/* ===========================================================
   Learn With Rinkesh — design tokens
   Concept: the site itself behaves like a spreadsheet —
   name box, formula bar, and a lettered/numbered cell grid.
   =========================================================== */

@import url('https://fonts.googleapis.com/css2?family=IBM+Plex+Mono:wght@400;500;600;700&family=IBM+Plex+Sans:wght@400;500;600&display=swap');

:root {
  --paper: #F6F4EC;
  --ink: #1C2321;
  --ink-soft: #4B5450;
  --grid-line: #D9D3C2;
  --excel-green: #1C6B41;
  --excel-green-deep: #124D2E;
  --amber: #C9971E;
  --cell-bg: #FFFFFF;
  --radius: 2px;
}

* { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  overflow-y: scroll;
  scrollbar-gutter: stable;
}

body {
  margin: 0;
  background-color: var(--paper);
  background-image:
    radial-gradient(circle, rgba(28,107,65,0.05) 1px, transparent 1px);
  background-size: 22px 22px;
  color: var(--ink);
  font-family: 'IBM Plex Sans', sans-serif;
  font-size: 16px;
  line-height: 1.55;
}

h1, h2, h3, .mono {
  font-family: 'IBM Plex Mono', monospace;
}

a { color: inherit; }

/* ---------- Top bar: styled like an actual Excel ribbon ---------- */

.topbar {
  background: var(--excel-green);
  position: sticky;
  top: 0;
  z-index: 99999;
}

.topbar-inner {
  max-width: 1320px;
  margin: 0 auto;
  padding: 14px 24px 0;
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  font-family: 'IBM Plex Mono', monospace;
  font-weight: 600;
  font-size: 15px;
  color: #fff;
  padding-bottom: 12px;
}

.brand .namebox {
  border: 1px solid #fff;
  border-radius: var(--radius);
  padding: 3px 8px;
  font-size: 12px;
  color: var(--excel-green-deep);
  background: #fff;
}

nav.mainnav {
  display: flex;
  gap: 4px;
  font-size: 13px;
  font-weight: 600;
  align-items: flex-end;
}

/* ---------- Shared sub-nav bar (identical on every page) ---------- */

.subnav-bar {
  background: var(--paper);
  padding: 6px 0;
}

.subnav-inner {
  max-width: 1320px;
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  justify-content: center;
  gap: 6px;
  flex-wrap: wrap;
}

.subnav-inner a {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 7px 15px;
  border-radius: 14px;
  background: var(--excel-green);
  color: #fff;
  text-decoration: none;
  font-family: 'IBM Plex Mono', monospace;
  font-size: 13px;
  font-weight: 700;
  transition: background 0.2s ease, transform 0.15s ease;
}

.subnav-inner a:hover {
  transform: translateY(-2px) scale(1.12);
  z-index: 2;
  position: relative;
}

.subnav-inner a.current-page {
  background: var(--amber);
}

nav.mainnav a {
  text-decoration: none;
  color: rgba(255,255,255,0.82);
  background: rgba(255,255,255,0.12);
  padding: 10px 18px;
  border-radius: 8px 8px 0 0;
  display: inline-block;
  line-height: 1.2;
  box-sizing: border-box;
  transition: color 0.2s ease, background 0.2s ease;
  outline: none;
  -webkit-tap-highlight-color: transparent;
}

nav.mainnav a:focus-visible {
  outline: 2px solid rgba(255,255,255,0.7);
  outline-offset: -2px;
}

nav.mainnav a:hover {
  background: rgba(255,255,255,0.22);
  color: #fff;
}

nav.mainnav a.active {
  background: var(--paper);
  color: var(--excel-green-deep);
}

/* ---------- Hero: literal formula bar ---------- */

.hero {
  max-width: 1320px;
  margin: 0 auto;
  padding: 64px 24px 40px;
}

.formula-bar {
  display: flex;
  align-items: stretch;
  border: 1px solid var(--grid-line);
  background: var(--cell-bg);
  border-radius: var(--radius);
  overflow: hidden;
  margin-bottom: 28px;
}

.formula-bar .fx {
  font-family: 'IBM Plex Mono', monospace;
  font-style: italic;
  color: var(--excel-green);
  padding: 10px 14px;
  border-right: 1px solid var(--grid-line);
  font-size: 14px;
  background: #F0F5F1;
  display: flex;
  align-items: center;
}

.formula-bar .content {
  padding: 10px 16px;
  font-family: 'IBM Plex Mono', monospace;
  font-size: 14px;
  color: var(--ink-soft);
  display: flex;
  align-items: center;
}

.hero h1 {
  font-size: clamp(32px, 5vw, 52px);
  line-height: 1.15;
  margin: 0 0 18px;
  font-weight: 700;
  letter-spacing: -0.01em;
}

.hero h1 .cellref {
  color: var(--excel-green);
}

.hero p.lede {
  max-width: 560px;
  font-size: 18px;
  color: var(--ink-soft);
  margin: 0 0 30px;
}

.cta-row { display: flex; gap: 14px; flex-wrap: wrap; }

.btn {
  display: inline-block;
  font-family: 'IBM Plex Mono', monospace;
  font-size: 14px;
  font-weight: 600;
  padding: 12px 22px;
  border-radius: var(--radius);
  text-decoration: none;
  border: 1px solid transparent;
  cursor: pointer;
}

.btn-primary {
  background: var(--excel-green);
  color: #fff;
}
.btn-primary:hover { background: var(--excel-green-deep); }

.btn-ghost {
  background: transparent;
  color: var(--ink);
  border-color: var(--grid-line);
}
.btn-ghost:hover { border-color: var(--ink); }

/* ---------- Grid section: feature "cells" ---------- */

.sheet {
  max-width: 1320px;
  margin: 40px auto 80px;
  padding: 0 24px;
}

.sheet-header {
  display: flex;
  align-items: baseline;
  gap: 12px;
  margin-bottom: 18px;
}

.sheet-header .colletter {
  font-family: 'IBM Plex Mono', monospace;
  color: var(--excel-green);
  font-weight: 700;
  font-size: 13px;
}

.sheet-header h2 {
  font-size: 22px;
  margin: 0;
  font-weight: 600;
}

.cell-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  border-top: 1px solid var(--grid-line);
  border-left: 1px solid var(--grid-line);
}

.cell {
  background: var(--cell-bg);
  border-right: 1px solid var(--grid-line);
  border-bottom: 1px solid var(--grid-line);
  padding: 26px 22px;
  position: relative;
  display: flex;
  flex-direction: column;
}

.cell .ref {
  position: absolute;
  top: 10px;
  right: 12px;
  font-family: 'IBM Plex Mono', monospace;
  font-size: 11px;
  color: var(--grid-line);
}

.cell h3 {
  font-size: 16px;
  margin: 0 0 8px;
  font-weight: 600;
}

.cell p {
  font-size: 14px;
  color: var(--ink-soft);
  margin: 0;
}

@media (max-width: 720px) {
  .cell-grid { grid-template-columns: 1fr; }

  /* Mobile nav — hides the inline Home/About/Rankers links behind a
     hamburger toggle, injected by mobile-nav.js. Desktop (min-width:721px
     below) is completely untouched by anything in this block. */
  .topbar-inner { position: relative; flex-wrap: wrap; }
  .mobile-menu-toggle {
    display: flex; align-items: center; justify-content: center;
    background: none; border: 1px solid rgba(255,255,255,0.4); border-radius: 6px;
    color: #fff; width: 34px; height: 34px; font-size: 16px; cursor: pointer;
    margin-bottom: 12px; flex-shrink: 0;
  }
  nav.mainnav {
    display: none; position: absolute; top: 100%; left: 0; right: 0;
    background: var(--excel-green); flex-direction: column; align-items: stretch;
    padding: 6px 24px 16px; gap: 0; z-index: 99998;
    box-shadow: 0 8px 16px rgba(0,0,0,0.15);
  }
  nav.mainnav.mobile-open { display: flex; }
  nav.mainnav a { padding: 12px 0; border-bottom: 1px solid rgba(255,255,255,0.15); }
  nav.mainnav #navAuthArea { padding: 12px 0; }
}

@media (min-width: 721px) {
  .mobile-menu-toggle { display: none; }
}

/* ---------- Footer ---------- */

footer {
  border-top: 1px solid var(--grid-line);
  padding: 24px;
  text-align: center;
  font-size: 13px;
  color: var(--ink-soft);
  font-family: 'IBM Plex Mono', monospace;
}

/* ---------- Formula detail page ---------- */

.formula-page {
  max-width: 760px;
  margin: 0 auto;
  padding: 48px 24px 80px;
}

.formula-title {
  font-family: 'IBM Plex Mono', monospace;
  background: var(--cell-bg);
  border: 1px solid var(--grid-line);
  border-radius: var(--radius);
  padding: 18px 22px;
  font-size: 22px;
  font-weight: 700;
  color: var(--excel-green-deep);
  margin-bottom: 8px;
}

.formula-category {
  display: inline-block;
  font-family: 'IBM Plex Mono', monospace;
  font-size: 12px;
  color: var(--amber);
  border: 1px solid var(--amber);
  border-radius: var(--radius);
  padding: 3px 8px;
  margin-bottom: 28px;
}

.formula-page section { margin-bottom: 32px; }

.formula-page h2 {
  font-size: 15px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--ink-soft);
  margin-bottom: 10px;
}

.video-slot {
  background: var(--cell-bg);
  border: 1px dashed var(--grid-line);
  border-radius: var(--radius);
  aspect-ratio: 16 / 9;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--ink-soft);
  font-family: 'IBM Plex Mono', monospace;
  font-size: 13px;
  max-width: 420px;
}

.params-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 14px;
}

.params-table th, .params-table td {
  text-align: left;
  padding: 10px 12px;
  border-bottom: 1px solid var(--grid-line);
}

.params-table th {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 12px;
  color: var(--ink-soft);
  text-transform: uppercase;
}

/* ---------- Logged-in account nav ---------- */

.nav-account { position: relative; }
#navAuthArea { display: inline-flex; align-items: flex-end; }
.nav-login-link {
  text-decoration: none;
  color: rgba(255,255,255,0.82);
  background: rgba(255,255,255,0.12);
  padding: 10px 18px;
  border-radius: 8px 8px 0 0;
  display: inline-block;
  line-height: 1.2;
  box-sizing: border-box;
  font-family: 'IBM Plex Mono', monospace;
  font-weight: 700;
  transition: color 0.2s ease, background 0.2s ease;
}
.nav-login-link:hover { background: rgba(255,255,255,0.22); color: #fff; }


.nav-account-btn {
  display: flex;
  align-items: center;
  gap: 8px;
  background: rgba(255,255,255,0.12);
  border: none;
  cursor: pointer;
  font-family: 'IBM Plex Mono', monospace;
  font-size: 11px;
  font-weight: 700;
  color: #fff;
  padding: 8px 16px 8px 10px;
  border-radius: 8px 8px 0 0;
  transition: background 0.2s ease, transform 0.15s ease;
}
.nav-account-btn:hover { background: rgba(255,255,255,0.22); }

.nav-avatar-img {
  width: 20px;
  height: 20px;
  border-radius: 50%;
  object-fit: cover;
}

.nav-avatar-initial {
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: #fff;
  color: var(--excel-green-deep);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: 'IBM Plex Mono', monospace;
  font-size: 10px;
  font-weight: 700;
}

.nav-avatar-img-lg {
  width: 42px;
  height: 42px;
  border-radius: 50%;
  object-fit: cover;
  flex-shrink: 0;
}

.nav-avatar-initial-lg {
  width: 42px;
  height: 42px;
  border-radius: 50%;
  background: var(--excel-green);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: 'IBM Plex Mono', monospace;
  font-size: 16px;
  font-weight: 700;
  flex-shrink: 0;
}

.nav-account-menu {
  display: none;
  position: absolute;
  right: 0;
  top: calc(100% + 10px);
  background: var(--cell-bg);
  border: 1px solid var(--grid-line);
  border-radius: 14px;
  min-width: 220px;
  box-shadow: 0 12px 32px rgba(28,35,33,0.18);
  overflow: hidden;
  z-index: 20;
}

.nav-account-menu.open {
  display: block;
  animation: navMenuPop 0.18s ease;
}
@keyframes navMenuPop {
  from { opacity: 0; transform: translateY(-6px); }
  to { opacity: 1; transform: translateY(0); }
}

.nav-account-menu-header {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 16px 14px;
  background: linear-gradient(135deg, #F0F5F1, #F9F8F3);
  border-bottom: 1px solid var(--grid-line);
}
.nav-account-menu-name { font-size: 14px; font-weight: 700; color: var(--ink); }
.nav-account-menu-email { font-size: 11px; color: var(--ink-soft); margin-top: 1px; }

.nav-account-menu a,
nav.mainnav .nav-account-menu a {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 11px 16px;
  font-size: 13px;
  font-weight: 500;
  text-decoration: none;
  color: var(--ink) !important;
  background: transparent !important;
  border-radius: 0 !important;
  border-bottom: 1px solid var(--grid-line);
  line-height: 1.4;
  transition: background 0.15s ease, padding-left 0.15s ease;
}
.nav-account-menu a:last-child { border-bottom: none; }
.nav-account-menu a:hover { background: #F0F5F1 !important; padding-left: 20px; }

.nav-account-menu-logout {
  color: #B3261E !important;
}
.nav-account-menu-logout:hover { background: #FBE6E2 !important; }

/* ---------- Profile setup form ---------- */

.setup-box {
  max-width: 460px;
  margin: 48px auto 80px;
  background: var(--cell-bg);
  border: 1px solid var(--grid-line);
  border-radius: var(--radius);
  padding: 32px;
}
.setup-box h1 { font-size: 20px; margin: 0 0 6px; }
.setup-box p.hint { font-size: 13px; color: var(--ink-soft); margin: 0 0 24px; }
.setup-box label {
  display: block;
  font-family: 'IBM Plex Mono', monospace;
  font-size: 12px;
  color: var(--ink-soft);
  margin-bottom: 6px;
  margin-top: 18px;
}
.setup-box input, .setup-box select {
  width: 100%;
  padding: 10px 12px;
  border: 1px solid var(--grid-line);
  border-radius: var(--radius);
  font-family: 'IBM Plex Sans', sans-serif;
  font-size: 14px;
  background: #fff;
}
.setup-box button { width: 100%; margin-top: 26px; }
.setup-box #message, .setup-box #passwordMessage, .setup-box #chatPrefsMessage { margin-top: 14px; font-size: 13px; font-family: 'IBM Plex Mono', monospace; }
.setup-box #message.error, .setup-box #passwordMessage.error, .setup-box #chatPrefsMessage.error { color: #B3261E; }
.setup-box #message.success, .setup-box #passwordMessage.success, .setup-box #chatPrefsMessage.success { color: var(--excel-green-deep); }

/* ---------- Practice grid ---------- */

.practice-grid {
  border: 1px solid var(--grid-line);
  border-radius: var(--radius);
  overflow: hidden;
  background: #fff;
  max-width: 620px;
}

.practice-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 13px;
  font-family: 'IBM Plex Mono', monospace;
}

.practice-table th, .practice-table td {
  border: 1px solid var(--grid-line);
  padding: 8px 10px;
  text-align: left;
}

.practice-table th {
  background: #F0F5F1;
  color: var(--excel-green-deep);
  font-weight: 600;
}

.practice-table td.colhead {
  background: #FAFAF7;
  color: var(--grid-line);
  text-align: center;
  width: 24px;
}

.practice-table td.target-cell {
  background: #FFFBEA;
  font-weight: 600;
}

.practice-input-row {
  display: flex;
  gap: 10px;
  padding: 16px;
  border-top: 1px solid var(--grid-line);
  background: var(--paper);
  align-items: center;
  flex-wrap: wrap;
}

.practice-input-row label {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 12px;
  color: var(--ink-soft);
}

.practice-input-row input {
  flex: 1;
  min-width: 220px;
  padding: 9px 12px;
  border: 1px solid var(--grid-line);
  border-radius: var(--radius);
  font-family: 'IBM Plex Mono', monospace;
  font-size: 14px;
}

.practice-feedback {
  padding: 0 16px 16px;
  font-size: 14px;
}

.practice-feedback.correct { color: var(--excel-green-deep); }
.practice-feedback.incorrect { color: #B3261E; }
.practice-feedback .explain {
  display: block;
  margin-top: 6px;
  font-size: 13px;
  color: var(--ink-soft);
}