/* =============================================================
   SekJote.com — Landing + Pricing
   Design system: Swiss minimal, slate-navy + scan-blue, IBM Plex Sans Thai.
   Self-contained (no app.css dependency) for a fast first paint.
   ============================================================= */

:root {
  --color-primary:       #1E293B;
  --color-primary-hover: #0F172A;
  --color-accent:        #2563EB;
  --color-accent-hover:  #1D4ED8;
  --color-accent-weak:   #EFF4FE;
  --color-paid:          #A85518;
  --color-foreground:    #0F172A;
  --color-muted:         #64748B;
  --color-border:        #E2E8F0;
  --color-surface:       #FFFFFF;
  --color-surface-tint:  #F1F5F9;
  --color-bg:            #F8FAFC;
  --success:             #15803D;

  --font-ui: "IBM Plex Sans Thai", "Noto Sans Thai", system-ui, -apple-system, "Segoe UI", sans-serif;

  --t-xs:12px; --t-sm:14px; --t-md:16px; --t-lg:20px; --t-xl:25px; --t-2xl:32px; --t-3xl:44px;
  --s-1:4px; --s-2:8px; --s-3:12px; --s-4:16px; --s-5:20px; --s-6:24px; --s-8:32px; --s-12:48px; --s-16:64px;
  --r-sm:6px; --r-md:10px; --r-lg:14px; --r-xl:20px;
  --shadow-1: 0 1px 2px rgba(15,23,42,.06);
  --shadow-2: 0 6px 20px rgba(15,23,42,.10);
  --shadow-pop: 0 16px 40px rgba(15,23,42,.16);
  --maxw: 1120px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font-ui);
  font-size: var(--t-md);
  line-height: 1.6;
  color: var(--color-foreground);
  background: var(--color-bg);
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; text-decoration: none; }
img { max-width: 100%; display: block; }
section { scroll-margin-top: 80px; }

.wrap { max-width: var(--maxw); margin: 0 auto; padding: 0 var(--s-6); }

/* ---------- buttons ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: var(--s-2);
  min-height: 48px; padding: 0 var(--s-6);
  border-radius: var(--r-sm); border: 1px solid transparent;
  font: inherit; font-weight: 600; cursor: pointer;
  transition: background 140ms, border-color 140ms, transform 60ms;
}
.btn:active { transform: translateY(1px); }
.btn-primary { background: var(--color-accent); color: #fff; }
.btn-primary:hover { background: var(--color-accent-hover); }
.btn-ghost { background: var(--color-surface); color: var(--color-foreground); border-color: var(--color-border); }
.btn-ghost:hover { background: var(--color-surface-tint); }
.btn-paid { background: var(--color-paid); color: #fff; }
.btn-paid:hover { background: #8B4814; }
.btn-lg { min-height: 54px; font-size: var(--t-lg); padding: 0 var(--s-8); }
.btn:focus-visible { outline: 2px solid var(--color-accent); outline-offset: 2px; }

/* ---------- nav ---------- */
.nav {
  position: sticky; top: 0; z-index: 50;
  background: rgba(255,255,255,.85); backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--color-border);
}
.nav-inner { display: flex; align-items: center; justify-content: space-between; height: 64px; }
.brand { display: flex; align-items: center; gap: 10px; color: var(--color-primary); }
.brand-logo { width: 40px; height: 40px; flex-shrink: 0; }
.brand-name { display: flex; flex-direction: column; line-height: 1.1; font-family: "Kanit", "IBM Plex Sans Thai", sans-serif; font-weight: 700; font-size: 26px; }
.brand-name small { font-family: "IBM Plex Sans Thai", sans-serif; font-weight: 500; font-size: 11px; color: var(--color-muted); letter-spacing: .03em; }
.nav-links { display: flex; align-items: center; gap: var(--s-6); }
.nav-links a { color: var(--color-muted); font-size: var(--t-sm); font-weight: 500; }
.nav-links a:hover { color: var(--color-foreground); }
.nav-cta { display: flex; align-items: center; gap: var(--s-3); }
.nav-toggle { display: none; }

/* ---------- hero ---------- */
.hero { padding: var(--s-16) 0 var(--s-12); }
.hero-grid { display: grid; grid-template-columns: 1.1fr .9fr; gap: var(--s-12); align-items: center; }
.eyebrow {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 4px 12px; border-radius: 999px;
  background: var(--color-accent-weak); color: var(--color-accent-hover);
  font-size: var(--t-sm); font-weight: 600; margin-bottom: var(--s-4);
}
.hero h1 {
  margin: 0 0 var(--s-4); font-size: var(--t-3xl); line-height: 1.2; font-weight: 700;
  letter-spacing: -.01em; color: var(--color-primary);
}
.hero h1 .hl { color: var(--color-accent); }
.hero-sub { font-size: var(--t-lg); color: var(--color-muted); margin: 0 0 var(--s-6); max-width: 32em; }
.hero-actions { display: flex; flex-wrap: wrap; gap: var(--s-3); margin-bottom: var(--s-5); }
.hero-trust { display: flex; flex-wrap: wrap; gap: var(--s-5); color: var(--color-muted); font-size: var(--t-sm); }
.hero-trust span { display: inline-flex; align-items: center; gap: 6px; }
.tick { color: var(--success); font-weight: 700; }

/* worksheet mock (trust via showing the output) */
.mock {
  background: var(--color-surface); border: 1px solid var(--color-border);
  border-radius: var(--r-lg); box-shadow: var(--shadow-pop);
  padding: var(--s-6); transform: rotate(1.2deg);
}
.mock-head { text-align: center; border-bottom: 1px solid var(--color-border); padding-bottom: var(--s-3); margin-bottom: var(--s-4); }
.mock-title { font-weight: 700; font-size: var(--t-lg); color: var(--color-primary); }
.mock-sub { color: var(--color-muted); font-size: var(--t-sm); }
.mock-q { margin-bottom: var(--s-4); }
.mock-q b { color: var(--color-accent); margin-right: 6px; }
.mock-line { height: 9px; border-radius: 4px; background: var(--color-surface-tint); margin-top: 8px; }
.mock-line.w-90 { width: 90%; } .mock-line.w-70 { width: 70%; } .mock-line.w-50 { width: 50%; }
.mock-space { height: 38px; border: 1px dashed var(--color-border); border-radius: 6px; margin-top: 10px; }

/* ---------- section scaffolding ---------- */
.section { padding: var(--s-16) 0; }
.section.tint { background: var(--color-surface); border-top: 1px solid var(--color-border); border-bottom: 1px solid var(--color-border); }
.section-head { text-align: center; max-width: 40em; margin: 0 auto var(--s-12); }
.section-head h2 { font-size: var(--t-2xl); font-weight: 700; color: var(--color-primary); margin: 0 0 var(--s-3); letter-spacing: -.01em; }
.section-head p { color: var(--color-muted); font-size: var(--t-lg); margin: 0; }

/* ---------- steps / how it works ---------- */
.steps { display: grid; grid-template-columns: repeat(3, 1fr); gap: var(--s-6); }
.step { background: var(--color-surface); border: 1px solid var(--color-border); border-radius: var(--r-lg); padding: var(--s-6); }
.step-n { width: 36px; height: 36px; border-radius: 999px; background: var(--color-accent-weak); color: var(--color-accent-hover); display: grid; place-items: center; font-weight: 700; margin-bottom: var(--s-3); }
.step h3 { margin: 0 0 var(--s-2); font-size: var(--t-lg); color: var(--color-primary); }
.step p { margin: 0; color: var(--color-muted); font-size: var(--t-sm); }

/* ---------- features grid ---------- */
.features { display: grid; grid-template-columns: repeat(3, 1fr); gap: var(--s-6); }
.feature { padding: var(--s-5); }
.feature-ic { width: 40px; height: 40px; border-radius: 10px; background: var(--color-accent-weak); color: var(--color-accent); display: grid; place-items: center; margin-bottom: var(--s-3); font-size: 20px; }
.feature h3 { margin: 0 0 var(--s-2); font-size: var(--t-md); color: var(--color-primary); }
.feature p { margin: 0; color: var(--color-muted); font-size: var(--t-sm); }

/* ---------- pricing ---------- */
.billing-toggle { display: flex; align-items: center; justify-content: center; gap: var(--s-3); margin-bottom: var(--s-8); }
.billing-toggle button { background: none; border: 0; font: inherit; cursor: pointer; color: var(--color-muted); font-weight: 600; padding: 8px 12px; border-radius: 999px; }
.billing-toggle button.active { background: var(--color-primary); color: #fff; }
.save-badge { background: #ecfdf3; color: var(--success); font-size: var(--t-xs); font-weight: 700; padding: 3px 8px; border-radius: 999px; border: 1px solid #bbf7d0; }

.plans { display: grid; grid-template-columns: repeat(4, 1fr); gap: var(--s-5); align-items: start; }
@media (max-width: 1024px) { .plans { grid-template-columns: repeat(2, 1fr); } }
.plan { background: var(--color-surface); border: 1px solid var(--color-border); border-radius: var(--r-lg); padding: var(--s-6); display: flex; flex-direction: column; gap: var(--s-4); box-shadow: var(--shadow-1); }
.plan.popular { border: 2px solid var(--color-accent); box-shadow: var(--shadow-2); position: relative; }
.plan-badge { position: absolute; top: -13px; left: 50%; transform: translateX(-50%); background: var(--color-accent); color: #fff; font-size: var(--t-xs); font-weight: 700; padding: 4px 12px; border-radius: 999px; white-space: nowrap; }
.plan-name { font-weight: 700; font-size: var(--t-lg); color: var(--color-primary); }
.plan-tag { color: var(--color-muted); font-size: var(--t-sm); min-height: 2.6em; }
.plan-price { display: flex; align-items: baseline; gap: 6px; }
.plan-price .amt { font-size: var(--t-3xl); font-weight: 700; color: var(--color-primary); letter-spacing: -.02em; }
.plan-price .per { color: var(--color-muted); font-size: var(--t-sm); }
.plan ul { list-style: none; margin: 0; padding: 0; display: grid; gap: var(--s-2); }
.plan li { display: flex; gap: var(--s-2); font-size: var(--t-sm); color: var(--color-foreground); }
.plan li .tick { flex-shrink: 0; }
.plan li.off { color: var(--color-muted); }
.plan li.off .tick { color: var(--color-border); }
.plan .btn { width: 100%; margin-top: auto; }

/* optional add-ons */
.addon-band { margin-top: var(--s-6); background: var(--color-surface); border: 1px solid var(--color-border); border-radius: var(--r-lg); padding: var(--s-5) var(--s-6); display: flex; align-items: center; justify-content: space-between; gap: var(--s-5); flex-wrap: wrap; box-shadow: var(--shadow-1); }
.addon-band .addon-ic { width: 44px; height: 44px; border-radius: 12px; background: #fdeee6; color: var(--color-paid); display: grid; place-items: center; font-size: 22px; flex-shrink: 0; }
.addon-main { display: flex; align-items: center; gap: var(--s-4); }
.addon-band h3 { margin: 0 0 2px; font-size: var(--t-md); color: var(--color-primary); }
.addon-band p { margin: 0; color: var(--color-muted); font-size: var(--t-sm); }
.addon-price { font-weight: 700; color: var(--color-paid); white-space: nowrap; }
.addon-price small { color: var(--color-muted); font-weight: 400; }

.school-band { margin-top: var(--s-6); background: var(--color-primary); color: #fff; border-radius: var(--r-lg); padding: var(--s-8); display: flex; align-items: center; justify-content: space-between; gap: var(--s-6); flex-wrap: wrap; }
.school-band h3 { margin: 0 0 6px; font-size: var(--t-xl); }
.school-band p { margin: 0; color: #cbd5e1; }
.school-band .btn-ghost { background: transparent; color: #fff; border-color: rgba(255,255,255,.4); }
.school-band .btn-ghost:hover { background: rgba(255,255,255,.1); }

/* ---------- testimonials ---------- */
.quotes { display: grid; grid-template-columns: repeat(3, 1fr); gap: var(--s-6); }
.quote { background: var(--color-surface); border: 1px solid var(--color-border); border-radius: var(--r-lg); padding: var(--s-6); }
.quote p { margin: 0 0 var(--s-4); font-size: var(--t-md); }
.quote .who { display: flex; align-items: center; gap: var(--s-3); }
.avatar { width: 40px; height: 40px; border-radius: 999px; background: var(--color-accent-weak); color: var(--color-accent-hover); display: grid; place-items: center; font-weight: 700; }
.who .name { font-weight: 600; font-size: var(--t-sm); }
.who .role { color: var(--color-muted); font-size: var(--t-xs); }

/* ---------- FAQ ---------- */
.faq { max-width: 760px; margin: 0 auto; display: grid; gap: var(--s-3); }
.faq details { background: var(--color-surface); border: 1px solid var(--color-border); border-radius: var(--r-md); padding: var(--s-4) var(--s-5); }
.faq summary { cursor: pointer; font-weight: 600; color: var(--color-primary); list-style: none; display: flex; justify-content: space-between; align-items: center; gap: var(--s-3); }
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after { content: "+"; color: var(--color-accent); font-size: 22px; line-height: 1; }
.faq details[open] summary::after { content: "−"; }
.faq p { margin: var(--s-3) 0 0; color: var(--color-muted); font-size: var(--t-sm); }

/* ---------- final CTA ---------- */
.cta-final { text-align: center; }
.cta-final h2 { font-size: var(--t-2xl); color: var(--color-primary); margin: 0 0 var(--s-3); }
.cta-final p { color: var(--color-muted); font-size: var(--t-lg); margin: 0 0 var(--s-6); }

/* ---------- footer ---------- */
.footer { border-top: 1px solid var(--color-border); background: var(--color-surface); padding: var(--s-8) 0; }
.footer-inner { display: flex; justify-content: space-between; gap: var(--s-6); flex-wrap: wrap; color: var(--color-muted); font-size: var(--t-sm); }
.footer a { color: var(--color-muted); }
.footer a:hover { color: var(--color-foreground); }

/* ---------- responsive ---------- */
@media (max-width: 900px) {
  .hero-grid, .steps, .features, .plans, .quotes { grid-template-columns: 1fr; }
  .hero { padding: var(--s-12) 0; }
  .mock { transform: none; }
  .nav-links { display: none; }
  .nav-links.open {
    display: flex; flex-direction: column; align-items: flex-start; gap: var(--s-4);
    position: absolute; top: 64px; left: 0; right: 0;
    background: var(--color-surface); border-bottom: 1px solid var(--color-border);
    padding: var(--s-5) var(--s-6);
  }
  .nav-toggle { display: inline-grid; place-items: center; width: 44px; height: 44px; background: none; border: 1px solid var(--color-border); border-radius: var(--r-sm); cursor: pointer; }
  .hero h1 { font-size: var(--t-2xl); }
  .school-band { flex-direction: column; align-items: flex-start; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  * { transition: none !important; }
}