.ab_list { 
    list-style-type: none; 
    padding-left: 1em; 
}
.ab_list li { 
    position: relative; 
    margin: 0; 
}
.ab_list li::before { 
    position: absolute; 
    content: "・"; 
    left: -1em; 
    font-weight: bold;
}

/* 下線付きタイトル */
.bb_index {
    width: 95%;
    margin: 15px auto 5px;
    padding-bottom: 0.1em;
    border-bottom: 1px solid #2dabea;
    text-align: center;
    color: #2dabea;
    font-weight: bold;
    font-size: 1.6rem;
}
/* ----- ページトップ 三角ナビ ----- */
.top_tri_list {
    width: 95%;

    display: grid;
    grid-template-columns: 1fr 1fr;
    grid-gap: 5px;
    margin: 1em auto;
}
.ttl_item {
    position: relative;
    margin: -1px 0 0 -1px;
    background-color: #fff;
    border-radius: 5px;
    box-shadow: -1px -1px 2px #eee, 2px 2px 2px #ccc;
    text-align: center;
}
.ttl_item a {
    display: block;
    padding: 10px 5px 10px 20px;
    /* background: linear-gradient(#fff, #f8ffed); */
    /* background: linear-gradient(#fff, #f2f2f2); */
    font-weight: bold;
    font-size: 1.6rem;
}
.ttl_item a:hover {
    background: #f7fcff;
    transition: 0.2s;
}
.ttl_item::before {
    position: absolute;
    content: "";
    width: 13px;
    height: 8px;
    background: #2dabea;
    clip-path: polygon(50% 0, 100% 100%, 0 100%);
    left: 10px;
    top: 19px;
    transform: rotate(90deg);
}

@media screen and (min-width: 600px) {
    /* 下線付きタイトル */
    .bb_index {
        width: 800px;
        margin: 40px auto 20px;
        font-size: 2rem;
    }
    /* ----- ページトップ 三角ナビ ----- */
    .top_tri_list {
        width: 800px;
        grid-template-columns: 1fr 1fr 1fr;
        grid-gap: 10px;
        margin: 0 auto;
    }
    .ttl_item::before {
        width: 15px;
        height: 9px;
        left: 14px;
        top: 18px;
    }
}