/* ===== Reset / Base ===== */
* { box-sizing: border-box; }
html, body { margin: 0; height: 100%; overflow-x: hidden; }

body {
  font-family: "Helvetica Neue", Arial, sans-serif;
  background:#fff; 
  color:#fff;
  background:url("../img/ushiro.png") center/cover no-repeat;
}

/* ===== Layout ===== */
main { padding: 2.5rem 5%; }

/* Headings */
h1 {
  margin: 0 0 0.75rem;
  font-size: clamp(28px, 4vw, 40px);
  line-height: 1.2;
  font-weight: 800;
  letter-spacing: .05em;
}

/* Links (統一) */
a { color: gray; text-decoration: none; }
a:visited { color: #fff; }
a:hover { color: orangered; }

/* ===== Hamburger Button (always on top) ===== */
.menu-btn{
  position: fixed;
  top: 20px; right: 20px;
  width: 40px; height: 30px;
  background: none; border: none; padding: 0;
  cursor: pointer;
  z-index: 3000;
}
.menu-btn span{
  position: absolute; left: 0; right: 0; margin: 0 auto;
  width: 100%; height: 4px; background:#000; border-radius: 2px;
  transform-origin: center;
  transition: transform .25s ease, opacity .2s ease, background .2s ease;
}
.menu-btn span:nth-child(1){ top: 50%; transform: translateY(-9px); }
.menu-btn span:nth-child(2){ top: 50%; transform: translateY(-50%); }
.menu-btn span:nth-child(3){ top: 50%; transform: translateY(7px); }

.menu-btn.open span{ background:#fff; }
.menu-btn.open span:nth-child(1){ transform: translateY(-50%) rotate(45deg); }
.menu-btn.open span:nth-child(2){ opacity: 0; }
.menu-btn.open span:nth-child(3){ transform: translateY(-50%) rotate(-45deg); }

/* ===== Slide-in Menu ===== */
#menu{
  position: fixed; inset: 0 0 0 auto;
  width: 250px; height: 100dvh;
  padding: 2rem; padding-right: calc(2rem + env(safe-area-inset-right));
  background: rgba(0,0,0,.95); color:#fff;
  transform: translateX(100%); transition: transform .3s ease;
  z-index: 2500;
}
#menu.active{ transform: translateX(0); }
#menu ul{ list-style: none; margin: 0; padding: 0; }
#menu li{ margin: 1rem 0; }
#menu a{ color:#fff; font-size: 1.2rem; }
#menu a:hover{ color: orangered; }

/* Backdrop */
.backdrop{
  position: fixed; inset: 0;
  background: rgba(0,0,0,.3);
  opacity: 0; pointer-events: none;
  transition: opacity .25s ease;
  z-index: 2400;
}
.backdrop.active{
  opacity: 1; pointer-events: auto;
}

/* ===== Movie Section ===== */
.movie-section{ padding: 2em 0; }
.movie-section h2{ margin-top: 2em; }

/* Grid for videos */
.video-list{
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 1.5em;
  margin-top: 1em;
}
.video-item{ max-width: 520px; }

/* Iframe: CSSで枠を消し、比率固定 */
.video-item iframe{
  width: 100%;
  aspect-ratio: 16 / 9;
  border: none;
  background: #ddd;
}

/* Title under video */
.video-title{ font-size: .9em; margin-top: .4em; }

/* ===== Footer ===== */
:root{
  --footer-pad-y: 18px;
  --footer-gap: 28px;
  --footer-icon: 28px;
}
footer{
  background:#000; color:#fff; text-align:center;
  padding: var(--footer-pad-y) 24px calc(env(safe-area-inset-bottom,0px) + var(--footer-pad-y));
  font-size: 0.9rem;
}
footer p{ margin: 0 0 10px; line-height: 1.4; }
footer .sns-icons{
  display:flex; justify-content:center; align-items:center;
  gap: var(--footer-gap); margin-top: 10px; flex-wrap: nowrap;
}
footer .sns-icons img{
  display:block; height: var(--footer-icon); width: auto;
}

/* Mobile tune */
@media (max-width: 600px){
  :root{ --footer-gap: 24px; --footer-icon: 26px; }
}

/* 背景をうっすら暗くして文字を読みやすく（壊さない薄さ） */
body::before{
  content:"";
  position: fixed;
  inset: 0;
  z-index: -1; /* 背景画像の直上、コンテンツの下 */
  background: linear-gradient(
    to bottom,
    rgba(0,0,0,.25) 0%,
    rgba(0,0,0,.15) 40%,
    rgba(0,0,0,.30) 100%
  );
  pointer-events: none;
}