/* Trichrome — the site.
   The game is additive light on a dark ground, so the page is too: colour that blooms
   rather than fills, and panels that glow at the edge instead of sitting flat. */

:root {
  --bg-top:   #1a1030;
  --bg-bot:   #07040e;
  --panel:    rgba(255,255,255,0.035);
  --line:     rgba(255,255,255,0.09);
  --text:     #ffffff;
  --dim:      rgba(255,255,255,0.66);
  --faint:    rgba(255,255,255,0.40);
  --accent:   #73c7ff;
  --red:      #ff3a5c;
  --green:    #3aff8f;
  --blue:     #4d94ff;
  --yellow:   #ffd83a;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  color: var(--text);
  background:
    radial-gradient(60rem 40rem at 50% -10rem, #2a1a4d 0%, transparent 70%),
    linear-gradient(180deg, var(--bg-top) 0%, var(--bg-bot) 55%);
  background-color: var(--bg-bot);
  background-attachment: fixed;
  font: 400 17px/1.7 -apple-system, BlinkMacSystemFont, "SF Pro Text", "Segoe UI", Roboto, sans-serif;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

.wrap { max-width: 44rem; margin: 0 auto; padding: 5rem 1.5rem 6rem; }

/* ---- Header -------------------------------------------------------------- */

header { text-align: center; margin-bottom: 4rem; }

.mark {
  width: 116px; height: 116px;
  filter: drop-shadow(0 0 26px rgba(120,110,255,0.45));
  animation: breathe 5.5s ease-in-out infinite;
}
@keyframes breathe {
  0%, 100% { opacity: 0.92; transform: scale(1); }
  50%      { opacity: 1;    transform: scale(1.035); }
}
@media (prefers-reduced-motion: reduce) { .mark { animation: none; } }

h1 {
  font-size: clamp(2rem, 7vw, 2.6rem);
  letter-spacing: 0.26em;
  margin: 1.4rem 0 0.4rem;
  font-weight: 700;
  text-indent: 0.26em;           /* re-centre against the trailing letter-space */
}

.tagline { color: var(--dim); margin: 0; font-size: 1.02rem; }

nav {
  display: flex; gap: 1.75rem; justify-content: center;
  margin-top: 1.75rem; font-size: 0.94rem;
}
nav a {
  color: var(--faint); text-decoration: none;
  padding-bottom: 0.3rem; border-bottom: 1px solid transparent;
  transition: color 0.18s ease, border-color 0.18s ease;
}
nav a:hover { color: var(--text); }
nav a.on { color: var(--accent); border-bottom-color: var(--accent); }

/* ---- Type ---------------------------------------------------------------- */

h2 {
  font-size: 1.05rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--accent);
  margin: 3.5rem 0 1rem;
  font-weight: 600;
}

h3 { font-size: 1.02rem; margin: 0 0 0.45rem; color: var(--text); font-weight: 600; }

p, li { color: var(--dim); }
strong { color: var(--text); font-weight: 600; }
em { color: var(--text); font-style: normal; opacity: 0.85; }

a { color: var(--accent); text-decoration-thickness: 1px; text-underline-offset: 2px; }

.lede {
  color: var(--text);
  font-size: clamp(1.1rem, 3.4vw, 1.28rem);
  line-height: 1.55;
  text-align: center;
  margin: 0 auto 2.5rem;
  max-width: 32rem;
}

/* ---- Surfaces ------------------------------------------------------------ */

.panel, .card {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 1.1rem;
  padding: 1.5rem 1.6rem;
  position: relative;
  overflow: hidden;
}
/* A soft bloom along the top edge, so a panel reads as lit rather than filled. */
.panel::before, .card::before {
  content: ""; position: absolute; inset: -40% 20% auto 20%; height: 70%;
  background: radial-gradient(closest-side, rgba(140,160,255,0.16), transparent);
  pointer-events: none;
}
.panel { margin: 2rem 0; }

.cols { display: grid; grid-template-columns: 1fr 1fr; gap: 1.1rem; margin: 1.5rem 0; }
@media (max-width: 36rem) { .cols { grid-template-columns: 1fr; } }

.card ul { margin: 0; padding-left: 1.15rem; }
.card li { margin-bottom: 0.45rem; }
.card li:last-child { margin-bottom: 0; }

/* ---- The colour arithmetic ---------------------------------------------- */

.sum {
  display: flex; align-items: center; justify-content: center;
  gap: clamp(0.5rem, 3vw, 1.1rem);
  margin: 2.5rem 0 1rem; flex-wrap: wrap;
}
.disc {
  width: clamp(38px, 11vw, 52px); aspect-ratio: 1; border-radius: 50%;
}
.disc.red    { background: var(--red);    box-shadow: 0 0 26px 2px rgba(255,58,92,0.65); }
.disc.green  { background: var(--green);  box-shadow: 0 0 26px 2px rgba(58,255,143,0.55); }
.disc.blue   { background: var(--blue);   box-shadow: 0 0 26px 2px rgba(77,148,255,0.6); }
.disc.yellow { background: var(--yellow); box-shadow: 0 0 30px 3px rgba(255,216,58,0.7); }
.disc.white  { background: #fffdf5;       box-shadow: 0 0 34px 4px rgba(255,255,255,0.75); }
.op { color: var(--faint); font-size: 1.35rem; font-weight: 300; }
.caption { text-align: center; color: var(--faint); font-size: 0.93rem; margin: 0.25rem 0 0; }

.swatch {
  display: inline-block; width: 0.72em; height: 0.72em; border-radius: 50%;
  vertical-align: -1px; margin-right: 0.2em;
}

/* ---- Q&A ----------------------------------------------------------------- */

.q { margin: 0 0 1.9rem; padding-left: 1rem; border-left: 2px solid var(--line); }
.q p { margin: 0; }

/* ---- Footer -------------------------------------------------------------- */

footer {
  margin-top: 4.5rem; padding-top: 1.75rem;
  border-top: 1px solid var(--line);
  color: var(--faint); font-size: 0.9rem; text-align: center;
}
footer a { color: var(--faint); }
footer a:hover { color: var(--text); }