/* ============================================
   SHARED RESPONSIVE CSS VARIABLES & UTILITIES
   Maintains proportions across all resolutions
   ============================================ */

:root {
    /* Color Palette - Purple, Black, White theme */
    --color-black: #0f0f1e;
    --color-dark-purple: #1a1a2e;
    --color-purple: #6c2d8f;
    --color-purple-light: #8e44ad;
    --color-white: #ffffff;
    --color-gray-light: #f0f0f0;
    --color-gray-medium: #d0d0d0;
    --color-gray-dark: #666666;

    /* Base Unit - Scales with viewport */
    --base-unit: clamp(8px, 1.5vw, 24px);
    
    /* Spacing Scale (all based on base-unit) */
    --spacing-xs: calc(var(--base-unit) * 0.5);
    --spacing-sm: var(--base-unit);
    --spacing-md: calc(var(--base-unit) * 1.5);
    --spacing-lg: calc(var(--base-unit) * 2);
    --spacing-xl: calc(var(--base-unit) * 3);
    --spacing-xxl: calc(var(--base-unit) * 4);

    /* Typography Scale (all based on base-unit) */
    --font-size-xs: calc(var(--base-unit) * 0.75);
    --font-size-sm: var(--base-unit);
    --font-size-md: calc(var(--base-unit) * 1.25);
    --font-size-lg: calc(var(--base-unit) * 1.5);
    --font-size-xl: calc(var(--base-unit) * 2);
    --font-size-2xl: calc(var(--base-unit) * 2.5);
    --font-size-3xl: calc(var(--base-unit) * 3);

    /* Border Radius (maintains visual consistency) */
    --border-radius-sm: calc(var(--base-unit) * 0.25);
    --border-radius-md: calc(var(--base-unit) * 0.5);
    --border-radius-lg: var(--base-unit);

    /* Shadows */
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 8px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 8px 16px rgba(0, 0, 0, 0.5);

    /* Transitions */
    --transition-fast: 150ms ease-in-out;
    --transition-normal: 300ms ease-in-out;
    --transition-slow: 500ms ease-in-out;

    /* Z-index stack */
    --z-dropdown: 100;
    --z-modal: 1000;
    --z-tooltip: 1100;
}

/* ============================================
   BASE STYLES
   ============================================ */

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    background: linear-gradient(135deg, var(--color-black) 0%, var(--color-dark-purple) 100%);
    color: var(--color-white);
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', sans-serif;
    line-height: 1.6;
    min-height: 100vh;
}

/* ============================================
   UTILITY CLASSES
   ============================================ */

.hidden {
    display: none !important;
}

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border-width: 0;
}

/* ============================================
   BUTTONS & INTERACTIVE ELEMENTS
   ============================================ */

.btn {
    padding: calc(var(--spacing-sm) * 0.75) var(--spacing-md);
    font-size: var(--font-size-sm);
    border: none;
    border-radius: var(--border-radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.btn-primary {
    background: var(--color-purple);
    color: var(--color-white);
}

.btn-primary:hover:not(:disabled) {
    background: var(--color-purple-light);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background: var(--color-gray-dark);
    color: var(--color-white);
}

.btn-secondary:hover:not(:disabled) {
    background: var(--color-gray-medium);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

/* ============================================
   MODALS & OVERLAYS
   ============================================ */

.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.7);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: var(--z-modal);
    backdrop-filter: blur(4px);
}

.modal.hidden {
    display: none;
}

.modal-content {
    background: var(--color-dark-purple);
    border: 2px solid var(--color-purple);
    border-radius: var(--border-radius-lg);
    width: 90%;
    max-width: 600px;
    max-height: 85vh;
    display: flex;
    flex-direction: column;
    box-shadow: var(--shadow-lg);
    animation: slideUp var(--transition-normal);
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ============================================
   RESPONSIVE HELPERS
   ============================================ */

@media (max-width: 768px) {
    :root {
        --base-unit: clamp(8px, 2vw, 20px);
    }
}

@media (max-width: 480px) {
    :root {
        --base-unit: clamp(6px, 2.5vw, 16px);
    }
    
    .modal-content {
        width: 95%;
        max-height: 95vh;
    }
}