.lecturetitle {
    padding: 0;
    font-size: 1.5em;
    font-weight: bold;
    color: hwb(218 18% 72%);
    text-shadow: 2px 2px 8px rgba(255, 255, 255, 0.8), 0 0 4px rgba(255, 255, 255, 0.5);
    position: relative;
    z-index: 1;
}

#yearlogo {
    align-items: center;
    justify-content: center;
    width: 100%;
    padding: 2rem 0;
    margin: 60px 0;
    text-align: center;
    background: transparent;
    backdrop-filter: none;
    border-radius: 0;
    box-shadow: none;
    border: none;
    position: relative;
    z-index: 1;
}

#yearlogo img {
    width: auto;
    height: 70px;
}

#header-title {
    margin: 15px 10px;
    text-align: left;
    position: relative;
    z-index: 1;
}

#header {
    position: relative;
    z-index: 0;
    align-content: flex-start;
    width: auto;
    height: auto;
    min-height: 420px;
    padding: 0;
    margin: 0;
    text-align: center;
    overflow: hidden;
}

#header::before {
    position: absolute;
    top: 0;
    left: 0;
    z-index: -1;
    width: 100%;
    height: 100%;
    content: "";
    background: url("../image/background.jpg");
    background-repeat: no-repeat;
    background-position: 50% 55%;
    background-size: cover;
    filter: blur(0px);
}

/* 透明度75%の白いオーバーレイ */
#header::after {
    position: absolute;
    top: 0;
    left: 0;
    z-index: 0;
    width: 100%;
    height: 100%;
    content: "";
    background: rgba(255, 255, 255, 0.35);
    pointer-events: none;
}

.flex-wrap {
    display: flex;
    flex-wrap: wrap;
}

#si-logo {
    height: auto;
    position: relative;
    z-index: 1;
}

#si-logo img {
    height: 80px;
    padding: 1.0em 1.0em;
}

#date-place {
    place-content: flex-end center;
    width: 100%;
    margin-right: 1em;
    font-size: 1.18em;
    font-weight: bold;
    color: #2d3748;
    text-shadow: 1px 1px 4px rgba(255, 255, 255, 0.8), 0 0 2px rgba(255, 255, 255, 0.5);
    text-align: right;
    position: relative;
    z-index: 1;
}

#date{
    justify-content: center;
}

#date p{
    margin: 0 5px;
}

#footer {
    position: sticky;
    top: 100vh;
    width: 100%;
    height: auto;
    padding: 2rem 0;
    clear: both;
    font-size: 1rem;
    color: #ffffff;
    text-align: center;
    background: linear-gradient(135deg, #5591af 0%, #3e6b82 100%);
    border-top: 1px solid rgba(255, 255, 255, 0.2);
}

#copyright {
    margin: 1em;
}

#footer-bottom {
    margin-bottom: 1em;
}

#footer-bottom a {
    margin: 0 5px;
    color: #ffffff;
}

ul {
    padding: 0 3em;
}