/* 重置與基本設定 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: Arial, sans-serif;
    min-height: 100vh;
    display: flex;
    flex-direction: row; /* 電腦：左右 */
}

/* ===== 導覽列 ===== */
nav {
    display: flex;
    justify-content: center;
    background-color: #333;
    padding: 10px;
    flex-direction: column; /* 預設直排（手機優先） */
    align-items: center;
    width: 100%; /* 手機時佔滿 */
}

nav a {
    position: relative;
    color: white;
    text-decoration: none;
    text-align: center;
    margin: 10px 20px;
    padding: 8px 16px;
    overflow: hidden;
    white-space: nowrap;
    z-index: 1;
    width: fit-content;
}

nav a::before {
    content: "";
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    background: radial-gradient(
        circle,
        rgba(250, 211, 255, 0) 20%,
        rgba(250, 211, 255, 0.2) 75%,
        rgba(250, 211, 255, 1) 100%
    );
    border-radius: 50%;
    transform: translate(-50%, -50%);
    transition: width 0.5s ease, height 0.5s ease;
    z-index: -1;
}

nav a:hover::before {
    width: 150px;
    height: 150px;
}

/* 讓 nav 在手機更美觀 */
nav::-webkit-scrollbar {
    height: 6px;
}
nav::-webkit-scrollbar-thumb {
    background: rgba(255,255,255,0.3);
    border-radius: 3px;
}

/* ===== 主內容 ===== */
main {
    flex: 1;
    padding: 20px;
    text-align: center;
}

/* ===== 電腦版（>= 768px） ===== */
@media screen and (min-width: 768px) {
    body {
        font-size: 18px;
        flex-direction: row;
    }

    nav {
        flex-direction: column;
        width: 200px;           /* 電腦時固定寬度 */
        justify-content: flex-start;
        padding: 20px 0;
    }

    nav a {
        margin: 15px 0;
        width: 100%;
    }

    main {
        padding: 40px;
    }
}

/* ===== 手機版（< 768px） ===== */
@media screen and (max-width: 767px) {
    body {
        font-size: 16px;
        flex-direction: column;
    }

    nav {
        flex-direction: row;     /* 手機橫排 */
        width: 100%;
        overflow-x: auto;        /* 太長可左右滑 */
        white-space: nowrap;
        padding: 10px 0;
    }

    nav a {
        margin: 0 10px;
        padding: 8px 12px;
        font-size: 14px;
    }
}