/* ==========================================================================
   💎 EDUHUB AI PREMIUM THEME SYSTEM (LINEAR & STRIPE AESTHETICS 2026)
   File: static/css/eduhub_premium_core.css
   ========================================================================== */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800&family=Montserrat:wght@500;600;700;800;900&display=swap');

:root {
    --bg-main: #030712;
    --bg-card: rgba(11, 15, 25, 0.65);
    --border-glow: rgba(255, 255, 255, 0.08);
    --accent-blue: #3B82F6;
    --accent-purple: #6366F1;
    --text-head: #FFFFFF;
    --text-body: #94A3B8;
    --font-head: 'Montserrat', system-ui, -apple-system, sans-serif;
    --font-body: 'Inter', system-ui, -apple-system, sans-serif;
}

/* Глобальная перезагрузка фона и шрифтов */
html {
    background-color: var(--bg-main) !important;
}

body {
    background-color: var(--bg-main) !important;
    color: var(--text-body) !important;
    font-family: var(--font-body);
    position: relative;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Заголовки: системный шрифт Montserrat с точным трекингом */
h1, h2, h3, h4, h5, h6, .font-heading {
    font-family: var(--font-head) !important;
    color: var(--text-head) !important;
    letter-spacing: -0.025em;
}

/* Фоновая световая вуаль (Ambient Glow) */
body::before {
    content: "";
    position: absolute;
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, rgba(99, 102, 241, 0.06) 0%, rgba(0,0,0,0) 70%);
    top: -10%;
    left: 50%;
    transform: translateX(-50%);
    z-index: -1;
    pointer-events: none;
}

/* Премиальные карточки с матовым стеклом */
.premium-card {
    background: var(--bg-card);
    border: 1px solid var(--border-glow);
    border-radius: 14px;
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.premium-card:hover {
    border-color: rgba(99, 102, 241, 0.4);
    box-shadow: 0 0 25px rgba(99, 102, 241, 0.12);
    transform: translateY(-2px);
}

/* Флагманская интерактивная кнопка */
.glow-btn-main, .glow-btn-cta {
    background: linear-gradient(135deg, #2563EB 0%, #4F46E5 50%, #7C3AED 100%) !important;
    color: #ffffff !important;
    font-weight: 700 !important;
    border-radius: 12px !important;
    border: none !important;
    transition: all 0.2s ease-in-out !important;
    position: relative;
    overflow: hidden;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    text-shadow: 0 1px 2px rgba(0, 0, 0, 0.3);
}

.glow-btn-main:hover, .glow-btn-cta:hover {
    transform: scale(1.02);
    box-shadow: 0 0 25px rgba(99, 102, 241, 0.5) !important;
}

.glow-btn-main:active, .glow-btn-cta:active {
    transform: scale(0.98);
}

/* Маска размытия для заблокированного контента (Пейволл) */
.paywall-blur-mask {
    mask-image: linear-gradient(to bottom, rgba(0,0,0,1) 0%, rgba(0,0,0,0) 100%);
    -webkit-mask-image: linear-gradient(to bottom, rgba(0,0,0,1) 0%, rgba(0,0,0,0) 100%);
    filter: blur(2px);
    pointer-events: none;
    user-select: none;
    transition: filter 0.3s ease;
}

/* Контейнер пейволла и модальная карточка разблокировки */
.paywall-container {
    position: relative;
    overflow: hidden;
    min-height: 180px;
}

.paywall-floating-overlay {
    position: absolute;
    inset: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 1.5rem;
    z-index: 20;
    background: radial-gradient(circle at center, rgba(3, 7, 18, 0.4) 0%, rgba(3, 7, 18, 0.88) 100%);
}

.paywall-glass-card {
    background: rgba(15, 23, 42, 0.88);
    border: 1px solid rgba(99, 102, 241, 0.3);
    border-radius: 16px;
    padding: 1.75rem;
    text-align: center;
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.6), 0 0 30px rgba(99, 102, 241, 0.15);
    max-width: 520px;
    width: 100%;
}

/* Поле ввода в песочнице чата */
.sandbox-chat-input {
    background: rgba(11, 15, 25, 0.85) !important;
    border: 1px solid var(--border-glow) !important;
    color: #F8FAFC !important;
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    transition: all 0.25s ease-in-out !important;
}

.sandbox-chat-input:focus {
    border-color: rgba(99, 102, 241, 0.6) !important;
    box-shadow: 0 0 20px rgba(99, 102, 241, 0.2) !important;
    outline: none !important;
}

.sandbox-chat-input::placeholder {
    color: #64748B !important;
}

/* Сегментированные вкладки витрины (Linear Style) */
.segmented-tabs-container {
    display: inline-flex;
    background: rgba(15, 23, 42, 0.7);
    border: 1px solid var(--border-glow);
    border-radius: 14px;
    padding: 4px;
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
}

.segmented-tab-btn {
    padding: 8px 18px;
    border-radius: 10px;
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-body);
    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    background: transparent;
    border: none;
    cursor: pointer;
}

.segmented-tab-btn:hover {
    color: #FFFFFF;
}

.segmented-tab-btn.active {
    background: rgba(255, 255, 255, 0.08);
    color: #FFFFFF;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.4);
    border: 1px solid rgba(255, 255, 255, 0.12);
}

.tab-pane-crossfade {
    opacity: 0;
    transform: translateY(6px);
    transition: opacity 0.3s ease, transform 0.3s ease;
}

.tab-pane-crossfade.pane-visible {
    opacity: 1;
    transform: translateY(0);
}

/* Тонкие светящиеся границы 1px для секций */
.linear-border {
    border: 1px solid var(--border-glow);
}

.linear-border-focus:focus-within {
    border-color: rgba(99, 102, 241, 0.5);
    box-shadow: 0 0 20px rgba(99, 102, 241, 0.15);
}

/* ==============================================================================
   SAFARI & IOS WEBKIT BACKDROP-FILTER FIX (Auto-applied by QA Guard Engine)
   ============================================================================== */
header,
nav,
.backdrop-blur-md,
.backdrop-blur-sm,
.backdrop-blur-lg,
.backdrop-blur-xl,
.paywall-floating-overlay,
.paywall-glass-card,
.premium-card {
    -webkit-backdrop-filter: blur(12px) !important;
    backdrop-filter: blur(12px) !important;
}