html, body {
    color: #5a6268;
}
nav {
    border-bottom: 1px solid lightgray;
}
.header {
    font-size:30px;
}
.header img {
    display: block;
    margin-left: auto;
}
@media(max-width: 768px) {
    .header img {
        margin-right: auto;
    }
    .img-resize {
        margin: auto auto;
        display: block;
        width: 85%!important;
        height: 85%!important;
    }
}
@media(max-width: 992px) {
    .header {
        align-content: center;
        font-size: 25px;
    }
}
.img-responsive {
    height: 100%;
    width: 100%;
    object-fit: contain;
}
.section-mt {
    margin-top: 1rem;
}
.section-mb {
    margin-bottom: 1rem;
}
.board-photo {
    max-height: 300px;
}
.viet {
    margin-top: 1rem;
    padding-left: 1rem;
    padding-right: 1rem;
    border-left: 1px lightgray dotted;
    color: gray;
    background-color: rgba(127,127,127,0.005);
}
.font {
    font-family:'Arima Madurai',cursive;
}
.title {
    font-weight:bold;
    font-size: 24px;
    color: #996944;
}
.subtitle {
    font-size: 20px;
    color: #996944;
}
footer {
    background-color: #ffb763;
    padding-top: 2rem;
    padding-bottom: 2rem;
}

:root { scroll-behavior: smooth; }

.stt {
    position: fixed;
    right: 1rem;
    bottom: 1rem;
    width: 3rem;
    height: 3rem;
    border-radius: 50%;
    background: rgb(128, 128, 255) url("data:image/svg+xml;utf8,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 384 512'%3E%3Cpath fill='currentColor' d='M352 352c-8.188 0-16.38-3.125-22.62-9.375L192 205.3l-137.4 137.4c-12.5 12.5-32.75 12.5-45.25 0s-12.5-32.75 0-45.25l160-160c12.5-12.5 32.75-12.5 45.25 0l160 160c12.5 12.5 12.5 32.75 0 45.25C368.4 348.9 360.2 352 352 352z'%3E%3C/path%3E%3C/svg%3E") center no-repeat;
    box-shadow: 0 0.25rem 0.5rem 0 gray;
    opacity: 0.7;
  }
  .stt:hover {
    opacity: 0.8;
  }
  .stt:focus {
    opacity: 0.9;
  }
  .stt:active {
    opacity: 1;
  }