/**
 * Bootstrap 4 → 5 CSS 兼容层
 * 将 BS4 类名映射到 BS5 等效样式，使旧插件/主题无需修改即可正常显示。
 * 配合 bs4-compat.js（处理 data 属性）一起使用。
 */

/* ===== 表单 ===== */

/* form-group → mb-3 */
.form-group {
    margin-bottom: 1rem;
}

/* custom-select → form-select */
.custom-select {
    display: block;
    width: 100%;
    padding: .375rem 2.25rem .375rem .75rem;
    font-size: 1rem;
    font-weight: 400;
    line-height: 1.5;
    color: #212529;
    background-color: #fff;
    background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 16'%3e%3cpath fill='none' stroke='%23343a40' stroke-linecap='round' stroke-linejoin='round' stroke-width='2' d='m2 5 6 6 6-6'/%3e%3c/svg%3e");
    background-repeat: no-repeat;
    background-position: right .75rem center;
    background-size: 16px 12px;
    border: 1px solid #ced4da;
    border-radius: .375rem;
    appearance: none;
    transition: border-color .15s ease-in-out, box-shadow .15s ease-in-out;
}
.custom-select:focus {
    border-color: #86b7fe;
    outline: 0;
    box-shadow: 0 0 0 .25rem rgba(13,110,253,.25);
}
.custom-select-sm {
    padding-top: .25rem;
    padding-bottom: .25rem;
    padding-left: .5rem;
    font-size: .875rem;
}
.custom-select-lg {
    padding-top: .5rem;
    padding-bottom: .5rem;
    padding-left: 1rem;
    font-size: 1.25rem;
}

/* custom-control (checkbox/radio) → form-check */
.custom-control {
    position: relative;
    display: block;
    min-height: 1.5rem;
    padding-left: 1.5em;
    margin-bottom: .125rem;
}
.custom-control-input {
    position: absolute;
    left: 0;
    z-index: -1;
    width: 1rem;
    height: 1.25rem;
    opacity: 0;
}
.custom-control-input:checked ~ .custom-control-label::before {
    color: #fff;
    border-color: #0d6efd;
    background-color: #0d6efd;
}
.custom-control-label {
    position: relative;
    margin-bottom: 0;
    vertical-align: top;
    cursor: pointer;
}
.custom-control-label::before {
    position: absolute;
    top: .25rem;
    left: -1.5em;
    display: block;
    width: 1rem;
    height: 1rem;
    content: "";
    background-color: #fff;
    border: 1px solid #adb5bd;
    border-radius: .25rem;
    transition: background-color .15s ease-in-out, border-color .15s ease-in-out;
}
.custom-control-label::after {
    position: absolute;
    top: .25rem;
    left: -1.5em;
    display: block;
    width: 1rem;
    height: 1rem;
    content: "";
    background: 50%/50% 50% no-repeat;
}
.custom-switch .custom-control-label::before {
    border-radius: .5rem;
    width: 1.75rem;
}
.custom-checkbox .custom-control-input:checked ~ .custom-control-label::after {
    background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 20 20'%3e%3cpath fill='none' stroke='%23fff' stroke-linecap='round' stroke-linejoin='round' stroke-width='3' d='m6 10 3 3 6-6'/%3e%3c/svg%3e");
}

/* custom-file → form-control */
.custom-file {
    position: relative;
    display: inline-block;
    width: 100%;
    height: calc(1.5em + .75rem + 2px);
    margin-bottom: 0;
}
.custom-file-input {
    position: relative;
    z-index: 2;
    width: 100%;
    height: calc(1.5em + .75rem + 2px);
    margin: 0;
    opacity: 0;
}
.custom-file-label {
    position: absolute;
    top: 0;
    right: 0;
    left: 0;
    z-index: 1;
    height: calc(1.5em + .75rem + 2px);
    padding: .375rem .75rem;
    overflow: hidden;
    font-weight: 400;
    line-height: 1.5;
    color: #495057;
    background-color: #fff;
    border: 1px solid #ced4da;
    border-radius: .25rem;
}

/* form-row → row with gutter */
.form-row {
    display: flex;
    flex-wrap: wrap;
    margin-right: -5px;
    margin-left: -5px;
}
.form-row > .col,
.form-row > [class*="col-"] {
    padding-right: 5px;
    padding-left: 5px;
}

/* input-group-append / input-group-prepend */
.input-group-append,
.input-group-prepend {
    display: flex;
}
.input-group-prepend {
    margin-right: -1px;
}
.input-group-append {
    margin-left: -1px;
}

/* ===== Badge ===== */

/* badge-* → bg-* */
.badge-primary   { color: #fff; background-color: #0d6efd; }
.badge-secondary { color: #fff; background-color: #6c757d; }
.badge-success   { color: #fff; background-color: #198754; }
.badge-danger    { color: #fff; background-color: #dc3545; }
.badge-warning   { color: #212529; background-color: #ffc107; }
.badge-info      { color: #fff; background-color: #0dcaf0; }
.badge-light     { color: #212529; background-color: #f8f9fa; }
.badge-dark      { color: #fff; background-color: #212529; }

/* badge-pill → rounded-pill */
.badge-pill {
    padding-right: .65em;
    padding-left: .65em;
    border-radius: 50rem;
}

/* ===== 布局/对齐 ===== */

/* float-left/right → float-start/end */
.float-left  { float: left !important; }
.float-right { float: right !important; }

/* text-left/right/center 保持兼容 */
.text-left   { text-align: left !important; }
.text-right  { text-align: right !important; }

/* no-gutters → g-0 */
.no-gutters {
    --bs-gutter-x: 0;
    --bs-gutter-y: 0;
}
.no-gutters > .col,
.no-gutters > [class*="col-"] {
    padding-right: 0;
    padding-left: 0;
}

/* ===== 排版 ===== */

/* font-weight-* → fw-* */
.font-weight-bold    { font-weight: 700 !important; }
.font-weight-bolder  { font-weight: bolder !important; }
.font-weight-normal  { font-weight: 400 !important; }
.font-weight-light   { font-weight: 300 !important; }
.font-weight-lighter { font-weight: lighter !important; }
.font-italic         { font-style: italic !important; }

/* ===== 无障碍 ===== */

/* sr-only → visually-hidden */
.sr-only,
.sr-only-focusable {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* ===== 按钮 ===== */

/* btn-block (BS5 移除，需 d-grid 包裹，这里直接兼容) */
.btn-block {
    display: block;
    width: 100%;
}

/* ===== Dropdown ===== */

/* dropdown-menu-right → dropdown-menu-end */
.dropdown-menu-right {
    right: 0;
    left: auto;
}
.dropdown-menu-left {
    right: auto;
    left: 0;
}

/* ===== 关闭按钮 ===== */

/* close (BS4) → btn-close (BS5) */
.close {
    float: right;
    font-size: 1.5rem;
    font-weight: 700;
    line-height: 1;
    color: #000;
    text-shadow: 0 1px 0 #fff;
    opacity: .5;
    padding: 0;
    background-color: transparent;
    border: 0;
    cursor: pointer;
}
.close:hover {
    opacity: .75;
}

/* ===== Media 对象 (BS5 已移除) ===== */

.media {
    display: flex;
    align-items: flex-start;
}
.media-body {
    flex: 1;
}

/* ===== Jumbotron (BS5 已移除) ===== */

.jumbotron {
    padding: 2rem 1rem;
    margin-bottom: 2rem;
    background-color: #e9ecef;
    border-radius: .3rem;
}
@media (min-width: 576px) {
    .jumbotron {
        padding: 4rem 2rem;
    }
}
.jumbotron-fluid {
    padding-right: 0;
    padding-left: 0;
    border-radius: 0;
}

/* ===== Card ===== */

/* card-deck / card-columns (BS5 已移除) */
.card-deck {
    display: flex;
    flex-flow: row wrap;
    margin-right: -15px;
    margin-left: -15px;
}
.card-deck .card {
    flex: 1 0 0%;
    margin-right: 15px;
    margin-bottom: 0;
    margin-left: 15px;
}
.card-columns {
    column-count: 3;
    column-gap: 1.25rem;
    orphans: 1;
    widows: 1;
}
.card-columns .card {
    display: inline-block;
    width: 100%;
}

/* ===== 响应式工具类 ===== */

/* hidden-xs/sm/md/lg/xl (BS3/4 遗留) */
@media (max-width: 575.98px) {
    .hidden-xs { display: none !important; }
}
@media (min-width: 576px) and (max-width: 767.98px) {
    .hidden-sm { display: none !important; }
}
@media (min-width: 768px) and (max-width: 991.98px) {
    .hidden-md { display: none !important; }
}
@media (min-width: 992px) and (max-width: 1199.98px) {
    .hidden-lg { display: none !important; }
}
@media (min-width: 1200px) {
    .hidden-xl { display: none !important; }
}

/* ===== Spacing / 尺寸 ===== */

/* rounded-sm / rounded-lg */
.rounded-sm { border-radius: .2rem !important; }
.rounded-lg { border-radius: .3rem !important; }

/* embed-responsive (BS4 → BS5 ratio) */
.embed-responsive {
    position: relative;
    display: block;
    width: 100%;
    padding: 0;
    overflow: hidden;
}
.embed-responsive::before {
    display: block;
    content: "";
}
.embed-responsive .embed-responsive-item,
.embed-responsive iframe,
.embed-responsive embed,
.embed-responsive object,
.embed-responsive video {
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border: 0;
}
.embed-responsive-16by9::before { padding-top: 56.25%; }
.embed-responsive-4by3::before  { padding-top: 75%; }
.embed-responsive-1by1::before  { padding-top: 100%; }
.embed-responsive-21by9::before { padding-top: 42.857143%; }

/* ===== 颜色/文本兼容 ===== */

/* text-gray (旧插件常用，BS5 无此类) */
.text-gray { color: #6c757d !important; }

/* ===== 头像尺寸兼容 ===== */

/* avatar-N 系列（旧插件常用，如 tt_sign / tt_ranklist） */
.avatar-1 { width: 20px; height: 20px; border-radius: 50%; object-fit: cover; }
.avatar-2 { width: 30px; height: 30px; border-radius: 50%; object-fit: cover; }
.avatar-3 { width: 40px; height: 40px; border-radius: 50%; object-fit: cover; }
.avatar-4 { width: 50px; height: 50px; border-radius: 50%; object-fit: cover; }
.avatar-5 { width: 60px; height: 60px; border-radius: 50%; object-fit: cover; }
img.avatar-1, img.avatar-2, img.avatar-3, img.avatar-4, img.avatar-5 {
    vertical-align: middle;
}

/* ===== 缺失资源降级 ===== */

/*
 * 当旧插件通过 inline style 引用了不存在的背景图时，
 * JS 兼容层会自动添加 .bs4c-bg-fallback 类，此处定义降级样式。
 * 同时提供 .bs4c-img-fallback 给失败的 <img> 元素。
 */
.bs4c-bg-fallback {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%) !important;
}
.bs4c-img-fallback {
    display: inline-block;
    background: #e9ecef;
    color: #adb5bd;
    text-align: center;
    line-height: 1;
    font-size: .75rem;
    object-fit: contain;
}

/* ===== input-group-prepend / input-group-append (BS4→BS5) ===== */

/*
 * BS4 的 .input-group-prepend/.input-group-append 包裹层在 BS5 中被移除。
 * BS5 中 .input-group-text / .btn 直接放入 .input-group 即可。
 * 此兼容层让旧插件的包裹结构继续正常显示。
 */
.input-group-prepend,
.input-group-append {
    display: flex;
}
.input-group-prepend { margin-right: -1px; }
.input-group-append  { margin-left: -1px; }
.input-group > .input-group-prepend > .btn,
.input-group > .input-group-prepend > .input-group-text,
.input-group > .input-group-append > .btn,
.input-group > .input-group-append > .input-group-text {
    position: relative;
    z-index: 2;
}
.input-group > .input-group-prepend > .btn:focus,
.input-group > .input-group-append > .btn:focus {
    z-index: 3;
}

/* ===== custom-file (BS4→BS5) ===== */

/*
 * BS4 的 .custom-file / .custom-file-input / .custom-file-label 在 BS5 中被移除，
 * 替代方案为普通的 .form-control[type=file]。
 * 此兼容层让旧插件的自定义文件上传组件继续正常显示。
 */
.custom-file {
    position: relative;
    display: inline-block;
    width: 100%;
    height: calc(1.5em + .75rem + 2px);
    margin-bottom: 0;
}
.custom-file-input {
    position: relative;
    z-index: 2;
    width: 100%;
    height: calc(1.5em + .75rem + 2px);
    margin: 0;
    opacity: 0;
}
.custom-file-label {
    position: absolute;
    top: 0;
    right: 0;
    left: 0;
    z-index: 1;
    height: calc(1.5em + .75rem + 2px);
    padding: .375rem .75rem;
    font-weight: 400;
    line-height: 1.5;
    color: #495057;
    background-color: #fff;
    border: 1px solid #ced4da;
    border-radius: .25rem;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}
.custom-file-label::after {
    position: absolute;
    top: 0;
    right: 0;
    bottom: 0;
    z-index: 3;
    display: block;
    height: calc(1.5em + .75rem);
    padding: .375rem .75rem;
    line-height: 1.5;
    color: #495057;
    content: "Browse";
    background-color: #e9ecef;
    border-left: inherit;
    border-radius: 0 .25rem .25rem 0;
}

/* ===== form-row (BS4→BS5) ===== */

/*
 * BS4 的 .form-row 在 BS5 中被移除，替代为 .row.g-3。
 */
.form-row {
    display: flex;
    flex-wrap: wrap;
    margin-right: -5px;
    margin-left: -5px;
}
.form-row > .col,
.form-row > [class*="col-"] {
    padding-right: 5px;
    padding-left: 5px;
}

/* ===== BS4→BS5 间距工具类兼容（left/right → start/end）===== */
/* BS5 将 ml/mr/pl/pr 重命名为 ms/me/ps/pe 以支持 RTL */
/* margin-left → margin-start */
.ml-0 { margin-left: 0 !important; }
.ml-1 { margin-left: 0.25rem !important; }
.ml-2 { margin-left: 0.5rem !important; }
.ml-3 { margin-left: 1rem !important; }
.ml-4 { margin-left: 1.5rem !important; }
.ml-5 { margin-left: 3rem !important; }
.ml-auto { margin-left: auto !important; }

/* margin-right → margin-end */
.mr-0 { margin-right: 0 !important; }
.mr-1 { margin-right: 0.25rem !important; }
.mr-2 { margin-right: 0.5rem !important; }
.mr-3 { margin-right: 1rem !important; }
.mr-4 { margin-right: 1.5rem !important; }
.mr-5 { margin-right: 3rem !important; }
.mr-auto { margin-right: auto !important; }

/* padding-left → padding-start */
.pl-0 { padding-left: 0 !important; }
.pl-1 { padding-left: 0.25rem !important; }
.pl-2 { padding-left: 0.5rem !important; }
.pl-3 { padding-left: 1rem !important; }
.pl-4 { padding-left: 1.5rem !important; }
.pl-5 { padding-left: 3rem !important; }

/* padding-right → padding-end */
.pr-0 { padding-right: 0 !important; }
.pr-1 { padding-right: 0.25rem !important; }
.pr-2 { padding-right: 0.5rem !important; }
.pr-3 { padding-right: 1rem !important; }
.pr-4 { padding-right: 1.5rem !important; }
.pr-5 { padding-right: 3rem !important; }

/* border-right → border-end */
.border-right { border-right: 1px solid #dee2e6 !important; }
.border-right-0 { border-right: 0 !important; }

/* rounded-right → rounded-end (未在 compat 中但预留) */
.rounded-right { border-top-right-radius: 0.25rem !important; border-bottom-right-radius: 0.25rem !important; }
.rounded-left { border-top-left-radius: 0.25rem !important; border-bottom-left-radius: 0.25rem !important; }

/* no-gutters → g-0 */
.no-gutters { --bs-gutter-x: 0; --bs-gutter-y: 0; }
.no-gutters > .col, .no-gutters > [class*="col-"] { padding-right: 0; padding-left: 0; }

/* ===== 旧版 icon 前缀兼容 ===== */

/* icon-calendar-check-o (Font Awesome 4 旧名) — 部分签到插件使用 */
.icon-calendar-check-o:before { content: "\f274"; }