/* PharmaKinetics Research — main stylesheet */

:root{
  --pkr-bg:#ffffff;
  --pkr-bg-soft:#f8fafc;
  --pkr-bg-card:#ffffff;
  --pkr-line:#e5e7eb;
  --pkr-line-soft:#f1f5f9;
  --pkr-text:#0f172a;
  --pkr-muted:#475569;
  --pkr-soft:#64748b;
  --pkr-accent:#2563eb;
  --pkr-accent-dark:#1d4ed8;
  --pkr-accent-soft:#dbeafe;
  --pkr-radius:10px;
  --pkr-radius-sm:6px;
  --pkr-display:'Inter',system-ui,-apple-system,Segoe UI,Roboto,sans-serif;
  --pkr-body:'Inter',system-ui,-apple-system,Segoe UI,Roboto,sans-serif;
}

*,*::before,*::after{box-sizing:border-box;}
html,body{margin:0;padding:0;background:var(--pkr-bg);color:var(--pkr-text);font-family:var(--pkr-body);font-size:15px;line-height:1.6;-webkit-font-smoothing:antialiased;}
img{max-width:100%;height:auto;display:block;}
a{color:var(--pkr-accent);text-decoration:none;}
a:hover{color:var(--pkr-accent-dark);}
button{cursor:pointer;font-family:inherit;}
h1,h2,h3,h4,h5{margin:0;color:var(--pkr-text);font-weight:700;letter-spacing:-.02em;font-family:var(--pkr-body);}
h1{font-weight:800;font-size:48px;line-height:1.05;letter-spacing:-.025em;}
h2{font-weight:700;font-size:32px;line-height:1.15;letter-spacing:-.02em;}
h3{font-weight:700;font-size:18px;line-height:1.3;}
h4{font-weight:600;font-size:16px;line-height:1.3;}
p{margin:0 0 1em;}
ul{margin:0;padding:0;list-style:none;}

.pkr-container{max-width:1280px;margin:0 auto;padding:0 24px;}
.pkr-svg{display:inline-block;vertical-align:middle;}

/* === Utility strip === */
.pkr-utility{background:#0f172a;color:#cbd5e1;font-size:12px;}
.pkr-utility-row{display:flex;justify-content:space-between;align-items:center;padding:8px 24px;}
.pkr-utility-left{display:flex;align-items:center;gap:8px;letter-spacing:.04em;}
.pkr-utility-right{display:flex;gap:18px;}
.pkr-utility-link{color:#cbd5e1;display:inline-flex;align-items:center;gap:6px;letter-spacing:.02em;}
.pkr-utility-link:hover{color:#fff;}

/* === Header === */
.pkr-header{background:#fff;border-bottom:1px solid var(--pkr-line);position:sticky;top:0;z-index:50;}
.pkr-header-row{display:flex;align-items:center;gap:36px;padding:14px 24px;}
.pkr-brand-link{display:flex;align-items:center;color:var(--pkr-text);}
.pkr-brand-link:hover{color:var(--pkr-text);}
.pkr-logo{height:46px;width:auto;display:block;}
.pkr-logo-footer{height:42px;width:auto;display:block;filter:brightness(1.15);}
.pkr-nav{flex:1;}
.pkr-menu{display:flex;gap:26px;align-items:center;flex-wrap:wrap;}
.pkr-menu > li{position:relative;}
.pkr-menu > li > a{color:var(--pkr-text);font-size:14px;padding:8px 0;display:inline-flex;align-items:center;gap:4px;font-weight:500;}
.pkr-menu > li > a:hover{color:var(--pkr-accent);}
.pkr-submenu{position:absolute;top:100%;left:-12px;background:#fff;border:1px solid var(--pkr-line);border-radius:var(--pkr-radius);padding:8px;min-width:220px;box-shadow:0 12px 28px rgba(15,23,42,.10);opacity:0;visibility:hidden;transform:translateY(-4px);transition:all .15s ease;}
.has-sub:hover .pkr-submenu{opacity:1;visibility:visible;transform:translateY(0);}
.pkr-submenu li a{display:flex;align-items:center;gap:10px;padding:9px 12px;color:var(--pkr-text);font-size:14px;border-radius:6px;}
.pkr-submenu li a:hover{background:var(--pkr-bg-soft);color:var(--pkr-accent);}
.pkr-header-actions{display:flex;align-items:center;gap:4px;}
.pkr-icon-btn{background:transparent;border:none;color:var(--pkr-muted);width:38px;height:38px;display:inline-flex;align-items:center;justify-content:center;border-radius:8px;}
.pkr-icon-btn:hover{background:var(--pkr-bg-soft);color:var(--pkr-text);}
.pkr-mobile-toggle{display:none;}
.pkr-search-bar{display:none;background:var(--pkr-bg-soft);padding:14px 0;border-top:1px solid var(--pkr-line);}
.pkr-search-open .pkr-search-bar{display:block;}

.pkr-search-form{display:flex;align-items:center;background:#fff;border:1px solid var(--pkr-line);border-radius:var(--pkr-radius);padding:6px;gap:8px;}
.pkr-search-label{padding:0 8px;color:var(--pkr-muted);}
.pkr-search-input{flex:1;background:transparent;border:none;outline:none;padding:8px;font-size:15px;color:var(--pkr-text);}
.pkr-search-submit{background:var(--pkr-accent);color:#fff;border:none;border-radius:6px;padding:9px 18px;font-weight:500;}
.pkr-search-submit:hover{background:var(--pkr-accent-dark);}

/* === Buttons & pills === */
.pkr-pill{display:inline-block;background:var(--pkr-accent-soft);color:var(--pkr-accent-dark);font-size:11px;font-weight:600;padding:4px 10px;border-radius:20px;letter-spacing:.06em;text-transform:uppercase;}
.pkr-pill:hover{color:var(--pkr-accent-dark);}
.pkr-view-all{color:var(--pkr-accent);font-size:14px;font-weight:500;display:inline-flex;align-items:center;gap:6px;}
.pkr-view-all:hover{gap:10px;transition:gap .15s ease;}

/* === Section spacing === */
.pkr-main{background:var(--pkr-bg);}
.pkr-hero,
.pkr-latest,
.pkr-compounds,
.pkr-ai,
.pkr-sys-topics{padding:64px 0;border-bottom:1px solid var(--pkr-line-soft);}
.pkr-hero{background:linear-gradient(180deg,#fafbff 0%,#ffffff 100%);}

.pkr-section-head{display:flex;justify-content:space-between;align-items:baseline;margin:0 0 28px;gap:20px;flex-wrap:wrap;}
.pkr-section-head h2{margin:0;}

/* === HERO: Explore Biological Systems === */
.pkr-hero-head{margin-bottom:36px;text-align:left;max-width:780px;}
.pkr-hero-head h1{margin:0 0 12px;font-size:54px;}
.pkr-hero-head p{color:var(--pkr-muted);font-size:17px;max-width:560px;}

.pkr-systems-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:18px;}
.pkr-system-card{display:flex;flex-direction:column;gap:10px;padding:24px;background:#fff;border:1px solid var(--pkr-line);border-radius:var(--pkr-radius);color:var(--pkr-text);transition:all .2s ease;position:relative;overflow:hidden;}
.pkr-system-card::before{content:"";position:absolute;top:0;left:0;right:0;height:3px;background:var(--accent);opacity:.85;}
.pkr-system-card:hover{transform:translateY(-3px);border-color:var(--accent);box-shadow:0 14px 30px rgba(15,23,42,.07);color:var(--pkr-text);}
.pkr-system-icon{display:inline-flex;align-items:center;justify-content:center;margin-bottom:6px;}
.pkr-system-icon img{width:64px;height:64px;display:block;object-fit:contain;}
.pkr-system-card h3{font-size:18px;color:var(--pkr-text);}
.pkr-system-card p{color:var(--pkr-muted);font-size:13.5px;flex:1;margin:0;line-height:1.5;}
.pkr-system-cta{color:var(--accent);font-size:13px;font-weight:600;display:inline-flex;align-items:center;gap:4px;margin-top:8px;}

/* === Latest research === */
.pkr-latest-grid{display:grid;grid-template-columns:1.2fr 1fr;gap:28px;align-items:start;}
.pkr-feature-card{display:grid;grid-template-columns:0.85fr 1fr;background:#fff;border:1px solid var(--pkr-line);border-radius:var(--pkr-radius);overflow:hidden;color:var(--pkr-text);transition:all .2s ease;align-items:stretch;}
.pkr-feature-card:hover{border-color:var(--pkr-accent);box-shadow:0 14px 30px rgba(15,23,42,.07);color:var(--pkr-text);transform:translateY(-2px);}
.pkr-feature-img{position:relative;background:linear-gradient(135deg,#dbeafe,#eff6ff);overflow:hidden;min-height:280px;}
.pkr-feature-img img,.pkr-feature-img svg{width:100%;height:100%;object-fit:cover;display:block;}
.pkr-feature-img::before{content:"FEATURED";position:absolute;top:14px;left:14px;z-index:2;background:#0f172a;color:#fff;font-size:10px;font-weight:700;letter-spacing:.08em;padding:5px 10px;border-radius:6px;}
.pkr-feature-body{padding:26px;display:flex;flex-direction:column;}
.pkr-feature-body .pkr-pill{margin-bottom:14px;align-self:flex-start;}
.pkr-feature-body h3{margin:0 0 12px;font-weight:700;font-size:22px;line-height:1.25;}
.pkr-feature-body p{color:var(--pkr-muted);margin:0 0 18px;font-size:14.5px;line-height:1.6;flex:1;}
.pkr-feature-meta{display:flex;justify-content:space-between;align-items:center;font-size:13px;color:var(--pkr-soft);margin-top:auto;}
.pkr-feature-meta span{display:inline-flex;align-items:center;gap:6px;}
.pkr-read-more{color:var(--pkr-accent);font-weight:600;}

.pkr-side-list{display:flex;flex-direction:column;gap:12px;}
.pkr-side-card{display:grid;grid-template-columns:110px 1fr;gap:14px;padding:12px;background:#fff;border:1px solid var(--pkr-line);border-radius:var(--pkr-radius);color:var(--pkr-text);transition:all .2s ease;align-items:center;}
.pkr-side-card:hover{border-color:var(--pkr-accent);transform:translateX(2px);color:var(--pkr-text);box-shadow:0 6px 18px rgba(15,23,42,.05);}
.pkr-side-thumb{aspect-ratio:1/.85;border-radius:8px;overflow:hidden;background:#0b1220;display:block;}
.pkr-side-thumb img,.pkr-side-thumb svg{width:100%;height:100%;object-fit:cover;display:block;}
.pkr-side-body{min-width:0;}
.pkr-side-tag{display:inline-block;font-size:10px;font-weight:600;padding:3px 9px;border-radius:20px;margin-bottom:8px;letter-spacing:.06em;}
.pkr-side-body h4{font-weight:700;font-size:15px;line-height:1.3;margin:0 0 8px;color:var(--pkr-text);}
.pkr-side-date{font-size:12px;color:var(--pkr-soft);display:inline-flex;align-items:center;gap:4px;}

/* === Featured compounds === */
.pkr-compounds{background:#ffffff;}
.pkr-compound-grid{display:grid;grid-template-columns:repeat(6,1fr);gap:14px;}
.pkr-compound-card{background:#fff;border:1px solid var(--pkr-line);border-radius:var(--pkr-radius);padding:14px 14px 18px;display:flex;flex-direction:column;color:var(--pkr-text);transition:all .2s ease;text-align:center;}
.pkr-compound-card:hover{border-color:var(--pkr-accent);transform:translateY(-2px);box-shadow:0 10px 24px rgba(15,23,42,.06);color:var(--pkr-text);}
.pkr-compound-structure{aspect-ratio:1/0.55;background:#fafbfc;border-radius:var(--pkr-radius-sm);display:flex;align-items:center;justify-content:center;margin-bottom:14px;overflow:hidden;padding:10px;}
.pkr-structure-svg{width:100%;height:100%;display:flex;align-items:center;justify-content:center;}
.pkr-structure-svg svg{width:100%;height:100%;display:block;}
.pkr-structure{width:100%;height:auto;max-height:100%;}
.pkr-structure-img{width:100%;height:100%;object-fit:contain;display:block;}
.pkr-compound-card h4{font-family:var(--pkr-body);font-size:14px;font-weight:600;margin:6px 0 4px;}
.pkr-compound-card p{font-size:12px;color:var(--pkr-muted);margin:0 0 10px;line-height:1.4;flex:1;}
.pkr-compound-cta{font-size:12px;font-weight:600;color:var(--pkr-accent);display:inline-flex;align-items:center;justify-content:center;gap:4px;}

/* === PK AI Search (2-col with knowledge graph, blue bg) === */
.pkr-ai{background:linear-gradient(180deg,#dbeafe 0%,#bfdbfe 100%);position:relative;}
.pkr-ai::before{content:"";position:absolute;top:0;left:0;right:0;height:120px;background:linear-gradient(180deg,#ffffff,transparent);pointer-events:none;}
.pkr-ai .pkr-container{position:relative;}
.pkr-ai-grid{display:grid;grid-template-columns:1.1fr .9fr;gap:48px;align-items:center;}
.pkr-ai-head{margin-bottom:18px;text-align:left;}
.pkr-ai-head h2{margin:0 0 12px;}
.pkr-ai-head p{color:var(--pkr-muted);max-width:480px;margin:0;font-size:15.5px;line-height:1.6;}
.pkr-ai-box{background:transparent;border:none;padding:0;box-shadow:none;}
.pkr-ai-form{display:flex;align-items:center;gap:6px;background:#fff;border:1px solid var(--pkr-line);border-radius:10px;padding:6px 6px 6px 14px;box-shadow:0 4px 14px rgba(15,23,42,.06);max-width:520px;}
.pkr-ai-icon{color:var(--pkr-muted);display:inline-flex;}
.pkr-ai-input{flex:1;background:transparent;border:none;outline:none;padding:12px 0;font-size:15px;color:var(--pkr-text);min-width:0;}
.pkr-ai-input::placeholder{color:var(--pkr-soft);}
.pkr-ai-submit{background:var(--pkr-accent);color:#fff;border:none;border-radius:6px;padding:10px 22px;font-weight:600;display:inline-flex;align-items:center;gap:6px;white-space:nowrap;}
.pkr-ai-submit:hover{background:var(--pkr-accent-dark);}
.pkr-ai-submit.is-loading{opacity:.6;cursor:wait;}
.pkr-ai-suggestions{display:flex;flex-wrap:wrap;gap:8px;margin-top:18px;align-items:center;font-size:13px;color:var(--pkr-soft);max-width:560px;}
.pkr-ai-suggestions > span{color:var(--pkr-accent);font-weight:600;font-size:13px;}
.pkr-ai-suggestions button{background:#fff;border:1px solid var(--pkr-line);border-radius:20px;padding:6px 14px;font-size:13px;color:var(--pkr-muted);}
.pkr-ai-suggestions button:hover{border-color:var(--pkr-accent);color:var(--pkr-accent);}
.pkr-ai-response{margin-top:22px;padding:20px;background:#fff;border:1px solid var(--pkr-line);border-radius:10px;max-width:560px;}
.pkr-ai-answer p{margin:0 0 14px;color:var(--pkr-text);font-size:15px;line-height:1.7;}
.pkr-ai-sources h4{font-size:12px;text-transform:uppercase;letter-spacing:.08em;color:var(--pkr-soft);margin:18px 0 8px;}
.pkr-ai-sources ul{display:flex;flex-direction:column;gap:6px;}
.pkr-ai-sources a{color:var(--pkr-accent);font-size:14px;}

/* Knowledge graph illustration */
.pkr-ai-graph{position:relative;width:100%;aspect-ratio:1/.85;max-width:480px;margin-left:auto;}
.pkr-ai-graph svg{width:100%;height:100%;}

/* === Footer (white) === */
.pkr-footer{background:#ffffff;color:var(--pkr-muted);padding:50px 0 24px;border-top:1px solid var(--pkr-line);}
.pkr-footer-grid{display:grid;grid-template-columns:1.4fr 1fr 1fr 1fr 1fr 1fr;gap:32px;padding-bottom:30px;border-bottom:1px solid var(--pkr-line);}
.pkr-footer-brand-col .pkr-footer-brand{display:flex;align-items:center;margin-bottom:14px;}
.pkr-footer-tagline{color:var(--pkr-muted);font-size:13.5px;line-height:1.6;max-width:300px;margin:0 0 14px;}
.pkr-footer-address{color:var(--pkr-muted);font-size:13px;line-height:1.7;margin:0 0 16px;}
.pkr-footer-address a{color:var(--pkr-accent);}
.pkr-footer-social{display:flex;gap:10px;margin-top:6px;}
.pkr-footer-social a{width:32px;height:32px;border:1px solid var(--pkr-line);border-radius:50%;display:inline-flex;align-items:center;justify-content:center;color:var(--pkr-muted);transition:all .15s ease;}
.pkr-footer-social a:hover{border-color:var(--pkr-accent);color:var(--pkr-accent);background:var(--pkr-accent-soft);}
.pkr-footer-col h4{color:var(--pkr-text);font-size:13px;letter-spacing:.02em;margin:0 0 16px;font-weight:700;}
.pkr-footer-col ul li{margin-bottom:10px;}
.pkr-footer-col ul a{color:var(--pkr-muted);font-size:13.5px;}
.pkr-footer-col ul a:hover{color:var(--pkr-accent);}
.pkr-footer-bottom{display:flex;justify-content:space-between;align-items:center;padding-top:20px;color:var(--pkr-soft);font-size:13px;flex-wrap:wrap;gap:14px;}
.pkr-footer-legal{display:flex;gap:22px;}
.pkr-footer-legal a{color:var(--pkr-muted);font-size:13px;}
.pkr-footer-legal a:hover{color:var(--pkr-accent);}

.pkr-back-top{position:fixed;right:18px;bottom:18px;width:42px;height:42px;border-radius:50%;background:var(--pkr-accent);color:#fff;display:flex;align-items:center;justify-content:center;z-index:60;box-shadow:0 8px 20px rgba(37,99,235,.3);}
.pkr-back-top:hover{background:var(--pkr-accent-dark);color:#fff;}

/* === Biological System landing page === */
.pkr-sys-hero{background:linear-gradient(180deg,#fafbff 0%,#ffffff 100%);padding:34px 0 0;border-bottom:1px solid var(--pkr-line-soft);}
.pkr-breadcrumb{font-size:13px;color:var(--pkr-muted);display:flex;align-items:center;gap:6px;margin-bottom:22px;}
.pkr-breadcrumb a{color:var(--pkr-muted);}
.pkr-breadcrumb a:hover{color:var(--pkr-accent);}
.pkr-breadcrumb strong{color:var(--pkr-text);font-weight:500;}
.pkr-sys-hero-grid{display:grid;grid-template-columns:1.1fr 1fr;gap:40px;align-items:center;padding:20px 0 60px;}
.pkr-sys-eyebrow{font-size:12px;color:var(--accent);font-weight:600;letter-spacing:.14em;text-transform:uppercase;display:block;margin-bottom:14px;}
.pkr-sys-hero-copy h1{font-size:60px;margin:0 0 18px;}
.pkr-sys-hero-copy p{font-size:17px;color:var(--pkr-muted);max-width:540px;margin:0 0 28px;}
.pkr-sys-stats{display:flex;gap:36px;flex-wrap:wrap;}
.pkr-sys-stats > div strong{font-family:var(--pkr-display);font-size:34px;color:var(--pkr-text);display:block;line-height:1;}
.pkr-sys-stats > div span{font-size:12px;color:var(--pkr-muted);letter-spacing:.04em;text-transform:uppercase;}
.pkr-sys-hero-illu{display:flex;justify-content:center;}
.pkr-sys-illu{width:100%;max-width:520px;height:auto;display:block;border-radius:12px;}

.pkr-sys-tabs{background:#fff;border-top:1px solid var(--pkr-line);}
.pkr-sys-tabs .pkr-container{display:flex;gap:0;overflow-x:auto;}
.pkr-sys-tabs a{display:inline-flex;align-items:center;gap:6px;padding:14px 18px;font-size:13px;color:var(--pkr-muted);white-space:nowrap;border-bottom:2px solid transparent;}
.pkr-sys-tabs a:hover{color:var(--pkr-text);border-bottom-color:var(--pkr-line);}

.pkr-topic-grid{display:grid;grid-template-columns:repeat(6,1fr);gap:14px;}
.pkr-topic-card{background:#fff;border:1px solid var(--pkr-line);border-radius:var(--pkr-radius);padding:20px;text-align:left;color:var(--pkr-text);transition:all .2s ease;display:flex;flex-direction:column;gap:8px;}
.pkr-topic-card:hover{border-color:var(--accent);transform:translateY(-2px);box-shadow:0 10px 24px rgba(15,23,42,.06);color:var(--pkr-text);}
.pkr-topic-icon{width:44px;height:44px;border-radius:50%;border:1.5px solid var(--accent);background:#fff;color:var(--accent);display:inline-flex;align-items:center;justify-content:center;margin-bottom:6px;}
.pkr-topic-icon .pkr-svg{width:22px;height:22px;}
.pkr-topic-card h4{font-size:14px;font-weight:600;margin:0;color:var(--pkr-text);}
.pkr-topic-card p{font-size:12px;color:var(--pkr-muted);margin:0;line-height:1.5;}

/* === Single compound page === */
.pkr-compound-single{padding:34px 0 60px;background:#fff;}
.pkr-compound-head{display:grid;grid-template-columns:1.6fr 1fr;gap:40px;align-items:center;padding:14px 0 32px;border-bottom:1px solid var(--pkr-line-soft);margin-bottom:30px;}
.pkr-compound-head h1{font-size:56px;margin:8px 0 14px;}
.pkr-compound-mechanism{font-size:17px;color:var(--pkr-muted);max-width:600px;}
.pkr-tag-row{display:flex;flex-wrap:wrap;gap:8px;margin-top:14px;}
.pkr-tag{display:inline-block;padding:5px 12px;background:var(--pkr-accent-soft);color:var(--pkr-accent-dark);border-radius:20px;font-size:12px;font-weight:500;}
.pkr-tag-muted{background:var(--pkr-bg-soft);color:var(--pkr-muted);}
.pkr-compound-head-structure{background:linear-gradient(180deg,#fafbff,#f1f5f9);border:1px solid var(--pkr-line);border-radius:var(--pkr-radius);padding:24px;display:flex;align-items:center;justify-content:center;}
.pkr-compound-head-structure svg{width:100%;max-width:280px;height:auto;}
.pkr-compound-grid-2{display:grid;grid-template-columns:1.7fr 1fr;gap:40px;align-items:start;}
.pkr-compound-body{font-size:16px;line-height:1.7;color:var(--pkr-text);}
.pkr-compound-body p{margin:0 0 16px;}
.pkr-compound-body strong{font-weight:600;}
.pkr-compound-side{background:var(--pkr-bg-soft);border:1px solid var(--pkr-line);border-radius:var(--pkr-radius);padding:24px;}
.pkr-compound-side h3{font-family:var(--pkr-body);font-size:13px;text-transform:uppercase;letter-spacing:.08em;color:var(--pkr-muted);margin:0 0 12px;font-weight:600;}
.pkr-proplist{margin:0;display:grid;gap:12px;}
.pkr-proplist dt{font-size:12px;text-transform:uppercase;letter-spacing:.04em;color:var(--pkr-soft);margin:0;}
.pkr-proplist dd{margin:2px 0 0;font-size:14px;color:var(--pkr-text);font-weight:500;}

/* === Article page === */
.pkr-article{padding:34px 0 60px;background:#fff;}
.pkr-article-container{max-width:780px;}
.pkr-article-head{padding:20px 0 24px;border-bottom:1px solid var(--pkr-line-soft);margin-bottom:30px;}
.pkr-article-head .pkr-pill{margin-bottom:14px;}
.pkr-article-head h1{font-size:48px;line-height:1.1;margin:0 0 18px;}
.pkr-article-meta{display:flex;gap:18px;color:var(--pkr-muted);font-size:13.5px;}
.pkr-article-meta span{display:inline-flex;align-items:center;gap:6px;}
.pkr-article-body{font-size:17px;line-height:1.75;color:var(--pkr-text);}
.pkr-article-body p{margin:0 0 18px;}
.pkr-article-body h3{font-weight:700;font-size:26px;margin:32px 0 14px;}
.pkr-article-body strong{font-weight:600;}
.pkr-article-body em{color:var(--pkr-muted);}

/* === Archive page === */
.pkr-archive-hero{background:var(--pkr-bg-soft);padding:50px 0;border-bottom:1px solid var(--pkr-line);}
.pkr-archive-grid-section{padding:50px 0;}
.pkr-archive-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:18px;}
.pkr-archive-card{display:flex;flex-direction:column;padding:24px;background:#fff;border:1px solid var(--pkr-line);border-radius:var(--pkr-radius);color:var(--pkr-text);transition:all .2s ease;}
.pkr-archive-card:hover{border-color:var(--accent,#2563eb);transform:translateY(-2px);box-shadow:0 12px 28px rgba(15,23,42,.06);color:var(--pkr-text);}
.pkr-archive-card h3{font-weight:700;font-size:22px;margin:8px 0 8px;line-height:1.25;}
.pkr-archive-card p{color:var(--pkr-muted);font-size:14px;margin:0 0 12px;line-height:1.55;}
.pkr-archive-date{margin-top:auto;font-size:12px;color:var(--pkr-soft);}
.pkr-pagination{margin-top:40px;display:flex;justify-content:center;}
.pkr-pagination .nav-links{display:inline-flex;align-items:center;gap:6px;background:#fff;border:1px solid var(--pkr-line);border-radius:10px;padding:6px;box-shadow:0 2px 6px rgba(15,23,42,.04);}
.pkr-pagination .page-numbers{display:inline-flex;align-items:center;justify-content:center;min-width:38px;height:38px;padding:0 12px;border-radius:8px;font-size:14px;font-weight:600;color:var(--pkr-muted);text-decoration:none;transition:all .15s ease;}
.pkr-pagination .page-numbers:hover{background:var(--pkr-bg-soft);color:var(--pkr-text);}
.pkr-pagination .page-numbers.current{background:var(--pkr-accent);color:#fff;}
.pkr-pagination .page-numbers.current:hover{background:var(--pkr-accent-dark);color:#fff;}
.pkr-pagination .page-numbers.dots{color:var(--pkr-soft);cursor:default;}
.pkr-pagination .page-numbers.dots:hover{background:transparent;}
.pkr-pagination .prev,
.pkr-pagination .next{color:var(--pkr-accent);font-weight:600;padding:0 14px;}
.pkr-pagination .prev:hover,
.pkr-pagination .next:hover{background:var(--pkr-accent-soft);color:var(--pkr-accent-dark);}
.pkr-pagination .screen-reader-text{position:absolute;left:-9999px;}

/* === Responsive === */

/* ---- Tablet landscape / small laptop (≤1100px) ---- */
@media (max-width:1100px){
  .pkr-systems-grid{grid-template-columns:repeat(2,1fr);}
  .pkr-compound-grid{grid-template-columns:repeat(3,1fr);}
  .pkr-topic-grid{grid-template-columns:repeat(3,1fr);}
  .pkr-footer-grid{grid-template-columns:repeat(3,1fr);}
  .pkr-footer-brand-col{grid-column:span 3;}
  .pkr-menu{gap:20px;}
  .pkr-menu > li > a{font-size:13px;}
}

/* ---- Tablet portrait / large phone (≤900px) ---- */
@media (max-width:900px){
  html,body{font-size:14.5px;}
  h1{font-size:36px;line-height:1.1;}
  h2{font-size:26px;line-height:1.2;}
  .pkr-hero-head h1{font-size:36px;}
  .pkr-sys-hero-copy h1{font-size:36px;}
  .pkr-compound-head h1{font-size:32px;}
  .pkr-article-head h1{font-size:28px;}
  .pkr-section-head h2{font-size:24px;}
  .pkr-hero,.pkr-latest,.pkr-compounds,.pkr-ai,.pkr-sys-topics{padding:40px 0;}
  .pkr-utility-row{font-size:11px;padding:7px 16px;}
  .pkr-utility-left span{display:none;}
  .pkr-utility-right{gap:14px;}
  .pkr-utility-link span{font-size:11px;}
  .pkr-header-row{padding:12px 16px;gap:14px;}
  .pkr-logo{height:38px;}

  /* Mobile nav drawer */
  .pkr-nav{position:fixed;top:0;right:0;bottom:0;width:300px;max-width:85vw;background:#fff;border-left:1px solid var(--pkr-line);transform:translateX(100%);transition:transform .25s ease;padding:80px 24px 24px;z-index:100;overflow-y:auto;}
  .pkr-nav-open .pkr-nav{transform:translateX(0);box-shadow:-12px 0 30px rgba(15,23,42,.15);}
  .pkr-nav-open::before{content:"";position:fixed;inset:0;background:rgba(15,23,42,.5);z-index:99;}
  .pkr-menu{flex-direction:column;align-items:flex-start;gap:0;width:100%;}
  .pkr-menu > li{width:100%;border-bottom:1px solid var(--pkr-line-soft);}
  .pkr-menu > li > a{padding:14px 0;display:block;font-size:14px;min-height:44px;}
  .pkr-submenu{position:static;opacity:1;visibility:visible;transform:none;box-shadow:none;border:none;background:transparent;padding-left:8px;min-width:auto;}
  .pkr-submenu li a{padding:11px 8px;min-height:40px;}
  .pkr-mobile-toggle{display:inline-flex;}
  .pkr-icon-btn{width:42px;height:42px;}

  /* Hero / 4 system cards */
  .pkr-hero-head p{font-size:15px;}
  .pkr-system-card{padding:18px;}
  .pkr-system-card p{font-size:13px;}

  /* Latest research — stack featured card vertically */
  .pkr-latest-grid{grid-template-columns:1fr;gap:18px;}
  .pkr-feature-card{grid-template-columns:1fr;}
  .pkr-feature-img{min-height:180px;aspect-ratio:16/9;}
  .pkr-feature-body{padding:20px;}
  .pkr-feature-body h3{font-size:20px;}
  .pkr-feature-body p{font-size:14px;}

  /* AI Search — stack form above graph, graph smaller */
  .pkr-ai-grid{grid-template-columns:1fr;gap:24px;}
  .pkr-ai-graph{max-width:380px;margin:0 auto;}
  .pkr-ai-head{text-align:center;}
  .pkr-ai-head p{margin-left:auto;margin-right:auto;}
  .pkr-ai-form{max-width:none;}

  /* System page hero — stack illustration below copy */
  .pkr-sys-hero-grid{grid-template-columns:1fr;gap:24px;text-align:left;padding:14px 0 36px;}
  .pkr-sys-stats{gap:24px;}
  .pkr-sys-stats > div strong{font-size:28px;}

  /* Single compound */
  .pkr-compound-head{grid-template-columns:1fr;gap:24px;}
  .pkr-compound-head-structure{padding:18px;}
  .pkr-compound-mechanism{font-size:15px;}
  .pkr-compound-grid-2{grid-template-columns:1fr;gap:24px;}

  /* Article body — smaller */
  .pkr-article-body{font-size:15.5px;line-height:1.7;}
  .pkr-article-meta{gap:14px;flex-wrap:wrap;font-size:12.5px;}

  /* Archive */
  .pkr-archive-grid{grid-template-columns:repeat(2,1fr);gap:14px;}
  .pkr-archive-card{padding:18px;}
  .pkr-archive-card h3{font-size:18px;}

  /* Footer */
  .pkr-footer-grid{grid-template-columns:repeat(2,1fr);gap:24px;}
  .pkr-footer-brand-col{grid-column:span 2;}
}

/* ---- Phone (≤560px) ---- */
@media (max-width:560px){
  html,body{font-size:14px;}
  h1{font-size:30px;}
  h2{font-size:24px;}
  .pkr-container{padding:0 16px;}
  .pkr-utility-row{padding:6px 16px;}
  .pkr-utility-right{gap:10px;}
  .pkr-utility-link span{display:none;}
  .pkr-utility-link{padding:4px;}
  .pkr-utility-link .pkr-svg{margin:0;}
  .pkr-header-row{padding:10px 16px;gap:8px;}
  .pkr-logo{height:34px;}
  .pkr-header-actions{gap:0;}

  /* Tighter section padding on phone */
  .pkr-hero,.pkr-latest,.pkr-compounds,.pkr-ai,.pkr-sys-topics,.pkr-archive-grid-section{padding:30px 0;}

  /* Hero copy */
  .pkr-hero-head{margin-bottom:24px;}
  .pkr-hero-head h1{font-size:28px;}
  .pkr-hero-head p{font-size:14px;}

  /* Hero / topic / compound / archive all single column */
  .pkr-systems-grid,
  .pkr-compound-grid,
  .pkr-topic-grid,
  .pkr-archive-grid{grid-template-columns:1fr;}

  .pkr-system-card{padding:18px;}
  .pkr-system-icon img{width:52px;height:52px;}
  .pkr-system-card h3{font-size:17px;}

  /* Featured card on phone */
  .pkr-feature-img{min-height:160px;aspect-ratio:16/9;}
  .pkr-feature-img::before{font-size:9px;padding:4px 8px;top:10px;left:10px;}
  .pkr-feature-body{padding:18px;}
  .pkr-feature-body h3{font-size:19px;}
  .pkr-feature-body p{font-size:13.5px;-webkit-line-clamp:3;}
  .pkr-feature-meta{font-size:12px;flex-wrap:wrap;gap:8px;}

  /* Sidebar cards — compact thumbnail */
  .pkr-side-card{grid-template-columns:84px 1fr;gap:12px;padding:10px;}
  .pkr-side-body h4{font-size:14px;}
  .pkr-side-tag{font-size:9.5px;padding:2px 7px;margin-bottom:6px;}
  .pkr-side-date{font-size:11.5px;}

  /* Compound cards on phone */
  .pkr-compound-card{padding:14px 14px 16px;}
  .pkr-compound-structure{aspect-ratio:1/0.55;padding:8px;margin-bottom:10px;}
  .pkr-compound-card h4{font-size:14px;}
  .pkr-compound-card p{font-size:12px;}

  /* AI Search */
  .pkr-ai-grid{gap:18px;}
  .pkr-ai-form{flex-direction:column;align-items:stretch;padding:8px;}
  .pkr-ai-input{padding:10px 8px;font-size:14px;}
  .pkr-ai-submit{width:100%;justify-content:center;padding:12px;min-height:44px;}
  .pkr-ai-suggestions{font-size:12px;justify-content:center;}
  .pkr-ai-suggestions button{font-size:12px;padding:5px 10px;}
  .pkr-ai-graph{max-width:280px;}
  .pkr-ai-response{padding:14px;}

  /* System hero stats — stack */
  .pkr-sys-hero-copy h1{font-size:30px;}
  .pkr-sys-hero-copy p{font-size:14.5px;}
  .pkr-sys-stats{gap:18px;}
  .pkr-sys-stats > div strong{font-size:24px;}
  .pkr-sys-stats > div span{font-size:11px;}
  .pkr-sys-tabs a{padding:12px 14px;font-size:12px;}

  /* Topic cards */
  .pkr-topic-icon{width:40px;height:40px;}
  .pkr-topic-icon .pkr-svg{width:20px;height:20px;}
  .pkr-topic-card{padding:16px;}
  .pkr-topic-card h4{font-size:14px;}
  .pkr-topic-card p{font-size:12px;}

  /* Section heads */
  .pkr-section-head{flex-direction:row;align-items:center;gap:12px;flex-wrap:wrap;}
  .pkr-section-head h2{font-size:22px;}
  .pkr-view-all{font-size:13px;margin-left:auto;}

  /* Compound page */
  .pkr-compound-head h1{font-size:26px;}
  .pkr-compound-head-text{order:2;}
  .pkr-compound-head-structure{order:1;padding:14px;}
  .pkr-compound-mechanism{font-size:14px;}
  .pkr-compound-side{padding:18px;}

  /* Article page */
  .pkr-article-head{padding:14px 0 18px;margin-bottom:22px;}
  .pkr-article-head h1{font-size:24px;}
  .pkr-article-body{font-size:15px;}
  .pkr-article-body h3{font-size:20px;margin:24px 0 10px;}

  /* Archive */
  .pkr-archive-hero{padding:30px 0;}
  .pkr-archive-card h3{font-size:17px;}

  /* Pagination */
  .pkr-pagination .nav-links{flex-wrap:wrap;justify-content:center;}
  .pkr-pagination .page-numbers{min-width:34px;height:34px;font-size:13px;padding:0 9px;}

  /* Footer */
  .pkr-footer{padding:36px 0 20px;}
  .pkr-footer-grid{grid-template-columns:1fr;gap:20px;padding-bottom:22px;}
  .pkr-footer-brand-col{grid-column:auto;}
  .pkr-footer-col h4{margin-bottom:10px;font-size:14px;}
  .pkr-footer-tagline{max-width:none;}
  .pkr-footer-social{margin-top:10px;}
  .pkr-footer-bottom{flex-direction:column;align-items:flex-start;gap:14px;text-align:left;padding-top:16px;margin-top:0;}
  .pkr-footer-legal{flex-wrap:wrap;gap:14px;}

  /* Back-to-top */
  .pkr-back-top{right:14px;bottom:14px;width:38px;height:38px;}

  /* PK AI search section background — keep blue but tighter */
  .pkr-ai::before{height:80px;}
}

/* ---- Small phone (≤400px) ---- */
@media (max-width:400px){
  .pkr-container{padding:0 14px;}
  .pkr-logo{height:30px;}
  .pkr-header-row{padding:9px 14px;gap:6px;}
  .pkr-utility-row{padding:5px 14px;font-size:10px;}
  .pkr-icon-btn{width:38px;height:38px;}

  h1{font-size:26px;}
  .pkr-hero-head h1{font-size:26px;}
  .pkr-sys-hero-copy h1{font-size:26px;}
  .pkr-compound-head h1{font-size:24px;}

  .pkr-side-card{grid-template-columns:72px 1fr;gap:10px;padding:9px;}
  .pkr-side-body h4{font-size:13.5px;line-height:1.3;}

  .pkr-system-icon img{width:46px;height:46px;}
  .pkr-feature-img{min-height:140px;}
  .pkr-feature-body{padding:16px;}

  .pkr-ai-graph{max-width:240px;}
  .pkr-sys-stats{gap:14px;}
  .pkr-sys-stats > div strong{font-size:22px;}
}

/* ---- Universal overflow safety ---- */
img,svg,video{max-width:100%;}
.pkr-feature-img img,
.pkr-feature-img svg,
.pkr-side-thumb img,
.pkr-side-thumb svg{display:block;}