/* ===== CSS Variables ===== */
:root {
  --bg: #F5F5F7;
  --card-bg: #FFFFFF;
  --text: #1D1D1F;
  --text-sub: #86868B;
  --accent: #007AFF;
  --danger: #FF3B30;
  --success: #34C759;
  --border: #E5E5EA;
  --card-shadow: 0 1px 3px rgba(0, 0, 0, 0.06);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #1C1C1E;
    --card-bg: #2C2C2E;
    --text: #F5F5F7;
    --text-sub: #98989D;
    --accent: #0A84FF;
    --danger: #FF453A;
    --success: #30D158;
    --border: #38383A;
    --card-shadow: 0 1px 3px rgba(0, 0, 0, 0.3);
  }
}

/* ===== Reset & Base ===== */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Hiragino Sans", "Hiragino Kaku Gothic ProN",
    "Noto Sans JP", "Yu Gothic", sans-serif;
  background-color: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
}

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

/* ===== Header ===== */
.header {
  padding: 16px 20px;
  text-align: center;
  border-bottom: 1px solid var(--border);
  background-color: var(--card-bg);
}

.header__title {
  font-size: 1.25rem;
  font-weight: 700;
}

.header__back {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-size: 0.9rem;
  position: absolute;
  left: 20px;
  top: 18px;
}

.header--counter {
  position: relative;
}

/* ===== Main ===== */
.main {
  flex: 1;
  padding: 24px 20px;
  max-width: 480px;
  width: 100%;
  margin: 0 auto;
}

/* ===== Footer ===== */
.footer {
  padding: 16px 20px;
  text-align: center;
  font-size: 0.75rem;
  color: var(--text-sub);
  border-top: 1px solid var(--border);
}

/* ===== Card ===== */
.card {
  background-color: var(--card-bg);
  border-radius: 16px;
  padding: 32px 24px;
  box-shadow: var(--card-shadow);
}

/* ===== Top Page ===== */
.hero {
  text-align: center;
  margin-bottom: 32px;
}

.hero__catchcopy {
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 8px;
  line-height: 1.4;
}

.hero__description {
  font-size: 0.95rem;
  color: var(--text-sub);
}

.steps {
  list-style: none;
  margin-bottom: 32px;
}

.steps__item {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 16px 0;
  border-bottom: 1px solid var(--border);
}

.steps__item:last-child {
  border-bottom: none;
}

.steps__number {
  flex-shrink: 0;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background-color: var(--accent);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1rem;
}

.steps__text {
  font-size: 0.95rem;
}

.cta-button {
  display: block;
  width: 100%;
  padding: 18px;
  font-size: 1.1rem;
  font-weight: 700;
  color: #fff;
  background-color: var(--accent);
  border: none;
  border-radius: 14px;
  cursor: pointer;
  transition: transform 0.1s ease, opacity 0.1s ease;
  -webkit-tap-highlight-color: transparent;
}

.cta-button:active {
  transform: scale(0.97);
  opacity: 0.85;
}

.existing-counter {
  margin-top: 24px;
  text-align: center;
}

.existing-counter__label {
  font-size: 0.85rem;
  color: var(--text-sub);
  margin-bottom: 8px;
}

.existing-counter__form {
  display: flex;
  gap: 8px;
}

.existing-counter__input {
  flex: 1;
  padding: 12px 14px;
  font-size: 0.9rem;
  border: 1px solid var(--border);
  border-radius: 10px;
  background-color: var(--card-bg);
  color: var(--text);
  outline: none;
}

.existing-counter__input:focus {
  border-color: var(--accent);
}

.existing-counter__submit {
  padding: 12px 18px;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--accent);
  background: none;
  border: 1px solid var(--accent);
  border-radius: 10px;
  cursor: pointer;
  white-space: nowrap;
  transition: transform 0.1s ease;
  -webkit-tap-highlight-color: transparent;
}

.existing-counter__submit:active {
  transform: scale(0.95);
}

/* ===== Use Cases ===== */
.use-cases {
  margin-top: 32px;
}

.use-cases__title {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 16px;
  text-align: center;
}

.use-cases__list {
  list-style: none;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
}

.use-cases__item {
  background-color: var(--card-bg);
  border-radius: 12px;
  padding: 16px;
  box-shadow: var(--card-shadow);
}

.use-cases__icon {
  font-size: 1.5rem;
  display: block;
  margin-bottom: 4px;
}

.use-cases__item strong {
  font-size: 0.9rem;
  display: block;
  margin-bottom: 2px;
}

.use-cases__item p {
  font-size: 0.78rem;
  color: var(--text-sub);
  line-height: 1.4;
}

/* ===== FAQ ===== */
.faq {
  margin-top: 32px;
}

.faq__title {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 16px;
  text-align: center;
}

.faq__list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.faq__item {
  background-color: var(--card-bg);
  border-radius: 12px;
  padding: 20px;
  box-shadow: var(--card-shadow);
}

.faq__question {
  font-size: 0.9rem;
  font-weight: 600;
  margin-bottom: 8px;
}

.faq__answer {
  font-size: 0.85rem;
  color: var(--text-sub);
  line-height: 1.6;
}

/* ===== Counter Page ===== */
.counter-name {
  text-align: center;
  margin-bottom: 4px;
}

.counter-name__display {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text-sub);
  cursor: pointer;
  padding: 4px 12px;
  border-radius: 8px;
  border: 1px dashed transparent;
  transition: border-color 0.2s, color 0.2s;
  display: inline-block;
  letter-spacing: 0.02em;
}

.counter-name__display:hover {
  border-color: var(--text-sub);
  color: var(--text);
}

.counter-name__input {
  font-size: 0.95rem;
  font-weight: 500;
  text-align: center;
  padding: 4px 12px;
  border: 1px solid var(--accent);
  border-radius: 8px;
  background-color: var(--card-bg);
  color: var(--text);
  width: 100%;
  max-width: 280px;
  outline: none;
}

.counter-value {
  text-align: center;
  padding: 40px 0 12px;
}

.counter-value__number {
  font-size: 6rem;
  font-weight: 800;
  line-height: 1;
  letter-spacing: -0.03em;
  transition: opacity 0.15s ease, transform 0.15s ease;
  display: inline-block;
  font-variant-numeric: tabular-nums;
}

.counter-value__number--animate {
  opacity: 0;
  transform: scale(0.92);
}

.counter-last-updated {
  text-align: center;
  font-size: 0.75rem;
  color: var(--text-sub);
  margin-bottom: 40px;
}

.counter-actions {
  display: flex;
  gap: 24px;
  justify-content: center;
  align-items: center;
  margin-bottom: 28px;
}

.counter-btn {
  border-radius: 50%;
  border: none;
  font-weight: 600;
  cursor: pointer;
  transition: transform 0.1s ease, opacity 0.1s ease;
  -webkit-tap-highlight-color: transparent;
  touch-action: manipulation;
  display: flex;
  align-items: center;
  justify-content: center;
}

.counter-btn:active {
  transform: scale(0.92);
}

.counter-btn--plus {
  width: 80px;
  height: 80px;
  font-size: 2.2rem;
  background-color: var(--accent);
  color: #fff;
}

.counter-btn--minus {
  width: 80px;
  height: 80px;
  font-size: 2.2rem;
  background-color: var(--card-bg);
  color: var(--text);
  border: 2px solid var(--border);
}

.counter-btn--minus:disabled {
  opacity: 0.3;
  cursor: not-allowed;
}

.counter-btn--minus:disabled:active {
  transform: none;
}

.counter-step {
  display: flex;
  justify-content: center;
  gap: 8px;
  margin-bottom: 28px;
}

.counter-step__btn {
  padding: 6px 16px;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-sub);
  background: none;
  border: 1.5px solid var(--border);
  border-radius: 20px;
  cursor: pointer;
  transition: background-color 0.15s, color 0.15s, border-color 0.15s;
  -webkit-tap-highlight-color: transparent;
  touch-action: manipulation;
}

.counter-step__btn:active {
  transform: scale(0.95);
}

.counter-step__btn--active {
  background-color: var(--accent);
  color: #fff;
  border-color: var(--accent);
}

.counter-secondary {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
}

.counter-share {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  width: 100%;
  max-width: 200px;
  padding: 12px 20px;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--success);
  background: none;
  border: 2px solid var(--success);
  border-radius: 12px;
  cursor: pointer;
  transition: transform 0.1s ease;
  -webkit-tap-highlight-color: transparent;
}

.counter-share:active {
  transform: scale(0.95);
}

.counter-url {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 12px;
  background-color: #E5E5EA;
  border: 1px solid #D1D1D6;
  border-radius: 8px;
  cursor: pointer;
  transition: border-color 0.15s;
  max-width: 300px;
  width: 100%;
}

@media (prefers-color-scheme: dark) {
  .counter-url {
    background-color: #3A3A3C;
    border-color: #48484A;
  }
}

.counter-url:active {
  border-color: var(--accent);
}

.counter-url__text {
  flex: 1;
  font-size: 0.75rem;
  color: var(--text-sub);
  word-break: break-all;
  line-height: 1.4;
  text-align: left;
  font-family: -apple-system, BlinkMacSystemFont, "SF Mono", "Menlo", monospace;
}

.counter-url__icon {
  flex-shrink: 0;
  color: var(--text-sub);
}

.counter-reset {
  font-size: 0.75rem;
  color: var(--text-sub);
  background: none;
  border: none;
  cursor: pointer;
  padding: 6px 12px;
  transition: color 0.15s;
  -webkit-tap-highlight-color: transparent;
}

.counter-reset:hover {
  color: var(--danger);
}


/* ===== Toast ===== */
.toast {
  position: fixed;
  bottom: 40px;
  left: 50%;
  transform: translateX(-50%) translateY(20px);
  background-color: var(--text);
  color: var(--bg);
  padding: 12px 24px;
  border-radius: 12px;
  font-size: 0.9rem;
  font-weight: 600;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s ease, transform 0.3s ease;
  z-index: 1000;
}

.toast--visible {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

/* ===== Ad Container ===== */
.ad-container {
  margin-top: 32px;
  text-align: center;
}

/* ===== Loading / Error ===== */
.loading {
  text-align: center;
  padding: 48px 0;
  color: var(--text-sub);
  font-size: 1rem;
}

.error-message {
  text-align: center;
  padding: 48px 20px;
  color: var(--danger);
  font-size: 1rem;
}

/* ===== Responsive ===== */
@media (min-width: 600px) {
  .main {
    padding: 40px 20px;
  }

  .counter-value__number {
    font-size: 7rem;
  }

  .counter-btn--plus,
  .counter-btn--minus {
    width: 88px;
    height: 88px;
  }
}