body {
  background-color: #222;
  margin: 0;
  font-family: sans-serif;
  color: white;
  user-select: none;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center; /* 居中 */
  height: 100vh; /* 占满窗口高度 */
}

#seedWrapper {
  position: relative;
  width: 400px;
  height: 600px;
  background: url("images/back.jpg") no-repeat center / contain;
  border: none;
  margin: auto;
  display: flex;
  justify-content: center;
  align-items: center;
}

#seedCanvas {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;   
  height: 100%;
  background: transparent;
  touch-action: none;
  cursor: crosshair;
  border: none;
}

#container {
  position: relative;
  width: 100vw;
  height: 90vh;
  background: #333;
  overflow: hidden;
  box-sizing: border-box;
  user-select: none;
  display: none;
}

.card {
  position: absolute;
  height: 25vh;
  width: calc(25vh * 0.583);
  perspective: 1000px;
  cursor: pointer;
  border-radius: 1.25vh;
  border: 0.5vh solid #666;
  overflow: hidden;
  transition:
    transform 0.4s,
    box-shadow 0.3s,
    left 0.6s,
    top 0.6s;
  user-select: none;
  background: transparent;
  transform-origin: center center;
  transform: translateX(-50%);
  left: 0;
  background-clip: padding-box;
}

.card.selected {
  box-shadow: 0 0 5vh 1.25vh gold;
  transform: translateX(-50%) scale(1.1);
  z-index: 10000 !important;
}

.card.enlarged {
  transform: translateX(-50%) scale(1.75);
  transition: transform 0.6s;
}

.inner {
  width: 100%;
  height: 100%;
  transition: transform 0.6s;
  transform-style: preserve-3d;
  position: relative;
  border-radius: 1.25vh;
}

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

.front, .back {
  position: absolute;
  width: 100%;
  height: 100%;
  backface-visibility: hidden;
}

.front {
  background: #888;
  background-size: cover;
  background-position: center;
}

.back {
  position: relative;
  background-size: cover;
  background-position: center;
  transform: rotateY(180deg);
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  font-weight: bold;
  font-size: 2vh;
  color: black;
  user-select: none;
  transition: transform 0.6s;
}

.back.reverse {
  transform: rotateY(180deg) rotateZ(180deg);
}

.overlay {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(255,255,255,1);
  border-radius: inherit;
  opacity: 0;
  transition: opacity 0.6s;
  pointer-events: none;
  z-index: 1;
}

.card.flipped:hover .overlay {
  opacity: 0.7;
}

.name, .hover-upright, .hover-reversed {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  z-index: 999;
  font-size: 1.4vh;
  color: black;
  text-align: center;
  word-break: break-word;
  width: 90%;
  line-height: 2.1vh;
  padding: 0;
  box-sizing: border-box;
  user-select: none;
  transition: opacity 0.3s;
}

/* === FIXED VISIBILITY RULES === */

/* hide by default */
.hover-upright,
.hover-reversed,
.name {
  opacity: 0;
}

/* show name on hover */
.card.flipped:hover .name {
  opacity: 1;
}

/* show upright text only when active + hover */
.card.flipped:hover .hover-upright[data-active="true"] {
  opacity: 1;
}

/* show reversed text only when active + hover */
.card.flipped:hover .hover-reversed[data-active="true"] {
  opacity: 1;
}

.back.reverse .name,
.back.reverse .hover-reversed {
  transform: translate(-50%, -50%) rotate(180deg);
}

button {
  margin-top: 2vh;
  padding: 1vh 2vh;
  font-size: 2vh;
  cursor: pointer;
  border-radius: 1vh;
  border: none;
  background-color: gray;
  color: white;
  transition: background-color 0.3s;
  user-select: none;
}

button:disabled {
  background-color: #555;
  cursor: not-allowed;
}

#flipBtn { display: none; }

.shrink-out {
  animation: shrinkOut 0.8s forwards;
}

@keyframes shrinkOut {
  0% { transform: scale(1) translateY(0); opacity: 1; }
  100% { transform: scale(0.1) translateY(-150%); opacity: 0; }
}