:root {
  --color-bg: #f4f6fb;
  --color-bg-gradient-a: #eef2ff;
  --color-bg-gradient-b: #f4f6fb;
  --color-card: #ffffff;
  --color-border: #e5e7eb;
  --color-text: #1a1d29;
  --color-muted: #6b7280;
  --color-primary: #4f46e5;
  --color-primary-dark: #4338ca;
  --color-ok: #16a34a;
  --color-ok-bg: #f0fdf4;
  --color-warn: #d97706;
  --color-warn-bg: #fffbeb;
  --color-ng: #dc2626;
  --color-ng-bg: #fef2f2;
  --shadow-sm: 0 1px 2px rgba(16, 24, 40, 0.06);
  --shadow-md: 0 4px 16px rgba(16, 24, 40, 0.08);
}

@media (prefers-color-scheme: dark) {
  :root {
    --color-bg: #14151f;
    --color-bg-gradient-a: #191a2e;
    --color-bg-gradient-b: #14151f;
    --color-card: #1d1f2e;
    --color-border: #2e3042;
    --color-text: #e8e9f0;
    --color-muted: #9497ab;
    --color-primary: #818cf8;
    --color-primary-dark: #a5b4fc;
    --color-ok: #4ade80;
    --color-ok-bg: rgba(74, 222, 128, 0.1);
    --color-warn: #fbbf24;
    --color-warn-bg: rgba(251, 191, 36, 0.1);
    --color-ng: #f87171;
    --color-ng-bg: rgba(248, 113, 113, 0.1);
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.35);
  }
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Hiragino Sans", "Yu Gothic", sans-serif;
  background: radial-gradient(ellipse at top, var(--color-bg-gradient-a), var(--color-bg-gradient-b));
  color: var(--color-text);
  min-height: 100vh;
}

.container {
  max-width: 640px;
  margin: 0 auto;
  padding: 56px 20px 80px;
}

header {
  text-align: center;
  margin-bottom: 36px;
}

h1 {
  font-size: 1.75rem;
  font-weight: 700;
  margin: 0 0 8px;
  letter-spacing: -0.02em;
}

.subtitle {
  color: var(--color-muted);
  margin: 0;
  font-size: 0.9rem;
}

.check-form {
  display: flex;
  gap: 8px;
  margin-bottom: 16px;
  background: var(--color-card);
  padding: 8px;
  border-radius: 14px;
  box-shadow: var(--shadow-md);
  border: 1px solid var(--color-border);
}

#url-input {
  flex: 1;
  padding: 12px 14px;
  border: none;
  border-radius: 8px;
  font-size: 1rem;
  background: transparent;
  color: var(--color-text);
}

#url-input:focus {
  outline: 2px solid var(--color-primary);
  outline-offset: -1px;
}

#check-button {
  padding: 12px 22px;
  border: none;
  border-radius: 8px;
  background: var(--color-primary);
  color: #fff;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s ease, transform 0.1s ease;
}

#check-button:hover {
  background: var(--color-primary-dark);
}

#check-button:active {
  transform: scale(0.97);
}

#check-button:disabled {
  background: #a5adc6;
  cursor: not-allowed;
}

.error-message {
  color: var(--color-ng);
  background: var(--color-ng-bg);
  border: 1px solid var(--color-ng);
  padding: 12px 16px;
  border-radius: 10px;
  font-size: 0.9rem;
  margin-bottom: 16px;
}

.loading {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  color: var(--color-muted);
  padding: 32px 0;
  font-size: 0.9rem;
}

.loading[hidden] {
  display: none;
}

.spinner {
  width: 18px;
  height: 18px;
  border: 2.5px solid var(--color-border);
  border-top-color: var(--color-primary);
  border-radius: 50%;
  animation: spin 0.7s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

.result {
  animation: fade-in 0.25s ease;
}

@keyframes fade-in {
  from { opacity: 0; transform: translateY(4px); }
  to { opacity: 1; transform: translateY(0); }
}

.checked-url {
  font-size: 0.85rem;
  color: var(--color-muted);
  word-break: break-all;
  margin-bottom: 20px;
  text-align: center;
}

.checked-url a {
  color: var(--color-primary);
  text-decoration: none;
}

.checked-url a:hover {
  text-decoration: underline;
}

.check-card {
  background: var(--color-card);
  border: 1px solid var(--color-border);
  border-left: 4px solid var(--color-border);
  border-radius: 12px;
  padding: 18px 20px;
  margin-bottom: 14px;
  box-shadow: var(--shadow-sm);
  transition: box-shadow 0.15s ease, transform 0.15s ease;
}

.check-card:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-1px);
}

.check-card.status-ok { border-left-color: var(--color-ok); }
.check-card.status-warn { border-left-color: var(--color-warn); }
.check-card.status-ng { border-left-color: var(--color-ng); }

.check-card-header {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 10px;
}

.check-card-header h2 {
  font-size: 0.95rem;
  font-weight: 600;
  margin: 0;
  flex: 1;
}

.status-badge {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 4px 11px;
  border-radius: 999px;
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.02em;
}

.status-badge.ok {
  background: var(--color-ok-bg);
  color: var(--color-ok);
}

.status-badge.warn {
  background: var(--color-warn-bg);
  color: var(--color-warn);
}

.status-badge.ng {
  background: var(--color-ng-bg);
  color: var(--color-ng);
}

.status-badge.ok::before { content: "✓"; }
.status-badge.warn::before { content: "!"; }
.status-badge.ng::before { content: "✕"; }

.check-content {
  font-size: 0.92rem;
  background: var(--color-bg);
  border-radius: 8px;
  padding: 12px 14px;
  word-break: break-word;
  white-space: pre-wrap;
  min-height: 1.2em;
  line-height: 1.6;
  margin: 0;
}

#headings-content {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.heading-row {
  display: flex;
  align-items: center;
  gap: 10px;
}

.h-tag {
  flex-shrink: 0;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 3px 10px;
  border-radius: 7px;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.78rem;
  font-weight: 700;
  color: #fff;
  background: var(--color-muted);
}

.check-card.status-ok .h-tag { background: var(--color-ok); }
.check-card.status-warn .h-tag { background: var(--color-warn); }
.check-card.status-ng .h-tag { background: var(--color-ng); }

.h-text {
  font-weight: 700;
  font-size: 1rem;
  line-height: 1.5;
  word-break: break-word;
}

.check-meta {
  font-size: 0.8rem;
  color: var(--color-muted);
  margin: 8px 0 0;
  white-space: pre-wrap;
  line-height: 1.6;
}