:root {
  --bg: #ffffff;
  --surface: #f7f9fc;
  --border: #e2e8f0;
  --text: #1e293b;
  --muted: #64748b;
  --primary: #6366f1;
  --primary-soft: #eef2ff;
  --accent: #14b8a6;
  --warn: #f59e0b;
  --code-bg: #f1f5f9;
  --ascii-print: #0f766e;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: -apple-system, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  padding: 24px;
}

.container { max-width: 1080px; margin: 0 auto; }

header { text-align: center; margin-bottom: 8px; }
header h1 {
  font-size: 1.6rem;
  background: linear-gradient(90deg, var(--primary), var(--accent));
  -webkit-background-clip: text; background-clip: text; color: transparent;
}
header .subtitle { color: var(--muted); font-size: 0.95rem; margin-top: 6px; }
.badge {
  display: inline-block; font-size: 0.75rem; color: var(--primary);
  background: var(--primary-soft); padding: 2px 10px; border-radius: 12px; margin-top: 8px;
}

.tabs { display: flex; gap: 8px; margin: 20px 0 12px; flex-wrap: wrap; }
.tab {
  padding: 8px 16px; border: 1px solid var(--border); background: var(--surface);
  border-radius: 8px; cursor: pointer; font-size: 0.9rem; color: var(--muted);
}
.tab.active { background: var(--primary); color: #fff; border-color: var(--primary); }

.panel { display: none; }
.panel.active { display: block; }

.card {
  background: var(--surface); border: 1px solid var(--border); border-radius: 12px;
  padding: 16px; margin-bottom: 16px;
}

label { display: block; font-size: 0.85rem; color: var(--muted); margin-bottom: 6px; }

textarea, input[type="text"], input[type="number"] {
  width: 100%; padding: 10px; border: 1px solid var(--border); border-radius: 8px;
  font-size: 0.9rem; font-family: "SF Mono", Consolas, monospace; background: #fff;
}
textarea { min-height: 100px; resize: vertical; }

.btn-row { display: flex; gap: 10px; flex-wrap: wrap; margin-top: 12px; }
.btn {
  padding: 9px 18px; border: none; border-radius: 8px; cursor: pointer;
  font-size: 0.9rem; background: var(--primary); color: #fff;
}
.btn.secondary { background: var(--surface); color: var(--text); border: 1px solid var(--border); }
.btn:hover { opacity: 0.9; }

.hex-view {
  background: var(--code-bg); border-radius: 8px; padding: 14px; overflow-x: auto;
  font-family: "SF Mono", Consolas, "Courier New", monospace; font-size: 0.85rem;
  line-height: 1.7; white-space: pre;
}
.hex-view .row { display: flex; }
.hex-view .offset { color: var(--muted); width: 90px; user-select: none; }
.hex-view .hex-cells { color: var(--text); }
.hex-view .ascii { color: var(--ascii-print); margin-left: 12px; }
.hex-view .row.current { background: var(--primary-soft); border-radius: 4px; }

.result {
  margin-top: 12px; padding: 12px; border-radius: 8px; background: #fff;
  border: 1px solid var(--border); font-size: 0.85rem;
}
.result.ok { border-color: var(--accent); }
.result.err { border-color: #ef4444; color: #dc2626; }

.hint { font-size: 0.8rem; color: var(--muted); margin-top: 6px; }

.info-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(140px, 1fr)); gap: 12px; margin-top: 12px; }
.info-grid .item { background: #fff; border: 1px solid var(--border); border-radius: 8px; padding: 10px; }
.info-grid .label { font-size: 0.75rem; color: var(--muted); }
.info-grid .value { font-size: 1.15rem; font-weight: 600; font-family: monospace; }

footer { margin-top: 28px; padding-top: 16px; border-top: 1px solid var(--border); font-size: 0.8rem; color: var(--muted); text-align: center; }
footer .disclaimer { max-width: 720px; margin: 0 auto 8px; }
a { color: var(--primary); }

@media (max-width: 640px) {
  body { padding: 14px; }
  .hex-view { font-size: 0.7rem; }
}