/* Watermelon — light, clean theme */
:root {
  --bg: #fafaf9;
  --panel: #ffffff;
  --ink: #1c1c1c;
  --muted: #6b7280;
  --line: #e5e7eb;
  --accent: #16a34a;
  --accent-ink: #ffffff;
  --good: #16a34a;
  --bad: #dc2626;
  --warn: #d97706;
  --radius: 10px;
  --shadow: 0 1px 3px rgba(0,0,0,0.08), 0 1px 2px rgba(0,0,0,0.04);
}
* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--ink);
  line-height: 1.5;
}
header {
  background: var(--panel);
  border-bottom: 1px solid var(--line);
  padding: 14px 24px;
  display: flex;
  align-items: center;
  gap: 16px;
}
header .logo { font-weight: 700; font-size: 18px; }
header .logo .melon { color: var(--accent); }
header nav { display: flex; gap: 16px; margin-left: auto; }
header nav a { color: var(--muted); text-decoration: none; font-size: 14px; }
header nav a:hover { color: var(--ink); }
main { max-width: 1000px; margin: 0 auto; padding: 24px; }
h1 { font-size: 22px; margin: 0 0 4px; }
h2 { font-size: 16px; margin: 0 0 12px; }
.sub { color: var(--muted); font-size: 14px; margin: 0 0 20px; }
.panel {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 18px;
  margin-bottom: 16px;
}
button {
  font: inherit;
  font-size: 14px;
  padding: 8px 14px;
  border-radius: 8px;
  border: 1px solid var(--line);
  background: var(--panel);
  color: var(--ink);
  cursor: pointer;
}
button:hover { border-color: var(--muted); }
button.primary {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--accent-ink);
}
button.primary:hover { filter: brightness(1.05); }
button.danger { color: var(--bad); }
button.review-btn { padding: 4px 10px; font-size: 13px; border-radius: 6px; }
button.review-btn.good { background: #dcfce7; border-color: var(--good); color: var(--good); }
button.review-btn.bad { background: #fee2e2; border-color: var(--bad); color: var(--bad); }
input, textarea, select {
  font: inherit;
  font-size: 14px;
  padding: 8px 10px;
  border: 1px solid var(--line);
  border-radius: 8px;
  width: 100%;
  background: var(--panel);
  color: var(--ink);
}
input:focus, textarea:focus, select:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(22,163,74,0.15);
}
label { font-size: 13px; color: var(--muted); display: block; margin-bottom: 4px; }
.field { margin-bottom: 12px; }
.row { display: flex; gap: 12px; }
.row > * { flex: 1; }
.muted { color: var(--muted); font-size: 13px; }
.badge {
  display: inline-block;
  font-size: 12px;
  padding: 2px 8px;
  border-radius: 999px;
  background: #f3f4f6;
  color: var(--muted);
}
.badge.good { background: #dcfce7; color: var(--good); }
.badge.bad { background: #fee2e2; color: var(--bad); }
.badge.warn { background: #fef3c7; color: var(--warn); }
.list { list-style: none; padding: 0; margin: 0; }
.list li {
  padding: 10px 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  margin-bottom: 8px;
  display: flex;
  align-items: center;
  gap: 10px;
  cursor: pointer;
}
.list li.active { border-color: var(--accent); background: #f0fdf4; }
.list li .title { font-weight: 600; }
.list li .meta { color: var(--muted); font-size: 13px; margin-left: auto; }
.exercise-card {
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 14px;
  margin-bottom: 12px;
  background: #fcfcfb;
}
.exercise-card .head { display: flex; align-items: center; gap: 10px; margin-bottom: 10px; }
.code {
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  font-size: 20px;
  letter-spacing: 2px;
  background: #f3f4f6;
  padding: 6px 12px;
  border-radius: 8px;
  display: inline-block;
}
.status-dot { width: 8px; height: 8px; border-radius: 50%; display: inline-block; }
.status-dot.on { background: var(--good); }
.status-dot.off { background: var(--line); }
.grid-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
@media (max-width: 700px) { .grid-2 { grid-template-columns: 1fr; } }
.flash { font-size: 13px; margin-top: 8px; min-height: 18px; }
.flash.ok { color: var(--good); }
.flash.err { color: var(--bad); }
.options-list { display: flex; flex-direction: column; gap: 8px; }
.options-list label {
  display: flex;
  align-items: center;
  gap: 8px;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 10px;
  cursor: pointer;
  color: var(--ink);
  font-size: 14px;
  margin: 0;
}
.options-list label:has(input:checked) { border-color: var(--accent); background: #f0fdf4; }
.options-list input { width: auto; }
.attempt-row {
  display: flex;
  gap: 10px;
  align-items: baseline;
  font-size: 13px;
  padding: 6px 0;
  border-bottom: 1px solid var(--line);
}
.attempt-row .n { color: var(--muted); width: 20px; }
.attempt-row .val { flex: 1; }
.empty { color: var(--muted); font-size: 14px; padding: 12px; text-align: center; }