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

:root {
  --teal: #0f766e;
  --teal-light: #14b8a6;

  --gradient-primary:
    linear-gradient(135deg,#0f766e 0%,#14b8a6 100%);

  --yellow: #fbbf24;
  --yellow2: #f59e0b;

  --safe: #14b8a6;
  --ok: #0ea5e9;
  --warn: #facc15;
  --danger: #ef4444;

  --bg: #f8fafc;
  --surface: #ffffff;
  --border: #e2e8f0;

  --ink: #1e293b;
  --ink2: #334155;
  --sub: #64748b;

  --radius: 1rem;
}

html.dark {
  --bg: #020617;
  --surface: #0f172a;
  --border: #1e293b;

  --ink: #f8fafc;
  --ink2: #e2e8f0;
  --sub: #94a3b8;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Inter', 'Noto Sans JP', sans-serif;
  background: var(--bg);
  color: var(--ink);
  line-height: 1.6;
  transition: background .25s ease;
}

.tool-container {
  background-image: radial-gradient(circle, #cbd5e1 1px, transparent 1px);
  background-size: 24px 24px;
  min-height: 100vh;
  padding: 24px 16px 80px;
}

html.dark .tool-container {
  background-image: radial-gradient(circle, #1e293b 1px, transparent 1px);
}

.panel {
  width: 100%;
  max-width: 640px;
  margin: 0 auto;
}

.hero {
  text-align: center;
  margin-bottom: 24px;
}

.hero h1 {
  font-size: clamp(2rem, 5vw, 3rem);
  line-height: 1.2;
  margin-bottom: 12px;
}

.hero p {
  color: var(--sub);
  font-size: 15px;
}

.panel-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  margin-bottom: 20px;
  box-shadow: 0 8px 30px rgba(0,0,0,.06);

  content-visibility: auto;
  contain-intrinsic-size: 500px;
}

.sec-title {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 18px;

  font-size: 14px;
  font-weight: 700;
  color: var(--sub);
  text-transform: uppercase;
  letter-spacing: .06em;
}

.step-badge {
  width: 28px;
  height: 28px;

  border-radius: 8px;

  display: flex;
  align-items: center;
  justify-content: center;

  background: var(--gradient-primary);
  color: white;
}

.plan-tabs {
  display: grid;
  grid-template-columns: repeat(3,1fr);
  gap: 10px;
}

.plan-tab {
  border: 2px solid var(--border);
  background: var(--bg);
  color: var(--ink);

  border-radius: 12px;

  padding: 14px 10px;

  cursor: pointer;

  font-weight: 700;
  font-size: 15px;

  transition: .2s ease;
}

.plan-tab:hover {
  border-color: var(--teal-light);
}

.plan-tab.active {
  background: var(--teal);
  color: white;
  border-color: var(--teal);
}

.custom-row {
  margin-top: 16px;
  display: flex;
  align-items: center;
  gap: 10px;
}

.custom-input,
input,
button {
  font-size: 16px;
}

.custom-input {
  width: 100px;
  border: 2px solid var(--border);
  border-radius: 10px;
  background: var(--bg);
  color: var(--ink);

  padding: 12px;

  outline: none;
}

.custom-input:focus {
  border-color: var(--teal-light);
}

.usage-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
}

.usage-card {
  border: 2px solid var(--border);
  background: var(--bg);
  border-radius: 18px;

  padding: 18px;

  text-align: center;
}

.usage-card-title {
  font-size: 12px;
  font-weight: 700;
  color: var(--sub);
  margin-bottom: 10px;
}

.usage-val {
  font-size: 34px;
  font-weight: 700;
}

.slider-row {
  margin-top: 18px;
}

.slider {
  width: 100%;
  height: 10px;
  appearance: none;
  border-radius: 999px;
  background: var(--border);
}

.slider::-webkit-slider-thumb {
  appearance: none;
  width: 24px;
  height: 24px;
  border-radius: 999px;
  background: var(--teal);
  cursor: pointer;
}

.result-header {
  text-align: center;
  margin-bottom: 24px;
}

.badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;

  background: var(--yellow);
  color: var(--teal);

  padding: 12px 22px;

  border-radius: 999px;

  font-weight: 700;
}

.donut-wrap {
  position: relative;
  width: 210px;
  height: 210px;
  margin: 0 auto 24px;
}

.donut-wrap svg {
  transform: rotate(-90deg);
}

.donut-bg {
  fill: none;
  stroke: var(--border);
  stroke-width: 18;
}

.donut-bar {
  fill: none;
  stroke-width: 18;
  stroke-linecap: round;
  stroke-dasharray: 565;
  stroke-dashoffset: 565;
  transition: stroke-dashoffset .6s ease;
}

.donut-center {
  position: absolute;
  inset: 0;

  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}

.donut-pct {
  font-size: 52px;
  font-weight: 700;
}

.donut-lbl {
  font-size: 12px;
  color: var(--sub);
  text-transform: uppercase;
  letter-spacing: .08em;
}

.result-grid {
  display: grid;
  gap: 16px;
}

.metric-card {
  border: 2px solid var(--border);
  background: var(--bg);
  border-radius: 18px;

  padding: 20px;

  text-align: center;
}

.metric-label {
  font-size: 11px;
  color: var(--sub);
  font-weight: 700;
  letter-spacing: .08em;
  text-transform: uppercase;
}

.metric-value {
  margin-top: 10px;
  font-size: 40px;
  font-weight: 700;
}

.metric-meta {
  margin-top: 8px;
  color: var(--sub);
  font-size: 14px;
}

.tips-grid {
  display: grid;
  gap: 14px;
  margin-top: 20px;
}

.tips-card {
  display: flex;
  gap: 14px;

  border: 2px solid var(--border);
  background: var(--bg);

  border-radius: 16px;

  padding: 18px;
}

.tips-icon {
  font-size: 28px;
}

.tips-title {
  font-weight: 700;
  margin-bottom: 4px;
}

.tips-desc {
  color: var(--sub);
  font-size: 14px;
}

.related-section {
  margin-top: 36px;
}

.related-title {
  text-align: center;
  margin-bottom: 16px;
}

.related-grid {
  display: grid;
  gap: 12px;
}

.related-link {
  display: block;
  text-decoration: none;

  border: 2px solid var(--border);
  background: var(--surface);
  color: var(--teal);

  border-radius: 14px;

  padding: 18px;

  font-weight: 700;

  transition: .2s ease;
}

.related-link:hover {
  transform: translateY(-2px);
  background: var(--teal);
  color: white;
}

.theme-toggle {
  position: fixed;
  right: 16px;
  bottom: 16px;

  width: 56px;
  height: 56px;

  border: none;
  border-radius: 999px;

  background: var(--surface);
  color: var(--ink);

  box-shadow: 0 4px 14px rgba(0,0,0,.18);

  cursor: pointer;

  z-index: 999;
}

@media (min-width: 641px) {
  .result-grid {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 640px) {

  .plan-tabs {
    grid-template-columns: repeat(2,1fr);
  }

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

  .metric-value {
    font-size: 32px;
  }

  .donut-wrap {
    width: 180px;
    height: 180px;
  }

  .donut-pct {
    font-size: 42px;
  }
  }