.btb-fspl,
.btb-fspl *,
.btb-fspl *::before,
.btb-fspl *::after {
  box-sizing: border-box;
}

.btb-fspl {
  --btb-fspl-vw: 100vw;
  --btb-fspl-bg-x: 0px;
  --btb-fspl-bg-y: 0px;
  position: relative;
  width: var(--btb-fspl-vw);
  max-width: none;
  margin-right: calc(50% - var(--btb-fspl-vw) / 2);
  margin-left: calc(50% - var(--btb-fspl-vw) / 2);
  overflow-x: clip;
  color: #1f2937;
  background: #fff;
  font-family: "Noto Sans JP", sans-serif;
}

.btb-fspl__main {
  position: relative;
  z-index: 1;
  width: 100%;
  max-width: 800px;
  margin: 0 auto;
  overflow: hidden;
  background: #fff;
}

.btb-fspl__section {
  display: block;
  width: 100%;
  margin: 0;
  padding: 0;
  overflow: hidden;
  font-size: 0;
  line-height: 0;
}

.btb-fspl__section img {
  display: block;
  width: 100%;
  max-width: none;
  height: auto;
  margin: 0;
  border: 0;
  border-radius: 0;
  box-shadow: none;
}

.btb-fspl__cta {
  display: flex;
  justify-content: center;
  width: 100%;
  padding: 16px 18px;
  background: linear-gradient(180deg, #ebf6fc, #e3f5fc);
}

.btb-fspl__cta--2 {
  background: linear-gradient(180deg, #f7fafc, #f7fbfc);
}

.btb-fspl__cta--3 {
  background: linear-gradient(180deg, #eaf7fd, #fcfcfd);
}

.btb-fspl__cta--4 {
  background: linear-gradient(180deg, #f2f7fc, #e3f1fd);
}

.btb-fspl__cta--5 {
  background: linear-gradient(180deg, #083b82, #eff7fd);
}

.btb-fspl__button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 100%;
  max-width: 560px;
  min-height: 56px;
  padding: 18px 30px;
  border: 0;
  border-radius: 12px;
  color: #fff !important;
  background: linear-gradient(180deg, #3a4f70, #031b44);
  box-shadow: 0 12px 28px rgba(3, 27, 66, 0.42), inset 0 1px 0 rgba(255, 255, 255, 0.35), inset 0 -2px 0 rgba(0, 0, 0, 0.1);
  font-family: "Noto Sans JP", sans-serif;
  font-size: 1.15rem;
  font-weight: 700;
  line-height: 1.35;
  letter-spacing: 0.02em;
  text-align: center;
  text-decoration: none !important;
  transition: transform 0.18s ease, opacity 0.18s ease, box-shadow 0.18s ease;
}

.btb-fspl__button:hover,
.btb-fspl__button:focus-visible {
  color: #fff !important;
  opacity: 0.95;
  transform: translateY(-3px) scale(1.02);
}

.btb-fspl__button:focus-visible {
  outline: 3px solid #fff;
  outline-offset: -6px;
}

.btb-fspl__button:active {
  transform: translateY(0) scale(0.98);
}

.btb-fspl__button--float {
  animation: btb-fspl-float 1.9s ease-in-out infinite;
}

.btb-fspl__sticky {
  position: fixed;
  z-index: 9998;
  right: 0;
  bottom: 0;
  left: 0;
  display: flex;
  justify-content: center;
  max-width: 800px;
  margin: 0 auto;
  padding: 22px 14px calc(12px + env(safe-area-inset-bottom));
  background: linear-gradient(180deg, rgba(255, 255, 255, 0) 0%, rgba(255, 255, 255, 0.55) 32%, rgba(255, 255, 255, 0.96) 72%);
  transition: transform 0.35s ease;
}

.btb-fspl__sticky--hidden {
  transform: translateY(130%);
}

.btb-fspl__button--sticky {
  min-height: 52px;
  padding: 15px 24px;
  font-size: 1.05rem;
  box-shadow: 0 6px 18px rgba(0, 0, 0, 0.22), inset 0 1px 0 rgba(255, 255, 255, 0.3);
}

.btb-fspl__progress {
  position: fixed;
  z-index: 9999;
  top: 0;
  right: 0;
  left: 0;
  height: 3px;
  background: rgba(0, 0, 0, 0.06);
  pointer-events: none;
}

.btb-fspl__progress span {
  display: block;
  width: 0;
  height: 100%;
  background: linear-gradient(180deg, #3a4f70, #031b44);
  transition: width 0.1s linear;
}

.btb-fspl--animated .btb-fspl__reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.7s ease, transform 0.7s ease;
}

.btb-fspl--animated .btb-fspl__reveal.is-visible {
  opacity: 1;
  transform: none;
}

@keyframes btb-fspl-float {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-10px); }
}

@media (min-width: 768px) {
  .btb-fspl {
    background-color: #fff7f4;
  }

  .btb-fspl::before {
    position: absolute;
    z-index: 0;
    top: 0;
    right: 0;
    left: 0;
    height: 1200px;
    background-image: url("../images/desktop-background.webp");
    background-repeat: no-repeat;
    background-position: center top;
    background-size: auto 100%;
    content: "";
    pointer-events: none;
    -webkit-mask-image: linear-gradient(180deg, #000 78%, rgba(0, 0, 0, 0) 100%);
    mask-image: linear-gradient(180deg, #000 78%, rgba(0, 0, 0, 0) 100%);
  }

  .btb-fspl--bg-depth::before {
    background-image: url("../images/desktop-background-3d.png");
    transform: translate3d(var(--btb-fspl-bg-x), var(--btb-fspl-bg-y), 0) scale(1.018);
    transform-origin: center top;
    transition: transform 0.45s ease-out;
  }

  .btb-fspl--bg-depth::after {
    position: absolute;
    z-index: 0;
    inset: 0 0 auto;
    height: 1200px;
    content: "";
    pointer-events: none;
    background: radial-gradient(ellipse at 18% 8%, rgba(255, 250, 231, 0.16), transparent 46%);
  }

  .btb-fspl__main {
    box-shadow: 0 0 60px rgba(0, 0, 0, 0.28);
  }

  .btb-fspl--bg-depth .btb-fspl__main {
    box-shadow: 0 20px 55px rgba(8, 34, 61, 0.25), 0 0 3px rgba(8, 34, 61, 0.14);
  }

  .btb-fspl__button {
    min-height: 68px;
    padding: 22px 37px;
    font-size: 1.4rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  .btb-fspl__button--float {
    animation: none;
  }

  .btb-fspl--animated .btb-fspl__reveal {
    opacity: 1;
    transform: none;
    transition: none;
  }

  .btb-fspl--bg-depth::before {
    transform: none;
    transition: none;
  }
}