body {
    font-family: Arial, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background: 
        linear-gradient(135deg, rgba(162, 217, 255, 0.8) 0%, rgba(255, 228, 235, 0.8) 50%, rgba(206, 235, 255, 0.8) 100%),
        linear-gradient(45deg, rgba(255, 255, 255, 0.9) 0%, rgba(220, 240, 255, 0.7) 100%);
    background-attachment: fixed;
    margin: 0;
    padding: 20px;
    box-sizing: border-box;
    position: relative;
    overflow: auto;
}

body::before {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: 
        radial-gradient(circle at 20% 30%, rgba(255, 255, 255, 0.4) 0%, transparent 25%),
        radial-gradient(circle at 80% 70%, rgba(255, 255, 255, 0.3) 0%, transparent 25%),
        radial-gradient(circle at 40% 80%, rgba(255, 255, 255, 0.2) 0%, transparent 30%),
        radial-gradient(circle at 60% 20%, rgba(255, 255, 255, 0.35) 0%, transparent 30%);
    pointer-events: none;
    animation: shimmer 8s infinite linear;
}

@keyframes shimmer {
    0% { opacity: 0.8; }
    50% { opacity: 1; }
    100% { opacity: 0.8; }
}

/* 气泡样式 */
.bubble {
    position: absolute;
    bottom: -100px;
    width: 40px;
    height: 40px;
    background: rgba(255, 255, 255, 0.15);
    border-radius: 50%;
    animation: bubble 15s infinite ease-in;
}

.bubble:nth-child(1) {
    left: 10%;
    animation-delay: 0s;
    width: 20px;
    height: 20px;
}

.bubble:nth-child(2) {
    left: 20%;
    animation-delay: 1s;
    width: 30px;
    height: 30px;
}

.bubble:nth-child(3) {
    left: 30%;
    animation-delay: 3s;
    width: 15px;
    height: 15px;
}

.bubble:nth-child(4) {
    left: 40%;
    animation-delay: 6s;
    width: 25px;
    height: 25px;
}

.bubble:nth-child(5) {
    left: 50%;
    animation-delay: 2s;
    width: 35px;
    height: 35px;
}

.bubble:nth-child(6) {
    left: 60%;
    animation-delay: 4s;
    width: 10px;
    height: 10px;
}

.bubble:nth-child(7) {
    left: 70%;
    animation-delay: 5s;
    width: 40px;
    height: 40px;
}

.bubble:nth-child(8) {
    left: 80%;
    animation-delay: 7s;
    width: 20px;
    height: 20px;
}

.bubble:nth-child(9) {
    left: 90%;
    animation-delay: 9s;
    width: 30px;
    height: 30px;
}

.bubble:nth-child(10) {
    left: 5%;
    animation-delay: 10s;
    width: 25px;
    height: 25px;
}

@keyframes bubble {
    0% {
        bottom: -100px;
        transform: translateX(0);
    }
    50% {
        transform: translateX(100px);
    }
    100% {
        bottom: 1080px;
        transform: translateX(-200px);
    }
}

.container {
    text-align: center;
    background: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(10px);
    border-radius: 20px;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
    padding: 30px;
    max-width: 800px;
    width: 100%;
}

h1 {
    color: #333;
    font-size: 2.5em;
    margin-bottom: 20px;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.1);
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.difficulty-controls {
    margin: 20px 0;
    padding: 15px;
    background: rgba(255, 255, 255, 0.7);
    border-radius: 10px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.difficulty-controls label {
    font-size: 18px;
    margin-right: 15px;
    color: #333;
    font-weight: bold;
}

.difficulty-controls select {
    padding: 8px 12px;
    font-size: 16px;
    border-radius: 8px;
    border: 1px solid #999;
    background: white;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.difficulty-controls button {
    padding: 8px 16px;
    font-size: 16px;
    cursor: pointer;
    border: none;
    border-radius: 8px;
    background-color: #2196F3;
    color: white;
    margin-left: 10px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    transition: all 0.3s ease;
}

.difficulty-controls button:hover {
    background-color: #0b7dda;
    transform: translateY(-2px);
    box-shadow: 0 6px 8px rgba(0, 0, 0, 0.15);
}

#sudoku-board {
    display: grid;
    grid-template-columns: repeat(9, 80px);
    grid-template-rows: repeat(9, 80px);
    gap: 1px;
    margin: 20px auto;
    border: 2px solid #333;
    width: 720px;
    height: 720px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.2);
    border-radius: 8px;
}

.cell {
    display: flex;
    justify-content: center;
    align-items: center;
    background-color: white;
    border: 1px solid #999;
    font-size: 20px;
    font-weight: bold;
    transition: all 0.3s ease;
}

.cell:nth-child(3n):not(:nth-child(9n)) {
    border-right: 2px solid #333;
}

.cell:nth-child(n+19):nth-child(-n+27),
.cell:nth-child(n+46):nth-child(-n+54) {
    border-bottom: 2px solid #333;
}

.cell:hover {
    background-color: #f0f8ff;
    transform: scale(1.05);
    z-index: 1;
    position: relative;
}

.input-cell {
    background-color: #e6f3ff;
}

.input-cell input {
    width: 100%;
    height: 100%;
    border: none;
    text-align: center;
    font-size: 20px;
    font-weight: bold;
    background-color: transparent;
}

.input-cell input:focus {
    outline: none;
    background-color: #cce6ff;
}

.controls {
    margin: 20px 0;
}

button {
    padding: 12px 24px;
    margin: 0 10px;
    font-size: 16px;
    cursor: pointer;
    border: none;
    border-radius: 8px;
    background-color: #4CAF50;
    color: white;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    transition: all 0.3s ease;
}

button:hover {
    background-color: #45a049;
    transform: translateY(-2px);
    box-shadow: 0 6px 8px rgba(0, 0, 0, 0.15);
}

#reveal-btn {
    background-color: #FF9800;
}

#reveal-btn:hover {
    background-color: #e68a00;
}

#reset-btn {
    background-color: #f44336;
}

#reset-btn:hover {
    background-color: #d32f2f;
}

#message {
    font-size: 20px;
    font-weight: bold;
    margin-top: 25px;
    padding: 15px;
    border-radius: 10px;
    background: rgba(255, 255, 255, 0.8);
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
    backdrop-filter: blur(5px);
    max-width: 720px;
    margin: 25px auto;
}

.success {
    color: #2E7D32;
    background: rgba(236, 249, 236, 0.8);
}

.error {
    color: #C62828;
    background: rgba(255, 235, 235, 0.8);
}

#game-info {
    text-align: left;
    max-width: 720px;
    margin: 30px auto;
    padding: 25px;
    background: rgba(255, 255, 255, 0.85);
    border-radius: 15px;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
    backdrop-filter: blur(5px);
    border: 1px solid rgba(255, 255, 255, 0.2);
}

#game-info h2 {
    color: #333;
    margin-top: 0;
}

#game-info ul {
    padding-left: 20px;
}

#game-info li {
    margin-bottom: 10px;
}