/*
 * Fun with Binary
 * Copyright (C) 2018–2026 Diogo Cordeiro
 * SPDX-License-Identifier: AGPL-3.0-or-later
 */

:root {
  color-scheme: dark;
  --bg: #06101b;
  --bg-soft: #0a1827;
  --panel: rgba(12, 29, 46, .82);
  --panel-strong: #0d2033;
  --line: rgba(158, 198, 225, .16);
  --line-strong: rgba(158, 198, 225, .28);
  --ink: #f4fbff;
  --ink-soft: #a8becd;
  --cyan: #75edff;
  --cyan-strong: #16c9e8;
  --mint: #7fffd4;
  --yellow: #ffe18a;
  --danger: #ff8f9c;
  --shadow: 0 30px 90px -48px rgba(0, 0, 0, .9);
  --radius: 28px;
  --mono: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
  --sans: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  min-width: 320px;
  margin: 0;
  color: var(--ink);
  background:
    radial-gradient(circle at 8% 4%, rgba(22, 201, 232, .14), transparent 28rem),
    radial-gradient(circle at 92% 24%, rgba(127, 255, 212, .08), transparent 24rem),
    linear-gradient(180deg, #07131f 0%, var(--bg) 55%, #050d16 100%);
  font-family: var(--sans);
  line-height: 1.55;
}
body::before {
  position: fixed;
  inset: 0;
  z-index: -1;
  content: "";
  opacity: .32;
  pointer-events: none;
  background-image:
    linear-gradient(rgba(255, 255, 255, .022) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, .022) 1px, transparent 1px);
  background-size: 42px 42px;
  mask-image: linear-gradient(to bottom, black, transparent 85%);
}
a { color: inherit; }
button, a { -webkit-tap-highlight-color: transparent; }
button { font: inherit; }
.skip-link {
  position: fixed;
  top: 0;
  left: 1rem;
  z-index: 100;
  padding: .75rem 1rem;
  color: #041019;
  background: var(--cyan);
  border-radius: 10px;
  font-weight: 800;
  transform: translateY(-120%);
}
.skip-link:focus { transform: translateY(1rem); }
.site-header, main, footer {
  width: min(1180px, calc(100% - 2rem));
  margin-inline: auto;
}
.site-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
  padding: 1.25rem 0;
}
.brand {
  display: inline-flex;
  align-items: center;
  gap: .8rem;
  text-decoration: none;
}
.brand img {
  display: block;
  filter: drop-shadow(0 12px 18px rgba(22, 201, 232, .18));
}
.brand span { display: grid; line-height: 1.1; }
.brand strong { font-size: .98rem; letter-spacing: -.015em; }
.brand small {
  margin-top: .3rem;
  color: var(--ink-soft);
  font-size: .72rem;
  letter-spacing: .08em;
  text-transform: uppercase;
}
nav { display: flex; align-items: center; gap: 1.2rem; }
nav a {
  color: var(--ink-soft);
  font-size: .9rem;
  font-weight: 700;
  text-decoration: none;
}
nav a:hover, nav a:focus-visible { color: var(--cyan); }
main { padding: clamp(3rem, 7vw, 7rem) 0 5rem; }
.hero {
  display: grid;
  grid-template-columns: minmax(0, 1.35fr) minmax(17rem, .65fr);
  align-items: end;
  gap: clamp(2rem, 6vw, 6rem);
  padding: 0 clamp(.2rem, 2vw, 1.5rem) clamp(3rem, 7vw, 6rem);
}
.eyebrow, .section-label {
  margin: 0;
  color: var(--cyan);
  font-family: var(--mono);
  font-size: .76rem;
  font-weight: 800;
  letter-spacing: .12em;
  text-transform: uppercase;
}
h1, h2, h3, p { margin-top: 0; }
h1 {
  max-width: 13ch;
  margin: .7rem 0 1.2rem;
  font-size: clamp(3.2rem, 8vw, 7rem);
  line-height: .88;
  letter-spacing: -.07em;
}
.hero-lede {
  max-width: 62ch;
  margin-bottom: 0;
  color: var(--ink-soft);
  font-size: clamp(1rem, 1.7vw, 1.24rem);
}
.hero-binary {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: .65rem;
  justify-self: end;
  width: min(100%, 23rem);
  transform: rotate(2deg);
}
.hero-binary span {
  display: grid;
  aspect-ratio: 1;
  place-items: center;
  border: 1px solid var(--line-strong);
  border-radius: 22px;
  color: var(--cyan);
  background: linear-gradient(145deg, rgba(15, 38, 60, .94), rgba(7, 21, 35, .88));
  box-shadow: inset 0 1px rgba(255, 255, 255, .08), 0 18px 50px -35px rgba(22, 201, 232, .9);
  font-family: var(--mono);
  font-size: clamp(2rem, 5vw, 4rem);
  font-weight: 900;
}
.hero-binary span:nth-child(2), .hero-binary span:nth-child(5) {
  color: var(--mint);
  transform: translateY(-.8rem);
}
.game-shell {
  overflow: hidden;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius);
  background:
    radial-gradient(circle at 0% 0%, rgba(22, 201, 232, .11), transparent 24rem),
    linear-gradient(150deg, rgba(14, 35, 55, .93), rgba(7, 20, 33, .94));
  box-shadow: var(--shadow);
}
.game-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
  padding: clamp(1.35rem, 3vw, 2.25rem);
  border-bottom: 1px solid var(--line);
}
.game-toolbar h2 {
  margin: .35rem 0 0;
  font-size: clamp(1.45rem, 3vw, 2.25rem);
  line-height: 1.08;
  letter-spacing: -.035em;
}
#target-number { color: var(--yellow); font-family: var(--mono); }
.toolbar-actions { display: flex; gap: .65rem; flex: 0 0 auto; }
.button {
  display: inline-flex;
  min-height: 2.9rem;
  align-items: center;
  justify-content: center;
  gap: .55rem;
  padding: .72rem 1rem;
  border: 1px solid transparent;
  border-radius: 13px;
  cursor: pointer;
  font-size: .86rem;
  font-weight: 800;
  transition: transform .16s ease, border-color .16s ease, background .16s ease;
}
.button:hover { transform: translateY(-2px); }
.button:focus-visible, .bit-button:focus-visible {
  outline: 3px solid rgba(117, 237, 255, .46);
  outline-offset: 3px;
}
.button-primary {
  color: #031018;
  background: linear-gradient(135deg, var(--cyan), var(--mint));
  box-shadow: 0 12px 35px -20px rgba(117, 237, 255, .9);
}
.button-quiet {
  color: var(--ink);
  border-color: var(--line-strong);
  background: rgba(255, 255, 255, .035);
}
.button-icon { font-family: var(--mono); }
.game-grid { display: grid; grid-template-columns: minmax(0, 1fr) minmax(15rem, .31fr); }
.bits-panel { padding: clamp(1.5rem, 4vw, 3rem); }
.bits-heading {
  display: flex;
  justify-content: space-between;
  margin-bottom: 1rem;
  color: var(--ink-soft);
  font-size: .72rem;
  font-weight: 800;
  letter-spacing: .08em;
  text-transform: uppercase;
}
.bits {
  display: grid;
  grid-template-columns: repeat(6, minmax(4.2rem, 1fr));
  gap: clamp(.55rem, 1.4vw, 1rem);
}
.bit { display: grid; gap: .65rem; min-width: 0; text-align: center; }
.bit-weight {
  display: grid;
  min-height: 1.5rem;
  place-items: center;
  color: var(--ink-soft);
  font-family: var(--mono);
  font-size: .78rem;
  font-weight: 800;
  transition: opacity .18s ease, transform .18s ease;
}
.bits.hide-weights .bit-weight { opacity: 0; transform: translateY(.35rem); }
.bit-button {
  position: relative;
  display: grid;
  width: 100%;
  min-height: clamp(7rem, 13vw, 10rem);
  place-items: center;
  padding: 1rem .35rem;
  overflow: hidden;
  color: #7f9aad;
  border: 1px solid var(--line-strong);
  border-radius: 20px;
  background: linear-gradient(180deg, rgba(255, 255, 255, .03), transparent), #071725;
  box-shadow: inset 0 1px rgba(255, 255, 255, .04);
  cursor: pointer;
  font-family: var(--mono);
  font-size: clamp(2.3rem, 5vw, 4.4rem);
  font-weight: 900;
  transition: color .18s ease, border-color .18s ease, background .18s ease, transform .18s ease, box-shadow .18s ease;
}
.bit-button::after {
  position: absolute;
  right: .55rem;
  bottom: .45rem;
  color: rgba(168, 190, 205, .5);
  content: attr(data-key);
  font-size: .65rem;
}
.bit-button:hover { border-color: rgba(117, 237, 255, .42); transform: translateY(-3px); }
.bit-button[aria-pressed="true"] {
  color: #03131d;
  border-color: rgba(127, 255, 212, .82);
  background:
    radial-gradient(circle at 50% 20%, rgba(255, 255, 255, .55), transparent 40%),
    linear-gradient(145deg, var(--mint), var(--cyan));
  box-shadow: 0 18px 45px -22px rgba(117, 237, 255, .85), inset 0 1px rgba(255, 255, 255, .75);
  transform: translateY(-5px);
}
.bit-index { color: #7891a3; font-family: var(--mono); font-size: .68rem; }
.keyboard-hint {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: .55rem;
  margin-top: 1.5rem;
  color: var(--ink-soft);
  font-size: .78rem;
}
.hint-dot {
  width: .45rem;
  height: .45rem;
  border-radius: 50%;
  background: var(--mint);
  box-shadow: 0 0 14px var(--mint);
}
kbd {
  display: inline-grid;
  min-width: 1.4rem;
  min-height: 1.35rem;
  place-items: center;
  padding: 0 .25rem;
  color: var(--ink);
  border: 1px solid var(--line-strong);
  border-bottom-width: 2px;
  border-radius: 5px;
  background: rgba(255, 255, 255, .04);
  font-family: var(--mono);
  font-size: .7rem;
}
.number-panel {
  display: flex;
  flex-direction: column;
  justify-content: center;
  min-width: 0;
  padding: clamp(1.5rem, 4vw, 2.6rem);
  border-left: 1px solid var(--line);
  background: rgba(3, 13, 23, .38);
}
.decimal-value {
  margin-top: .5rem;
  font-family: var(--mono);
  font-size: clamp(4rem, 8vw, 7rem);
  font-weight: 900;
  line-height: 1;
  letter-spacing: -.08em;
}
.binary-value {
  margin-top: .8rem;
  color: var(--cyan);
  font-family: var(--mono);
  font-size: clamp(1.2rem, 2.3vw, 1.8rem);
  font-weight: 800;
  letter-spacing: .16em;
}
.sum {
  min-height: 1.5rem;
  margin-top: .65rem;
  color: var(--ink-soft);
  font-family: var(--mono);
  font-size: .78rem;
}
.progress-track {
  height: .45rem;
  margin-top: 1.6rem;
  overflow: hidden;
  border-radius: 999px;
  background: rgba(255, 255, 255, .07);
}
.progress-track span {
  display: block;
  width: 0;
  height: 100%;
  border-radius: inherit;
  background: linear-gradient(90deg, var(--cyan), var(--mint));
  transition: width .2s ease;
}
.difference {
  min-height: 2.7rem;
  margin: .75rem 0 1.35rem;
  color: var(--ink-soft);
  font-size: .82rem;
}
.difference.too-high { color: var(--danger); }
.scoreboard { display: grid; grid-template-columns: 1fr 1fr; gap: .6rem; margin-top: auto; }
.scoreboard div {
  display: grid;
  gap: .2rem;
  padding: .8rem;
  border: 1px solid var(--line);
  border-radius: 13px;
  background: rgba(255, 255, 255, .025);
}
.scoreboard span {
  color: var(--ink-soft);
  font-size: .68rem;
  font-weight: 800;
  letter-spacing: .06em;
  text-transform: uppercase;
}
.scoreboard strong { font-family: var(--mono); font-size: 1.35rem; }
.success {
  display: flex;
  align-items: center;
  gap: .9rem;
  padding: 1rem clamp(1.5rem, 4vw, 3rem);
  color: #062017;
  background: linear-gradient(90deg, var(--mint), #b7ffe7);
}
.success[hidden] { display: none; }
.success-mark {
  display: grid;
  width: 2rem;
  height: 2rem;
  flex: 0 0 auto;
  place-items: center;
  border: 2px solid currentColor;
  border-radius: 50%;
  font-weight: 900;
}
.success div { display: grid; line-height: 1.25; }
.success span:last-child { font-family: var(--mono); font-size: .78rem; }
.explanation {
  display: grid;
  grid-template-columns: minmax(16rem, .65fr) minmax(0, 1.35fr);
  gap: clamp(2rem, 7vw, 6rem);
  padding: clamp(5rem, 9vw, 8rem) clamp(.2rem, 2vw, 1.5rem) 1rem;
}
.explanation h2 {
  max-width: 12ch;
  margin: .65rem 0 0;
  font-size: clamp(2.1rem, 5vw, 4rem);
  line-height: .97;
  letter-spacing: -.055em;
}
.explanation-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: .8rem; }
.explanation article {
  padding: 1.35rem;
  border: 1px solid var(--line);
  border-radius: 18px;
  background: rgba(255, 255, 255, .025);
}
.step-number { color: var(--cyan); font-family: var(--mono); font-size: .8rem; font-weight: 900; }
.explanation h3 { margin: 1.5rem 0 .45rem; font-size: 1rem; }
.explanation article p { margin-bottom: 0; color: var(--ink-soft); font-size: .86rem; }
footer {
  display: flex;
  justify-content: space-between;
  gap: 2rem;
  padding: 2rem 0 2.5rem;
  color: var(--ink-soft);
  border-top: 1px solid var(--line);
  font-size: .8rem;
}
footer p { margin: 0; }
footer a:hover, footer a:focus-visible { color: var(--cyan); }
.confetti {
  position: fixed;
  inset: 0;
  z-index: 90;
  overflow: hidden;
  pointer-events: none;
}
.confetti i {
  position: absolute;
  top: 42%;
  left: 50%;
  width: .45rem;
  height: .75rem;
  border-radius: 2px;
  background: var(--cyan);
  animation: confetti .9s cubic-bezier(.2, .8, .3, 1) forwards;
}
@keyframes confetti {
  from { opacity: 1; transform: translate(-50%, -50%) rotate(0deg); }
  to { opacity: 0; transform: translate(calc(-50% + var(--x)), calc(-50% + var(--y))) rotate(var(--r)); }
}
@media (max-width: 900px) {
  .hero { grid-template-columns: 1fr; }
  .hero-binary { justify-self: start; width: min(100%, 29rem); }
  .game-grid { grid-template-columns: 1fr; }
  .number-panel {
    display: grid;
    grid-template-columns: auto 1fr;
    column-gap: 1.4rem;
    align-items: center;
    border-top: 1px solid var(--line);
    border-left: 0;
  }
  .number-panel .section-label, .number-panel .decimal-value, .number-panel .binary-value,
  .number-panel .sum, .number-panel .progress-track, .number-panel .difference { grid-column: 1; }
  .scoreboard { grid-column: 2; grid-row: 1 / span 6; align-self: center; margin: 0; }
  .explanation { grid-template-columns: 1fr; }
}
@media (max-width: 700px) {
  .site-header nav a:first-child { display: none; }
  main { padding-top: 2.5rem; }
  .game-toolbar { align-items: flex-start; flex-direction: column; }
  .toolbar-actions { width: 100%; }
  .toolbar-actions .button { flex: 1; }
  .bits { grid-template-columns: repeat(3, 1fr); }
  .bits-heading { display: none; }
  .bit-button { min-height: 7rem; }
  .explanation-grid { grid-template-columns: 1fr; }
  footer { flex-direction: column; gap: .6rem; }
}
@media (max-width: 460px) {
  .site-header, main, footer { width: min(100% - 1.1rem, 1180px); }
  .brand small { display: none; }
  nav { gap: .6rem; }
  .hero { padding-inline: .2rem; }
  h1 { font-size: clamp(3rem, 17vw, 4.6rem); }
  .game-shell { border-radius: 21px; }
  .toolbar-actions { flex-direction: column; }
  .number-panel { display: block; }
  .scoreboard { margin-top: 1.2rem; }
  .keyboard-hint { display: none; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: .01ms !important;
    animation-iteration-count: 1 !important;
    scroll-behavior: auto !important;
    transition-duration: .01ms !important;
  }
}