/* ============================================================
   Background Remover — monochrome base, electric-blue accent.
   Same token system as the other base31 tools, so the page
   inherits the family look while reading as a distinct tool.
   ============================================================ */
:root {
  --bg: #fafafa;
  --bg-elev: #ffffff;
  --card: #ffffff;
  --line: #e6e6e6;
  --line-strong: #d4d4d4;
  --fg: #0a0a0a;
  --fg-soft: #171717;
  --muted: #6b7280;
  --muted-2: #9ca3af;
  --hover: #f4f4f5;
  --accent: #4f8cff;
  --accent-strong: #2563eb;
  --accent-soft: #eef4ff;
  --accent-2: #22d3ee;
  --warn: #d97706;
  --warn-soft: #fffbeb;
  --danger: #ef4444;
  --danger-soft: #fef2f2;
  --ring: rgba(79, 140, 255, 0.35);
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.04);
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.06), 0 10px 30px rgba(0, 0, 0, 0.06);
  --radius: 14px;
  --radius-sm: 9px;
  --grid: rgba(0, 0, 0, 0.04);
  --checker-a: #ffffff;
  --checker-b: #e9edf3;
}
html[data-theme="dark"] {
  --bg: #050506;
  --bg-elev: #0a0a0c;
  --card: #0d0d10;
  --line: #232329;
  --line-strong: #333340;
  --fg: #f5f6f8;
  --fg-soft: #ededed;
  --muted: #9aa1ad;
  --muted-2: #6b7280;
  --hover: #15151a;
  --accent: #6ea1ff;
  --accent-strong: #8ab5ff;
  --accent-soft: rgba(79, 140, 255, 0.12);
  --accent-2: #34d3ea;
  --warn: #fbbf24;
  --warn-soft: rgba(251, 191, 36, 0.1);
  --danger: #f87171;
  --danger-soft: rgba(248, 113, 113, 0.1);
  --ring: rgba(110, 161, 255, 0.4);
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.4);
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.5), 0 14px 36px rgba(0, 0, 0, 0.5);
  --grid: rgba(255, 255, 255, 0.03);
  --checker-a: #16161c;
  --checker-b: #1f1f27;
}

*, *::before, *::after { box-sizing: border-box; }
[hidden] { display: none !important; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
[id] { scroll-margin-top: 5rem; }
body {
  margin: 0;
  background:
    radial-gradient(1200px 600px at 80% -10%, color-mix(in srgb, var(--accent) 9%, transparent), transparent 60%),
    var(--bg);
  color: var(--fg);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, "Segoe UI", sans-serif;
  -webkit-font-smoothing: antialiased;
  line-height: 1.55;
}
.mono { font-family: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; }
a { color: inherit; }
.skip {
  position: absolute; left: 12px; top: -60px; z-index: 100;
  padding: 9px 14px; border-radius: 10px; background: var(--accent); color: #fff;
  text-decoration: none; transition: top 140ms ease;
}
.skip:focus { top: 12px; }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.wrap { width: min(100% - 40px, 1080px); margin: 0 auto; }

/* Top bar -------------------------------------------------------------- */
.topbar {
  position: sticky; top: 0; z-index: 40;
  border-bottom: 1px solid var(--line);
  background: color-mix(in srgb, var(--bg) 82%, transparent);
  backdrop-filter: blur(12px) saturate(150%);
  -webkit-backdrop-filter: blur(12px) saturate(150%);
}
.topbar-inner { display: flex; align-items: center; justify-content: space-between; min-height: 60px; gap: 16px; }
.brand { display: inline-flex; align-items: center; gap: 10px; font-weight: 600; font-size: 14px; text-decoration: none; }
.brand-mark {
  display: grid; place-items: center; width: 30px; height: 30px; border-radius: 9px;
  background: linear-gradient(135deg, var(--accent), var(--accent-2)); color: #fff;
}
.topbar-actions { display: flex; align-items: center; gap: 10px; }
.icon-btn {
  display: grid; place-items: center; width: 34px; height: 34px;
  border: 1px solid var(--line); border-radius: 9px; background: var(--card); color: var(--muted);
  cursor: pointer; transition: color 150ms ease, border-color 150ms ease, background 150ms ease;
}
.icon-btn:hover { color: var(--fg); border-color: var(--line-strong); background: var(--hover); }
.icon-btn svg { width: 16px; height: 16px; }

/* Hero ----------------------------------------------------------------- */
main { padding: 40px 0 90px; }
.hero { max-width: 720px; padding: 26px 0 8px; }
.pill {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 6px 12px; border: 1px solid color-mix(in srgb, var(--accent) 34%, var(--line));
  border-radius: 999px; background: var(--accent-soft); color: var(--fg-soft);
  font-size: 12px; font-weight: 500;
}
.dot { width: 7px; height: 7px; border-radius: 50%; background: var(--accent); box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 22%, transparent); }
.hero h1 { margin: 18px 0 0; font-size: clamp(30px, 5.4vw, 52px); font-weight: 700; letter-spacing: -0.04em; line-height: 1.05; }
.grad { background: linear-gradient(100deg, var(--accent), var(--accent-2)); -webkit-background-clip: text; background-clip: text; color: transparent; }
.hero p { margin: 16px 0 0; max-width: 640px; color: var(--muted); font-size: 16px; }
.hero-features { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 18px; }
.chip {
  padding: 5px 11px; border: 1px solid var(--line); border-radius: 999px;
  background: var(--card); color: var(--muted); font-size: 12px;
}

/* Card ----------------------------------------------------------------- */
.card { margin-top: 28px; border: 1px solid var(--line); border-radius: var(--radius); background: var(--card); box-shadow: var(--shadow); overflow: hidden; }
.card-head { display: flex; align-items: flex-start; justify-content: space-between; gap: 16px; padding: 20px 22px 16px; border-bottom: 1px solid var(--line); }
.card-head h2 { margin: 0; font-size: 16px; font-weight: 600; letter-spacing: -0.01em; }
.card-head p { margin: 4px 0 0; color: var(--muted); font-size: 13px; }
.badge { padding: 5px 10px; border: 1px solid var(--line-strong); border-radius: 999px; color: var(--muted); font-size: 11px; white-space: nowrap; }
.card-body { padding: 22px; }

/* Drop zone ------------------------------------------------------------ */
.dz {
  display: grid; place-items: center; gap: 8px; text-align: center;
  padding: 40px 22px; border: 1.5px dashed var(--line-strong); border-radius: var(--radius);
  background: linear-gradient(180deg, var(--hover), transparent);
  cursor: pointer; transition: border-color 160ms ease, background 160ms ease, transform 160ms ease;
}
.dz:hover, .dz:focus-visible { border-color: var(--accent); background: var(--accent-soft); }
.dz.is-over { border-color: var(--accent); background: var(--accent-soft); transform: scale(1.005); }
.dz-icon { display: grid; place-items: center; width: 52px; height: 52px; border-radius: 15px; background: color-mix(in srgb, var(--accent) 14%, var(--card)); color: var(--accent); }
.dz-icon svg { width: 26px; height: 26px; }
.dz-title { margin: 6px 0 0; font-weight: 600; font-size: 15px; }
.dz-hint { margin: 0; color: var(--muted); font-size: 12.5px; }
.dz-actions { display: flex; flex-wrap: wrap; gap: 10px; justify-content: center; margin-top: 10px; }

/* Buttons -------------------------------------------------------------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  padding: 10px 16px; min-height: 42px; border: 1px solid var(--line-strong); border-radius: var(--radius-sm);
  background: var(--card); color: var(--fg); font: inherit; font-size: 13.5px; font-weight: 500;
  cursor: pointer; transition: border-color 150ms ease, background 150ms ease, color 150ms ease, transform 120ms ease;
}
.btn:hover { border-color: var(--fg); background: var(--hover); }
.btn:active { transform: translateY(1px); }
.btn:disabled { opacity: 0.5; cursor: not-allowed; }
.btn-primary { border-color: transparent; background: linear-gradient(120deg, var(--accent), var(--accent-strong)); color: #fff; }
.btn-primary:hover { background: linear-gradient(120deg, var(--accent-strong), var(--accent)); border-color: transparent; }
.btn-ghost { border-color: transparent; background: transparent; color: var(--muted); }
.btn-ghost:hover { background: var(--hover); color: var(--fg); border-color: transparent; }
.btn-sm { padding: 7px 12px; min-height: 34px; font-size: 12.5px; }

/* Studio layout -------------------------------------------------------- */
.studio { display: none; }
.studio.is-active { display: block; }
.studio-grid { display: grid; grid-template-columns: minmax(0, 1.6fr) minmax(260px, 0.9fr); gap: 22px; }
@media (max-width: 860px) { .studio-grid { grid-template-columns: 1fr; } }

.stage {
  display: grid; gap: 14px; align-content: start;
}
.board-shell {
  position: relative; display: grid; place-items: center;
  min-height: 240px; padding: 22px; border: 1px solid var(--line);
  border-radius: var(--radius); overflow: hidden;
}
.board-wrap {
  position: relative; display: grid; place-items: center;
  max-width: 100%;
  background-color: var(--checker-a);
  background-image:
    linear-gradient(45deg, var(--checker-b) 25%, transparent 25%, transparent 75%, var(--checker-b) 75%),
    linear-gradient(45deg, var(--checker-b) 25%, transparent 25%, transparent 75%, var(--checker-b) 75%);
  background-size: 20px 20px;
  background-position: 0 0, 10px 10px;
  transition: padding 160ms ease;
}
.board-wrap.bg-color, .board-wrap.bg-gradient { background-image: none; }
.board-wrap.mode-magic { cursor: crosshair; }
.board {
  display: block; max-width: 100%; height: auto;
  border-radius: 2px;
}
.board-wrap.shadow .board { filter: drop-shadow(0 14px 18px rgba(0, 0, 0, 0.38)); }

.stage-bar { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; }
.stage-bar .spacer { flex: 1; }
.status { color: var(--muted); font-size: 12.5px; }
.status.is-error { color: var(--danger); }
.status.is-ok { color: var(--accent-strong); }

/* Controls ------------------------------------------------------------- */
.panel { border: 1px solid var(--line); border-radius: var(--radius); background: var(--bg-elev); }
.panel + .panel { margin-top: 16px; }
.panel-head { padding: 14px 16px 0; }
.panel-head h3 { margin: 0; font-size: 13px; font-weight: 600; letter-spacing: 0.02em; }
.panel-head p { margin: 3px 0 0; color: var(--muted); font-size: 12px; }
.panel-body { display: grid; gap: 16px; padding: 14px 16px 18px; }
.field { display: grid; gap: 7px; }
.field-row { display: flex; align-items: center; justify-content: space-between; gap: 12px; }
.field label, .field .label { font-size: 12.5px; font-weight: 500; color: var(--fg-soft); }
.field .value { color: var(--muted); font-size: 11.5px; font-variant-numeric: tabular-nums; }
.field small { color: var(--muted); font-size: 11.5px; }
input[type="range"] { width: 100%; accent-color: var(--accent); }
select, input[type="number"] {
  width: 100%; padding: 9px 10px; border: 1px solid var(--line-strong); border-radius: 8px;
  background: var(--card); color: var(--fg); font: inherit; font-size: 13px;
}
select:focus-visible, input:focus-visible { outline: 2px solid var(--accent); outline-offset: 1px; }
.swatches { display: flex; flex-wrap: wrap; gap: 8px; }
.swatch {
  width: 30px; height: 30px; padding: 0; border: 2px solid var(--line-strong); border-radius: 8px;
  cursor: pointer; background-clip: padding-box;
}
.swatch[aria-pressed="true"] { border-color: var(--accent); box-shadow: 0 0 0 2px color-mix(in srgb, var(--accent) 30%, transparent); }
.color-input { display: flex; gap: 8px; align-items: center; }
input[type="color"] { width: 42px; height: 34px; padding: 2px; border: 1px solid var(--line-strong); border-radius: 8px; background: var(--card); cursor: pointer; }
.toggle { display: flex; align-items: center; gap: 10px; font-size: 12.5px; cursor: pointer; }
.toggle input { width: 16px; height: 16px; accent-color: var(--accent); }
.seg { display: grid; grid-template-columns: repeat(3, 1fr); gap: 6px; }
.seg button {
  padding: 9px 6px; border: 1px solid var(--line-strong); border-radius: 8px; background: var(--card);
  color: var(--muted); font: inherit; font-size: 12px; cursor: pointer;
}
.seg button[aria-pressed="true"] { border-color: var(--accent); color: var(--accent-strong); background: var(--accent-soft); }
.hint { color: var(--muted); font-size: 11.5px; line-height: 1.5; margin: 0; }

/* Loading overlay ------------------------------------------------------ */
.board-shell.is-busy::after {
  content: ""; position: absolute; inset: 0; background: color-mix(in srgb, var(--bg) 62%, transparent);
}
.board-shell.is-busy::before {
  content: ""; position: absolute; z-index: 2; width: 30px; height: 30px; border-radius: 50%;
  border: 3px solid color-mix(in srgb, var(--accent) 30%, transparent); border-top-color: var(--accent);
  animation: spin 700ms linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }
@media (prefers-reduced-motion: reduce) { .board-shell.is-busy::before { animation: none; } }

/* Explainer / FAQ ------------------------------------------------------ */
.section { margin-top: 64px; }
.section h2 { font-size: clamp(22px, 3.4vw, 30px); letter-spacing: -0.03em; margin: 0 0 8px; }
.section > p { color: var(--muted); max-width: 720px; margin: 0 0 22px; font-size: 15px; }
.steps { display: grid; gap: 12px; grid-template-columns: repeat(3, 1fr); margin: 0; padding: 0; list-style: none; }
@media (max-width: 760px) { .steps { grid-template-columns: 1fr; } }
.step { padding: 18px; border: 1px solid var(--line); border-radius: var(--radius); background: var(--card); }
.step-num { display: grid; place-items: center; width: 28px; height: 28px; border-radius: 8px; background: var(--accent-soft); color: var(--accent-strong); font-size: 13px; font-weight: 600; }
.step h3 { margin: 12px 0 4px; font-size: 15px; }
.step p { margin: 0; color: var(--muted); font-size: 13px; }
.faq-list { display: grid; gap: 10px; }
details.faq { border: 1px solid var(--line); border-radius: var(--radius-sm); background: var(--card); padding: 0 16px; }
details.faq summary { cursor: pointer; padding: 15px 0; font-weight: 500; font-size: 14.5px; list-style: none; display: flex; justify-content: space-between; gap: 14px; }
details.faq summary::-webkit-details-marker { display: none; }
details.faq summary::after { content: "+"; color: var(--muted); font-size: 18px; line-height: 1; }
details.faq[open] summary::after { content: "–"; }
details.faq p { margin: 0 0 16px; color: var(--muted); font-size: 14px; }

/* Footer --------------------------------------------------------------- */
.site-footer { border-top: 1px solid var(--line); background: var(--bg-elev); }
.site-footer .wrap { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 12px; padding: 22px 0; color: var(--muted); font-size: 12.5px; }
.site-footer a { color: var(--fg); text-decoration: none; }
.site-footer a:hover { text-decoration: underline; text-underline-offset: 3px; }
.foot-links { display: flex; flex-wrap: wrap; gap: 14px; }

@media (max-width: 600px) {
  main { padding: 26px 0 70px; }
  .card-body { padding: 18px 14px; }
  .card-head { padding: 16px 16px 14px; }
  .dz { padding: 30px 16px; }
  .wrap { width: min(100% - 24px, 1080px); }
}