* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}
body {
    font-family: 'PingFang TC', 'Microsoft JhengHei', -apple-system, sans-serif;
    background: radial-gradient(circle, #ffffff 0%, #eef2f3 100%);
    color: #333;
    display: flex;
    align-items: center;
    justify-content: center;
    height: 100vh;
    overflow: hidden;
}
.container {
    text-align: center;
    padding: 20px;
    max-width: 500px;
}

.error-code-container {
    display: flex;
    align-items: center;
    justify-content: center;
    line-height: 1;
    margin-bottom: 10px;
}

/* 數字 4 的樣式 */
.error-code {
    font-size: 10rem;
    font-weight: 900;
    background: linear-gradient(135deg, #db4734, #b94b29);
    background-clip: content-box;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    letter-spacing: -2px;
    transform: translateY(-12px);
}

.error-emoji {
    font-size: 8.5rem;
    display: inline-block;
    animation: float 4s ease-in-out infinite;
    margin: 0 -5px;
}

/* 氣球正下方的陰影 */
.shadow {
    width: 80px;
    height: 16px;
    background: rgba(0, 0, 0, 0.08);
    border-radius: 50%;
    margin: 0 auto 30px auto;
    animation: shrink 4s ease-in-out infinite;
}

/* 提示文字 */
.error-title {
    margin-top: 67px;
    font-size: 1.8rem;
    color: #2c3e50;
    font-weight: 700;
}
.error-message {
    font-size: 1rem;
    color: #7f8c8d;
    line-height: 1.6;
}

/* 返回按鈕 */
.home-btn {
    margin-top: 20px;
    display: inline-block;
    padding: 14px 35px;
    background: linear-gradient(135deg, #db4734, #b94b29);
    color: #fff;
    text-decoration: none;
    border-radius: 50px;
    font-weight: bold;
    font-size: 1rem;
    box-shadow: 0 10px 20px rgba(219, 71, 52, 0.3);
    transition: all 0.3s ease;
}
.home-btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 15px 25px rgba(219, 71, 52, 0.4);
    background: linear-gradient(135deg, #b94b29, #a03c1e);
}
.home-btn:active {
    transform: translateY(-1px);
}

/* 動態效果：氣球上下漂浮 */
@keyframes float {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-18px); }
}

/* 動態效果：陰影隨氣球升高而變小 */
@keyframes shrink {
    0%, 100% { transform: scale(1); opacity: 0.8; }
    50% { transform: scale(0.6); opacity: 0.3; }
}