/* ============================================================
   CrowdStrike Falcon Study Platform
   Design System v4.0 — Premium Light (duetri-inspired)
   ============================================================ */

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

/* ============================================================
   LIGHT MODE (default)
   ============================================================ */
:root {
    /* --- Surfaces --- */
    --bg-base: #f0f0f3;
    --bg-raised: #ffffff;
    --bg-overlay: #e8e8ec;
    --bg-hover: #dcdce0;
    --bg-glass: rgba(255, 255, 255, 0.75);
    --border-subtle: rgba(0, 0, 0, 0.1);
    --border-default: rgba(0, 0, 0, 0.14);
    --border-strong: rgba(0, 0, 0, 0.2);

    /* --- Accent (orange) --- */
    --accent: #f97316;
    --accent-hover: #fb923c;
    --accent-muted: #ea580c;
    --accent-soft: rgba(249, 115, 22, 0.1);
    --accent-glow: rgba(249, 115, 22, 0.18);
    --gradient-accent: linear-gradient(135deg, #f97316, #ef4444);
    --gradient-accent-2: linear-gradient(135deg, #f97316, #ec4899);
    --gradient-accent-3: linear-gradient(135deg, #8b5cf6, #06b6d4);
    --gradient-warm: linear-gradient(135deg, #fbbf24, #f97316, #ef4444);

    /* --- Card gradient border (purple-blue-teal) --- */
    --gradient-border: linear-gradient(135deg, #8b5cf6, #3b82f6, #06b6d4);
    --card-glow-color: rgba(139, 92, 246, 0.12);

    /* --- Semantic colors --- */
    --green: #22c55e;
    --green-soft: rgba(34, 197, 94, 0.1);
    --red: #ef4444;
    --red-soft: rgba(239, 68, 68, 0.1);
    --blue: #3b82f6;
    --blue-soft: rgba(59, 130, 246, 0.1);
    --yellow: #eab308;
    --yellow-soft: rgba(234, 179, 8, 0.1);
    --purple: #8b5cf6;
    --purple-soft: rgba(139, 92, 246, 0.08);
    --teal: #14b8a6;
    --teal-soft: rgba(20, 184, 166, 0.1);

    /* --- Text --- */
    --text-primary: #18181b;
    --text-secondary: #52525b;
    --text-muted: #a1a1aa;
    --text-inverted: #fafafa;
    --font-sans: 'Inter', system-ui, -apple-system, sans-serif;

    /* --- Radius --- */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 20px;
    --radius-full: 9999px;

    /* --- Shadows (light mode: visible, elevated) --- */
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08), 0 1px 2px rgba(0, 0, 0, 0.12);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.1), 0 2px 4px rgba(0, 0, 0, 0.08);
    --shadow-lg: 0 12px 40px rgba(0, 0, 0, 0.12), 0 4px 12px rgba(0, 0, 0, 0.08);
    --shadow-glow: 0 0 40px rgba(249, 115, 22, 0.15);
    --shadow-card-hover: 0 20px 60px rgba(139, 92, 246, 0.12), 0 8px 20px rgba(0, 0, 0, 0.1);

    /* --- Transitions --- */
    --ease: cubic-bezier(0.16, 1, 0.3, 1);
    --t-fast: 0.15s var(--ease);
    --t-base: 0.25s var(--ease);
    --t-slow: 0.4s var(--ease);
    --t-theme: 0.35s ease;
}

/* ============================================================
   DARK MODE
   ============================================================ */
[data-theme="dark"] {
    /* --- Surfaces (dark navy blue) --- */
    --bg-base: #0f1729;
    --bg-raised: #162040;
    --bg-overlay: #1c2a4a;
    --bg-hover: #243456;
    --bg-glass: rgba(22, 32, 64, 0.85);
    --border-subtle: rgba(255, 255, 255, 0.08);
    --border-default: rgba(255, 255, 255, 0.12);
    --border-strong: rgba(255, 255, 255, 0.18);

    /* --- Accent (unchanged) --- */
    --accent-soft: rgba(249, 115, 22, 0.12);
    --accent-glow: rgba(249, 115, 22, 0.22);

    /* --- Card gradient border --- */
    --card-glow-color: rgba(139, 92, 246, 0.18);

    /* --- Semantic soft backgrounds (brighter in dark) --- */
    --green-soft: rgba(34, 197, 94, 0.12);
    --red-soft: rgba(239, 68, 68, 0.12);
    --blue-soft: rgba(59, 130, 246, 0.12);
    --yellow-soft: rgba(234, 179, 8, 0.12);
    --purple-soft: rgba(139, 92, 246, 0.12);
    --teal-soft: rgba(20, 184, 166, 0.12);

    /* --- Text --- */
    --text-primary: #fafafa;
    --text-secondary: #a1a1aa;
    --text-muted: #52525b;
    --text-inverted: #18181b;

    /* --- Shadows (dark mode: deeper) --- */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.4);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.5);
    --shadow-lg: 0 12px 40px rgba(0, 0, 0, 0.6);
    --shadow-glow: 0 0 40px rgba(249, 115, 22, 0.15);
    --shadow-card-hover: 0 20px 60px rgba(139, 92, 246, 0.15), 0 8px 20px rgba(0, 0, 0, 0.4);
}

/* Scrollbar dark mode */
[data-theme="dark"] ::-webkit-scrollbar-thumb { background: rgba(255, 255, 255, 0.1); }
[data-theme="dark"] ::-webkit-scrollbar-thumb:hover { background: rgba(255, 255, 255, 0.2); }

/* ============================================================
   RESET & BASE
   ============================================================ */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    background: var(--bg-base);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    position: relative;
    transition:
        background var(--t-theme),
        color var(--t-theme);
}

/* Subtle ambient gradient blobs */
body::before {
    content: '';
    position: fixed;
    top: -20%;
    left: -10%;
    width: 50%;
    height: 50%;
    background: radial-gradient(circle, rgba(139, 92, 246, 0.04) 0%, transparent 70%);
    pointer-events: none;
    z-index: -1;
}

body::after {
    content: '';
    position: fixed;
    bottom: -20%;
    right: -10%;
    width: 50%;
    height: 50%;
    background: radial-gradient(circle, rgba(6, 182, 212, 0.03) 0%, transparent 70%);
    pointer-events: none;
    z-index: -1;
}

[data-theme="dark"] body::before {
    background: radial-gradient(circle, rgba(249, 115, 22, 0.05) 0%, transparent 70%);
}

[data-theme="dark"] body::after {
    background: radial-gradient(circle, rgba(139, 92, 246, 0.04) 0%, transparent 70%);
}

::selection {
    background: rgba(139, 92, 246, 0.2);
    color: var(--text-primary);
}

/* Custom scrollbar (light mode) */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: rgba(0, 0, 0, 0.12); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: rgba(0, 0, 0, 0.2); }

/* ============================================================
   THEME TOGGLE BUTTON
   ============================================================ */
.theme-toggle {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    border: 1px solid var(--border-default);
    background: var(--bg-raised);
    color: var(--text-secondary);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.1rem;
    transition:
        background var(--t-base),
        border-color var(--t-base),
        color var(--t-base),
        transform var(--t-fast),
        box-shadow var(--t-base);
    box-shadow: var(--shadow-sm);
    position: relative;
    overflow: hidden;
    flex-shrink: 0;
}

.theme-toggle:hover {
    border-color: var(--purple);
    color: var(--purple);
    background: var(--purple-soft);
    transform: scale(1.05);
    box-shadow: 0 0 20px rgba(139, 92, 246, 0.15);
}

.theme-toggle:active {
    transform: scale(0.95);
}

/* ============================================================
   TOP NAV — Glassmorphism
   ============================================================ */
.top-bar {
    background: var(--bg-glass);
    backdrop-filter: blur(24px) saturate(1.8);
    -webkit-backdrop-filter: blur(24px) saturate(1.8);
    padding: 10px 20px;
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 2px;
    flex-wrap: wrap;
    border-bottom: 1px solid var(--border-subtle);
    position: sticky;
    top: 0;
    z-index: 200;
    transition:
        background var(--t-theme),
        border-color var(--t-theme);
}

[data-theme="dark"] .top-bar {
    background: rgba(9, 9, 11, 0.75);
}

.top-bar a {
    padding: 8px 18px;
    border-radius: var(--radius-full);
    border: none;
    color: var(--text-muted);
    text-decoration: none;
    font-size: 0.82rem;
    font-weight: 500;
    transition: all var(--t-base);
    background: transparent;
    letter-spacing: 0.01em;
}

.top-bar a:hover {
    color: var(--text-primary);
    background: var(--bg-hover);
}

/* Active tab: orange accent text, subtle underline feel */
.top-bar a.active {
    background: transparent;
    color: var(--accent);
    font-weight: 600;
    position: relative;
}

.top-bar a.active::after {
    content: '';
    position: absolute;
    bottom: 2px;
    left: 50%;
    transform: translateX(-50%);
    width: 16px;
    height: 2px;
    background: var(--accent);
    border-radius: 1px;
}

/* ============================================================
   HEADER
   ============================================================ */
.header {
    padding: 52px 24px 44px;
    text-align: center;
    position: relative;
    overflow: hidden;
    background: var(--bg-base);
    border-bottom: 1px solid var(--border-subtle);
    transition:
        background var(--t-theme),
        border-color var(--t-theme);
}

/* Soft gradient mesh */
.header::before {
    content: '';
    position: absolute;
    inset: 0;
    background:
        radial-gradient(ellipse 60% 80% at 25% 0%, rgba(139, 92, 246, 0.06) 0%, transparent 60%),
        radial-gradient(ellipse 50% 70% at 75% 10%, rgba(6, 182, 212, 0.04) 0%, transparent 60%);
    pointer-events: none;
}

[data-theme="dark"] .header::before {
    background:
        radial-gradient(ellipse 50% 80% at 30% 0%, rgba(249, 115, 22, 0.07) 0%, transparent 60%),
        radial-gradient(ellipse 40% 60% at 70% 20%, rgba(139, 92, 246, 0.05) 0%, transparent 60%);
}

.header::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 1px;
    background: linear-gradient(90deg, transparent, rgba(139, 92, 246, 0.2), rgba(6, 182, 212, 0.2), transparent);
}

.header h1 {
    font-size: 2.1rem;
    font-weight: 800;
    letter-spacing: -0.035em;
    color: var(--text-primary);
    margin-bottom: 8px;
    position: relative;
    line-height: 1.2;
}

.header h1 span {
    background: var(--gradient-border);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.header p {
    color: var(--text-secondary);
    font-size: 0.92rem;
    font-weight: 400;
    position: relative;
    max-width: 540px;
    margin: 0 auto;
    line-height: 1.6;
}

/* ============================================================
   CONTAINER
   ============================================================ */
.container {
    max-width: 920px;
    margin: 0 auto;
    padding: 36px 24px;
}

/* ============================================================
   CARDS — Gradient border + mouse-track glow
   ============================================================ */
.card {
    background: var(--bg-raised);
    border-radius: var(--radius-lg);
    padding: 22px 24px;
    border: 1px solid var(--border-subtle);
    box-shadow: var(--shadow-sm);
    transition:
        border-color var(--t-base),
        transform var(--t-base),
        box-shadow var(--t-base),
        background var(--t-theme);
    position: relative;
    overflow: hidden;
}

/* Gradient border glow (behind the card) */
.card::before {
    content: '';
    position: absolute;
    top: -1px;
    left: -1px;
    right: -1px;
    bottom: -1px;
    border-radius: inherit;
    background: var(--gradient-border);
    opacity: 0;
    z-index: -1;
    transition: opacity var(--t-base);
    filter: blur(10px);
}

/* Mouse-tracking glow overlay */
.card::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border-radius: inherit;
    background: radial-gradient(
        300px circle at var(--mouse-x, 50%) var(--mouse-y, 50%),
        var(--card-glow-color) 0%,
        transparent 70%
    );
    opacity: 0;
    transition: opacity var(--t-base);
    pointer-events: none;
    z-index: 0;
}

.card:hover {
    border-color: rgba(139, 92, 246, 0.25);
    transform: translateY(-2px);
    box-shadow: var(--shadow-card-hover);
}

.card:hover::before {
    opacity: 0.2;
}

.card:hover::after {
    opacity: 1;
}

/* Ensure card content sits above the glow */
.card > * {
    position: relative;
    z-index: 1;
}

/* ============================================================
   BUTTONS
   ============================================================ */
.btn {
    padding: 10px 24px;
    border-radius: var(--radius-full);
    border: none;
    font-size: 0.88rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--t-base);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
    font-family: var(--font-sans);
    letter-spacing: 0.01em;
}

.btn:active { transform: scale(0.97); }

.btn-primary {
    background: var(--gradient-accent);
    color: #fff;
    box-shadow: var(--shadow-sm);
}

.btn-primary:hover {
    box-shadow: var(--shadow-glow);
    transform: translateY(-1px);
    filter: brightness(1.05);
}

.btn-secondary {
    background: var(--bg-overlay);
    border: 1px solid var(--border-default);
    color: var(--text-secondary);
}

.btn-secondary:hover {
    border-color: var(--border-strong);
    color: var(--text-primary);
    background: var(--bg-hover);
}

.btn-success {
    background: var(--green);
    color: #fff;
}

.btn-success:hover {
    filter: brightness(1.1);
    transform: translateY(-1px);
}

/* ============================================================
   TAGS
   ============================================================ */
.tag {
    display: inline-block;
    padding: 3px 10px;
    border-radius: var(--radius-full);
    font-size: 0.7rem;
    font-weight: 600;
    letter-spacing: 0.03em;
    text-transform: uppercase;
}

.tag-red    { background: var(--red-soft);    color: var(--red);    }
.tag-blue   { background: var(--blue-soft);   color: var(--blue);   }
.tag-yellow { background: var(--yellow-soft); color: var(--yellow); }
.tag-green  { background: var(--green-soft);  color: var(--green);  }
.tag-purple { background: var(--purple-soft); color: var(--purple); }

/* ============================================================
   INPUTS & FORM ELEMENTS (shared)
   ============================================================ */
input, textarea, select {
    transition:
        border-color var(--t-base),
        box-shadow var(--t-base),
        background var(--t-theme),
        color var(--t-theme);
}

/* ============================================================
   FOOTER
   ============================================================ */
.footer {
    text-align: center;
    padding: 44px 20px;
    color: var(--text-muted);
    font-size: 0.78rem;
    border-top: 1px solid var(--border-subtle);
    margin-top: 60px;
    transition:
        border-color var(--t-theme),
        color var(--t-theme);
}

/* ============================================================
   BILINGUAL QUESTION STYLES
   ============================================================ */
/* Translation help hint (shown when ? help is ON) */
.question-hint {
    font-size: 0.82rem;
    color: var(--text-muted);
    margin-bottom: 12px;
    padding: 8px 14px;
    background: var(--bg-overlay);
    border-left: 3px solid var(--purple);
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
    font-style: italic;
    line-height: 1.5;
}

/* ============================================================
   UTILITY: Smooth theme transition on ALL themed elements
   ============================================================ */
.top-bar,
.header,
.card,
.btn-secondary,
.footer,
.nav,
.search-container input {
    transition:
        background var(--t-theme),
        border-color var(--t-theme),
        color var(--t-theme),
        box-shadow var(--t-base);
}

/* ============================================================
   RESPONSIVE
   ============================================================ */
@media (max-width: 640px) {
    .header h1 { font-size: 1.5rem; }
    .container { padding: 20px 16px; }
    .top-bar { padding: 8px 12px; }
    .top-bar a { padding: 6px 12px; font-size: 0.75rem; }
    .card { padding: 16px 18px; }
}

/* ============================================================
   MOUSE-TRACKING GLOW — inline JS helper
   ============================================================
   Add this <script> at the bottom of each page (or in a shared JS):

   <script>
   document.addEventListener('mousemove', e => {
     document.querySelectorAll('.card').forEach(card => {
       const rect = card.getBoundingClientRect();
       const x = e.clientX - rect.left;
       const y = e.clientY - rect.top;
       card.style.setProperty('--mouse-x', x + 'px');
       card.style.setProperty('--mouse-y', y + 'px');
     });
   });
   </script>

   ============================================================

   THEME TOGGLE — inline JS helper
   ============================================================
   Add a button like:
   <button class="theme-toggle" onclick="toggleTheme()" title="Toggle theme">🌓</button>

   <script>
   function toggleTheme() {
     const html = document.documentElement;
     const isDark = html.getAttribute('data-theme') === 'dark';
     html.setAttribute('data-theme', isDark ? 'light' : 'dark');
     localStorage.setItem('theme', isDark ? 'light' : 'dark');
   }
   // Load saved preference
   (function() {
     const saved = localStorage.getItem('theme');
     if (saved) document.documentElement.setAttribute('data-theme', saved);
   })();
   </script>
   ============================================================ */