body
{
   background-color: #FFFFFF;
   color: #000000;
   font-family: Arial;
   font-weight: normal;
   font-size: 13px;
   line-height: 1.1875;
   margin: 0;
   padding: 0;
}
a
{
   color: #0000FF;
   text-decoration: underline;
}
a:visited
{
   color: #800080;
}
a:active
{
   color: #FF0000;
}
a:hover
{
   color: #0000FF;
   text-decoration: underline;
}
input:focus, textarea:focus, select:focus
{
   outline: none;
}
        :root {
            --primary: #4a90e2;
            --bg: #f5f7fa;
        }
        body {
            font-family: "Meiryo", sans-serif;
            background: var(--bg);
            margin: 0;
            display: flex;
            flex-direction: column;
            align-items: center; /* 水平居中 */
            justify-content: flex-start; /* 從頂部開始 */
            min-height: 100vh;
            padding: 20px 0;
        }
        h2 {
            margin-bottom: 1rem;
            color: #333;
            white-space: nowrap;
            font-size: 2rem;
            text-align: center;
        }
        /* 3x3 網格 */
        #cardGrid {
            display: grid;
            grid-template-columns: repeat(3, 10cm);
            gap: 20px;
        }
        .card-container {
            width: 10cm;
            height: 3cm;
            perspective: 1000px;
            cursor: pointer;
        }
        .card-inner {
            position: relative;
            width: 100%;
            height: 100%;
            transition: transform 0.6s cubic-bezier(0.4, 0, 0.2, 1);
            transform-style: preserve-3d;
            box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
            border-radius: 10px;
        }
        .card-container.flipped .card-inner {
            transform: rotateY(180deg);
        }
        .front, .back {
            position: absolute;
            width: 100%;
            height: 100%;
            backface-visibility: hidden;
            display: flex;
            align-items: center;
            justify-content: center;
            border-radius: 10px;
            padding: 10px;
            box-sizing: border-box;
            white-space: normal; /* 允許文字太長時換行 */
            text-align: center;
        }
        .front {
            background: white;
            color: var(--primary);
            border: 2px solid var(--primary);
            font-size: 2rem;
            font-weight: bold;
        }
        .back {
            background: var(--primary);
            color: white;
            transform: rotateY(180deg);
            font-size: 2rem;
        }