*{margin:0;padding:0;box-sizing:border-box}
:root{--primary:#4A90D9;--primary-dark:#2D6BB3;--secondary:#F5A623;--accent:#7ED321;--bg:#F8FAFC;--card-bg:#fff;--text:#2C3E50;--text-light:#7F8C9A;--border:#E1E8EF;--shadow:0 4px 20px rgba(74,144,217,0.1);--radius:16px}
body{font-family:'Segoe UI','Nunito',system-ui,sans-serif;background:var(--bg);color:var(--text);line-height:1.7;min-height:100vh}
a{color:var(--primary);text-decoration:none;transition:.2s}
a:hover{color:var(--primary-dark)}
img{max-width:100%;height:auto}
.container{ max-width:1200px;margin:0 auto;padding:0 20px}

/* Header */
header{background:linear-gradient(135deg,#4A90D9 0%,#7B68EE 100%);padding:0;position:sticky;top:0;z-index:100;box-shadow:0 2px 20px rgba(74,144,217,0.25)}
nav{display:flex;align-items:center;justify-content:space-between;padding:0 30px;height:70px;max-width:1200px;margin:0 auto}
.logo{font-size:1.6rem;font-weight:800;color:#fff;display:flex;align-items:center;gap:8px}
.nav-links{display:flex;gap:8px;align-items:center}
.nav-links a{color:rgba(255,255,255,0.9);padding:8px 16px;border-radius:8px;font-weight:500;transition:.2s;font-size:.95rem}
.nav-links a:hover,.nav-links a.active{background:rgba(255,255,255,0.2);color:#fff}
.hamburger{display:none;flex-direction:column;gap:5px;cursor:pointer;padding:8px}
.hamburger span{width:25px;height:3px;background:#fff;border-radius:2px;transition:.3s}

/* Hero */
.hero{background:linear-gradient(135deg,#667EEA 0%,#764BA2 100%);color:#fff;padding:60px 0;text-align:center;position:relative;overflow:hidden}
.hero::before{content:'';position:absolute;inset:0;background:url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='none' fill-rule='evenodd'%3E%3Cg fill='%23ffffff' fill-opacity='0.05'%3E%3Cpath d='M36 34v-4h-2v4h-4v2h4v4h2v-4h4v-2h-4zm0-30V0h-2v4h-4v2h4v4h2V6h4V4h-4zM6 34v-4H4v4H0v2h4v4h2v-4h4v-2H6zM6 4V0H4v4H0v2h4v4h2V6h4V4H6z'/%3E%3C/g%3E%3C/g%3E%3C/svg%3E");opacity:.5}
.hero h1{font-size:2.8rem;margin-bottom:16px;font-weight:800;position:relative}
.hero p{font-size:1.25rem;opacity:0.9;max-width:600px;margin:0 auto 30px;position:relative}
.hero-btns{display:flex;gap:16px;justify-content:center;flex-wrap:wrap;position:relative}
.btn{background:#fff;color:var(--primary);padding:14px 32px;border-radius:50px;font-weight:700;font-size:1rem;display:inline-flex;align-items:center;gap:8px;transition:.3s;box-shadow:0 4px 15px rgba(0,0,0,0.15)}
.btn:hover{transform:translateY(-2px);box-shadow:0 8px 25px rgba(0,0,0,0.2);color:var(--primary-dark)}
.btn-outline{background:transparent;border:2px solid #fff;color:#fff}
.btn-outline:hover{background:#fff;color:var(--primary)}

/* Section styles */
.section{padding:60px 0}
.section-header{text-align:center;margin-bottom:40px}
.section-header h2{font-size:2.2rem;color:var(--text);margin-bottom:12px;font-weight:800}
.section-header p{color:var(--text-light);font-size:1.1rem;max-width:600px;margin:0 auto}
.section-alt{background:#fff}

/* Cards */
.card-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(280px,1fr));gap:24px}
.card{background:var(--card-bg);border-radius:var(--radius);padding:28px;box-shadow:var(--shadow);transition:.3s;border:1px solid var(--border)}
.card:hover{transform:translateY(-4px);box-shadow:0 8px 30px rgba(74,144,217,0.18)}
.tool-card{display:flex;flex-direction:column;height:100%}
.tool-icon{font-size:2.8rem;margin-bottom:16px;line-height:1}
.tool-name{font-size:1.15rem;font-weight:700;margin-bottom:8px;color:var(--text)}
.tool-desc{color:var(--text-light);font-size:.9rem;flex:1}
.article-card{border-radius:var(--radius);overflow:hidden;background:#fff;box-shadow:var(--shadow);transition:.3s;border:1px solid var(--border)}
.article-card:hover{transform:translateY(-4px);box-shadow:0 8px 30px rgba(74,144,217,0.18)}
.article-card img{width:100%;height:180px;object-fit:cover}
.article-card-content{padding:20px}
.article-card h3{font-size:1.1rem;margin-bottom:8px;color:var(--text);font-weight:700}
.article-card p{color:var(--text-light);font-size:.88rem;line-height:1.6}
.read-more{color:var(--primary);font-weight:600;font-size:.9rem;display:inline-flex;align-items:center;gap:4px;margin-top:12px}
.read-more:hover{gap:8px}

/* Nav bar for articles */
.article-nav{background:linear-gradient(90deg,#4A90D9,#7B68EE,#667EEA);padding:12px 0;position:sticky;top:70px;z-index:99}
.article-nav-inner{max-width:1200px;margin:0 auto;padding:0 20px;display:flex;gap:8px;overflow-x:auto;scrollbar-width:none}
.article-nav-inner::-webkit-scrollbar{display:none}
.article-nav a{color:rgba(255,255,255,0.85);padding:6px 16px;border-radius:20px;font-size:.88rem;white-space:nowrap;font-weight:500;transition:.2s;background:rgba(255,255,255,0.1)}
.article-nav a:hover,.article-nav a.active{background:rgba(255,255,255,0.25);color:#fff}

/* Page content */
.page-content{max-width:900px;margin:0 auto;padding:40px 20px}
.page-content h1{font-size:2rem;margin-bottom:24px;font-weight:800;color:var(--text);line-height:1.3}
.page-content h2{font-size:1.5rem;margin:28px 0 14px;font-weight:700;color:var(--text)}
.page-content p{margin-bottom:16px;color:var(--text);font-size:1.05rem}
.page-content ul,.page-content ol{margin:16px 0;padding-left:28px}
.page-content li{margin-bottom:8px;font-size:1rem}
.page-content img{margin:20px 0;border-radius:12px;box-shadow:var(--shadow)}

/* Article page */
.article-body{max-width:800px;margin:0 auto;padding:40px 20px}
.article-body h1{font-size:2.2rem;margin-bottom:16px;font-weight:800;color:var(--text)}
.article-meta{color:var(--text-light);font-size:.9rem;margin-bottom:24px;display:flex;gap:16px}
.article-body h2{font-size:1.6rem;margin:36px 0 16px;font-weight:700;color:var(--text)}
.article-body p{margin-bottom:18px;font-size:1.08rem;line-height:1.8}
.article-body img{width:100%;max-height:400px;object-fit:cover;border-radius:16px;margin:28px 0;box-shadow:0 8px 30px rgba(0,0,0,0.12)}

/* Forms */
.form-group{margin-bottom:20px}
.form-group label{display:block;font-weight:600;margin-bottom:6px;color:var(--text)}
.form-group input,.form-group textarea,.form-group select{width:100%;padding:12px 16px;border:2px solid var(--border);border-radius:10px;font-size:1rem;font-family:inherit;transition:.2s;background:#fff}
.form-group input:focus,.form-group textarea:focus,.form-group select:focus{outline:none;border-color:var(--primary);box-shadow:0 0 0 3px rgba(74,144,217,0.1)}
.form-group textarea{resize:vertical;min-height:120px}
.btn-primary{background:var(--primary);color:#fff;padding:12px 28px;border:none;border-radius:10px;font-size:1rem;font-weight:600;cursor:pointer;transition:.2s}
.btn-primary:hover{background:var(--primary-dark);transform:translateY(-1px)}

/* Tool page */
.tool-container{max-width:900px;margin:0 auto;padding:30px 20px}
.tool-header{text-align:center;margin-bottom:32px}
.tool-header h1{font-size:2rem;font-weight:800;margin-bottom:12px}
.tool-header .tool-icon{font-size:4rem;margin-bottom:16px}
.tool-panel{background:#fff;border-radius:var(--radius);padding:28px;box-shadow:var(--shadow);margin-bottom:24px;border:1px solid var(--border)}
.tool-panel h2{font-size:1.3rem;font-weight:700;margin-bottom:16px;color:var(--text)}
.tool-input{display:flex;gap:10px;flex-wrap:wrap;margin-bottom:16px}
.tool-input input,.tool-input select{padding:10px 16px;border:2px solid var(--border);border-radius:10px;font-size:1rem;flex:1;min-width:150px}
.tool-input input:focus{outline:none;border-color:var(--primary)}
.tool-btn{background:var(--primary);color:#fff;padding:12px 28px;border:none;border-radius:10px;font-weight:600;cursor:pointer;font-size:1rem;transition:.2s}
.tool-btn:hover{background:var(--primary-dark)}
.tool-result{background:linear-gradient(135deg,#F8FAFC,#EDF2F7);border-radius:12px;padding:20px;min-height:60px;font-size:1.1rem;text-align:center;font-weight:600;color:var(--text);margin-top:16px;border:1px solid var(--border)}

/* Footer */
footer{background:var(--text);color:rgba(255,255,255,0.7);padding:40px 0;text-align:center}
footer a{color:rgba(255,255,255,0.7)}
footer a:hover{color:#fff}
.footer-links{display:flex;justify-content:center;gap:24px;margin-bottom:20px;flex-wrap:wrap}
.footer-links a{padding:4px 0}

/* Responsive */
@media(max-width:768px){
  .nav-links{display:none;position:absolute;top:70px;left:0;right:0;background:var(--primary);flex-direction:column;padding:16px;gap:4px}
  .nav-links.open{display:flex}
  .hamburger{display:flex}
  .hero h1{font-size:2rem}
  .hero p{font-size:1rem}
  .section{padding:40px 0}
  .section-header h2{font-size:1.7rem}
  .card-grid{grid-template-columns:1fr}
  .page-content{padding:24px 16px}
  .article-nav{top:70px}
}

/* Utilities */
.text-center{text-align:center}
.mt-2{margin-top:16px}
.mb-2{margin-bottom:16px}
.flex{display:flex;gap:12px;flex-wrap:wrap}
.badge{display:inline-block;padding:4px 12px;border-radius:20px;font-size:.8rem;font-weight:600}
.badge-math{background:#E3F2FD;color:#1565C0}
.badge-science{background:#E8F5E9;color:#2E7D32}
.badge-reading{background:#FFF3E0;color:#E65100}
.badge-social{background:#F3E5F5;color:#7B1FA2}
.badge-art{background:#FCE4EC;color:#C2185B}