/* ============================================================
   PCM By Kolhe — Design System
   Signature idea: the site borrows its structure from a school
   binder — three colour-coded subject tabs (Physics / Chemistry
   / Maths) that recur as navigation, filters and section markers,
   set against a quiet ruled-paper background.
   ============================================================ */

:root{
  /* --- palette --- */
  --ink:        #16233F;   /* deep fountain-pen navy — headings, nav */
  --ink-soft:   #4C5A72;   /* secondary text */
  --paper:      #F5F5F0;   /* cool paper background */
  --paper-line: #E2E1D6;   /* ruled-notebook hairlines */
  --card:       #FFFFFF;
  --marigold:   #E08A2C;   /* primary accent / CTA */
  --marigold-dark:#B96E1C;

  /* subject tabs */
  --physics:    #1D6E8C;  /* teal-blue, wave/energy */
  --physics-tint:#E4F0F4;
  --chem:       #3F7D52;  /* litmus green */
  --chem-tint:  #E7F1E9;
  --math:       #7A4468;  /* plum, geometry */
  --math-tint:  #F2E7EE;

  --success:    #2F7A52;
  --danger:     #B23A2E;

  /* type */
  --font-display: 'Fraunces', Georgia, serif;
  --font-body: 'Source Sans 3', 'Segoe UI', sans-serif;
  --font-mono: 'IBM Plex Mono', monospace;

  --radius: 10px;
  --shadow: 0 1px 2px rgba(22,35,63,0.06), 0 8px 24px rgba(22,35,63,0.06);
}

*{box-sizing:border-box;}
html{scroll-behavior:smooth;}
body{
  margin:0;
  font-family:var(--font-body);
  color:var(--ink);
  background:var(--paper);
  line-height:1.55;
  -webkit-font-smoothing:antialiased;
}
img{max-width:100%;display:block;}
a{color:inherit;}
.container{max-width:1140px;margin:0 auto;padding:0 24px;}
.container-narrow{max-width:760px;margin:0 auto;padding:0 24px;}

h1,h2,h3,h4{
  font-family:var(--font-display);
  font-weight:600;
  line-height:1.15;
  margin:0 0 .5em;
  letter-spacing:-0.01em;
}
h1{font-size:clamp(2.1rem,4.5vw,3.4rem);font-weight:560;}
h2{font-size:clamp(1.6rem,3vw,2.3rem);}
h3{font-size:1.3rem;}
p{margin:0 0 1em;color:var(--ink-soft);}
.eyebrow{
  font-family:var(--font-mono);
  font-size:.78rem;
  letter-spacing:.08em;
  text-transform:uppercase;
  color:var(--marigold-dark);
  display:inline-block;
  margin-bottom:.6em;
}
.lead{font-size:1.15rem;color:var(--ink-soft);}

/* buttons */
.btn{
  display:inline-flex;align-items:center;gap:8px;
  font-family:var(--font-body);font-weight:600;font-size:.95rem;
  padding:13px 24px;border-radius:8px;text-decoration:none;
  border:1.5px solid transparent;cursor:pointer;transition:transform .15s ease, box-shadow .15s ease;
}
.btn:focus-visible{outline:3px solid var(--marigold);outline-offset:2px;}
.btn-primary{background:var(--marigold);color:#fff;box-shadow:0 6px 16px rgba(224,138,44,.35);}
.btn-primary:hover{background:var(--marigold-dark);transform:translateY(-1px);}
.btn-ghost{background:transparent;border-color:var(--paper-line);color:var(--ink);}
.btn-ghost:hover{border-color:var(--ink);}
.btn-light{background:#fff;color:var(--ink);border-color:var(--paper-line);}

/* ---------------- NAV : the "binder spine" ---------------- */
.site-header{
  position:sticky;top:0;z-index:50;
  background:rgba(245,245,240,.92);
  backdrop-filter:blur(6px);
  border-bottom:1px solid var(--paper-line);
}
.nav-wrap{
  display:flex;align-items:center;justify-content:space-between;
  padding:14px 24px;max-width:1140px;margin:0 auto;
}
.brand{
  display:flex;align-items:center;gap:10px;
  font-family:var(--font-display);font-weight:600;font-size:1.15rem;
  text-decoration:none;color:var(--ink);
}
.brand .mark{display:flex;gap:3px;}
.brand .mark span{width:7px;height:20px;border-radius:2px;display:block;}
.brand .mark span:nth-child(1){background:var(--physics);}
.brand .mark span:nth-child(2){background:var(--chem);}
.brand .mark span:nth-child(3){background:var(--math);}

.nav-links{display:flex;align-items:center;gap:2px;list-style:none;margin:0;padding:0;}
.nav-links a{
  font-size:.92rem;font-weight:500;text-decoration:none;color:var(--ink-soft);
  padding:8px 12px;border-radius:6px;
}
.nav-links a:hover{color:var(--ink);background:#fff;}
.nav-links a.active{color:var(--ink);background:#fff;font-weight:700;}
.nav-cta{display:flex;align-items:center;gap:10px;}
.nav-toggle{display:none;background:none;border:none;font-size:1.5rem;cursor:pointer;color:var(--ink);}
.lang-switch{
  font-family:var(--font-mono);font-size:.78rem;border:1px solid var(--paper-line);
  border-radius:20px;padding:5px 4px;background:#fff;display:flex;gap:2px;
}
.lang-switch button{
  border:none;background:transparent;padding:4px 10px;border-radius:16px;cursor:pointer;
  font-family:var(--font-mono);font-size:.78rem;color:var(--ink-soft);
}
.lang-switch button.active{background:var(--ink);color:#fff;}

@media (max-width:880px){
  .nav-links{
    position:fixed;top:64px;left:0;right:0;bottom:0;
    background:var(--paper);flex-direction:column;align-items:stretch;
    padding:20px;gap:6px;transform:translateX(100%);transition:transform .25s ease;
    overflow-y:auto;
  }
  .nav-links.open{transform:translateX(0);}
  .nav-links a{padding:14px;font-size:1.05rem;border-bottom:1px solid var(--paper-line);border-radius:0;}
  .nav-toggle{display:block;}
  .nav-cta .btn-ghost{display:none;}
}

/* ---------------- subject tabs (signature element) ---------------- */
.subject-tabs{display:flex;gap:10px;flex-wrap:wrap;}
.tab{
  display:inline-flex;align-items:center;gap:8px;
  font-family:var(--font-mono);font-size:.82rem;font-weight:500;
  padding:9px 16px 9px 12px;border-radius:0 6px 6px 0;
  border-left:4px solid; background:var(--card); box-shadow:var(--shadow);
}
.tab-physics{border-color:var(--physics);color:var(--physics);}
.tab-chem{border-color:var(--chem);color:var(--chem);}
.tab-math{border-color:var(--math);color:var(--math);}

.subject-card{
  background:var(--card);border-radius:var(--radius);padding:26px;
  border-top:4px solid; box-shadow:var(--shadow);
}
.subject-card.physics{border-color:var(--physics);}
.subject-card.chem{border-color:var(--chem);}
.subject-card.math{border-color:var(--math);}
.subject-card .subject-label{font-family:var(--font-mono);font-size:.78rem;letter-spacing:.06em;text-transform:uppercase;}
.subject-card.physics .subject-label{color:var(--physics);}
.subject-card.chem .subject-label{color:var(--chem);}
.subject-card.math .subject-label{color:var(--math);}

/* ---------------- ruled paper section ---------------- */
.ruled{
  background-image:repeating-linear-gradient(
    to bottom, transparent 0 37px, var(--paper-line) 37px 38px
  );
}

/* ---------------- hero ---------------- */
.hero{padding:64px 0 40px;}
.hero-grid{display:grid;grid-template-columns:1.15fr .85fr;gap:48px;align-items:center;}
@media (max-width:880px){.hero-grid{grid-template-columns:1fr;}}
.hero-badges{display:flex;gap:14px;margin-top:28px;flex-wrap:wrap;align-items:center;}
.store-badge{
  display:flex;align-items:center;gap:10px;background:var(--ink);color:#fff;
  padding:11px 18px;border-radius:8px;text-decoration:none;font-size:.9rem;
}
.store-badge svg{flex-shrink:0;}
.qr{width:78px;height:78px;border-radius:8px;border:1px solid var(--paper-line);background:#fff;padding:6px;}

.notebook{
  background:var(--card);border-radius:14px;box-shadow:var(--shadow);
  border:1px solid var(--paper-line);position:relative;overflow:hidden;padding:28px;
}
.notebook::before{
  content:"";position:absolute;left:34px;top:0;bottom:0;width:1px;background:#E9C7C2;
}
.notebook-row{
  display:flex;justify-content:space-between;align-items:center;
  padding:12px 0 12px 22px;border-bottom:1px solid var(--paper-line);font-size:.92rem;
}
.notebook-row:last-child{border-bottom:none;}
.notebook-row .code{font-family:var(--font-mono);font-size:.78rem;color:var(--ink-soft);}

/* ---------------- generic sections ---------------- */
section{padding:64px 0;}
.section-head{max-width:640px;margin:0 0 40px;}
.section-head.center{margin:0 auto 40px;text-align:center;}

.grid-3{display:grid;grid-template-columns:repeat(3,1fr);gap:22px;}
.grid-2{display:grid;grid-template-columns:repeat(2,1fr);gap:22px;}
@media (max-width:880px){.grid-3,.grid-2{grid-template-columns:1fr;}}

.card{background:var(--card);border-radius:var(--radius);padding:26px;box-shadow:var(--shadow);}
.card h3{margin-bottom:.4em;}
.stat{font-family:var(--font-mono);font-size:2.1rem;font-weight:600;color:var(--ink);}
.stat-label{font-size:.85rem;color:var(--ink-soft);}

.strip{
  background:var(--ink);color:#fff;border-radius:16px;padding:44px;
  display:flex;align-items:center;justify-content:space-between;gap:24px;flex-wrap:wrap;
}
.strip h2{color:#fff;margin-bottom:.2em;}
.strip p{color:#C9D0DE;}

table{width:100%;border-collapse:collapse;background:var(--card);border-radius:var(--radius);overflow:hidden;box-shadow:var(--shadow);}
th,td{text-align:left;padding:12px 16px;border-bottom:1px solid var(--paper-line);font-size:.92rem;}
th{font-family:var(--font-mono);font-size:.75rem;text-transform:uppercase;letter-spacing:.05em;color:var(--ink-soft);background:#FAFAF6;}
tr:last-child td{border-bottom:none;}

/* testimonial */
.quote-card{background:var(--card);border-radius:var(--radius);padding:26px;box-shadow:var(--shadow);}
.quote-card p.quote{font-family:var(--font-display);font-size:1.15rem;color:var(--ink);font-style:italic;}
.quote-meta{display:flex;align-items:center;gap:10px;margin-top:14px;}
.avatar{width:38px;height:38px;border-radius:50%;background:var(--paper-line);display:flex;align-items:center;justify-content:center;font-family:var(--font-mono);font-weight:600;font-size:.8rem;color:var(--ink-soft);}

/* faq accordion */
.faq-item{background:var(--card);border-radius:var(--radius);box-shadow:var(--shadow);margin-bottom:12px;overflow:hidden;}
.faq-item summary{padding:18px 22px;cursor:pointer;font-weight:600;list-style:none;display:flex;justify-content:space-between;align-items:center;}
.faq-item summary::-webkit-details-marker{display:none;}
.faq-item summary::after{content:"+";font-family:var(--font-mono);font-size:1.3rem;color:var(--marigold-dark);}
.faq-item[open] summary::after{content:"–";}
.faq-item .faq-body{padding:0 22px 20px;color:var(--ink-soft);}

/* footer */
.site-footer{background:var(--ink);color:#C9D0DE;padding:52px 0 24px;margin-top:60px;}
.footer-grid{display:grid;grid-template-columns:1.4fr 1fr 1fr 1fr;gap:32px;}
@media (max-width:880px){.footer-grid{grid-template-columns:1fr 1fr;}}
.footer-grid h4{color:#fff;font-family:var(--font-body);font-size:.85rem;text-transform:uppercase;letter-spacing:.06em;margin-bottom:14px;}
.footer-grid a{display:block;color:#C9D0DE;text-decoration:none;font-size:.92rem;padding:5px 0;}
.footer-grid a:hover{color:#fff;}
.footer-tabs{display:flex;gap:4px;margin:18px 0;}
.footer-tabs span{width:26px;height:8px;border-radius:2px;}
.footer-bottom{border-top:1px solid rgba(255,255,255,.12);margin-top:36px;padding-top:20px;display:flex;justify-content:space-between;flex-wrap:wrap;gap:12px;font-size:.82rem;color:#8E99B0;}

/* legal pages */
.legal-body h2{margin-top:1.6em;}
.legal-body h3{margin-top:1.2em;}
.legal-body ul{color:var(--ink-soft);}
.legal-updated{font-family:var(--font-mono);font-size:.82rem;color:var(--ink-soft);}
.legal-toc{background:var(--card);border-radius:var(--radius);padding:22px;box-shadow:var(--shadow);margin-bottom:36px;}
.legal-toc a{display:block;padding:4px 0;text-decoration:none;color:var(--ink-soft);font-size:.92rem;}
.legal-toc a:hover{color:var(--marigold-dark);}

.pill{display:inline-block;font-family:var(--font-mono);font-size:.75rem;padding:4px 10px;border-radius:20px;background:var(--paper-line);color:var(--ink-soft);}

::selection{background:var(--marigold);color:#fff;}
:focus-visible{outline:3px solid var(--marigold);outline-offset:2px;}
@media (prefers-reduced-motion: reduce){*{transition:none !important;scroll-behavior:auto !important;}}

/* ---------------- confirmation dialog ---------------- */
.modal-overlay{
  position:fixed;inset:0;z-index:200;
  background:rgba(22,35,63,.55);
  display:flex;align-items:center;justify-content:center;padding:20px;
  opacity:0;pointer-events:none;transition:opacity .2s ease;
}
.modal-overlay.open{opacity:1;pointer-events:auto;}
.modal-box{
  background:#fff;border-radius:14px;padding:34px 30px;max-width:380px;width:100%;
  text-align:center;box-shadow:0 24px 60px rgba(22,35,63,.32);
  transform:translateY(12px);transition:transform .2s ease;
}
.modal-overlay.open .modal-box{transform:translateY(0);}
.modal-icon{
  width:54px;height:54px;border-radius:50%;margin:0 auto 16px;
  background:var(--chem-tint);color:var(--success);
  display:flex;align-items:center;justify-content:center;font-size:1.5rem;font-weight:700;
}
.modal-box h3{margin-bottom:8px;}
.modal-box p{margin-bottom:22px;color:var(--ink-soft);}
.modal-close{width:100%;justify-content:center;}