/* ==========================================================================
   RUSOV ACADEMY — DESIGN SYSTEM 2.0 / LAYOUT
   Mobile-first «app frame»: 480px колонка, safe-area, слоистый фон.
   ========================================================================== */

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html, body {
  background: var(--bg-primary);
  color: var(--text);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  -webkit-tap-highlight-color: transparent;
  overscroll-behavior-y: none;
}

body { min-height: 100vh; min-height: 100dvh; display: flex; justify-content: center; }

/* ---------- App frame ---------- */
.ds-app {
  width: 100%;
  max-width: var(--app-max);
  min-height: 100vh;
  min-height: 100dvh;
  position: relative;
  display: flex;
  flex-direction: column;
  background: var(--bg-primary);
  overflow: hidden;
}
@media (min-width: 481px) {
  .ds-app { box-shadow: 0 0 80px rgba(0,0,0,.6); }
}
@media (min-width: 768px) {
  .ds-app { border-left: 1px solid rgba(255,255,255,.03); border-right: 1px solid rgba(255,255,255,.03); }
}

/* ---------- Слоистый фон: аврора + зерно + виньетка ----------
   Разметка:
   <div class="ds-fx">
     <div class="ds-fx__aurora ds-fx__aurora--a"></div>
     <div class="ds-fx__aurora ds-fx__aurora--b"></div>
     <div class="ds-fx__aurora ds-fx__aurora--c"></div>
     <div class="ds-fx__grain"></div>
     <div class="ds-fx__vignette"></div>
   </div>                                        */
.ds-fx { position: fixed; inset: 0; z-index: var(--z-bg); pointer-events: none; overflow: hidden; }
@media (min-width: 481px) {
  .ds-fx { position: absolute; } /* внутри app-frame на десктопе */
}

.ds-fx__aurora { position: absolute; width: 140%; height: 60%; filter: blur(40px); will-change: transform; }
.ds-fx__aurora--a { top: -18%; left: -20%; background: var(--aurora-1); animation: ds-aurora-a 26s ease-in-out infinite; }
.ds-fx__aurora--b { top: 30%;  right: -30%; background: var(--aurora-2); animation: ds-aurora-b 32s ease-in-out infinite; }
.ds-fx__aurora--c { bottom: -20%; left: -10%; background: var(--aurora-3); animation: ds-aurora-c 38s ease-in-out infinite; }

.ds-fx__grain {
  position: absolute; inset: 0; opacity: .05; mix-blend-mode: overlay;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='160' height='160'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='2'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
}

.ds-fx__vignette {
  position: absolute; inset: 0;
  background: radial-gradient(ellipse 90% 70% at 50% 40%, transparent 55%, rgba(0,0,0,.45) 100%);
}

/* ---------- Экран ---------- */
.ds-screen {
  flex: 1;
  display: none;
  flex-direction: column;
  padding: 24px var(--app-pad-x) calc(var(--app-pad-b) + env(safe-area-inset-bottom, 0px));
  position: relative;
  z-index: var(--z-screen);
}
.ds-screen.active { display: flex; animation: ds-screen-in .55s var(--ease-out-expo); }

.ds-screen--center { justify-content: center; }