {
  .hero { grid-template-columns: 1fr; }
  .hero-art { order: -1; max-width: min(460px, 100%); justify-self: start; }
}
.hero-art { min-width: 0; }
.brief { max-width: 100%; }

/* hero mock brief card */
.brief {
  background: var(--card); border: 1px solid var(--rule); border-radius: 14px;
  padding: 22px 22px 16px; box-shadow: 0 1px 0 rgba(0,0,0,.02), 0 24px 48px -32px rgba(20,20,20,.28);
  transform: rotate(-.6deg);
}
.brief-top { display: flex; align-items: baseline; gap: 6px; margin-bottom: 12px; }
.brief-day { font-family: var(--display); font-weight: 600; font-size: 1.05rem; }
.brief-date { color: var(--ink-faint); font-size: .85rem; }
.brief-bottomline { font-size: 1.02rem; line-height: 1.45; margin: 0 0 16px; }
.brief-list { list-style: none; margin: 0; padding: 0; display: grid; gap: 10px; }
.brief-list li {
  font-size: .93rem; color: var(--ink-soft); display: flex; gap: 10px; align-items: baseline;
  padding-top: 10px; border-top: 1px solid var(--rule);
}
.tag {
  font-family: var(--sans); font-size: .66rem; font-weight: 700; text-transform: uppercase;
  letter-spacing: .06em; padding: 3px 7px; border-radius: 5px; white-space: nowrap;
  border: 1px solid currentColor;
}
.tag-due { color: var(--tag-due); }
.tag-prep { color: var(--tag-prep); }
.tag-open { color: var(--tag-open); }
.brief-foot { margin-top: 14px; color: var(--ink-faint); font-size: .76rem; letter-spacing: .02em; }

/* ---------- sections ---------- */
.section { padding-block: clamp(56px, 9vw, 104px); }
.section-head { max-width: 40ch; margin-bottom: clamp(32px, 5vw, 56px); }
.kicker {
  text-transform: uppercase; letter-spacing: .16em; font-size: .74rem; font-weight: 600;
  color: var(--ink-faint); margin: 0 0 1em;
}
.band { background: var(--paper-2); border-block: 1px solid var(--rule); }

.grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 0; }
@media (max-width: 860px) { .grid { grid-template-columns: 1fr 1fr; } }
@media (max-width: 560px) { .grid { grid-template-columns: 1fr; } }
.cap {
  padding: 28px 28px 30px; border-top: 1px solid var(--rule);
  border-left: 1px solid var(--rule);
}
.grid .cap:nth-child(3n+1) { border-left: none; padding-left: 0; }
@media (max-width: 860px) {
  .grid .cap { border-left: 1px solid var(--rule); padding-left: 28px; }
  .grid .cap:nth-child(2n+1) { border-left: none; padding-left: 0; }
}
@media (max-width: 560px) {
  .grid .cap, .grid .cap:nth-child(n) { border-left: none; padding-left: 0; }
}
.cap-no { font-family: var(--display); font-size: .95rem; color: var(--accent); display: block; margin-bottom: 14px; }
.cap p { color: var(--ink-soft); font-size: .98rem; margin: 0; }

/* steps */
.steps { list-style: none; margin: 0; padding: 0; display: grid; gap: 4px; max-width: 720px; counter-reset: s; }
.step { display: grid; grid-template-columns: 56px 1fr; gap: 20px; padding: 24px 0; border-top: 1px solid var(--rule); align-items: start; }
.step:first-child { border-top: none; }
.step-no {
  font-family: var(--display); font-size: 1.5rem; color: var(--accent);
  width: 44px; height: 44px; border: 1px solid var(--rule); border-radius: 50%;
  display: grid; place-items: center;
}
.step p { color: var(--ink-soft); margin: 0; }

/* private split */
.split { display: grid; grid-template-columns: 1fr 1fr; gap: clamp(28px, 6vw, 72px); align-items: start; }
@media (max-width: 800px) { .split { grid-template-columns: 1fr; } }
.prose p { color: var(--ink-soft); font-size: 1.05rem; }
.prose strong { color: var(--ink); font-weight: 600; }

/* closer */
.closer { text-align: center; padding-block: clamp(64px, 10vw, 120px); }
.closer h2 { margin-bottom: .3em; }
.closer p { color: var(--ink-soft); font-size: 1.12rem; margin-bottom: 1.8em; }

/* footer */
.site-foot { border-top: 1px solid var(--rule); padding-block: 28px; }
.foot { display: flex; align-items: center; gap: 18px; flex-wrap: wrap; }
.foot .mono { font-size: 1rem; }
.foot-note { color: var(--ink-soft); font-size: .9rem; margin-right: auto; }
.site-foot a { color: var(--ink-soft); text-decoration: none; font-size: .9rem; }
.site-foot a:hover { color: var(--ink); }

/* reveal on scroll */
.reveal { opacity: 0; transform: translateY(14px); transition: opacity .7s ease, transform .7s ease; }
.reveal.in { opacity: 1; transform: none; }
@media (prefers-reduced-motion: reduce) { .reveal { opacity: 1; transform: none; transition: none; } }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; border-radius: 3px; }

/* desktop-app requirement note under the download CTAs */
.req { margin-top: 14px; font-size: .82rem; color: var(--ink-faint); }
.closer .req { text-align: center; }

/* mobile "this is a desktop app" warning dialog */
.mnote { max-width: 430px; width: calc(100% - 40px); border: 1px solid var(--rule); border-radius: 16px;
  background: var(--card); color: var(--ink); padding: 26px 26px 22px; box-shadow: 0 24px 60px rgba(20,19,17,.22); }
.mnote::backdrop { background: rgba(20,19,17,.45); }
.mnote h3 { font-family: var(--display); font-weight: 600; font-size: 1.35rem; letter-spacing: -.01em; margin: 0 0 .55rem; }
.mnote p { color: var(--ink-soft); line-height: 1.55; margin: 0 0 1.15rem; }
.mnote-actions { display: flex; gap: .6rem; flex-wrap: wrap; }