:root {
  --bg: #ffffff;
  --fg: #1a1a1a;
  --muted: #5a5a5a;
  --accent: #990000;
  --heading: #000066;
  --border: #d8d8d8;
  --surface: #f7f7f5;
  --link: #0055cc;
  --error-bg: #fdf2f2;
  --error-border: #d98282;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  padding: 0 1rem 4rem;
  font-family: system-ui, -apple-system, "Segoe UI", Helvetica, Arial, sans-serif;
  font-size: 16px;
  line-height: 1.55;
  color: var(--fg);
  background: var(--bg);
}

.wrap { max-width: 60rem; margin: 0 auto; }

header.masthead {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  padding: 1.5rem 0 1rem;
  flex-wrap: wrap;
}
header.masthead img { width: 110px; height: auto; }
header.masthead .titles { flex: 1 1 20rem; }
header.masthead h1 {
  margin: 0;
  font-size: 2.4rem;
  color: var(--accent);
  letter-spacing: -0.01em;
}
header.masthead p.tagline {
  margin: 0.25rem 0 0;
  color: var(--heading);
  font-weight: 600;
}

nav.tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 0.25rem;
  border-bottom: 2px solid var(--border);
  margin-bottom: 1.5rem;
}
nav.tabs a {
  padding: 0.5rem 0.9rem;
  text-decoration: none;
  color: var(--muted);
  border-bottom: 2px solid transparent;
  margin-bottom: -2px;
  font-size: 0.95rem;
}
nav.tabs a:hover { color: var(--fg); }
nav.tabs a[aria-current="page"] {
  color: var(--accent);
  border-bottom-color: var(--accent);
  font-weight: 600;
}

a { color: var(--link); }

h2 { font-size: 1.5rem; margin-top: 2rem; }
h3 { font-size: 1.15rem; margin-top: 1.75rem; }

label { display: block; font-weight: 600; margin-bottom: 0.35rem; }

textarea, input[type=text], input[type=file] {
  width: 100%;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.9rem;
  padding: 0.5rem;
  border: 1px solid var(--border);
  border-radius: 4px;
  background: var(--bg);
  color: var(--fg);
}
textarea { min-height: 9rem; resize: vertical; }

fieldset {
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 0.9rem 1.1rem;
  margin: 1.25rem 0;
}
fieldset legend { font-weight: 600; padding: 0 0.4rem; }
fieldset label { font-weight: 400; display: flex; gap: 0.5rem; align-items: baseline; }
fieldset label + label { margin-top: 0.4rem; }

.hint { color: var(--muted); font-size: 0.9rem; }

button {
  font: inherit;
  font-weight: 600;
  padding: 0.55rem 1.4rem;
  border: 0;
  border-radius: 5px;
  background: var(--accent);
  color: #fff;
  cursor: pointer;
}
button:hover { background: #7a0000; }
button.secondary { background: var(--surface); color: var(--fg); border: 1px solid var(--border); }
button.secondary:hover { background: #ececea; }

pre {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 5px;
  padding: 0.85rem;
  overflow-x: auto;
  font-size: 0.85rem;
  line-height: 1.45;
}

table.constraints { border-collapse: collapse; width: 100%; }
table.constraints td { padding: 0.3rem 0.5rem 0.3rem 0; vertical-align: middle; }
table.constraints td:first-child { width: 14rem; font-weight: 600; }

.result { border-top: 1px solid var(--border); padding-top: 1.5rem; margin-top: 2rem; }
.result:first-of-type { border-top: 0; }
.result h3 { margin-top: 0; font-family: ui-monospace, SFMono-Regular, Menlo, monospace; }
.result figure { margin: 1rem 0 0; }
.result figure svg { max-width: 100%; height: auto; border: 1px solid var(--border); border-radius: 5px; }

.error {
  background: var(--error-bg);
  border: 1px solid var(--error-border);
  border-left: 4px solid var(--accent);
  border-radius: 4px;
  padding: 0.85rem 1rem;
  margin: 1.5rem 0;
}
.error h2 { margin: 0 0 0.4rem; font-size: 1.1rem; color: var(--accent); }
.error p { margin: 0; }

footer {
  margin-top: 3rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
  font-size: 0.85rem;
  color: var(--muted);
}
footer a { color: var(--muted); }

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #16181c;
    --fg: #e8e8e6;
    --muted: #a0a0a0;
    --accent: #ff6b6b;
    --heading: #8fb8ff;
    --border: #33363c;
    --surface: #1e2126;
    --link: #74a9f7;
    --error-bg: #2a1c1c;
    --error-border: #7a3b3b;
  }
  button { color: #1a1a1a; }
  .result figure svg { background: #fff; }
}

/* --- licence dialog on the download page --- */
dialog.licence {
  max-width: 34rem;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1.5rem 1.75rem;
  background: var(--bg);
  color: var(--fg);
  box-shadow: 0 10px 40px rgba(0, 0, 0, 0.25);
}
dialog.licence::backdrop { background: rgba(0, 0, 0, 0.45); }
dialog.licence h3 { margin-top: 0; color: var(--accent); }
dialog.licence p { margin: 0.75rem 0; }
.licence-actions {
  display: flex;
  gap: 0.75rem;
  align-items: center;
  margin-top: 1.25rem !important;
  flex-wrap: wrap;
}
a.button {
  display: inline-block;
  font-weight: 600;
  padding: 0.55rem 1.4rem;
  border-radius: 5px;
  background: var(--accent);
  color: #fff;
  text-decoration: none;
}
a.button:hover { background: #7a0000; }
@media (prefers-color-scheme: dark) {
  a.button { color: #1a1a1a; }
}

/* --- copyable example block --- */
.example { position: relative; }
.example pre { margin-top: 0; }
.example .copy-example {
  position: absolute;
  top: 0.5rem;
  right: 0.5rem;
  padding: 0.3rem 0.75rem;
  font-size: 0.8rem;
  z-index: 1;
}