#message .error-anim {
    font-size: 1.1em;
    color: #c0392b;
    background: #ffeaea;
    border-radius: 12px;
    padding: 14px 10px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.10);
    margin-top: 10px;
    border: 2px solid #c0392b;
    text-align: center;
}

@keyframes shake {
    0% { transform: translateX(0); }
    25% { transform: translateX(-8px); }
    50% { transform: translateX(8px); }
    75% { transform: translateX(-8px); }
    100% { transform: translateX(0); }
}
#message .congrats-anim {
    font-size: 1.3em;
    color: #bfa05a;
    background: #fffbe6;
    border-radius: 12px;
    padding: 18px 12px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.10);
    margin-top: 10px;
    border: 2px solid #bfa05a;
    text-align: center;
}

@keyframes pulse {
    0% { box-shadow: 0 0 10px #bfa05a; }
    100% { box-shadow: 0 0 30px #bfa05a; }
}

body {
    background: url('https://images.unsplash.com/photo-1506744038136-46273834b3fb?auto=format&fit=crop&w=1500&q=80') no-repeat center center fixed;
    background-size: cover;
    font-family: 'Noto Sans JP', 'Yu Gothic', 'Meiryo', sans-serif;
    margin: 0;
    padding: 0;
}
.container {
    background: rgba(255, 255, 255, 0.85);
    max-width: 500px;
    margin: 40px auto;
    border-radius: 16px;
    box-shadow: 0 8px 32px rgba(0,0,0,0.2);
    padding: 32px 24px 24px 24px;
    border: 2px solid #bfa05a;
    position: relative;
}
h1 {
    font-family: 'Sawarabi Mincho', serif;
    font-size: 2.2em;
    color: #bfa05a;
    text-align: center;
    margin-bottom: 24px;
    letter-spacing: 2px;
}
.controls {
    display: flex;
    justify-content: space-between;
    margin-bottom: 18px;
}
button, select {
    font-size: 1em;
    padding: 8px 16px;
    border-radius: 8px;
    border: 1px solid #bfa05a;
    background: #fffbe6;
    color: #7c5c20;
    cursor: pointer;
    transition: background 0.2s;
}
button:hover, select:hover {
    background: #f5e1a4;
}
#sudoku-board {
    display: grid;
    grid-template-rows: repeat(9, 1fr);
    gap: 2px;
    background: #bfa05a;
    border-radius: 8px;
    padding: 8px;
    margin-bottom: 18px;
}
.row {
    display: grid;
    grid-template-columns: repeat(9, 1fr);
    gap: 2px;
}
.cell {
    width: 38px;
    height: 38px;
    text-align: center;
    font-size: 1.2em;
    border: none;
    background: #fffbe6;
    color: #7c5c20;
    border-radius: 4px;
    box-shadow: 0 1px 2px rgba(0,0,0,0.05);
    outline: none;
    transition: background 0.2s;
    border-top: 2px solid #bfa05a;
    border-left: 2px solid #bfa05a;
}
.cell:focus {
    background: #f5e1a4;
}
.prefilled {
    background: #e6d3a3;
    color: #bfa05a;
    font-weight: bold;
}
.cell {
}
.cell:nth-child(1), .cell:nth-child(4), .cell:nth-child(7) {
    border-left: 4px solid #bfa05a;
}
.cell:nth-child(3), .cell:nth-child(6), .cell:nth-child(9) {
    border-right: 4px solid #bfa05a;
}
.row:nth-child(1) .cell, .row:nth-child(4) .cell, .row:nth-child(7) .cell {
    border-top: 4px solid #bfa05a;
}
.row:nth-child(3) .cell, .row:nth-child(6) .cell, .row:nth-child(9) .cell {
    border-bottom: 4px solid #bfa05a;
}
#message {
    text-align: center;
    font-size: 1.1em;
    color: #bfa05a;
    margin-top: 10px;
}