/* ========================================
   TadMenu - 垂直三層選單元件
   WCAG 2.2 AAA 無障礙設計
   ======================================== */

:root {
    --tadmenu-transition-duration: 300ms;
    --tadmenu-focus-color: #005fcc;
    --tadmenu-focus-outline-width: 3px;
    --tadmenu-border-radius: 4px;
    --tadmenu-indent: 20px;
}

/* 選單容器 */
.tadmenu {
    width: 100%;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    line-height: 1.5;
}

.tadmenu ul {
    list-style: none;
    margin: 0;
    padding: 0;
}

/* 選單項目 */
.tadmenu-item {
    position: relative;
}

/* 選單按鈕/連結基礎樣式 */
.tadmenu-link {
    display: flex;
    align-items: center;
    width: 100%;
    padding: 12px 16px;
    border: none;
    text-decoration: none;
    cursor: pointer;
    transition: background-color 0.2s ease, filter 0.2s ease;
    position: relative;
    min-height: 48px;
    box-sizing: border-box;
    font-size: inherit;
    font-family: inherit;
    text-align: left;
    background: none;
}

.tadmenu-link:hover {
    filter: brightness(0.92);
}

.tadmenu-link:active {
    filter: brightness(0.88);
}

/* 高對比焦點指示器 - WCAG AAA */
.tadmenu-link:focus {
    outline: var(--tadmenu-focus-outline-width) solid var(--tadmenu-focus-color);
    outline-offset: -3px;
    z-index: 10;
}

.tadmenu-link:focus:not(:focus-visible) {
    outline: none;
}

.tadmenu-link:focus-visible {
    outline: var(--tadmenu-focus-outline-width) solid var(--tadmenu-focus-color);
    outline-offset: -3px;
    z-index: 10;
}

/* 圖示樣式 */
.tadmenu-icon {
    margin-right: 12px;
    width: 20px;
    text-align: center;
    flex-shrink: 0;
}

/* 選單文字 */
.tadmenu-text {
    flex-grow: 1;
    text-align: left;
}

/* 展開箭頭指示器 */
.tadmenu-arrow {
    margin-left: 8px;
    transition: transform var(--tadmenu-transition-duration) ease;
    flex-shrink: 0;
}

.tadmenu-arrow i {
    font-size: 12px;
}

.tadmenu-item.tadmenu-expanded>.tadmenu-link .tadmenu-arrow {
    transform: rotate(90deg);
}

/* ========================================
   第二層選單
   ======================================== */
.tadmenu-submenu-2 {
    max-height: 0;
    overflow: hidden;
    transition: max-height var(--tadmenu-transition-duration) ease-out;
}

.tadmenu-submenu-2.tadmenu-open {
    overflow: visible;
}

.tadmenu-submenu-2>.tadmenu-item>.tadmenu-link {
    padding-left: calc(16px + var(--tadmenu-indent));
}

/* ========================================
   第三層浮動選單 - 使用 fixed 定位
   ======================================== */
.tadmenu-submenu-3 {
    position: fixed;
    min-width: 220px;
    max-width: 18.75rem;
    background: #ffffff;
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.2), 0 4px 8px rgba(0, 0, 0, 0.1);
    border-radius: var(--tadmenu-border-radius);
    border: 1px solid #d0d0d0;
    opacity: 0;
    visibility: hidden;
    transform: translateX(-10px);
    transition: opacity var(--tadmenu-transition-duration) ease,
        transform var(--tadmenu-transition-duration) ease,
        visibility var(--tadmenu-transition-duration);
    z-index: 99999;
    pointer-events: none;
}

.tadmenu-submenu-3.tadmenu-visible {
    opacity: 1;
    visibility: visible;
    transform: translateX(0);
    pointer-events: auto;
}

.tadmenu-submenu-3>.tadmenu-item>.tadmenu-link {
    padding: 12px 16px;
}

.tadmenu-submenu-3>.tadmenu-item:first-child>.tadmenu-link {
    border-radius: var(--tadmenu-border-radius) var(--tadmenu-border-radius) 0 0;
}

.tadmenu-submenu-3>.tadmenu-item:last-child>.tadmenu-link {
    border-radius: 0 0 var(--tadmenu-border-radius) var(--tadmenu-border-radius);
}

/* 新視窗指示器 */
.tadmenu-new-window {
    margin-left: 6px;
    font-size: 10px;
    opacity: 0.7;
}

/* Skip Link */
.tadmenu-skip-link {
    position: absolute;
    top: -100px;
    left: 0;
    background: var(--tadmenu-focus-color);
    color: #ffffff;
    padding: 12px 24px;
    z-index: 999999;
    text-decoration: none;
    font-weight: bold;
    border-radius: 0 0 var(--tadmenu-border-radius) 0;
}

.tadmenu-skip-link:focus {
    top: 0;
}

/* 螢幕閱讀器專用文字 */
.tadmenu-sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* ========================================
   響應式設計 - 行動裝置
   ======================================== */

@media (max-width: 768px) {
    .tadmenu {
        max-width: 100%;
    }

    /* 第三層在手機上改為展開式 */
    .tadmenu-submenu-3 {
        position: static !important;
        min-width: auto;
        max-width: none;
        box-shadow: none;
        border-radius: 0;
        border: none;
        background: transparent;
        transform: none !important;
        max-height: 0;
        overflow: hidden;
        opacity: 1;
        visibility: visible;
        pointer-events: auto;
        transition: max-height var(--tadmenu-transition-duration) ease-out;
    }

    .tadmenu-submenu-3.tadmenu-visible {
        transform: none !important;
    }

    .tadmenu-submenu-3>.tadmenu-item>.tadmenu-link {
        padding-left: calc(16px + var(--tadmenu-indent) * 2);
    }

    .tadmenu-submenu-3>.tadmenu-item:first-child>.tadmenu-link,
    .tadmenu-submenu-3>.tadmenu-item:last-child>.tadmenu-link {
        border-radius: 0;
    }

    /* 觸控目標 */
    .tadmenu-link {
        min-height: 52px;
        padding: 14px 16px;
    }
}

/* 高對比模式 */
@media (prefers-contrast: high) {
    .tadmenu-link {
        border: 2px solid currentColor;
    }

    .tadmenu-submenu-3 {
        border: 2px solid #000;
    }
}

/* 減少動態效果 */
@media (prefers-reduced-motion: reduce) {

    .tadmenu-arrow,
    .tadmenu-submenu-2,
    .tadmenu-submenu-3,
    .tadmenu-link {
        transition: none !important;
    }
}