:root {
  --bg: #f7f7f8;
  --panel: #ffffff;
  --panel-shadow: 0 1px 2px rgba(15, 17, 21, 0.04), 0 4px 12px rgba(15, 17, 21, 0.05);
  --border: #e5e7eb;
  --text: #111418;
  --muted: #6b7280;
  --accent: #e11d2c;
  --accent-hover: #b8121f;
  --accent-soft: #fff1f2;
  --warn: #b45309;
  --warn-bg: #fff7ed;
  --note-bg: #f3f4f6;
  --ok: #047857;
  --ok-bg: #ecfdf5;
  --error: #b91c1c;
  --error-bg: #fef2f2;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Sans", "Yu Gothic UI", "Meiryo", system-ui, sans-serif;
  font-size: 16px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

main {
  max-width: 720px;
  margin: 0 auto;
  padding: 56px 24px 96px;
}

header h1 {
  font-size: 1.9rem;
  margin: 0 0 6px;
  letter-spacing: 0.2px;
}

header p.tagline {
  margin: 0 0 32px;
  color: var(--muted);
}

section {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 22px 26px;
  margin: 16px 0;
  box-shadow: var(--panel-shadow);
}

section h2 {
  font-size: 1.05rem;
  margin: 0 0 12px;
  letter-spacing: 0.2px;
}

ol, ul { padding-left: 22px; margin: 8px 0; }
li { margin: 6px 0; }

code, kbd {
  background: #eef0f3;
  padding: 1px 6px;
  border-radius: 4px;
  font-family: "SF Mono", Menlo, Consolas, monospace;
  font-size: 0.88em;
  color: #1f2937;
}

kbd {
  border: 1px solid #d1d5db;
  border-bottom-width: 2px;
}

.device-row {
  display: flex;
  gap: 22px;
  align-items: center;
}

.device-img {
  width: 140px;
  height: 140px;
  flex-shrink: 0;
  object-fit: contain;
  background: #f7f7f8;
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 6px;
}

.device-text { flex: 1; min-width: 0; }
.device-text p:first-child { margin-top: 0; }
.device-text p:last-child { margin-bottom: 0; }

@media (max-width: 520px) {
  .device-row {
    flex-direction: column;
    align-items: flex-start;
    gap: 14px;
  }
  .device-img { width: 120px; height: 120px; }
}

.checkbox-row {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  background: var(--note-bg);
  border-radius: 8px;
  padding: 12px 14px;
  margin: 16px 0 0;
  cursor: pointer;
  user-select: none;
}

.checkbox-row input[type="checkbox"] {
  margin-top: 4px;
  width: 16px;
  height: 16px;
  accent-color: var(--accent);
}

.checkbox-row strong { color: var(--text); }

.install-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 16px;
  margin-top: 18px;
}

button.primary,
button#retry-btn,
button#restart-btn {
  background: var(--accent);
  color: #ffffff;
  border: none;
  border-radius: 8px;
  padding: 10px 22px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  font-family: inherit;
  transition: background 0.15s ease;
}

button.primary:hover,
button#retry-btn:hover,
button#restart-btn:hover {
  background: var(--accent-hover);
}

button.primary:disabled {
  background: #9ca3af;
  cursor: not-allowed;
}

button#retry-btn,
button#restart-btn {
  margin-top: 12px;
}

.unsupported {
  display: none;
  background: var(--accent-soft);
  border-color: #fbcfd3;
}

.unsupported.show { display: block; }
.unsupported h2 { color: var(--accent); }

.status {
  font-size: 1.05rem;
  font-weight: 600;
  margin: 0 0 12px;
}

.status.ok {
  color: var(--ok);
  background: var(--ok-bg);
  border-radius: 8px;
  padding: 10px 14px;
  border: 1px solid #a7f3d0;
}

.status.error {
  color: var(--error);
  background: var(--error-bg);
  border-radius: 8px;
  padding: 10px 14px;
  border: 1px solid #fecaca;
}

.callout {
  background: var(--warn-bg);
  border: 1px solid #fde68a;
  border-radius: 8px;
  padding: 12px 16px;
  margin: 12px 0;
  font-size: 0.92rem;
  color: var(--warn);
}

.progress {
  position: relative;
  height: 22px;
  background: #eef0f3;
  border-radius: 999px;
  overflow: hidden;
  margin: 8px 0 6px;
}

.progress-bar {
  height: 100%;
  width: 0;
  background: linear-gradient(90deg, var(--accent), #f97171);
  transition: width 0.2s ease;
  border-radius: 999px;
}

.progress-pct {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--text);
  text-shadow: 0 0 2px rgba(255, 255, 255, 0.6);
}

.meta {
  font-size: 0.85rem;
  color: var(--muted);
}

.meta strong { color: var(--text); }

footer {
  margin-top: 56px;
  text-align: center;
  color: var(--muted);
  font-size: 0.82rem;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

#error-msg { font-weight: 600; margin-top: 6px; }