:root {
    /* 
       Premium Theme: Deep Indigo/Navy & Glass 
       Palette Inspired by modern SaaS & FinTech 
    */
    --primary-hue: 250;
    --primary-sat: 80%;
    --primary-lig: 60%;

    --color-primary: hsl(var(--primary-hue), var(--primary-sat), var(--primary-lig));
    --color-primary-dark: hsl(var(--primary-hue), var(--primary-sat), 40%);
    --color-primary-light: hsl(var(--primary-hue), var(--primary-sat), 75%);

    --color-accent: #00d4ff;
    /* Cyan accent for gradients */

    --bg-body: #090e17;
    /* Darker Slate */
    --bg-glass: rgba(9, 14, 23, 0.55);
    --bg-card: rgba(30, 41, 59, 0.4);
    /* Lighter glass */

    --text-main: #f8fafc;
    /* Slate 50 */
    --text-muted: #94a3b8;
    /* Slate 400 */

    --border-glass: rgba(255, 255, 255, 0.15);
    --border-glass-hover: rgba(255, 255, 255, 0.3);

    --font-heading: 'Outfit', sans-serif;
    --font-body: 'Inter', sans-serif;

    --radius-sm: 0.5rem;
    --radius-md: 0.75rem;
    --radius-lg: 1rem;

    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-glow: 0 0 30px rgba(0, 212, 255, 0.3), 0 0 10px rgba(99, 102, 241, 0.4);
}

/* --- Animations --- */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes pulseGlow {
    0% { opacity: 0.5; transform: translateX(-50%) scale(1); }
    50% { opacity: 0.8; transform: translateX(-50%) scale(1.1); }
    100% { opacity: 0.5; transform: translateX(-50%) scale(1); }
}

.animate-fade-in-up {
    opacity: 0;
    animation: fadeInUp 0.8s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}

.delay-1 { animation-delay: 0.1s; }
.delay-2 { animation-delay: 0.2s; }
.delay-3 { animation-delay: 0.3s; }
.delay-4 { animation-delay: 0.4s; }

/* --- Global Resets & Typography --- */
html {
    background-color: var(--bg-body);
}

body {
    min-height: 100vh;
    font-family: var(--font-body);
    background-color: var(--bg-body);
    color: var(--text-main);
    overflow-x: hidden;
    /* Flexbox for sticky footer */
    display: flex;
    flex-direction: column;
}

h1,
h2,
h3,
h4,
h5,
h6 {
    font-family: var(--font-heading);
    color: var(--text-main);
    font-weight: 600;
    letter-spacing: -0.02em;
}

a {
    color: var(--color-primary-light);
    text-decoration: none;
    transition: color 0.2s;
}

a:hover {
    color: var(--color-accent);
}

/* --- Layout Utilities --- */
.font-heading {
    font-family: var(--font-heading);
}

.text-gradient {
    background: linear-gradient(135deg, var(--color-primary-light), var(--color-accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.text-secondary {
    color: var(--text-muted) !important;
}

/* --- Components --- */

/* Glass Navbar */
.glass-nav {
    background: var(--bg-glass);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-bottom: 1px solid var(--border-glass);
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 4px 30px rgba(0, 0, 0, 0.1);
}

.navbar-brand {
    font-size: 1.5rem;
    letter-spacing: -0.03em;
}

.nav-link {
    color: var(--text-muted) !important;
    font-weight: 500;
    transition: all 0.3s ease;
    border-radius: var(--radius-sm);
    padding: 0.5rem 1rem !important;
    position: relative;
}

.nav-link::after {
    content: '';
    position: absolute;
    width: 0;
    height: 2px;
    bottom: 0;
    left: 50%;
    background: var(--color-accent);
    transition: all 0.3s ease;
    transform: translateX(-50%);
}

.nav-link:hover::after,
.nav-link.active::after {
    width: 70%;
}

.nav-link:hover,
.nav-link.active {
    color: var(--text-main) !important;
    background: rgba(255, 255, 255, 0.05);
}

/* Footer */
.glass-footer {
    background: var(--bg-card);
    border-top: 1px solid var(--border-glass) !important;
    padding: 1rem 0;
    /* Reduced from 2rem */
    margin-top: auto;
    /* Push to bottom */
}

/* Buttons */
.btn {
    font-family: var(--font-heading);
    font-weight: 500;
    border-radius: var(--radius-sm);
    padding: 0.6rem 1.2rem;
    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    letter-spacing: 0.02em;
}

.btn-primary {
    background: linear-gradient(135deg, var(--color-primary), var(--color-primary-dark));
    border: 1px solid rgba(255, 255, 255, 0.1);
    box-shadow: 0 4px 15px rgba(99, 102, 241, 0.3), inset 0 1px 0 rgba(255, 255, 255, 0.2);
    position: relative;
    overflow: hidden;
}

.btn-primary::before {
    content: '';
    position: absolute;
    top: 0; left: -100%; width: 100%; height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: all 0.5s;
}

.btn-primary:hover::before {
    left: 100%;
}

.btn-primary:hover {
    transform: translateY(-2px) scale(1.02);
    box-shadow: 0 8px 25px rgba(99, 102, 241, 0.5), inset 0 1px 0 rgba(255, 255, 255, 0.3);
    background: linear-gradient(135deg, var(--color-primary-light), var(--color-primary));
}

.btn-outline-light {
    border-color: var(--border-glass);
    color: var(--text-main);
    background: rgba(255, 255, 255, 0.05);
}

.btn-outline-light:hover {
    background: rgba(255, 255, 255, 0.1);
    transform: translateY(-1px);
    border-color: var(--text-main);
}

/* Cards (Glass) */
.glass-card {
    background: var(--bg-card);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border: 1px solid var(--border-glass);
    border-radius: var(--radius-lg);
    padding: 2.5rem 2rem;
    transition: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
    height: 100%;
    position: relative;
    overflow: hidden;
}

.glass-card::before {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0; height: 1px;
    background: linear-gradient(90deg, transparent, var(--color-accent), transparent);
    opacity: 0;
    transition: opacity 0.4s ease;
}

.glass-card:hover {
    transform: translateY(-8px) scale(1.01);
    box-shadow: var(--shadow-glow), 0 20px 40px rgba(0, 0, 0, 0.4);
    border-color: var(--border-glass-hover);
    background: rgba(40, 55, 75, 0.6);
}

.glass-card:hover::before {
    opacity: 1;
}

/* --- Hero Section Helpers --- */
.hero-gradient-bg {
    position: absolute;
    top: -50%;
    left: 50%;
    transform: translateX(-50%);
    width: 70%;
    height: 70%;
    background: radial-gradient(circle at center, rgba(0, 212, 255, 0.15) 0%, rgba(99, 102, 241, 0.25) 30%, rgba(15, 23, 42, 0) 70%);
    z-index: -1;
    pointer-events: none;
    animation: pulseGlow 10s ease-in-out infinite;
    filter: blur(40px);
}

/* --- KaTeX Overrides --- */
.katex,
.katex * {
    color: var(--color-primary-light) !important;
}

.katex-display {
    margin: 0.5rem 0 !important;
    overflow-x: auto;
    overflow-y: hidden;
    padding-bottom: 0.5rem;
    /* Space for potential scrollbar */
}

.katex-display,
.katex-display * {
    color: var(--color-accent) !important;
}

.katex .mathnormal {
    font-style: italic;
}

.math {
    color: inherit;
    /* Prevent Markdig .math wrapper from applying colors */
}

/* --- Form Control Enhancements for Dark Mode --- */

/* Fix Bootstrap select arrow for dark mode */
.form-select.bg-dark {
    background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 16'%3e%3cpath fill='none' stroke='%23f8fafc' stroke-linecap='round' stroke-linejoin='round' stroke-width='2' d='m2 5 6 6 6-6'/%3e%3c/svg%3e");
}

/* Lighten calendar icon slightly on hover if needed, or just set opacity */
input[type="date"].bg-dark::-webkit-calendar-picker-indicator {
    opacity: 0.8;
    cursor: pointer;
}

/* Style file upload button for dark theme */
input[type="file"].bg-dark::file-selector-button {
    background: rgba(255, 255, 255, 0.1);
    color: var(--text-main);
    border: none;
    border-right: 1px solid var(--border-glass);
    padding: 0.375rem 0.75rem;
    margin-right: 1rem;
    transition: background 0.2s;
    cursor: pointer;
}

input[type="file"].bg-dark:hover::file-selector-button,
input[type="file"].bg-dark::file-selector-button:hover {
    background: rgba(255, 255, 255, 0.2) !important;
}

/* Force browser native popups to dark mode */
input.bg-dark, select.bg-dark {
    color-scheme: dark;
}