/* ===== CSS Custom Properties (Light Theme) ===== */
:root {
    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fa;
    --bg-card: #ffffff;
    --text-primary: #1a1a2e;
    --text-secondary: #6c757d;
    --text-muted: #adb5bd;
    --border-color: #dee2e6;
    --accent: #2563eb;
    --accent-hover: #1d4ed8;
    --success: #16a34a;
    --danger: #dc2626;
    --warning: #f59e0b;
    --chart-1: #2563eb;
    --chart-2: #dc2626;
    --chart-3: #16a34a;
    --chart-4: #f59e0b;
    --chart-5: #8b5cf6;
    --chart-6: #06b6d4;
    --nav-width: 260px;
    --content-max-width: 1200px;
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.25rem;
    --font-size-xl: 1.5rem;
    --font-size-xxl: 2rem;
    --radius: 0.5rem;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 4px 12px rgba(0, 0, 0, 0.1);
}

/* ===== Dark Theme ===== */
[data-theme="dark"] {
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --bg-card: #1e293b;
    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;
    --border-color: #334155;
    --accent: #3b82f6;
    --accent-hover: #60a5fa;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 4px 12px rgba(0, 0, 0, 0.3);
}

/* ===== Base Reset ===== */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html, body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    font-size: var(--font-size-base);
    color: var(--text-primary);
    background-color: var(--bg-primary);
    line-height: 1.6;
    min-height: 100vh;
}

/* ===== App Layout: Sidebar + Content ===== */
.app-container {
    min-height: 100vh;
}

/* ===== Sidebar Nav ===== */
.sidebar {
    background-color: var(--bg-secondary);
    border-right: 1px solid var(--border-color);
    padding: var(--spacing-lg) 0;
    position: fixed;
    top: 0;
    left: 0;
    width: var(--nav-width);
    height: 100vh;
    overflow-y: auto;
    z-index: 100;
}

.sidebar-brand {
    display: block;
    padding: var(--spacing-md) var(--spacing-lg);
    font-size: var(--font-size-xl);
    font-weight: 700;
    color: var(--accent);
    text-decoration: none;
    border-bottom: 1px solid var(--border-color);
    margin-bottom: var(--spacing-md);
}

.nav-link {
    display: block;
    padding: var(--spacing-sm) var(--spacing-lg);
    color: var(--text-secondary);
    text-decoration: none;
    font-size: var(--font-size-sm);
    transition: color 0.15s, background-color 0.15s;
}

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

.nav-link.active {
    color: var(--accent);
    font-weight: 600;
}

.nav-section-label {
    padding: var(--spacing-lg) var(--spacing-lg) var(--spacing-xs);
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-muted);
}

/* ===== Main Content ===== */
.main-content {
    margin-left: var(--nav-width);
    padding: var(--spacing-xl);
    max-width: calc(var(--content-max-width) + 2 * var(--spacing-xl));
}

.main-content h1 {
    font-size: var(--font-size-xxl);
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

.main-content h2 {
    font-size: var(--font-size-xl);
    font-weight: 600;
    margin-top: var(--spacing-xl);
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

/* ===== Page Prose Blockquote ===== */
blockquote {
    border-left: 4px solid var(--accent);
    padding: var(--spacing-md) var(--spacing-lg);
    margin: var(--spacing-md) 0 var(--spacing-xl);
    background-color: var(--bg-secondary);
    color: var(--text-secondary);
    font-style: italic;
    border-radius: 0 var(--radius) var(--radius) 0;
}

/* ===== Theme Toggle ===== */
.theme-toggle {
    position: fixed;
    top: var(--spacing-md);
    right: var(--spacing-md);
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: var(--spacing-xs) var(--spacing-sm);
    cursor: pointer;
    color: var(--text-primary);
    font-size: var(--font-size-sm);
    z-index: 200;
    box-shadow: var(--shadow);
}

/* ===== Hamburger (mobile) ===== */
.hamburger {
    display: none;
    position: fixed;
    top: var(--spacing-md);
    left: var(--spacing-md);
    z-index: 200;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: var(--spacing-xs) var(--spacing-sm);
    cursor: pointer;
    color: var(--text-primary);
    font-size: var(--font-size-lg);
}

/* ===== Blazor Error UI ===== */
#blazor-error-ui {
    color-scheme: light only;
    background: lightyellow;
    bottom: 0;
    box-shadow: 0 -1px 2px rgba(0, 0, 0, 0.2);
    display: none;
    left: 0;
    padding: 0.6rem 1.25rem 0.7rem;
    position: fixed;
    width: 100%;
    z-index: 1000;
}

#blazor-error-ui .dismiss {
    cursor: pointer;
    position: absolute;
    right: 0.75rem;
    top: 0.5rem;
}

/* ===== Loading Progress ===== */
.loading-progress {
    position: absolute;
    display: block;
    width: 8rem;
    height: 8rem;
    inset: 20vh 0 auto 0;
    margin: 0 auto;
}

.loading-progress circle {
    fill: none;
    stroke: #e0e0e0;
    stroke-width: 0.6rem;
    transform-origin: 50% 50%;
    transform: rotate(-90deg);
}

.loading-progress circle:last-child {
    stroke: var(--accent);
    stroke-dasharray: calc(3.141 * var(--blazor-load-percentage, 0%) * 0.8), 500%;
    transition: stroke-dasharray 0.05s ease-in-out;
}

.loading-progress-text {
    position: absolute;
    text-align: center;
    font-weight: bold;
    inset: calc(20vh + 3.25rem) 0 auto 0.2rem;
}

.loading-progress-text:after {
    content: var(--blazor-load-percentage-text, "Loading");
}

/* ===== Home Page Nav Cards ===== */
.nav-cards {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: var(--spacing-lg);
    margin-top: var(--spacing-xl);
}

.nav-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: var(--spacing-lg);
    text-decoration: none;
    color: var(--text-primary);
    transition: box-shadow 0.15s, border-color 0.15s;
    box-shadow: var(--shadow);
}

.nav-card:hover {
    box-shadow: var(--shadow-lg);
    border-color: var(--accent);
}

.nav-card.hub {
    border-color: var(--accent);
    border-width: 2px;
    grid-column: span 2;
}

.nav-card h3 {
    font-size: var(--font-size-lg);
    margin-bottom: var(--spacing-xs);
    color: var(--accent);
}

.nav-card p {
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
    margin: 0;
}

.nav-card .equations {
    font-size: 0.75rem;
    color: var(--text-muted);
    margin-top: var(--spacing-sm);
}

/* ===== Inline-style Replacements ===== */
.cascade-svg {
    max-width: 1000px;
    margin: 1.5rem auto;
    display: block;
    overflow: visible;
}

.hysteresis-caption {
    text-align: center;
    font-size: 0.9em;
    color: var(--text-muted);
}

.hysteresis-alert {
    color: var(--danger);
}

.cross-links {
    margin-top: 2rem;
    padding: 1rem 0;
    border-top: 1px solid var(--border-color);
}

.threshold-indicators {
    margin-top: 0.5rem;
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

.cascade-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
}

/* ===== Chart / SVG Responsive ===== */
svg {
    max-width: 100%;
    height: auto;
}

.chart-card-content {
    overflow: hidden;
}

/* ===== Responsive: Tablet ===== */
@media (max-width: 1200px) {
    :root {
        --nav-width: 220px;
    }

    /* SplitPanel stacks vertically on tablet */
    .split-panel {
        grid-template-columns: 1fr;
    }

    /* Tighten content spacing */
    .main-content {
        padding: var(--spacing-lg);
    }

    /* Cards reduce minimum width for better fit */
    .nav-cards {
        grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
    }

    .nav-card.hub {
        grid-column: span 1;
    }
}

/* ===== Responsive: Mobile ===== */
@media (max-width: 768px) {
    .sidebar {
        transform: translateX(-100%);
        transition: transform 0.3s ease;
    }

    .sidebar.open {
        transform: translateX(0);
    }

    .hamburger {
        display: block;
    }

    .main-content {
        margin-left: 0;
        padding: var(--spacing-md);
        padding-top: calc(var(--spacing-xl) + 2rem);
    }

    .main-content h1 {
        font-size: var(--font-size-xl);
    }

    .main-content h2 {
        font-size: var(--font-size-lg);
    }

    /* Single-column card grid on mobile */
    .nav-cards {
        grid-template-columns: 1fr;
        gap: var(--spacing-md);
    }

    .nav-card.hub {
        grid-column: span 1;
    }

    /* Reduce blockquote padding */
    blockquote {
        padding: var(--spacing-sm) var(--spacing-md);
    }

    /* SplitPanel tighter gap */
    .split-panel {
        gap: var(--spacing-md);
    }

    /* Chart cards tighter padding */
    .chart-card-content {
        padding: var(--spacing-sm) var(--spacing-md) var(--spacing-md);
    }

    .chart-card-header {
        padding: var(--spacing-sm) var(--spacing-md) var(--spacing-xs);
    }

    /* Slider panel tighter on mobile */
    .slider-panel-content {
        padding: var(--spacing-sm);
    }
}