/* ===== CSS VARIABLES & BASE STYLES ===== */

:root {
    /* Colors - Easy to change for themes! */
    --color-primary: #667eea;
    --color-primary-dark: #764ba2;
    --color-success: #2ecc71;
    --color-danger: #e74c3c;
    --color-warning: #f39c12;
    --color-info: #3498db;
    
    --color-text-primary: #333;
    --color-text-secondary: #666;
    --color-text-light: #999;
    
    --color-bg-dark: #1a1a2e;
    --color-bg-dark-alt: #16213e;
    
    /* Spacing */
    --spacing-xs: 5px;
    --spacing-sm: 10px;
    --spacing-md: 15px;
    --spacing-lg: 20px;
    --spacing-xl: 30px;
    --spacing-xxl: 40px;
    
    /* Border Radius */
    --radius-sm: 5px;
    --radius-md: 10px;
    --radius-lg: 15px;
    --radius-xl: 20px;
    --radius-round: 50%;
    
    /* Shadows */
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 8px rgba(0, 0, 0, 0.15);
    --shadow-lg: 0 10px 20px rgba(0, 0, 0, 0.2);
    --shadow-xl: 0 20px 60px rgba(0, 0, 0, 0.3);
    
    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
    
    /* Typography */
    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    --font-size-xs: 0.8em;
    --font-size-sm: 0.9em;
    --font-size-md: 1em;
    --font-size-lg: 1.2em;
    --font-size-xl: 1.5em;
    --font-size-xxl: 2em;
    --font-size-huge: 5em;
}

/* ===== RESET & BASE ===== */

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

body {
    font-family: var(--font-family);
    background: linear-gradient(135deg, var(--color-bg-dark) 0%, var(--color-bg-dark-alt) 100%);
    min-height: 100vh;
    overflow-x: hidden;
    color: white;
}

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

.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.mb-sm { margin-bottom: var(--spacing-sm); }
.mb-md { margin-bottom: var(--spacing-md); }
.mb-lg { margin-bottom: var(--spacing-lg); }
.mb-xl { margin-bottom: var(--spacing-xl); }

.mt-sm { margin-top: var(--spacing-sm); }
.mt-md { margin-top: var(--spacing-md); }
.mt-lg { margin-top: var(--spacing-lg); }
.mt-xl { margin-top: var(--spacing-xl); }

.hidden { display: none !important; }
.visible { display: block !important; }

/* ===== COMMON COMPONENTS ===== */

.loading {
    text-align: center;
    padding: var(--spacing-xxl);
}

.spinner {
    border: 4px solid #f3f3f3;
    border-top: 4px solid var(--color-primary);
    border-radius: var(--radius-round);
    width: 50px;
    height: 50px;
    animation: spin 1s linear infinite;
    margin: 0 auto var(--spacing-lg);
}

.error {
    background: #fee;
    border: 2px solid #fcc;
    border-radius: var(--radius-md);
    padding: var(--spacing-md);
    color: #c33;
    margin-top: var(--spacing-lg);
}

/* ===== BUTTONS ===== */

.btn {
    width: 100%;
    padding: 14px;
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
    color: white;
    border: none;
    border-radius: var(--radius-md);
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: transform var(--transition-fast), box-shadow var(--transition-fast);
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 20px rgba(102, 126, 234, 0.3);
}

.btn:active {
    transform: translateY(0);
}

.btn:disabled {
    background: #ccc;
    cursor: not-allowed;
    transform: none;
}

.btn-secondary {
    background: #f0f0f0;
    color: var(--color-text-primary);
    margin-top: var(--spacing-sm);
}

.btn-secondary:hover {
    background: #e0e0e0;
    box-shadow: var(--shadow-md);
}