/* =============================================
   Watarionn's Aquarium — aquarium.css
   国語辞典 用例カード × 水族館
   ============================================= */

/* ─── Custom Properties ─── */
:root {
  --clr-water-top:    #0a1628;
  --clr-water-mid:    #0d2240;
  --clr-water-deep:   #071020;
  --clr-paper:        #f0e8cc;
  --clr-paper-aged:   #e8dab0;
  --clr-paper-back:   #e2d49a;
  --clr-ink:          #1a0f05;
  --clr-ink-mid:      #2c1f0e;
  --clr-vermilion:    #c0392b;
  --clr-gold:         #9a7a32;
  --clr-rule:         #b8a270;

  --font-mincho: 'Noto Serif JP', 'Yu Mincho', 'Hiragino Mincho ProN', serif;

  --ease-flip: cubic-bezier(0.4, 0, 0.2, 1);
  --dur-flip:  0.55s;
}

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

html { font-size: 16px; }

body {
  font-family: var(--font-mincho);
  background: var(--clr-water-deep);
  min-height: 100svh;
  overflow-x: hidden;
  position: relative;
}

/* ─── 水中背景 ─── */
.water-bg {
  position: fixed;
  inset: 0;
  z-index: 0;
  background:
    radial-gradient(ellipse at 20% 0%,   rgba(20, 80, 160, 0.6) 0%, transparent 55%),
    radial-gradient(ellipse at 80% 100%, rgba(8,  40, 100, 0.7) 0%, transparent 60%),
    linear-gradient(to bottom, var(--clr-water-top), var(--clr-water-mid) 50%, var(--clr-water-deep));
  pointer-events: none;
}

/* 光のゆらぎ */
.water-caustic {
  position: fixed;
  inset: 0;
  z-index: 1;
  pointer-events: none;
  background:
    radial-gradient(ellipse 40% 20% at 30% 25%, rgba(100,180,255,0.07) 0%, transparent 100%),
    radial-gradient(ellipse 30% 15% at 70% 55%, rgba(100,200,255,0.05) 0%, transparent 100%),
    radial-gradient(ellipse 50% 10% at 55% 10%, rgba(150,220,255,0.06) 0%, transparent 100%);
  animation: causticDrift 14s ease-in-out infinite alternate;
}
@keyframes causticDrift {
  from { transform: translateX(-1.5vw) translateY(-1vh) scale(1); }
  to   { transform: translateX(1.5vw)  translateY(1.5vh) scale(1.03); }
}

/* ─── 泡 ─── */
#bubble-container {
  position: fixed;
  inset: 0;
  z-index: 2;
  pointer-events: none;
}

.bubble {
  position: absolute;
  bottom: -5vh;
  border-radius: 50%;
  background: radial-gradient(circle at 32% 30%, rgba(255,255,255,0.55), rgba(255,255,255,0.05));
  border: 1px solid rgba(255,255,255,0.2);
  animation: bubbleRise linear infinite;
  will-change: transform, opacity;
}
@keyframes bubbleRise {
  0%   { transform: translateY(0) translateX(0);     opacity: 0.7; }
  40%  { transform: translateY(-40vh) translateX(1vw);  opacity: 0.5; }
  80%  { transform: translateY(-90vh) translateX(-1.5vw); opacity: 0.25; }
  100% { transform: translateY(-115vh) translateX(0.5vw); opacity: 0; }
}

/* ─── ヘッダー ─── */
header {
  position: relative;
  z-index: 20;
  text-align: center;
  padding: clamp(1.5rem, 5vw, 3rem) var(--content-pad, 5vw);
  border-bottom: 1px solid rgba(255,255,255,0.08);
}

.header-kana {
  display: block;
  font-size: clamp(0.6rem, 1.2vw, 0.75rem);
  letter-spacing: 0.5em;
  color: rgba(180,200,255,0.5);
  margin-bottom: 0.5rem;
  font-style: normal;
}

header h1 {
  font-size: clamp(1.3rem, 4vw, 2.2rem);
  font-weight: 700;
  color: var(--clr-paper);
  letter-spacing: 0.25em;
  text-shadow:
    0 0 30px rgba(100,160,255,0.4),
    0 2px 8px rgba(0,0,0,0.8);
  margin-bottom: 0.4rem;
}

.header-en {
  display: block;
  font-size: clamp(0.55rem, 1vw, 0.7rem);
  letter-spacing: 0.4em;
  color: rgba(180,210,255,0.4);
  font-style: italic;
  text-transform: uppercase;
}

.header-rule {
  width: clamp(3rem, 8vw, 6rem);
  height: 1px;
  background: linear-gradient(to right, transparent, rgba(180,210,255,0.3), transparent);
  margin: 0.8rem auto 0;
}

/* ─── メインエリア ─── */
main {
  position: relative;
  z-index: 10;
  padding: clamp(1.5rem, 4vw, 3rem) clamp(1rem, 4vw, 3rem);
  min-height: 80svh;
}

/* ─── カードグリッド（散らばり感） ─── */
.card-sea {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: clamp(1rem, 2.5vw, 2rem);
  position: relative;
}

@media (max-width: 900px) {
  .card-sea { grid-template-columns: repeat(3, 1fr); }
}
@media (max-width: 540px) {
  .card-sea { grid-template-columns: repeat(2, 1fr); gap: 0.75rem; }
}

/* ─── 用例カード外枠 ─── */
.fish-card {
  aspect-ratio: 3 / 4;
  perspective: 900px;
  cursor: pointer;
  position: relative;
  /* 散らばりの傾き（JS で上書き） */
  transform: rotate(var(--tilt, 0deg));
  transition: transform 0.25s ease, filter 0.25s ease;
  will-change: transform;
  /* ふよふよ */
  animation: cardFloat var(--float-speed, 5s) ease-in-out infinite;
  animation-delay: var(--float-delay, 0s);
}

.fish-card:hover,
.fish-card:focus-within {
  transform: rotate(0deg) scale(1.06) translateY(-4px);
  filter: drop-shadow(0 8px 24px rgba(100,160,255,0.35));
  z-index: 5;
}

@keyframes cardFloat {
  0%   { translate: 0 0; }
  25%  { translate: var(--float-x,  1px) calc(var(--float-y,  2px) * -1); }
  50%  { translate: 0 calc(var(--float-y, 2px) * -0.5); }
  75%  { translate: calc(var(--float-x, 1px) * -1) var(--float-y, 2px); }
  100% { translate: 0 0; }
}

/* ─── フリップ構造 ─── */
.fish-inner {
  width: 100%;
  height: 100%;
  position: relative;
  transform-style: preserve-3d;
  transition: transform var(--dur-flip) var(--ease-flip);
}

.fish-card.flipped .fish-inner {
  transform: rotateY(180deg);
}

/* ─── 表・裏 共通 ─── */
.fish-front,
.fish-back {
  position: absolute;
  inset: 0;
  border-radius: 4px;
  backface-visibility: hidden;
  overflow: hidden;
  /* 古紙テクスチャ風の影 */
  box-shadow:
    0 2px 6px rgba(0,0,0,0.5),
    0 8px 20px rgba(0,0,0,0.4),
    inset 0 0 0 1px rgba(180,160,100,0.25);
}

/* 横罫線（辞書の用紙） */
.fish-front::after,
.fish-back::after {
  content: '';
  position: absolute;
  inset: 0;
  background-image: repeating-linear-gradient(
    to bottom,
    transparent,
    transparent calc(1.8em - 1px),
    rgba(139,110,60,0.12) calc(1.8em - 1px),
    rgba(139,110,60,0.12) 1.8em
  );
  pointer-events: none;
}

.fish-front {
  background-color: var(--clr-paper);
  /* 左端の朱線 */
  border-left: 3px solid var(--clr-vermilion);
}

.fish-back {
  background-color: var(--clr-paper-aged);
  border-left: 3px solid var(--clr-gold);
  transform: rotateY(180deg);
}

/* ─── 表：漢字（墨書き） ─── */
.card-front-inner {
  position: relative;
  z-index: 1;
  width: 100%;
  height: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: clamp(0.5rem, 2vw, 1rem);
  gap: 0.5rem;
}

/* 品詞マーク */
.card-pos {
  font-size: clamp(0.45rem, 1vw, 0.6rem);
  color: var(--clr-paper);
  background: var(--clr-vermilion);
  padding: 0.1em 0.45em;
  border-radius: 2px;
  letter-spacing: 0.05em;
  align-self: flex-start;
  margin-left: clamp(0.3rem, 1vw, 0.6rem);
  opacity: 0.9;
}

/* 漢字本体 */
.fish-name {
  font-size: clamp(1.6rem, 6vw, 3.2rem);
  font-weight: 700;
  color: var(--clr-ink);
  letter-spacing: 0.05em;
  line-height: 1.1;
  text-align: center;
  /* 墨の滲み */
  text-shadow:
    1px  1px 0   rgba(26,15,5,0.25),
    0    0   6px rgba(26,15,5,0.12),
    2px  2px 8px rgba(26,15,5,0.08);
  filter: url('#ink-blur');
  position: relative;
}

/* 右下の小さい番号 */
.card-num {
  position: absolute;
  bottom: clamp(0.3rem, 1vw, 0.5rem);
  right: clamp(0.4rem, 1.2vw, 0.7rem);
  font-size: clamp(0.4rem, 0.8vw, 0.55rem);
  color: var(--clr-rule);
  letter-spacing: 0.05em;
  font-family: 'Libre Baskerville', Georgia, serif;
  font-style: italic;
}

/* ─── 裏：読み ─── */
.card-back-inner {
  position: relative;
  z-index: 1;
  width: 100%;
  height: 100%;
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: clamp(0.6rem, 2.5vw, 1.2rem) clamp(0.6rem, 2vw, 1rem);
  gap: 0.5rem;
}

.card-label {
  font-size: clamp(0.45rem, 0.9vw, 0.58rem);
  letter-spacing: 0.25em;
  color: var(--clr-gold);
  border-bottom: 1px solid rgba(154,122,50,0.35);
  padding-bottom: 0.2rem;
  margin-bottom: 0.15rem;
}

.fish-reading-main {
  font-size: clamp(0.85rem, 2.5vw, 1.3rem);
  font-weight: 700;
  color: var(--clr-ink);
  letter-spacing: 0.12em;
  line-height: 1.4;
}

.fish-reading-sub {
  font-size: clamp(0.7rem, 2vw, 1rem);
  color: var(--clr-ink-mid);
  letter-spacing: 0.1em;
  line-height: 1.4;
  opacity: 0.8;
}

.card-back-kanji {
  margin-top: auto;
  font-size: clamp(0.7rem, 1.5vw, 0.9rem);
  color: rgba(26,15,5,0.18);
  font-weight: 700;
  text-align: right;
  letter-spacing: 0.05em;
}

/* ─── SVGフィルター（墨の滲み） ─── */
.svg-filters {
  position: absolute;
  width: 0;
  height: 0;
  overflow: hidden;
}

/* ─── フッター ─── */
footer {
  position: relative;
  z-index: 10;
  text-align: center;
  padding: clamp(1rem, 3vw, 2rem);
  border-top: 1px solid rgba(255,255,255,0.06);
}

.footer-text {
  font-size: clamp(0.55rem, 1vw, 0.65rem);
  color: rgba(180,200,255,0.25);
  letter-spacing: 0.3em;
}

/* ─── Reduced Motion ─── */
@media (prefers-reduced-motion: reduce) {
  .fish-card, .water-caustic, .bubble {
    animation: none !important;
  }
  .fish-inner {
    transition-duration: 0.01ms !important;
  }
}

/* ─── Focus ─── */
.fish-card:focus-visible {
  outline: 2px solid rgba(180,210,255,0.7);
  outline-offset: 4px;
}