* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: Arial, sans-serif;
}

body {
    background-color: #f0f0f0;
    text-align: center;
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
    height: 100vh;
}

/* CSS */

header {
    background-image: url('背景.jpg');
    background-size: cover;
    background-position: center;
    padding: 60px 0;
    color: #333;
    height: 150px;
    width: 100%;
    position: fixed; /* 固定在視窗頂部 */
    top: 0;
    left: 0;
    z-index: 1000; /* 確保置於其他元素之上 */
}

nav {
    background-color: #4b6769;
    padding: 10px;
    width: 100%;
    position: fixed; /* 固定在視窗頂部 */
    top: 150px; /* 確保 nav 在 header 之下 */
    z-index: 999; /* 保持在 header 下層，但仍高於其他內容 */
}

main {
    margin-top: 10%; /* 預留空間，避免內容被 header 和 nav 覆蓋 */
    background-color: #d1d1d1;
    padding: 25px;
    border-radius: 10%;
    width: 30%;
}


header h1 {
    font-size: 50px;
    color: #1a0a40;
    font-weight: 800;
}

nav ul {
    display: flex;
    justify-content: center;
    list-style: none;
}

nav ul li {
    margin: 0 15px;
}

nav ul li a {
    color: white;
    text-decoration: none;
    font-weight: bold;
}

nav ul li a.active {
    color: rgb(255, 237, 147);
}

main form {
    display: flex;
    flex-direction: column;
    align-items: center;
    margin-bottom: 10px;
}

main form label {
    margin: 10px 0 5px;
}

main form input {
    width: 250px;
    padding: 8px;
    margin-bottom: 5px;
    border: 2px solid #ccc;
    border-radius: 5px;
    font-size: 16px;
}

main form button {
    padding: 10px 20px;
    background-color: #4b6769;
    color: white;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    font-size: 16px;
    font-weight: bold;
    transition: background-color 0.3s ease;
    margin: 10px;
}

main form button:hover {
    background-color: #365152;
}

#random-number-display {
    text-align: center;
    margin-top: 10px;
}

#random-number {
    font-size: 80px;
    font-weight: bold;
    color: #1a0a40;
    transition: transform 0.3s ease, color 0.3s ease;
    animation: number-bounce 1s infinite;
}

#random-number.roll {
    animation: number-roll 0.5s ease-in-out;
    color: #ff5722;
}

@keyframes number-roll {
    0% {
        transform: translateY(-100%);
    }
    100% {
        transform: translateY(0%);
    }
}

@keyframes number-bounce {
    0%, 100% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.2);
    }
}