/* ============================================
   SBTI Base Styles — Light Theme
   ============================================ */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700;800;900&family=Outfit:wght@400;500;600;700;800;900&display=swap');

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

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  background: var(--bg-primary);
  color: var(--text-primary);
  min-height: 100vh;
  line-height: var(--leading-normal);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
  padding-top: var(--navbar-height);
}

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-display);
  font-weight: 800;
  line-height: var(--leading-tight);
  letter-spacing: var(--tracking-tight);
}

p { margin: 0; }

a {
  color: var(--accent);
  text-decoration: none;
  transition: color var(--duration-fast) ease;
}
a:hover { color: var(--accent-hover); }

img {
  max-width: 100%;
  display: block;
}

/* === Navbar === */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--navbar-height);
  background: rgba(245, 243, 239, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  z-index: var(--z-sticky);
  padding: 0 var(--space-xl);
}

.navbar-inner {
  max-width: var(--max-width-wide);
  margin: 0 auto;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.navbar-brand {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  cursor: pointer;
  text-decoration: none;
}

.navbar-brand .brand-icon {
  font-size: 1.5rem;
}

.navbar-brand .brand-text {
  display: flex;
  flex-direction: column;
  line-height: 1;
}

.navbar-brand .brand-name {
  font-family: var(--font-display);
  font-weight: 900;
  font-size: 1.3rem;
  letter-spacing: 0.06em;
  color: var(--text-primary);
}

.navbar-brand .brand-sub {
  font-size: 0.55rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--accent);
  font-weight: 600;
  margin-top: 1px;
}

.navbar-actions {
  display: flex;
  align-items: center;
  gap: var(--space-xl);
  margin-left: auto;
}

.navbar-menu {
  display: none; /* Mobile hidden by default */
  align-items: center;
  gap: var(--space-2xl);
}

@media (min-width: 768px) {
  .navbar-menu {
    display: flex;
  }
}

.nav-link {
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--text-secondary);
  text-decoration: none;
  transition: color var(--duration-fast);
}

.nav-link:hover {
  color: var(--text-primary);
}

.navbar-cta {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  padding: 8px 16px;
  border-radius: var(--radius-full);
  background: var(--accent);
  color: #fff;
  font-size: var(--text-sm);
  font-weight: 600;
  border: none;
  cursor: pointer;
  transition: background var(--duration-fast) ease, transform var(--duration-fast) var(--ease-spring);
}

.navbar-cta:hover {
  background: var(--accent-hover);
  transform: translateY(-1px);
}

/* === Layout Shell === */
.shell {
  position: relative;
  z-index: var(--z-base);
  max-width: var(--max-width-wide);
  margin: 0 auto;
  padding: var(--space-xl) var(--space-lg) var(--space-4xl);
}

.shell-wide {
  max-width: var(--max-width-wide);
}

/* === Screen System === */
.screen {
  display: none;
  animation: fadeIn var(--duration-normal) var(--ease-out);
}
.screen.active {
  display: block;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(12px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes slideUp {
  from { opacity: 0; transform: translateY(24px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes slideInRight {
  from { opacity: 0; transform: translateX(40px); }
  to { opacity: 1; transform: translateX(0); }
}

@keyframes slideInLeft {
  from { opacity: 0; transform: translateX(-40px); }
  to { opacity: 1; transform: translateX(0); }
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.6; }
}

@keyframes shimmer {
  0% { background-position: -200% 0; }
  100% { background-position: 200% 0; }
}

/* Question transitions */
.question-slide {
  animation: slideInRight var(--duration-normal) var(--ease-out);
}
.question-slide-back {
  animation: slideInLeft var(--duration-normal) var(--ease-out);
}

/* === Scrollbar === */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb {
  background: var(--border-hover);
  border-radius: var(--radius-full);
}
::-webkit-scrollbar-thumb:hover {
  background: var(--text-muted);
}