*, *::before, *::after { box-sizing: border-box; }

[hidden] { display: none !important; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } *, *::before, *::after { animation: none !important; transition: none !important; } }

body {
  margin: 0;
  font-family: var(--font);
  font-size: var(--fs-base);
  line-height: var(--lh);
  color: var(--text);
  background-color: var(--bg);
  background-image:
    linear-gradient(var(--grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: 28px 28px; /* клетка 5×5 мм */
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  overflow-wrap: break-word;
}

h1, h2, h3, h4 { line-height: 1.2; margin: 0 0 0.6em; letter-spacing: -0.02em; font-weight: 800; }
h1 { font-size: clamp(1.8rem, 5.5vw, 2.6rem); }
h2 { font-size: clamp(1.35rem, 4vw, 1.75rem); }
h3 { font-size: 1.2rem; }
p { margin: 0 0 1em; }
a { color: var(--primary-text); text-underline-offset: 3px; }
a:hover { color: var(--primary-hover); }
img, svg { max-width: 100%; }
code { font-family: var(--font-mono); font-size: 0.92em; background: var(--surface-2); padding: 0.1em 0.4em; border-radius: 6px; }

:focus-visible { outline: 3px solid var(--focus); outline-offset: 2px; border-radius: 4px; }

.container { width: 100%; max-width: var(--container); margin-inline: auto; padding-inline: var(--gutter); }
.container--narrow { max-width: 760px; }
.container--medium { max-width: 880px; }
.muted { color: var(--muted); }
.small { font-size: 0.875rem; }
.lead { font-size: 1.15rem; color: var(--muted); max-width: 46rem; }
.eyebrow { font-size: 0.875rem; font-weight: 700; color: var(--primary-text); text-transform: uppercase; letter-spacing: 0.06em; margin-bottom: 0.5rem; }
.hand { font-family: var(--font-hand); }
::selection { background: var(--amber); color: var(--ink); }

.sr-only {
  position: absolute !important; width: 1px; height: 1px; padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0;
}
.skip-link {
  position: absolute; left: 0.5rem; top: -4rem; background: var(--primary); color: var(--on-primary);
  padding: 0.6rem 1rem; border-radius: var(--radius-sm); z-index: 100;
}
.skip-link:focus { top: 0.5rem; }
.hp { position: absolute; left: -9999px; width: 1px; height: 1px; overflow: hidden; }

.site-main { flex: 1; outline: none; }
.page { padding-block: 1.5rem 3rem; }

/* ---------- шапка ---------- */
.site-header { background: var(--surface); border-bottom: 3px solid var(--outline); position: sticky; top: 0; z-index: 50; }
.site-header__inner { display: flex; align-items: center; justify-content: space-between; min-height: 64px; gap: 1rem; flex-wrap: wrap; }
.logo { display: inline-flex; align-items: center; gap: 0.6rem; text-decoration: none; color: var(--text); font-weight: 800; font-size: 1.25rem; letter-spacing: -0.02em; min-height: var(--tap); }
.logo:hover { color: var(--text); }
.logo__mark { transition: transform 0.3s cubic-bezier(.3, 1.8, .5, 1); }
.logo:hover .logo__mark { transform: rotate(-12deg) scale(1.12); }

/* переключатель ОГЭ / ЕГЭ: два сегмента и ползунок под активным (здесь активен ЕГЭ, справа) */
.exam-switch { position: relative; display: inline-grid; grid-template-columns: 1fr 1fr; flex: none; padding: 3px; background: var(--surface-2); border: 2px solid var(--outline); border-radius: 999px; box-shadow: var(--shadow-sm); }
.exam-switch__thumb { position: absolute; top: 3px; bottom: 3px; left: 3px; width: calc(50% - 3px); background: var(--amber); border: 2px solid var(--outline); border-radius: 999px; transform: translateX(100%); transition: transform 0.22s cubic-bezier(.3, 1.4, .5, 1); }
.exam-switch.is-leaving .exam-switch__thumb { transform: none; }
.exam-switch__opt { position: relative; z-index: 1; display: flex; align-items: center; justify-content: center; min-width: 3.1rem; min-height: 34px; padding: 0 0.7rem; font-weight: 800; font-size: 0.95rem; letter-spacing: 0.02em; color: var(--text); text-decoration: none; border-radius: 999px; transition: color 0.15s; }
.exam-switch__opt.is-active, .exam-switch.is-leaving .exam-switch__opt:not(.is-active) { color: var(--on-amber); }
.exam-switch.is-leaving .exam-switch__opt.is-active { color: var(--text); }
a.exam-switch__opt:not(.is-active):hover { color: var(--primary-text); }
.exam-switch__opt.is-disabled { opacity: 0.55; cursor: not-allowed; }
@media (max-width: 420px) { .logo__text { display: none; } .site-header__inner { gap: 0.6rem; } }

.burger { display: none; width: var(--tap); height: var(--tap); border: 2px solid var(--outline); box-shadow: var(--shadow-sm); background: var(--amber); border-radius: var(--radius-sm); cursor: pointer; align-items: center; justify-content: center; }
.burger__bars, .burger__bars::before, .burger__bars::after { display: block; width: 20px; height: 2px; background: var(--text); border-radius: 2px; content: ""; position: relative; transition: transform 0.2s, opacity 0.2s; }
.burger__bars::before { position: absolute; top: -6px; }
.burger__bars::after { position: absolute; top: 6px; }
.burger[aria-expanded="true"] .burger__bars { background: transparent; }
.burger[aria-expanded="true"] .burger__bars::before { transform: translateY(6px) rotate(45deg); }
.burger[aria-expanded="true"] .burger__bars::after { transform: translateY(-6px) rotate(-45deg); }

.theme-toggle { order: 1; margin-left: auto; width: var(--tap); height: var(--tap); display: inline-flex; align-items: center; justify-content: center; border: 2px solid var(--outline); box-shadow: var(--shadow-sm); background: var(--surface); color: var(--text); border-radius: var(--radius-sm); cursor: pointer; padding: 0; }
.theme-toggle:hover { background: var(--amber-soft); }
.theme-toggle svg { width: 22px; height: 22px; fill: none; stroke: currentColor; stroke-width: 2; stroke-linecap: round; stroke-linejoin: round; }
.theme-toggle__moon { display: block; }
.theme-toggle__sun { display: none; }
:root[data-theme="dark"] .theme-toggle__moon { display: none; }
:root[data-theme="dark"] .theme-toggle__sun { display: block; }
html:not(.js) .theme-toggle { display: none; }
.burger { order: 2; margin-left: 0.5rem; }

.site-nav { order: 3; display: flex; flex-direction: column; width: 100%; padding-bottom: 0.75rem; }
.site-nav ul { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; }
.site-nav a, .nav-button {
  display: flex; align-items: center; min-height: var(--tap); padding: 0.4rem 0.65rem; color: var(--text);
  text-decoration: none; border-radius: var(--radius-sm); font-weight: 500; font: inherit; font-weight: 500; background: none; border: 0; cursor: pointer; width: 100%; text-align: left;
}
.site-nav a:hover, .nav-button:hover { background: var(--amber-soft); color: var(--text); }
.site-nav a[aria-current="page"] { color: var(--ink); background: var(--amber); font-weight: 700; }
.site-nav a.btn--primary, .site-nav a.btn--primary:hover { color: var(--on-primary); background: var(--primary); }
.site-nav .btn { justify-content: center; }
.site-nav__user { border-top: 1px solid var(--border); margin-top: 0.5rem; padding-top: 0.5rem; }
.inline-form { margin: 0; }

/* JS есть → на мобильных меню прячется за бургер; JS нет → просто показано */
.js .burger { display: inline-flex; }
.js .site-nav { display: none; }
.js .site-nav.is-open { display: flex; }

@media (min-width: 1100px) {
  .site-nav { order: 1; margin-left: auto; }
  .theme-toggle { order: 2; margin-left: 0.5rem; }
  .burger, .js .burger { display: none; }
  .site-nav, .js .site-nav, .js .site-nav.is-open { display: flex; flex-direction: row; width: auto; padding-bottom: 0; align-items: center; gap: 0.5rem; }
  .site-nav ul { flex-direction: row; align-items: center; gap: 0.15rem; }
  .site-nav__user { border: 0; margin: 0 0 0 0.5rem; padding: 0; }
  .site-nav a, .nav-button { width: auto; white-space: nowrap; padding-inline: 0.5rem; }}

/* ---------- подвал ---------- */
.site-footer { background: var(--footer-bg); color: #dfe5ff; border-top: 3px solid var(--outline); margin-top: 3rem; padding-block: 2rem; }
.site-footer a { color: #fff; }
.site-footer a:hover { color: var(--amber); }
.site-footer .muted { color: #b4bfe6; }
.footer-joke { font-family: var(--font-hand); color: var(--amber); margin: 0.6rem 0 0; font-size: 1rem; }
.site-footer__inner { display: grid; gap: 1rem; }
.site-footer p { margin: 0.25rem 0 0; }
.footer-links { list-style: none; margin: 0; padding: 0; display: flex; flex-wrap: wrap; gap: 0 1.25rem; }
@media (min-width: 768px) { .footer-links { flex-direction: column; } }
.footer-links a { display: inline-flex; align-items: center; min-height: var(--tap); }
@media (min-width: 768px) { .site-footer__inner { grid-template-columns: 1fr 1fr; align-items: start; } .footer-copy { grid-column: 1 / -1; } }

/* ---------- сообщения ---------- */
.flashes { padding-top: 1rem; display: grid; gap: 0.5rem; }
.flash { padding: 0.75rem 1rem; border-radius: var(--radius-sm); border: 2px solid; margin-bottom: 1rem; box-shadow: var(--shadow-sm); }
.flashes .flash { margin-bottom: 0; }
.flash--success { background: var(--success-soft); border-color: var(--success-border); color: var(--success-text); }
.flash--error { background: var(--danger-soft); border-color: var(--danger-border); color: var(--danger-text); }
.flash--info { background: var(--primary-soft); border-color: var(--primary); color: var(--primary-text); }
.dev-banner { background: var(--amber-soft); border-bottom: 1px solid var(--amber-border); color: var(--amber-text); padding-block: 0.75rem; }
.dev-banner pre { white-space: pre-wrap; font-family: var(--font-mono); font-size: 0.85rem; margin: 0.5rem 0 0; }