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

:root {
  --bg-primary: #0a0a0f;
  --bg-secondary: #12121a;
  --surface: rgba(255, 255, 255, 0.05);
  --surface-hover: rgba(255, 255, 255, 0.09);
  --border: rgba(255, 255, 255, 0.08);
  --border-hover: rgba(255, 255, 255, 0.2);
  --text-primary: #f0f0f5;
  --text-secondary: #8888aa;
  --accent-1: #7c6fff;
  --accent-2: #ff6fb0;
  --accent-3: #6fefff;
  --glow: rgba(124, 111, 255, 0.35);
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  background-color: var(--bg-primary);
  color: var(--text-primary);
  min-height: 100vh;
  overflow-x: hidden;
}

/* 背景グラデーションアニメーション */
body::before {
  content: '';
  position: fixed;
  inset: 0;
  background:
    radial-gradient(ellipse 80% 60% at 20% 10%, rgba(124, 111, 255, 0.12) 0%, transparent 60%),
    radial-gradient(ellipse 60% 50% at 80% 80%, rgba(255, 111, 176, 0.08) 0%, transparent 55%),
    radial-gradient(ellipse 50% 40% at 60% 40%, rgba(111, 239, 255, 0.06) 0%, transparent 50%);
  pointer-events: none;
  z-index: 0;
  animation: bgShift 12s ease-in-out infinite alternate;
}

@keyframes bgShift {
  0% {
    opacity: 1;
    transform: scale(1);
  }

  100% {
    opacity: 0.7;
    transform: scale(1.05);
  }
}

.container {
  position: relative;
  z-index: 1;
  max-width: 860px;
  margin: 0 auto;
  padding: 4rem 2rem 6rem;
}

/* ヘッダー */
header {
  text-align: center;
  margin-bottom: 3.5rem;
}

.header-badge {
  display: inline-block;
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent-1);
  border: 1px solid rgba(124, 111, 255, 0.35);
  border-radius: 100px;
  padding: 0.3rem 1rem;
  margin-bottom: 1.25rem;
  background: rgba(124, 111, 255, 0.08);
}

h1 {
  font-size: clamp(2rem, 5vw, 3.2rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.1;
  background: linear-gradient(135deg, #fff 0%, var(--accent-3) 40%, var(--accent-1) 70%, var(--accent-2) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 0.9rem;
}

.header-sub {
  font-size: 1rem;
  color: var(--text-secondary);
  font-weight: 400;
}

/* グリッド */
.tool-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 1.25rem;
  list-style: none;
}

/* カード */
.tool-card {
  position: relative;
  border-radius: 18px;
  overflow: hidden;
  transition: transform 0.3s cubic-bezier(0.34, 1.56, 0.64, 1),
    box-shadow 0.3s ease;
}

.tool-card::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: 18px;
  padding: 1px;
  background: linear-gradient(135deg, var(--border-hover), transparent 60%);
  -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  -webkit-mask-composite: xor;
  mask-composite: exclude;
  opacity: 0;
  transition: opacity 0.3s ease;
  pointer-events: none;
}

.tool-card:hover {
  transform: translateY(-5px) scale(1.02);
  box-shadow: 0 24px 50px rgba(0, 0, 0, 0.5), 0 0 30px var(--glow);
}

.tool-card:hover::before {
  opacity: 1;
}

.tool-card a {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  padding: 1.6rem 1.5rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 18px;
  text-decoration: none;
  color: var(--text-primary);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  transition: background 0.3s ease, border-color 0.3s ease;
  height: 100%;
}

.tool-card:hover a {
  background: var(--surface-hover);
  border-color: var(--border-hover);
}

.tool-icon {
  width: 48px;
  height: 48px;
  border-radius: 14px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  flex-shrink: 0;
}

.tool-name {
  font-size: 1.05rem;
  font-weight: 600;
  letter-spacing: -0.01em;
}

.tool-desc {
  font-size: 0.85rem;
  color: var(--text-secondary);
  line-height: 1.55;
}

.tool-arrow {
  margin-top: auto;
  font-size: 0.8rem;
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  gap: 0.3rem;
  transition: color 0.2s ease, gap 0.2s ease;
}

.tool-card:hover .tool-arrow {
  color: var(--accent-1);
  gap: 0.55rem;
}

/* 各カードのアクセントカラー */
.card-converter .tool-icon {
  background: linear-gradient(135deg, #7c6fff33, #6fefff22);
  color: var(--accent-3);
}

.card-timer .tool-icon {
  background: linear-gradient(135deg, #ff6fb033, #ff9b6f22);
  color: var(--accent-2);
}

.card-tarot .tool-icon {
  background: linear-gradient(135deg, #7c6fff33, #ff6fb022);
  color: var(--accent-1);
}

.card-string .tool-icon {
  background: linear-gradient(135deg, #6fefff33, #7c6fff22);
  color: var(--accent-3);
}

/* フッター */
footer {
  text-align: center;
  margin-top: 4rem;
  font-size: 0.8rem;
  color: var(--text-secondary);
  opacity: 0.6;
}

/* フェードインアニメーション */
@keyframes fadeUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

header {
  animation: fadeUp 0.6s ease both;
}

.tool-card:nth-child(1) {
  animation: fadeUp 0.6s 0.1s ease both;
}

.tool-card:nth-child(2) {
  animation: fadeUp 0.6s 0.18s ease both;
}

.tool-card:nth-child(3) {
  animation: fadeUp 0.6s 0.26s ease both;
}

footer {
  animation: fadeUp 0.6s 0.4s ease both;
}

@media (max-width: 480px) {
  .container {
    padding: 2.5rem 1.25rem 4rem;
  }

  .tool-grid {
    grid-template-columns: 1fr;
  }
}