/* ==========================================================================
   1. 基礎重設與全域變數
   ========================================================================== */
:root {
    --bg-color: #f8f9fa;
    --card-bg: #ffffff;
    --text-main: #1f1f1f;
    --text-muted: #5f6368;
    --accent-color: #1a73e8; /* Google 藍 */
    --border-color: #dadce0;
    --shadow-md: 0 4px 16px rgba(0,0,0,0.08);
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

/* 確保手機端與電腦端絕對不會往橫向溢出變形 */
html, body {
    max-width: 100%;
    overflow-x: hidden;
    -webkit-overflow-scrolling: touch; /* 讓 iOS 手機滾動更流暢 */
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Microsoft JhengHei", sans-serif;
    background-color: var(--bg-color);
    color: var(--text-main);
    line-height: 1.5;
}

/* ==========================================================================
   2. 頂部導覽列與大搜尋框 (移除舊提示燈，放大搜尋感)
   ========================================================================== */
.navbar {
    background-color: var(--card-bg);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 100;
    padding: 14px 24px 0 24px; 
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 24px; 
}

.logo {
    font-size: 1.4rem;
    font-weight: 600;
    color: var(--accent-color);
    letter-spacing: -0.5px;
    white-space: nowrap;
}

/* 放大後的現代感搜尋框 */
.search-box {
    position: relative;
    flex-grow: 1;
    max-width: 800px; 
}

.search-box input {
    width: 100%;
    padding: 12px 44px 12px 18px; 
    font-size: 1rem;             
    border: 1px solid transparent;
    background-color: #f1f3f4;
    border-radius: 8px;
    transition: background-color 0.2s, border-color 0.2s, box-shadow 0.2s;
}

.search-box input:focus {
    outline: none;
    background-color: var(--card-bg);
    border-color: var(--accent-color);
    box-shadow: 0 1px 6px rgba(32,33,36,0.28); 
}

#clear-search {
    position: absolute;
    right: 14px;
    top: 50%;
    transform: translateY(-50%);
    background: none;
    border: none;
    font-size: 1.4rem; 
    color: var(--text-muted);
    cursor: pointer;
}

/* ==========================================================================
   3. 主題篩選標籤列 (支援手機端橫向滑動)
   ========================================================================== */
.filter-tabs-wrapper {
    max-width: 1200px;
    margin: 12px auto 0 auto;
    overflow-x: auto; 
    scrollbar-width: none; /* 隱藏 Firefox 滾動條 */
}

.filter-tabs-wrapper::-webkit-scrollbar {
    display: none; /* 隱藏 Chrome/Safari 滾動條 */
}

.filter-tabs {
    display: flex;
    gap: 8px;
    padding-bottom: 8px;
}

.tab {
    background: none;
    border: none;
    padding: 8px 16px;
    font-size: 0.9rem;
    color: var(--text-muted);
    border-radius: 20px;
    cursor: pointer;
    white-space: nowrap;
    transition: background-color 0.2s, color 0.2s;
}

.tab:hover {
    background-color: #f1f3f4;
    color: var(--text-main);
}

.tab.active {
    background-color: #e8f0fe;
    color: var(--accent-color);
    font-weight: 500;
}

/* ==========================================================================
   4. 主要卡片排版與瀑布流區域 (升級版：加入互動按鈕與選單)
   ========================================================================== */
.wall-wrapper {
    max-width: 1200px;
    margin: 0 auto;
    padding: 24px 16px;
}

.wall-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 16px;
}

/* 卡片主體 (加上 position: relative 讓右上角按鈕能定位) */
.card {
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 20px;
    display: flex;
    flex-direction: column;
    position: relative; /* 💡 必須加上這行 */
    transition: transform 0.2s ease, box-shadow 0.2s ease;
    cursor: pointer;
}

.card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
    border-color: transparent;
}

@media (min-width: 768px) {
    .card.featured {
        grid-column: span 2;
    }
}

/* 右上角三點點按鈕 */
.card-more-btn {
    position: absolute;
    top: 16px;
    right: 16px;
    background: none;
    border: none;
    color: var(--text-muted);
    cursor: pointer;
    padding: 4px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background-color 0.2s, color 0.2s;
}

.card-more-btn:hover {
    background-color: #f1f3f4;
    color: var(--text-main);
}

/* 點開後出現的懸浮選單 */
.more-menu {
    position: absolute;
    top: 45px;
    right: 16px;
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.15);
    z-index: 10;
    width: 120px;
    padding: 4px 0;
}

.menu-item {
    width: 100%;
    background: none;
    border: none;
    padding: 8px 16px;
    font-size: 0.85rem;
    color: var(--text-main);
    text-align: left;
    cursor: pointer;
    transition: background-color 0.2s;
}

.menu-item:hover {
    background-color: #f1f3f4;
}

/* 卡片內部元素 */
.card-tag {
    font-size: 0.75rem;
    font-weight: 700;
    color: var(--text-muted);
    text-transform: uppercase;
    margin-bottom: 8px;
    letter-spacing: 0.5px;
    max-width: 80%; /* 💡 避免字蓋到右上角的三個點 */
}

.card-tag.font-important {
    color: #ea4335;
}

.card-title {
    font-size: 1.15rem;
    font-weight: 600;
    color: var(--text-main);
    margin-bottom: 10px;
    line-height: 1.4;
    padding-right: 20px; /* 💡 防標題撞到按鈕 */
}

.card.featured .card-title {
    font-size: 1.4rem;
}

.card-snippet {
    font-size: 0.9rem;
    color: var(--text-muted);
    margin-bottom: 16px;
    flex-grow: 1;
    display: -webkit-box;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

/* 底部 Meta 與按鈕區塊 */
.card-meta {
    font-size: 0.8rem;
    color: var(--text-muted);
    display: flex;
    align-items: center;
    justify-content: space-between; /* 💡 讓左邊時間與右邊按鈕分開 */
    border-top: 1px solid #f1f3f4;
    padding-top: 12px;
}

.meta-left {
    display: flex;
    align-items: center;
    gap: 6px;
}

.card-meta .source {
    font-weight: 500;
    color: var(--text-main);
}

/* 右下角愛心與分享按鈕組 */
.meta-actions {
    display: flex;
    gap: 12px;
}

.action-btn {
    background: none;
    border: none;
    color: var(--text-muted);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 4px;
    border-radius: 50%;
    transition: color 0.2s, background-color 0.2s;
}

.action-btn:hover {
    background-color: #f1f3f4;
}

/* 愛心啟動時變紅 */
.action-btn.like-btn.liked {
    color: #ea4335;
}

.action-btn.share-btn:hover {
    color: var(--accent-color);
}

/* ==========================================================================
   5. 功能性元件（隱藏、載入哨兵、懸浮按鈕）
   ========================================================================== */
.hidden {
    display: none !important;
}

.loading-text, #sentinel {
    grid-column: 1 / -1;
    text-align: center;
    padding: 30px;
    color: var(--text-muted);
    font-size: 0.95rem;
    display: flex;
    justify-content: center;
    align-items: center;
}

/* 修正後的防溢出懸浮回到頂部按鈕 */
.btt-btn {
    position: fixed;
    bottom: 24px;   
    right: 24px;    
    width: 48px;
    height: 48px;
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 50%;
    color: var(--accent-color);
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    cursor: pointer;
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 999;
    transition: transform 0.2s, box-shadow 0.2s, opacity 0.2s;
    box-sizing: border-box;
    flex-shrink: 0; 
}

.btt-btn:hover {
    transform: translateY(-4px);
    box-shadow: 0 4px 16px rgba(26, 115, 232, 0.25);
    background-color: #f8f9fa;
}

/* 提示紅點 */
.btt-btn .badge {
    position: absolute;
    top: 2px;
    right: 2px;
    width: 10px;
    height: 10px;
    background-color: #ea4335; 
    border-radius: 50%;
    border: 2px solid var(--card-bg);
    box-shadow: 0 0 0 0 rgba(234, 67, 53, 0.7);
    animation: badgePulse 1.6s infinite;
}

@keyframes badgePulse {
    0% { transform: scale(0.95); box-shadow: 0 0 0 0 rgba(234, 67, 53, 0.7); }
    70% { transform: scale(1); box-shadow: 0 0 0 5px rgba(234, 67, 53, 0); }
    100% { transform: scale(0.95); box-shadow: 0 0 0 0 rgba(234, 67, 53, 0); }
}