body,
h1,
p,
ul,
li,
input,
button {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html,
body {
    margin: 0;
    padding: 0;
    width: 100%;
}

body {
    font-family: Arial, sans-serif;
    background-color: #fff;
    color: #333;
    line-height: 1.6;
}

.header {
    background-color: #000;
    color: #fff;
    padding: 0px 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 60px;
    box-sizing: border-box;
}

.header .container {
    display: flex;
    align-items: center;
    width: 100%;
    justify-content: space-between;
}

.header .logo {
    flex: 1;
}

.header .logo img {
    max-height: 30px;
    height: auto;
    max-width: 100%;
}

.header .search-form {
    flex: 1;
    display: flex;
    justify-content: center;
}

.search-form input {
    width: 100%;
    padding: 8px;
    border: none;
    border-radius: 5px;
    font-size: 16px;
}

.header .nav {
    flex: 1;
    display: flex;
    justify-content: flex-end;
    gap: 30px;
    align-items: center;
}

#logout-form button {
    font-size: 20px;
    color: #fff;
    background-color: #000;
    border: none;
    cursor: pointer;
}

.nav a {
    font-size: 20px;
    text-decoration: none;
    color: #fff;
}

.nav .sell-btn {
    background-color: #fff;
    padding: 4px 20px;
    border-radius: 5px;
    color: #000;
    text-decoration: none;
    text-align: center;
}

/* タブレット用 */
@media (max-width: 1024px) and (min-width: 768px) {
    .header {
        height: auto;
        padding: 5px;
    }

    .header .logo img {
        max-height: 23px;
    }

    .search-form input {
        width: 100%;
    }

    .header .nav {
        justify-content: flex-end;
        gap: 10px;
    }

    #logout-form button {
        font-size: 13px;
    }

    .nav a {
        font-size: 13px;
    }

    .nav .sell-btn {
        padding: 5px 8px;
        font-size: 13px;
    }
}

/* スマホ用 */
@media (max-width: 767px) {
    .header {
        height: auto;
        padding: 10px;
    }

    .header .container {
        flex-direction: column;
        gap: 10px;
    }

    .header .logo {
        flex: none;
        width: 100%;
        text-align: center;
    }

    .header .logo img {
        max-height: 25px;
    }

    .header .search-form {
        flex: none;
        width: 100%;
    }

    .search-form input {
        font-size: 14px;
        padding: 6px;
    }

    .header .nav {
        flex: none;
        width: 100%;
        justify-content: center;
        gap: 15px;
    }

    #logout-form button {
        font-size: 14px;
    }

    .nav a {
        font-size: 14px;
    }

    .nav .sell-btn {
        padding: 4px 12px;
        font-size: 14px;
    }
}