:root {
  --bg: #0d0d0d;
  --fg: #e6e6e6;
  --muted: #888;
  --accent: #fff;
  --border: #2a2a2a;
  --card: #161616;
}
* { box-sizing: border-box; margin: 0; padding: 0; }
body {
  background: var(--bg);
  color: var(--fg);
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  line-height: 1.6;
  padding: 2rem 1rem;
  max-width: 640px;
  margin: 0 auto;
}
nav { margin-bottom: 2.5rem; font-size: .9rem; }
nav a { color: var(--muted); text-decoration: none; margin-right: 1rem; }
nav a:hover { color: var(--accent); }
h1 { font-size: 1.6rem; font-weight: 600; margin-bottom: .3rem; }
.sub { color: var(--muted); font-size: .9rem; margin-bottom: 2rem; }
label { display: block; font-size: .85rem; color: var(--muted); margin: 1.1rem 0 .3rem; }
input {
  width: 100%;
  background: var(--card);
  border: 1px solid var(--border);
  color: var(--fg);
  font-family: inherit;
  font-size: 1rem;
  padding: .65rem .8rem;
  border-radius: 4px;
}
input:focus { outline: none; border-color: var(--muted); }
button {
  width: 100%;
  margin-top: 1.6rem;
  background: var(--fg);
  color: var(--bg);
  border: none;
  font-family: inherit;
  font-size: 1rem;
  font-weight: 600;
  padding: .8rem;
  border-radius: 4px;
  cursor: pointer;
}
button:hover { opacity: .85; }
#out { margin-top: 2rem; display: none; }
.row {
  display: flex;
  justify-content: space-between;
  padding: .8rem 0;
  border-bottom: 1px solid var(--border);
}
.row span:first-child { color: var(--muted); }
.row span:last-child { font-weight: 600; }
.total { font-size: 1.15rem; }
.note { color: var(--muted); font-size: .8rem; margin-top: 1.2rem; }
footer { color: var(--muted); font-size: .8rem; margin-top: 3rem; }