@charset "utf-8";

/*
chudig/index.html用のcss
*/

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

html {
  font-family: 'メイリオ', Meiryo, 'Hiragino Kaku Gothic ProN', 'ヒラギノ角ゴ ProN W3', Osaka, sans-serif;
  -webkit-font-smoothing: antialiased;
  -webkit-text-size-adjust: 100%;
  overflow-x: hidden;
}

body {
  margin: 1rem 0;
  color: #000;
  overflow-x: hidden;
}

body.page-flat {
  display: grid;
  grid-template-rows: auto 1fr auto;
  min-height: 100vh;
}

a { color: #0066c0; }
a:hover,
a:visited { color: #333; font-weight: bold; }

/* ---------- header ---------- */
header {
  padding: 0.5rem 0;
  text-align: center;
}
header h1 { margin: 0.67em 0; font-size: 2rem; }
header a { text-decoration: none; }
header a:hover { opacity: 0.6; }

/* ---------- main ---------- */
main {
  width: min(960px, 92%);
  margin: 0 auto;
  padding: 0 0 3rem;
  background-color: #fff;
}

.topimg {
  display: block;
  max-width: 100%;
  height: auto;
  margin: 1rem auto 2rem;
}

/* ---------- 学年ボタン ---------- */
.grade {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-around;
  gap: 2rem 0;
  margin: 1em 0 0;
  padding: 0;
  list-style: none;
}
.grade li {
  width: 30%;
  border-radius: 0.5rem;
  transition: transform 0.2s ease;
}
.grade li:hover,
.grade li:focus-within { transform: translateY(-4px); }

.grade a,
.grade a:hover,
.grade a:visited {
  display: block;
  padding: 1rem 0;
  border-radius: inherit;
  color: #fff;
  font-size: 1.618rem;
  font-weight: normal;
  text-align: center;
  text-decoration: none;
}
.grade a:focus-visible { outline: 3px solid #333; outline-offset: 2px; }

.grade li:nth-child(1) { background-color: rgba(233, 85, 19, 0.8); }
.grade li:nth-child(2) { background-color: rgba(16, 140, 207, 0.8); }
.grade li:nth-child(3) { background-color: rgba(144, 112, 175, 0.8); }

/* ---------- footer ---------- */
footer p {
  margin: 0;
  padding: 14px 0;
  font-size: 12px;
  line-height: 2;
  text-align: center;
}

/* ---------- スマートフォン ---------- */
@media (max-width: 559px) {
  header h1 { margin: 26px 0 5px; font-size: 1.4rem; }
  .topimg { max-width: 90%; }
  .grade { gap: 1.2rem 0; }
  .grade li { width: 90%; }
}

@media (prefers-reduced-motion: reduce) {
  .grade li { transition: none; }
}