*,
*::before,
*::after{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
:focus:not(:focus-visible) {
    outline: 0;
    /* キーボード操作"以外"でフォーカスされた際はoutlineを消す */
}

::selection {
    color: var(--clear-color);
    background: var(--main-color);
}

html {
    font-size: clamp(14px, 1vw, 18px);
    -webkit-text-size-adjust: 100%;
    text-size-adjust: 100%;
}
@media (min-width: 1600px){
    html {
        font-size: clamp(12px, 0.8vw, 16px);
    }
}
@media (min-width: 481px) and (max-width: 768px){
    html {
        font-size: clamp(14px, 1.25vw, 18px);
    }
}
@media (max-width: 480px){
    html {
        font-size: clamp(14px, 1.5vw, 18px);
    }
}
@media (min-resolution: 2dppx) and (max-width: 480px){
    html {
        font-size: clamp(16px, 2vw, 20px);
    }
}


body{
    font-family: sans-serif;
    color: var(--text-color);
    font-weight: 400;
    letter-spacing: .1rem;
    line-height: 1.7;
    overflow-x: hidden;
}
ul,ol,li{
    list-style-type: none;
}
img{
    max-width: 100%;
    height: auto;
    vertical-align: bottom;
}
a{
    text-decoration: none;
    display: block;
}

#footer{
    padding: 4rem 0;
    text-align: center;
    small{
        font-size: .85rem;
    }
}

#back-to-top {
    position: fixed;
    bottom: 20px;
    right: 20px;
    width: 50px;
    height: 50px;
    border: none;
    border-radius: 50%;
    background-color: var(--main-color);
    color: var(--clear-color);
    font-size: 18px;
    cursor: pointer;
    display: none;
    z-index: 1000;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.2);
    transition: opacity 0.3s ease;
}