/* ============================================================
   B910Pro — Professional Chemistry Information Theme
   Clean. Authoritative. Readable.
   ============================================================ */

/* ---- Reset ---- */
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
html{font-size:16px;-webkit-text-size-adjust:100%;scroll-behavior:smooth}
body{font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Noto Sans CJK SC","Microsoft YaHei",sans-serif;color:var(--text);background:var(--bg);line-height:1.7;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale;overflow-x:hidden;word-break:break-word;overflow-wrap:break-word}
a{color:var(--link);text-decoration:none;transition:color .15s}
a:hover{color:var(--link-hover)}
img{max-width:100%;height:auto}
ul,ol{list-style:none}
button{font:inherit;cursor:pointer;border:0;background:none;color:inherit}
input,textarea{font:inherit;outline:none}

/* ---- Design Tokens ---- */
:root{
  --primary:#0d3b5c;
  --primary-light:#1a5f8a;
  --primary-tint:#e8f0f6;
  --accent:#c2410c;
  --accent-tint:#fff3e6;
  --success:#059669;
  --bg:#f5f7fa;
  --surface:#ffffff;
  --text:#1a2332;
  --text-2:#475569;
  --muted:#8896a6;
  --border:#e2e8f0;
  --border-light:#f1f5f9;
  --link:#155e8a;
  --link-hover:#0d3b5c;
  --shadow-xs:0 1px 2px rgba(13,59,92,.05);
  --shadow-sm:0 2px 8px rgba(13,59,92,.06);
  --shadow-md:0 4px 16px rgba(13,59,92,.08);
  --shadow-lg:0 12px 36px rgba(13,59,92,.10);
  --r:8px;
  --r-lg:12px;
  --maxw:1100px;
  --header-h:56px;
}

/* ---- Layout ---- */
.wrap{max-width:var(--maxw);margin:0 auto;padding:0 16px;overflow-x:hidden}
.main{padding:20px 0 60px}

/* ---- Header ---- */
.site-header{
  position:sticky;top:0;z-index:100;
  background:var(--surface);
  border-bottom:1px solid var(--border);
  box-shadow:var(--shadow-xs);
}
.header-inner{
  display:flex;align-items:center;
  height:var(--header-h);gap:20px;
}
.logo{flex-shrink:0;display:flex;align-items:center}
.logo img{height:38px;width:auto}
.logo-text{font-size:20px;font-weight:800;color:var(--primary);letter-spacing:-.02em}
.nav-main{display:flex;gap:4px;align-items:center}
.nav-main a{
  padding:8px 14px;font-size:15px;font-weight:500;
  color:var(--text);border-radius:var(--r);
  transition:all .15s;
}
.nav-main a:hover,.nav-main a.active{color:var(--primary);background:var(--primary-tint)}

.header-search{
  margin-left:auto;display:flex;align-items:center;gap:8px;
}
.header-search input{
  width:180px;padding:7px 12px;font-size:14px;
  border:1px solid var(--border);border-radius:var(--r);
  background:var(--bg);transition:all .15s;
}
.header-search input:focus{border-color:var(--primary);background:var(--surface);box-shadow:0 0 0 3px rgba(13,59,92,.08)}
.header-search button{padding:7px 14px;font-size:14px;font-weight:500;color:#fff;background:var(--primary);border-radius:var(--r);transition:background .15s}
.header-search button:hover{background:var(--primary-light)}

.menu-toggle{display:none}

/* ---- Content Layout ---- */
.content-area{display:flex;gap:24px;align-items:flex-start}
.main-col{flex:1;min-width:0}
.side-col{width:280px;flex-shrink:0}

/* ---- Breadcrumb ---- */
.breadcrumb{
  padding:10px 0;font-size:13px;color:var(--muted);
  display:flex;gap:6px;align-items:center;flex-wrap:wrap;
}
.breadcrumb a{color:var(--muted)}
.breadcrumb a:hover{color:var(--primary)}
.breadcrumb span.sep{color:var(--border)}

/* ---- Article List ---- */
.news-list{display:flex;flex-direction:column}
.news-item{
  display:flex;gap:16px;padding:18px 0;
  border-bottom:1px solid var(--border-light);
  transition:all .15s;
}
.news-item:last-child{border-bottom:0}
.news-item:hover{background:var(--surface);border-radius:var(--r);padding-left:12px;padding-right:12px}

.news-date{
  flex-shrink:0;width:54px;text-align:center;
  padding-top:2px;
}
.news-date .day{font-size:24px;font-weight:800;color:var(--primary);line-height:1.1}
.news-date .month{font-size:11px;color:var(--muted);text-transform:uppercase;letter-spacing:.05em;margin-top:2px}

.news-body{flex:1;min-width:0}
.news-title{font-size:17px;font-weight:600;line-height:1.45;color:var(--text);margin-bottom:6px}
.news-title a{color:inherit}
.news-title a:hover{color:var(--primary)}
.news-excerpt{font-size:14px;color:var(--text-2);line-height:1.65;display:-webkit-box;-webkit-line-clamp:2;-webkit-box-orient:vertical;overflow:hidden;margin-bottom:8px}
.news-meta{display:flex;gap:12px;font-size:13px;color:var(--muted);flex-wrap:wrap;align-items:center}
.news-meta .cat{padding:2px 8px;background:var(--primary-tint);color:var(--primary);border-radius:4px;font-weight:500;font-size:12px}
.news-meta .views{display:flex;align-items:center;gap:3px}

/* ---- Pagination ---- */
.pagination{display:flex;gap:6px;justify-content:center;padding:28px 0 8px;flex-wrap:wrap}
.pagination a,.pagination span{
  min-width:36px;height:36px;padding:0 10px;
  display:inline-flex;align-items:center;justify-content:center;
  font-size:14px;font-weight:500;border:1px solid var(--border);border-radius:var(--r);
  background:var(--surface);color:var(--text-2);transition:all .15s;
}
.pagination a:hover{border-color:var(--primary);color:var(--primary)}
.pagination span.current{background:var(--primary);color:#fff;border-color:var(--primary)}

/* ---- Article Detail ---- */
.article-header{padding-bottom:20px;border-bottom:2px solid var(--primary);margin-bottom:28px}
.article-cat-tag{
  display:inline-block;padding:3px 10px;margin-bottom:12px;
  font-size:12px;font-weight:600;color:var(--accent);
  background:var(--accent-tint);border-radius:4px;letter-spacing:.03em;
}
.article-title{font-size:26px;font-weight:800;line-height:1.35;color:var(--text);letter-spacing:-.01em;margin-bottom:14px}
.article-meta{display:flex;gap:16px;font-size:13px;color:var(--muted);flex-wrap:wrap;align-items:center}
.article-meta .author{font-weight:500;color:var(--text-2)}
.article-meta .views::before{content:"";display:inline-block;width:14px;height:14px;margin-right:3px;background:currentColor;-webkit-mask:url("data:image/svg+xml,%3Csvg viewBox='0 0 24 24' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath d='M12 4.5C7 4.5 2.7 7.6 1 12c1.7 4.4 6 7.5 11 7.5s9.3-3.1 11-7.5c-1.7-4.4-6-7.5-11-7.5zm0 12.5a5 5 0 110-10 5 5 0 010 10zm0-8a3 3 0 100 6 3 3 0 000-6z'/%3E%3C/svg%3E") center/contain no-repeat;mask:url("data:image/svg+xml,%3Csvg viewBox='0 0 24 24' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath d='M12 4.5C7 4.5 2.7 7.6 1 12c1.7 4.4 6 7.5 11 7.5s9.3-3.1 11-7.5c-1.7-4.4-6-7.5-11-7.5zm0 12.5a5 5 0 110-10 5 5 0 010 10zm0-8a3 3 0 100 6 3 3 0 000-6z'/%3E%3C/svg%3E") center/contain no-repeat;vertical-align:-2px}

.article-content{font-size:17px;line-height:1.85;color:var(--text)}
.article-content p{margin-bottom:1.3em}
.article-content h2{font-size:1.5em;font-weight:700;color:var(--text);margin:1.8em 0 .6em;padding-left:12px;border-left:4px solid var(--primary)}
.article-content h3{font-size:1.25em;font-weight:600;color:var(--text);margin:1.5em 0 .5em}
.article-content blockquote{margin:1.5em 0;padding:14px 18px;border-left:3px solid var(--accent);background:var(--accent-tint);border-radius:0 var(--r) var(--r) 0;font-size:.95em;color:var(--text-2)}
.article-content ul,.article-content ol{margin:1em 0;padding-left:1.5em}
.article-content li{margin-bottom:.4em}
.article-content img{max-width:100%;height:auto;border-radius:var(--r);margin:1em 0}
.article-content iframe,.article-content video,.article-content embed,.article-content object{max-width:100%}
.article-content table{display:block;overflow-x:auto;max-width:100%;-webkit-overflow-scrolling:touch}
.article-content strong{font-weight:700;color:var(--text)}
.article-content a{color:var(--link);border-bottom:1px solid transparent;transition:border-color .15s}
.article-content a:hover{border-bottom-color:var(--link)}
.article-content table{width:100%;border-collapse:collapse;margin:1.2em 0;font-size:.95em}
.article-content th,.article-content td{padding:8px 12px;border:1px solid var(--border);text-align:left}
.article-content th{background:var(--bg);font-weight:600}

.article-footer{margin-top:32px;padding-top:20px;border-top:1px solid var(--border)}
.article-tags{display:flex;gap:6px;flex-wrap:wrap;align-items:center}
.article-tags .label{font-size:13px;color:var(--muted);margin-right:4px}
.article-tags a{padding:4px 10px;font-size:13px;color:var(--primary);background:var(--primary-tint);border-radius:4px;transition:all .15s}
.article-tags a:hover{background:var(--primary);color:#fff}

.article-nav{display:flex;gap:12px;margin-top:24px}
.article-nav a{flex:1;padding:12px 16px;background:var(--surface);border:1px solid var(--border);border-radius:var(--r);font-size:14px;transition:all .15s;min-width:0}
.article-nav a:hover{border-color:var(--primary);box-shadow:var(--shadow-sm)}
.article-nav a .label{display:block;font-size:12px;color:var(--muted);margin-bottom:2px}
.article-nav a .title{display:block;font-weight:500;color:var(--text);overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.article-nav .next{text-align:right}

/* ---- Sidebar ---- */
.side-box{background:var(--surface);border:1px solid var(--border);border-radius:var(--r-lg);padding:16px 18px;margin-bottom:16px;box-shadow:var(--shadow-xs)}
.side-title{font-size:16px;font-weight:700;color:var(--text);margin-bottom:14px;padding-bottom:10px;border-bottom:2px solid var(--primary);display:flex;align-items:center;gap:6px}
.side-title::before{content:"";width:4px;height:16px;background:var(--accent);border-radius:2px}
.side-list li{padding:8px 0;border-bottom:1px solid var(--border-light);font-size:14px;line-height:1.5}
.side-list li:last-child{border-bottom:0}
.side-list li a{color:var(--text-2);transition:color .15s}
.side-list li a:hover{color:var(--primary)}
.side-meta{font-size:12px;color:var(--muted);margin-top:2px}

.tag-cloud{display:flex;flex-wrap:wrap;gap:6px}
.tag-cloud a{padding:4px 10px;font-size:13px;border:1px solid var(--border);border-radius:999px;color:var(--text-2);background:var(--surface);transition:all .15s}
.tag-cloud a:hover{border-color:var(--primary);color:var(--primary);background:var(--primary-tint)}

/* ---- Footer ---- */
.site-footer{background:var(--surface);border-top:1px solid var(--border);padding:24px 0;margin-top:40px}
.footer-inner{display:flex;justify-content:space-between;align-items:center;flex-wrap:wrap;gap:12px}
.footer-copy{font-size:13px;color:var(--muted);line-height:1.6}
.footer-copy a{color:var(--text-2)}
.footer-copy a:hover{color:var(--primary)}

/* ---- Mobile Bottom Nav ---- */
.mobile-nav{
  display:none;position:fixed;bottom:0;left:0;right:0;z-index:200;
  background:var(--surface);border-top:1px solid var(--border);
  box-shadow:0 -2px 12px rgba(13,59,92,.06);
  padding-bottom:env(safe-area-inset-bottom);
}
.mobile-nav ul{display:flex}
.mobile-nav li{flex:1}
.mobile-nav button,.mobile-nav a{
  width:100%;height:54px;display:flex;flex-direction:column;
  align-items:center;justify-content:center;gap:2px;
  font-size:10px;color:var(--muted);transition:color .15s;
}
.mobile-nav button.active,.mobile-nav a.active{color:var(--primary)}
.mobile-nav svg{width:22px;height:22px;stroke-width:2;fill:none;stroke:currentColor;stroke-linecap:round;stroke-linejoin:round}

/* ---- Reading Progress ---- */
.read-progress{position:fixed;top:0;left:0;height:3px;background:var(--accent);z-index:300;transition:width .1s;width:0}

/* ---- Responsive ---- */
@media(max-width:900px){
  .side-col{display:none}
  .content-area{flex-direction:column}
}
@media(max-width:768px){
  .nav-main,.header-search{display:none}
  .menu-toggle{
    display:flex;flex-direction:column;gap:4px;
    margin-left:auto;padding:8px;cursor:pointer;
  }
  .menu-toggle span{width:22px;height:2px;background:var(--text);border-radius:2px}
  
  .mobile-nav{display:block}
  body{padding-bottom:54px}
  
  .article-title{font-size:21px}
  .article-content{font-size:16px;line-height:1.8}
  .article-content h2{font-size:1.35em}
  
  .news-item{gap:12px;padding:14px 0}
  .news-date{width:44px}
  .news-date .day{font-size:20px}
  .news-title{font-size:16px}
  .news-excerpt{font-size:13px;-webkit-line-clamp:1}
  
  /* Mobile slide menu */
  .nav-main.mobile-open{
    display:flex;position:fixed;top:var(--header-h);left:0;right:0;
    flex-direction:column;background:var(--surface);
    padding:12px 16px;gap:0;z-index:99;
    border-bottom:1px solid var(--border);box-shadow:var(--shadow-md);
  }
  .nav-main.mobile-open a{padding:12px 16px;border-radius:var(--r);font-size:16px}
  
  .mobile-search-bar{
    display:flex;gap:8px;padding:12px 16px;
    background:var(--surface);border-bottom:1px solid var(--border);
  }
  .mobile-search-bar input{flex:1;padding:8px 12px;border:1px solid var(--border);border-radius:var(--r);font-size:15px}
  .mobile-search-bar button{padding:8px 16px;background:var(--primary);color:#fff;border-radius:var(--r);font-weight:500}

  /* Mobile compatibility fixes */
  body{touch-action:manipulation;-webkit-text-size-adjust:100%;text-size-adjust:100%}
  .article-content{overflow-wrap:break-word;word-break:break-word}
  .article-content img,.article-content iframe,.article-content video{max-width:100%;height:auto}
  .article-content table{display:block;overflow-x:auto;-webkit-overflow-scrolling:touch}
  .article-content pre{white-space:pre-wrap;word-wrap:break-word;overflow-x:auto;max-width:100%}
  .news-excerpt{word-break:break-all;overflow-wrap:break-word}
  .article-title{word-break:break-word;overflow-wrap:break-word}
  .news-title{word-break:break-word;overflow-wrap:break-word}
  .wrap,.main-col{min-width:0;overflow-x:hidden}
  .header-inner{flex-wrap:nowrap;overflow:hidden}
  .logo img{max-height:36px;width:auto}
}
.mobile-search-bar{display:none}