/* ============================================================
   TIN TỨC 24H — Professional Newspaper Design System
   Inspired by VnExpress, Tuổi Trẻ, Thanh Niên
   ============================================================ */

/* Fonts loaded locally via /static/css/fonts.css */

/* ── Reset ── */
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}

:root{
    /* Brand */
    --red:#d32f2f;
    --red-dark:#b71c1c;
    --red-light:#ffcdd2;
    --blue:#1565c0;
    --blue-dark:#0d47a1;
    --orange:#ef6c00;
    --green:#2e7d32;

    /* Neutral */
    --ink:#1a1a1a;
    --ink-light:#424242;
    --ink-muted:#757575;
    --ink-faint:#595959;
    --line:#e0e0e0;
    --line-light:#eeeeee;
    --surface:#ffffff;
    --surface-warm:#fafafa;
    --surface-gray:#f5f5f5;

    /* Typography */
    --font-sans:'Inter','Segoe UI','Helvetica Neue',Arial,sans-serif;
    --font-serif:'Noto Serif','Georgia','Times New Roman',serif;

    /* Spacing */
    --container:1200px;
    --gap:24px;
    --radius:6px;

    /* Shadows */
    --shadow-sm:0 1px 2px rgba(0,0,0,.06);
    --shadow:0 2px 8px rgba(0,0,0,.08);
    --shadow-lg:0 8px 30px rgba(0,0,0,.12);
}

html{font-size:16px;-webkit-font-smoothing:antialiased;scroll-behavior:smooth}
body{font-family:var(--font-sans);line-height:1.6;color:var(--ink);background:var(--surface)}
a{color:inherit;text-decoration:none}
img{max-width:100%;height:auto;display:block}
ul,ol{list-style:none}
button{font-family:inherit}

.container{max-width:var(--container);margin:0 auto;padding:0 16px}

/* ── Buttons ── */
.btn{
    display:inline-flex;align-items:center;justify-content:center;gap:6px;
    padding:8px 18px;font-size:13px;font-weight:600;border-radius:var(--radius);
    border:1px solid transparent;cursor:pointer;transition:all .15s;text-decoration:none;
    font-family:var(--font-sans);line-height:1.4;
}
.btn-primary{background:var(--red);color:#fff;border-color:var(--red)}
.btn-primary:hover{background:var(--red-dark);border-color:var(--red-dark)}
.btn-outline{background:transparent;color:var(--ink);border-color:var(--line)}
.btn-outline:hover{border-color:var(--red);color:var(--red)}
.btn-sm{padding:5px 12px;font-size:12px}
.btn-block{display:block;width:100%}

/* ============================================================
   HEADER — Newspaper Masthead
   ============================================================ */
.top-bar{
    background:var(--ink);color:#fff;font-size:12px;padding:6px 0;
    display:flex;align-items:center;
}
.top-bar .container{display:flex;justify-content:space-between;align-items:center}
.top-bar-date{opacity:.7}
.top-bar-links a{color:#fff;opacity:.7;margin-left:16px;transition:opacity .2s}
.top-bar-links a:hover{opacity:1}

.header{background:var(--surface);border-bottom:3px solid var(--red)}
.header-inner{
    display:flex;align-items:center;justify-content:space-between;
    padding:16px 0;gap:20px;
}
.logo{
    font-family:var(--font-serif);font-size:32px;font-weight:700;
    color:var(--red);letter-spacing:-1px;line-height:1;white-space:nowrap;
}
.logo small{font-size:12px;color:var(--ink-muted);font-family:var(--font-sans);font-weight:400;display:block;letter-spacing:0}

.header-actions{display:flex;align-items:center;gap:10px}

/* Search */
.search-form{display:flex;align-items:center;position:relative}
.search-input{
    padding:7px 34px 7px 12px;border:1px solid var(--line);border-radius:20px;
    font-size:13px;width:220px;outline:none;transition:all .2s;background:var(--surface-gray);
}
.search-input:focus{border-color:var(--red);background:var(--surface);width:260px}
.search-btn{
    position:absolute;right:4px;top:50%;transform:translateY(-50%);
    background:none;border:none;cursor:pointer;font-size:15px;padding:4px 6px;color:var(--ink-muted);
}

/* Navigation */
.main-nav{
    background:var(--surface);border-bottom:1px solid var(--line);
}
.main-nav .container{display:flex;align-items:center;gap:0;overflow-x:auto}
.nav-link{
    display:block;padding:12px 16px;font-size:14px;font-weight:600;
    color:var(--ink-light);white-space:nowrap;
    border-bottom:2px solid transparent;transition:all .15s;
}
.nav-link:hover,.nav-link.active{color:var(--red);border-bottom-color:var(--red)}
.nav-link:first-child{padding-left:0}

/* Dropdown menu */
.nav-item-wrap{position:relative;display:inline-block}
.nav-dropdown{
    display:none;position:absolute;top:100%;left:0;
    background:var(--bg);box-shadow:0 4px 16px rgba(0,0,0,.15);
    border-radius:var(--radius);min-width:200px;z-index:100;
    padding:6px 0;border:1px solid var(--line);
}
.nav-item-wrap:hover .nav-dropdown{display:block}
.nav-dropdown-item{
    display:block;padding:10px 18px;font-size:13px;font-weight:500;
    color:var(--ink);text-decoration:none;white-space:nowrap;
    transition:all .15s;
}
.nav-dropdown-item:hover{background:var(--bg-alt);color:var(--red)}

.menu-toggle{
    display:none;background:none;border:1px solid var(--line);
    font-size:22px;padding:6px 10px;border-radius:var(--radius);cursor:pointer;
}

/* Navigation */

/* ============================================================
   MAIN CONTENT
   ============================================================ */
.main{padding:28px 0 0;min-height:60vh}

.section-title{
    font-family:var(--font-serif);font-size:22px;font-weight:700;
    color:var(--ink);margin-bottom:20px;padding-bottom:10px;
    border-bottom:2px solid var(--red);position:relative;
}

/* ── Featured / Hero Section ── */
.featured-section{margin-bottom:40px}

.featured-grid{
    display:grid;grid-template-columns:1.8fr 1fr;gap:20px;
}
.featured-grid .featured-card:first-child{grid-row:span 2}
.featured-grid .featured-card:first-child .card-title{font-size:24px;font-family:var(--font-serif)}
.featured-grid .featured-card:first-child .card-image{aspect-ratio:16/10}

.featured-card{
    position:relative;border-radius:var(--radius);overflow:hidden;
    background:var(--surface);transition:box-shadow .2s;
}
.featured-card:hover{box-shadow:var(--shadow-lg)}
.featured-card a{display:block;color:inherit}

/* ── Cards ── */
.card-image{
    position:relative;aspect-ratio:16/9;overflow:hidden;background:var(--surface-gray);
}
.card-image img{width:100%;height:100%;object-fit:cover;transition:transform .3s}
.featured-card:hover .card-image img,
.article-card:hover .card-image img{transform:scale(1.04)}

.card-placeholder{
    display:flex;align-items:center;justify-content:center;
    width:100%;height:100%;font-size:48px;
    background:linear-gradient(135deg,var(--surface-gray),var(--line-light));color:var(--ink-faint);
}

.card-content{padding:14px 16px}
.card-title{
    font-size:15px;font-weight:700;line-height:1.45;margin-bottom:6px;
    display:-webkit-box;-webkit-line-clamp:2;-webkit-box-orient:vertical;overflow:hidden;
    transition:color .15s;
}
.featured-card:hover .card-title,.article-card:hover .card-title{color:var(--red)}

.card-excerpt{
    font-size:13px;color:var(--ink-muted);line-height:1.5;
    display:-webkit-box;-webkit-line-clamp:2;-webkit-box-orient:vertical;overflow:hidden;
    margin-bottom:8px;
}
.card-meta{display:flex;align-items:center;gap:10px;font-size:12px;color:var(--ink-faint)}
.card-meta time{color:var(--blue-dark)}

/* ── Content Layout (2-column) ── */
.content-layout{display:grid;grid-template-columns:1fr 320px;gap:36px;align-items:start}
.content-main{min-width:0}

.articles-grid{
    display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));
    gap:20px;margin-bottom:24px;
}
.article-card{
    background:var(--surface);border-radius:var(--radius);overflow:hidden;
    border:1px solid var(--line-light);transition:all .2s;
}
.article-card:hover{border-color:var(--line);box-shadow:var(--shadow)}
.article-card a{display:block;color:inherit}

/* ── Sidebar ── */
.sidebar{position:sticky;top:80px}
.widget{
    background:var(--surface);border:1px solid var(--line-light);
    border-radius:var(--radius);padding:20px;margin-bottom:20px;
}
.widget-title{
    font-size:15px;font-weight:700;text-transform:uppercase;letter-spacing:.5px;
    margin-bottom:14px;padding-bottom:8px;
    border-bottom:2px solid var(--red);color:var(--ink);
}
.category-list li a{
    display:flex;align-items:center;padding:8px 10px;font-size:14px;
    border-radius:4px;transition:all .15s;color:var(--ink-light);
}
.category-list li a::before{content:"›";margin-right:8px;color:var(--red);font-weight:700}
.category-list li a:hover,.category-list li a.active{background:var(--red-light);color:var(--red-dark)}

.tag-cloud{display:flex;flex-wrap:wrap;gap:6px}
.tag-link{
    display:inline-block;padding:4px 12px;background:var(--surface-gray);
    border:1px solid var(--line-light);border-radius:20px;font-size:12px;
    font-weight:500;color:var(--ink-light);transition:all .15s;
}
.tag-link:hover{background:var(--red);color:#fff;border-color:var(--red)}

/* ── Widget extras ── */
.widget-post-list{display:flex;flex-direction:column;gap:0}
.widget-post-item{display:flex;gap:14px;padding:12px 0;border-bottom:1px solid var(--line-light);text-decoration:none;align-items:center}
.widget-post-item:last-child{border-bottom:none}
.widget-post-item:hover .widget-post-title{color:var(--red)}
.widget-post-thumb{width:100px;height:68px;object-fit:cover;border-radius:var(--radius);flex-shrink:0}
.widget-post-info{flex:1;min-width:0}
.widget-post-title{display:-webkit-box;-webkit-line-clamp:3;-webkit-box-orient:vertical;overflow:hidden;font-size:15px;font-weight:700;line-height:1.45;color:var(--ink);transition:color .15s}
.widget-post-meta{display:none}
.widget-ad{padding:0;overflow:hidden}
.widget-ad img{border-radius:var(--radius)}
.widget-search-form{display:flex;gap:0}
.widget-search-input{flex:1;padding:8px 12px;border:1px solid var(--line);border-radius:var(--radius) 0 0 var(--radius);font-size:14px;outline:none;transition:border-color .15s}
.widget-search-input:focus{border-color:var(--red)}
.widget-search-btn{padding:8px 14px;background:var(--red);color:#fff;border:none;border-radius:0 var(--radius) var(--radius) 0;cursor:pointer;transition:background .15s;font-size:13px;white-space:nowrap}
.widget-search-btn:hover{background:var(--red-dark)}
.widget-newsletter p{font-size:13px;color:var(--ink-muted);margin-bottom:10px}
.newsletter-form{display:flex;gap:0}

/* ── Pagination ── */
.pagination{display:flex;align-items:center;justify-content:center;gap:8px;padding:28px 0}
.page-link{
    display:inline-flex;align-items:center;padding:8px 16px;
    border:1px solid var(--line);border-radius:var(--radius);
    font-size:13px;font-weight:500;transition:all .15s;background:var(--surface);
}
.page-link:hover{border-color:var(--red);color:var(--red)}
.page-info{font-size:13px;color:var(--ink-muted)}

/* ── Breadcrumb ── */
.breadcrumb{
    display:flex;align-items:center;gap:6px;font-size:13px;
    color:var(--ink-muted);padding:14px 0;flex-wrap:wrap;
}
.breadcrumb a{color:var(--blue);transition:color .15s;white-space:nowrap}
.breadcrumb a:hover{color:var(--red)}
.breadcrumb span{color:var(--ink-faint)}
.breadcrumb .current{
    overflow:hidden;text-overflow:ellipsis;white-space:nowrap;max-width:100%;
    display:inline-block;vertical-align:middle;
}
@media(max-width:768px){
    .breadcrumb{font-size:12px;gap:4px;padding:10px 0}
    .breadcrumb .current{max-width:55vw}
}

/* ============================================================
   ARTICLE DETAIL — Newspaper Reading Experience
   ============================================================ */
.article-detail{max-width:100%}
.article-title{
    font-family:var(--font-serif);font-size:34px;font-weight:700;
    line-height:1.3;color:var(--ink);margin-bottom:14px;
}
.article-meta-detail{
    display:flex;align-items:center;gap:14px;flex-wrap:wrap;
    font-size:13px;color:var(--ink-light);margin-bottom:20px;
    padding-bottom:14px;border-bottom:1px solid var(--line-light);
}
.meta-category{
    display:inline-block;padding:3px 10px;background:var(--red);color:#fff;
    border-radius:3px;font-size:11px;font-weight:700;text-transform:uppercase;letter-spacing:.5px;
}
.article-hero{margin-bottom:24px;border-radius:var(--radius);overflow:hidden;margin:0}
.article-hero img{width:100%}
.article-hero-copyright{font-size:12px;color:#888;text-align:right;padding:4px 8px;background:#f8f9fa;font-style:italic}

.article-excerpt{
    font-family:var(--font-serif);font-size:19px;font-weight:700;
    color:var(--ink);line-height:1.65;margin-bottom:24px;
    padding:16px 20px;background:var(--surface-warm);
    border-left:4px solid var(--red);border-radius:0 var(--radius) var(--radius) 0;
}

.article-content{font-size:17px;line-height:1.85;color:var(--ink-light)}
.article-content p{margin-bottom:20px}
.article-content h2{font-family:var(--font-serif);font-size:24px;color:var(--ink);margin:32px 0 14px}
.article-content h3{font-size:20px;color:var(--ink);margin:24px 0 10px}
.article-content img{border-radius:var(--radius);margin:24px 0}
.article-content blockquote{
    border-left:4px solid var(--red);padding:14px 20px;margin:20px 0;
    background:var(--surface-warm);border-radius:0 var(--radius) var(--radius) 0;
    font-style:italic;color:var(--ink-light);
}
.article-content ul,.article-content ol{
    margin:16px 0;padding-left:24px;list-style:disc;
}
.article-content li{margin-bottom:6px}

.article-tags{
    display:flex;flex-wrap:wrap;gap:8px;align-items:center;
    margin-top:28px;padding-top:20px;border-top:1px solid var(--line-light);
}
.article-tags>span{font-weight:700;color:var(--ink);font-size:14px}

.article-share{
    display:flex;align-items:center;gap:8px;margin-top:16px;flex-wrap:wrap;
}
.article-share>span{font-weight:700;color:var(--ink);font-size:14px}
.share-btn{
    display:inline-block;padding:6px 14px;border-radius:4px;
    font-size:12px;font-weight:600;color:#fff;transition:opacity .15s;
}
.share-btn:hover{opacity:.85}
.share-fb{background:#1877f2}.share-tw{background:#000}.share-li{background:#0077b5}
.share-btn:hover,.share-copy:hover{opacity:.85}


.related-section{margin-top:36px;padding-top:28px;border-top:1px solid var(--line-light)}

/* ── Comments ── */
.comments-section{margin-top:36px;padding-top:28px;border-top:1px solid var(--line-light)}
.comment-form textarea{
    width:100%;padding:12px;border:1px solid var(--line);border-radius:var(--radius);
    font-family:var(--font-sans);font-size:14px;resize:vertical;margin-bottom:10px;
}
.comment-form textarea:focus{outline:none;border-color:var(--red)}

/* ============================================================
   PAGE TITLES (Category, Tag, Search)
   ============================================================ */
.page-title{
    font-family:var(--font-serif);font-size:28px;font-weight:700;
    color:var(--ink);margin-bottom:6px;
}
.page-desc{font-size:14px;color:var(--ink-muted);margin-bottom:24px}
.no-results{padding:48px 16px;text-align:center;color:var(--ink-muted);font-size:15px}

/* ── Search Page ── */
.search-form-large{display:flex;gap:8px;margin-bottom:28px}
.search-input-large{
    flex:1;padding:12px 18px;border:2px solid var(--line);border-radius:var(--radius);
    font-size:16px;outline:none;transition:border-color .2s;
}
.search-input-large:focus{border-color:var(--red)}
.search-results-info{font-size:14px;color:var(--ink-muted);margin-bottom:16px}
.search-hint{color:var(--ink-muted);font-size:15px}

.articles-list{display:flex;flex-direction:column;gap:16px;margin-bottom:24px}
.article-row{
    display:flex;gap:16px;background:var(--surface);border:1px solid var(--line-light);
    border-radius:var(--radius);overflow:hidden;transition:all .2s;
}
.article-row:hover{border-color:var(--line);box-shadow:var(--shadow)}
.row-image{width:200px;min-height:120px;flex-shrink:0;overflow:hidden;background:var(--surface-gray)}
.row-image img{width:100%;height:100%;object-fit:cover}
.row-content{padding:14px 16px;flex:1;min-width:0}
.row-content h3{font-size:16px;font-weight:700;margin-bottom:6px}
.row-content h3 a:hover{color:var(--red)}
.row-content p{font-size:13px;color:var(--ink-muted);display:-webkit-box;-webkit-line-clamp:2;-webkit-box-orient:vertical;overflow:hidden;margin-bottom:6px}

/* ============================================================
   AUTH PAGES (Login, Register)
   ============================================================ */
.auth-container{display:flex;align-items:center;justify-content:center;min-height:60vh;padding:48px 0}
.auth-card{
    background:var(--surface);border:1px solid var(--line);border-radius:10px;
    box-shadow:var(--shadow-lg);padding:40px;width:100%;max-width:420px;
}
.auth-title{
    font-family:var(--font-serif);font-size:26px;font-weight:700;
    text-align:center;margin-bottom:28px;color:var(--ink);
}
.auth-form .form-group{margin-bottom:16px}
.auth-form .form-group label{
    display:block;font-size:13px;font-weight:600;margin-bottom:5px;color:var(--ink-light);
}
.auth-form .form-group input{
    width:100%;padding:10px 14px;border:1px solid var(--line);border-radius:var(--radius);
    font-size:15px;outline:none;transition:border-color .2s;
}
.auth-form .form-group input:focus{border-color:var(--red)}
.auth-footer{text-align:center;margin-top:20px;font-size:13px;color:var(--ink-muted)}
.auth-footer a{color:var(--red);font-weight:600}

.alert{padding:10px 14px;border-radius:var(--radius);font-size:13px;margin-bottom:16px}
.alert-error{background:#fef2f2;color:#b91c1c;border:1px solid #fecaca}
.alert-success{background:#f0fdf4;color:#166534;border:1px solid #bbf7d0}

/* ============================================================
   404 ERROR PAGE
   ============================================================ */
.error-page{text-align:center;padding:80px 20px}
.error-code{font-size:120px;font-weight:800;color:var(--red);line-height:1;margin-bottom:12px;font-family:var(--font-serif)}
.error-page h1{font-family:var(--font-serif);font-size:28px;margin-bottom:10px}
.error-page p{color:var(--ink-muted);font-size:15px;margin-bottom:32px}
.error-actions{display:flex;gap:10px;justify-content:center}

/* ============================================================
   FOOTER — Newspaper Footer
   ============================================================ */
.footer{background:var(--ink);color:rgba(255,255,255,.85);padding:40px 0 20px;margin-top:0}
.footer-grid{display:grid;grid-template-columns:2fr 1fr 1fr;gap:32px;margin-bottom:28px}
.footer h4{font-size:15px;font-weight:700;margin-bottom:14px;color:#fff;text-transform:uppercase;letter-spacing:.5px}
.footer ul li{margin-bottom:6px}
.footer ul li a{font-size:13px;opacity:.85;transition:opacity .15s}
.footer ul li a:hover{opacity:1;color:var(--red-light)}
.footer-bottom{
    text-align:center;padding-top:20px;border-top:1px solid rgba(255,255,255,.1);
    font-size:12px;color:rgba(255,255,255,.65);
}

/* ============================================================
   RESPONSIVE
   ============================================================ */
@media(max-width:1024px){
    .content-layout{grid-template-columns:1fr}
    .sidebar{position:static}
    .featured-grid{grid-template-columns:1fr 1fr}
    .featured-grid .featured-card:first-child{grid-row:auto}
}
@media(max-width:768px){
    .top-bar{display:none}
    .header-inner{flex-wrap:wrap;padding:12px 0;gap:10px}
    .logo{font-size:24px}
    .main-nav .container{display:none}
    .main-nav.active .container{display:flex;flex-direction:column;padding:8px 16px}
    .main-nav.active .nav-link{
        padding:10px 12px;border-bottom:none;border-left:3px solid transparent;
        font-size:14px;text-align:left;
    }
    .main-nav.active .nav-link:hover,
    .main-nav.active .nav-link.active{border-left-color:var(--red);background:var(--surface-gray)}
    .main-nav.active .nav-item-wrap{display:block}
    .main-nav.active .nav-dropdown{
        position:static;box-shadow:none;border:none;padding:0 0 0 16px;min-width:0;
    }
    .main-nav.active .nav-dropdown-item{padding:8px 12px;font-size:13px}
    .menu-toggle{display:block}
    .header-actions{order:3;width:100%;flex:none}
    .header-actions .search-form{display:flex;width:100%;position:relative}
    .header-actions .search-input{
        width:100%;font-size:16px;padding:10px 44px 10px 16px;
        border-radius:24px;border:1px solid var(--line);background:var(--surface-gray);
        -webkit-appearance:none;appearance:none;
    }
    .header-actions .search-input:focus{width:100%;border-color:var(--red);background:var(--surface)}
    .header-actions .search-btn{
        position:absolute;right:4px;top:50%;transform:translateY(-50%);
        background:var(--red);border:none;color:#fff;width:36px;height:36px;
        border-radius:50%;font-size:15px;display:flex;align-items:center;justify-content:center;
    }
    .featured-grid{grid-template-columns:1fr}
    .featured-grid .featured-card:first-child .card-title{font-size:18px}
    .articles-grid{grid-template-columns:1fr}
    .article-title{font-size:26px}
    .article-row{flex-direction:column}
    .row-image{width:100%;aspect-ratio:16/9;min-height:0}
    .footer-grid{grid-template-columns:1fr}
    .search-form-large{flex-direction:column}
    .auth-card{padding:24px;margin:0 16px}
}
@media(max-width:480px){
    .article-title{font-size:22px}
    .error-code{font-size:80px}
    .error-actions{flex-direction:column}
}

/* ============================================================
   DARK MODE
   ============================================================ */
.dark-toggle{
    background:none;border:1px solid var(--line);border-radius:50%;width:36px;height:36px;
    cursor:pointer;display:flex;align-items:center;justify-content:center;
    font-size:16px;color:var(--ink-muted);transition:all .2s;flex-shrink:0;
}
.dark-toggle:hover{border-color:var(--red);color:var(--red)}

html.dark-early body,
body.dark-mode{
    --ink:#e0e0e0;
    --ink-light:#bdbdbd;
    --ink-muted:#9e9e9e;
    --ink-faint:#888;
    --line:#333;
    --line-light:#2a2a2a;
    --surface:#1a1a1a;
    --surface-warm:#222;
    --surface-gray:#252525;
}
body.dark-mode .header,
html.dark-early .header{background:#1a1a1a}
body.dark-mode .top-bar,
html.dark-early .top-bar{background:#111}
body.dark-mode .main-nav,
html.dark-early .main-nav{background:#1a1a1a;border-color:#333}
body.dark-mode .featured-card,
body.dark-mode .article-card,
body.dark-mode .widget,
html.dark-early .featured-card,
html.dark-early .article-card,
html.dark-early .widget{background:#222;border-color:#333}
body.dark-mode .search-input,
html.dark-early .search-input{background:#252525;border-color:#333;color:#e0e0e0}
body.dark-mode .footer,
html.dark-early .footer{background:#111}
body.dark-mode .comment{background:#252525!important}
body.dark-mode .article-excerpt{background:#252525}
body.dark-mode .auth-card{background:#222;border-color:#333}
body.dark-mode .dark-toggle{border-color:#444;color:#ffc107}
body.dark-mode .dark-toggle .fa-moon{display:none}
body.dark-mode .dark-toggle .fa-sun{display:inline}
.dark-toggle .fa-sun{display:none}
body.dark-mode .dark-toggle .fa-sun{display:inline}
body.dark-mode .dark-toggle .fa-moon{display:none}
body.dark-mode .nav-dropdown{background:#222;border-color:#333}
body.dark-mode .nav-dropdown-item:hover{background:#333}

/* ============================================================
   BACK TO TOP
   ============================================================ */
.back-to-top{
    position:fixed;bottom:28px;right:28px;width:44px;height:44px;
    background:var(--red);color:#fff;border:none;border-radius:50%;
    font-size:18px;cursor:pointer;display:flex;align-items:center;justify-content:center;
    opacity:0;visibility:hidden;transform:translateY(12px);
    transition:all .3s;z-index:999;box-shadow:0 4px 12px rgba(0,0,0,.2);
}
.back-to-top.visible{opacity:1;visibility:visible;transform:translateY(0)}
.back-to-top:hover{background:var(--red-dark);transform:translateY(-2px)}

/* ============================================================
   READING PROGRESS BAR
   ============================================================ */
.reading-progress{
    position:fixed;top:0;left:0;width:0;height:3px;
    background:linear-gradient(90deg,var(--red),var(--orange,#ef6c00));
    z-index:9999;transition:width 60ms linear;pointer-events:none;
}

/* ============================================================
   COPY LINK BUTTON
   ============================================================ */
.share-copy{
    background:var(--surface-gray);color:var(--ink-muted);border:1px solid var(--line);
    padding:6px 14px;border-radius:4px;font-size:12px;font-weight:600;
    cursor:pointer;transition:all .2s;display:inline-flex;align-items:center;gap:5px;
}
.share-copy:hover{border-color:var(--red);color:var(--red)}
.share-copy.copied{background:#e8f5e9;color:#2e7d32;border-color:#a5d6a7}

/* ============================================================
   TABLE OF CONTENTS (TOC)
   ============================================================ */
.article-toc{
    background:var(--surface-warm);border:1px solid var(--line-light);
    border-radius:var(--radius);padding:16px 20px;margin-bottom:24px;
}
.article-toc-title{
    font-size:14px;font-weight:700;color:var(--ink);margin-bottom:10px;
    display:flex;align-items:center;gap:8px;cursor:pointer;user-select:none;
}
.article-toc-title i{font-size:12px;transition:transform .2s}
.article-toc.collapsed .article-toc-title i{transform:rotate(-90deg)}
.article-toc-list{list-style:none;padding:0;margin:0}
.article-toc.collapsed .article-toc-list{display:none}
.article-toc-list li{margin-bottom:4px}
.article-toc-list li a{
    display:block;padding:5px 0 5px 0;font-size:13px;color:var(--ink-light);
    text-decoration:none;transition:color .15s;border-left:2px solid transparent;
    padding-left:10px;
}
.article-toc-list li a:hover,.article-toc-list li a.active{color:var(--red);border-left-color:var(--red)}
.article-toc-list li.toc-h3 a{padding-left:24px;font-size:12px}