/* Main CSS - Layout and Base Styles */

:root {
    /* Colors */
    --color-primary: #2563eb;
    --color-primary-dark: #1d4ed8;
    --color-primary-light: #3b82f6;
    --color-secondary: #64748b;
    --color-secondary-dark: #475569;
    --color-success: #22c55e;
    --color-error: #ef4444;
    --color-warning: #f59e0b;

    /* Neutrals */
    --color-bg: #f8fafc;
    --color-surface: #ffffff;
    --color-border: #e2e8f0;
    --color-text: #1e293b;
    --color-text-muted: #64748b;

    /* Graph colors */
    --color-parabola: #2563eb;
    --color-solution: rgba(34, 197, 94, 0.3);
    --color-solution-border: #22c55e;
    --color-roots: #ef4444;
    --color-grid: #e2e8f0;
    --color-axis: #334155;

    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;

    /* Typography */
    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
    --font-family-mono: 'SF Mono', 'Fira Code', 'Fira Mono', Consolas, monospace;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 2rem;

    /* Borders */
    --border-radius-sm: 0.25rem;
    --border-radius: 0.5rem;
    --border-radius-lg: 0.75rem;

    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.1), 0 1px 2px rgba(0, 0, 0, 0.06);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1), 0 2px 4px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1), 0 4px 6px rgba(0, 0, 0, 0.05);

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 200ms ease;
    --transition-slow: 300ms ease;
}

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

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: 1.6;
    color: var(--color-text);
    background-color: var(--color-bg);
    min-height: 100vh;
}

/* App Container */
.app-container {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    max-width: 1400px;
    margin: 0 auto;
    padding: var(--spacing-md);
}

/* Header */
.header {
    text-align: center;
    padding: var(--spacing-xl) var(--spacing-md);
    margin-bottom: var(--spacing-lg);
}

.header h1 {
    font-size: var(--font-size-3xl);
    font-weight: 700;
    color: var(--color-primary);
    margin-bottom: var(--spacing-sm);
}

.header .subtitle {
    font-size: var(--font-size-lg);
    color: var(--color-text-muted);
}

/* Main Content - Grid Layout */
.main-content {
    display: grid;
    grid-template-columns: 1fr;
    grid-template-rows: auto;
    gap: var(--spacing-lg);
    flex: 1;
}

@media (min-width: 768px) {
    .main-content {
        grid-template-columns: 1fr 1fr;
        grid-template-rows: auto 1fr;
    }

    .input-panel {
        grid-column: 1;
        grid-row: 1;
    }

    .graph-panel {
        grid-column: 2;
        grid-row: 1 / 3;
    }

    .solution-panel {
        grid-column: 1;
        grid-row: 2;
    }
}

@media (min-width: 1024px) {
    .main-content {
        grid-template-columns: 350px 1fr 350px;
        grid-template-rows: 1fr;
    }

    .input-panel {
        grid-column: 1;
        grid-row: 1;
    }

    .graph-panel {
        grid-column: 2;
        grid-row: 1;
    }

    .solution-panel {
        grid-column: 3;
        grid-row: 1;
    }
}

/* Section Panels */
.input-panel,
.graph-panel,
.solution-panel {
    background: var(--color-surface);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow);
}

.input-panel h2,
.graph-panel h2,
.solution-panel h2 {
    font-size: var(--font-size-xl);
    font-weight: 600;
    margin-bottom: var(--spacing-md);
    padding-bottom: var(--spacing-sm);
    border-bottom: 2px solid var(--color-border);
}

/* Footer */
.footer {
    text-align: center;
    padding: var(--spacing-lg) var(--spacing-md);
    color: var(--color-text-muted);
    font-size: var(--font-size-sm);
    margin-top: var(--spacing-lg);
}

/* Utility Classes */
.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* Dark mode support (optional, uses system preference) */
@media (prefers-color-scheme: dark) {
    :root {
        --color-bg: #0f172a;
        --color-surface: #1e293b;
        --color-border: #334155;
        --color-text: #f1f5f9;
        --color-text-muted: #94a3b8;
        --color-grid: #334155;
        --color-axis: #94a3b8;
    }
}