*{box-sizing:border-box}
:root{
  --sky:#1794ff;--sky-dark:#0f6fca;--pink:#ff5a9f;--yellow:#ffd54f;--green:#45c486;
  --ink:#17324d;--muted:#5f7288;--bg:#f8fbff;--white:#fff;--border:#dce8f5;
  --shadow:0 16px 40px rgba(33,76,127,.12);--radius:28px
}
html{scroll-behavior:smooth}
body{
  margin:0;font-family:Arial,Helvetica,sans-serif;color:var(--ink);
  background:
    radial-gradient(circle at top left,#fff3bf 0,transparent 25%),
    radial-gradient(circle at top right,#ffd2e5 0,transparent 23%),
    linear-gradient(180deg,#f5fbff,#fff)
}
img{max-width:100%;display:block}
.container{width:min(1120px,calc(100% - 32px));margin:0 auto}
.site-header{position:sticky;top:0;z-index:20;background:rgba(255,255,255,.92);backdrop-filter:blur(8px);border-bottom:1px solid #eef4fb}
.nav{display:flex;align-items:center;justify-content:space-between;gap:24px;padding:16px 0}
.brand{display:flex;align-items:center;gap:14px}
.brand-logo{width:74px;height:auto;border-radius:18px}
.brand h1{margin:0;font-size:2rem;color:var(--sky-dark)}
.brand p{margin:4px 0 0;color:var(--pink);font-weight:700}
nav{display:flex;gap:20px;flex-wrap:wrap}
nav a{text-decoration:none;color:var(--ink);font-weight:700}
nav a:hover{color:var(--sky)}
.hero,.page-hero{padding:52px 0 28px}
.hero-grid{display:grid;grid-template-columns:1.05fr .95fr;gap:34px;align-items:center}
.tag{display:inline-block;padding:10px 16px;border-radius:999px;background:var(--white);box-shadow:0 6px 18px rgba(0,0,0,.06);font-weight:800;color:var(--sky-dark);margin-bottom:18px}
.pink-tag{color:#d6427e;background:#ffe1ef}.green-tag{color:#218a5a;background:#dcf8e8}.yellow-tag{color:#946200;background:#fff1b8}
.hero-copy h2,.section h2,.contact-card h2,.page-hero h2{font-size:clamp(2rem,4vw,3.8rem);line-height:1.05;margin:0 0 16px}
.section h2,.contact-card h2,.page-hero h2{font-size:clamp(1.8rem,3vw,2.6rem)}
.hero-copy p,.section-text,.contact-card p,.page-hero p{font-size:1.1rem;line-height:1.8;color:var(--muted)}
.hero-buttons,.hero-badges{display:flex;gap:14px;flex-wrap:wrap;margin-top:24px}
.hero-badges span{display:inline-block;border-radius:999px;padding:10px 14px;font-weight:700;background:#eef7ff}
.hero-card{background:var(--white);padding:22px;border-radius:32px;box-shadow:var(--shadow);border:1px solid var(--border)}
.professor-img{width:100%;max-height:410px;object-fit:contain;border-radius:24px;background:linear-gradient(180deg,#fdfefe,#f3fbff);padding:14px}
.mini-cards{display:grid;grid-template-columns:1fr 1fr;gap:14px;margin-top:16px}
.mini-card{border-radius:24px;padding:18px;text-align:center}
.mini-card h3{margin:8px 0 6px}.mini-card p{margin:0;color:var(--muted);font-size:.95rem}
.yellow{background:#fff2b5}.pink{background:#ffe0ec}.blue{background:#dff2ff}.green{background:#def7e8}.emoji{font-size:2.5rem}
.section{padding:44px 0}.alt{background:linear-gradient(180deg,#f8fbff,#fff)}
.card-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:24px;margin-top:22px}
.content-card{overflow:hidden;background:var(--white);border-radius:32px;box-shadow:var(--shadow);border:1px solid var(--border)}
.card-media{height:180px;display:grid;place-items:center;font-size:4rem}
.card-body{padding:22px}.card-body h3{margin-top:0;margin-bottom:10px}
.card-body p,.worksheet-item p,.library-card p{color:var(--muted);line-height:1.6}
.card-meta{color:var(--sky-dark);font-weight:800;margin:10px 0 16px}
.worksheet-list{display:grid;gap:16px;margin-top:22px}
.worksheet-item{background:var(--white);border:1px solid var(--border);border-radius:24px;padding:18px 20px;box-shadow:0 8px 24px rgba(33,76,127,.08);display:flex;justify-content:space-between;gap:16px;align-items:center}
.about-box{background:var(--white);border:1px solid var(--border);border-radius:32px;box-shadow:var(--shadow);padding:28px;display:grid;grid-template-columns:1.2fr .8fr;gap:24px;align-items:center}
.math-icons{display:grid;grid-template-columns:1fr 1fr;gap:14px}
.math-icons div{background:#eef7ff;border-radius:24px;font-size:3rem;min-height:120px;display:grid;place-items:center}
.contact-grid{display:grid;grid-template-columns:1fr 1fr;gap:24px}
.contact-card{border-radius:32px;padding:28px;box-shadow:var(--shadow)}
.contact-card.color{background:linear-gradient(135deg,#1391ff,#ff5a9f);color:white}
.contact-card.color p,.contact-card.color .contact-lines p{color:rgba(255,255,255,.94)}
.form-card{background:var(--white);border:1px solid var(--border)}
.form-card h3{font-size:1.8rem;margin-top:0}
.form-card input,.form-card textarea{width:100%;padding:14px 16px;border-radius:18px;border:1px solid #cfddec;margin-bottom:14px;font:inherit}
.form-card textarea{min-height:130px;resize:vertical}
.btn{display:inline-block;text-decoration:none;border:0;cursor:pointer;border-radius:18px;padding:14px 20px;font-weight:800;text-align:center}
.btn.primary{background:var(--sky);color:white}.btn.primary:hover{background:var(--sky-dark)}
.btn.secondary{background:var(--yellow);color:var(--ink)}.btn.dark{background:#13263b;color:white}.btn.full{width:100%}
.site-footer{border-top:1px solid #eef4fb;background:white;margin-top:18px}
.footer-wrap{padding:24px 0;display:flex;justify-content:space-between;gap:18px;flex-wrap:wrap;color:var(--muted);font-weight:700}
.footer-accent{color:var(--pink)}
/* Worksheets library */
.search-row{display:flex;gap:14px;flex-wrap:wrap;margin-top:18px}
.search-row input,.search-row select{padding:14px 16px;border-radius:18px;border:1px solid #cfddec;font:inherit;background:#fff}
.search-row input{min-width:280px;flex:1}
.library-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:22px;margin-top:28px}
.library-card{background:#fff;border:1px solid var(--border);border-radius:28px;box-shadow:var(--shadow);overflow:hidden}
.library-top{padding:24px 22px 10px}
.library-icon{width:78px;height:78px;border-radius:22px;display:grid;place-items:center;font-size:2.4rem;margin-bottom:10px}
.library-card h3{margin:0 0 8px}
.meta-pill{display:inline-block;background:#eef7ff;color:var(--sky-dark);font-weight:800;padding:8px 12px;border-radius:999px;font-size:.9rem}
.library-actions{display:flex;gap:10px;padding:0 22px 22px;flex-wrap:wrap}
.notice-box{background:#fff;border:1px solid var(--border);box-shadow:var(--shadow);border-radius:28px;padding:22px;margin-top:28px}
@media (max-width:900px){
  .hero-grid,.card-grid,.about-box,.contact-grid,.library-grid{grid-template-columns:1fr}
  nav{display:none}.hero,.page-hero{padding-top:28px}
}
@media (max-width:640px){
  .worksheet-item{flex-direction:column;align-items:flex-start}
  .brand h1{font-size:1.45rem}.brand-logo{width:60px}
}