/* ============================================
   CSS VARIABLES / THEME SYSTEM
   ============================================ */
:root {
    /* Base Colors */
    --color-bg-primary: #1e1e1e;
    --color-bg-secondary: #252526;
    --color-bg-tertiary: #2d2d2d;
    --color-bg-hover: #3e3e3e;
    
    /* Text Colors */
    --color-text-primary: #d4d4d4;
    --color-text-secondary: #858585;
    --color-text-code: #ce9178;
    --color-text-inverse: #1e1e1e;
    
    /* Accent Colors */
    --color-primary: #4ec9b0;
    --color-primary-rgb: 78, 201, 176;
    --color-primary-hover: #5ed9c0;
    --color-secondary: #569cd6;
    --color-secondary-hover: #6aadd6;
    --color-danger: #f48771;
    --color-danger-hover: #f59a88;
    
    /* Status Colors */
    --color-success: #4ec9b0;
    --color-success-bg: #1f2a2a;
    --color-warning: #f48771;
    --color-warning-bg: #2a1f1f;
    --color-info: #569cd6;
    --color-info-bg: #1f1f2a;
    --color-planned-bg: #2a2a1f;
    
    /* Borders */
    --color-border: #3e3e3e;
    --color-border-accent: #4ec9b0;
    
    /* Spacing */
    --spacing-xs: 5px;
    --spacing-sm: 10px;
    --spacing-md: 15px;
    --spacing-lg: 20px;
    --spacing-xl: 30px;
    --spacing-xxl: 40px;
    
    /* Border Radius */
    --radius-sm: 3px;
    --radius-md: 4px;
    --radius-lg: 6px;
    --radius-xl: 8px;
    --radius-full: 50%;
    
    /* Transitions */
    --transition-fast: 0.2s;
    --transition-normal: 0.3s;
    
    /* Breakpoints (for reference, used in media queries) */
    --breakpoint-mobile: 768px;
    --breakpoint-tablet: 1024px;
    --breakpoint-desktop: 1200px;
}

/* Future: Light Theme Support
[data-theme="light"] {
    --color-bg-primary: #ffffff;
    --color-bg-secondary: #f5f5f5;
    --color-text-primary: #1e1e1e;
    --color-text-secondary: #666666;
    ... etc
}
*/

/* Base Styles - Global styles for all pages */
* { 
    margin: 0; 
    padding: 0; 
    box-sizing: border-box; 
}

body { 
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: linear-gradient(135deg, var(--color-bg-primary) 0%, var(--color-bg-tertiary) 100%);
    color: var(--color-text-primary);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Navigation */
nav {
    background: var(--color-bg-secondary);
    border-bottom: 2px solid var(--color-border);
    padding: var(--spacing-md) var(--spacing-lg);
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
}

.nav-brand {
    font-size: 1.5em;
    font-weight: bold;
    color: var(--color-primary);
    text-decoration: none;
}

.nav-links {
    display: flex;
    gap: var(--spacing-lg);
    align-items: center;
}

.nav-links a {
    color: var(--color-text-primary);
    text-decoration: none;
    padding: 8px var(--spacing-md);
    border-radius: var(--radius-md);
    transition: background var(--transition-fast);
}

.nav-links a:hover {
    background: var(--color-bg-hover);
}

.nav-links a.active {
    background: var(--color-primary);
    color: var(--color-text-inverse);
}

.lang-selector {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.lang-selector select {
    background: var(--color-bg-primary);
    color: var(--color-text-primary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    padding: 6px var(--spacing-sm);
    cursor: pointer;
}

.lang-selector select:hover {
    border-color: var(--color-primary);
}

/* Main Content */
.main-content {
    flex: 1;
    padding: var(--spacing-lg);
}

.container { 
    max-width: var(--breakpoint-desktop); 
    margin: 0 auto; 
    width: 100%;
    padding: 0 var(--spacing-lg);
}

header { 
    text-align: center; 
    padding: var(--spacing-xxl) var(--spacing-lg); 
}

h1 { 
    color: var(--color-primary); 
    font-size: 2.5em; 
    margin-bottom: var(--spacing-sm); 
}

.subtitle { 
    color: var(--color-text-secondary); 
    font-size: 1.2em; 
    margin-bottom: var(--spacing-xl); 
}

.section { 
    background: var(--color-bg-secondary); 
    border-radius: var(--radius-xl); 
    padding: var(--spacing-xl); 
    margin: var(--spacing-lg) 0;
    border-left: 4px solid var(--color-primary);
}

h2 { 
    color: var(--color-secondary); 
    margin-bottom: var(--spacing-lg); 
    font-size: 1.8em; 
}

h3 { 
    color: var(--color-primary); 
    margin: var(--spacing-lg) 0 var(--spacing-sm) 0; 
}

.info-box {
    background: var(--color-bg-primary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    margin: var(--spacing-md) 0;
}

.warning { 
    border-left: 4px solid var(--color-warning); 
    background: var(--color-warning-bg); 
}

.success { 
    border-left: 4px solid var(--color-success); 
    background: var(--color-success-bg); 
}

.info { 
    border-left: 4px solid var(--color-info); 
    background: var(--color-info-bg); 
}

.btn {
    display: inline-block;
    background: var(--color-primary);
    color: var(--color-text-inverse);
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--radius-md);
    text-decoration: none;
    font-weight: bold;
    margin-top: var(--spacing-sm);
    transition: background var(--transition-fast);
    border: none;
    cursor: pointer;
}

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

.btn-secondary {
    background: var(--color-secondary);
    color: var(--color-text-inverse);
}

.btn-secondary:hover {
    background: var(--color-secondary-hover);
}

.btn-danger {
    background: var(--color-danger);
    color: var(--color-text-inverse);
}

.btn-danger:hover {
    background: var(--color-danger-hover);
}

code { 
    background: var(--color-bg-primary); 
    padding: 2px 6px; 
    border-radius: var(--radius-sm); 
    font-family: 'Courier New', monospace;
    color: var(--color-text-code);
}

/* Footer */
footer {
    background: var(--color-bg-secondary);
    border-top: 2px solid var(--color-border);
    padding: var(--spacing-lg);
    text-align: center;
    color: var(--color-text-secondary);
    font-size: 0.9em;
    margin-top: auto;
}

footer a {
    color: var(--color-primary);
    text-decoration: none;
}

footer a:hover {
    text-decoration: underline;
}

footer p {
    margin-top: var(--spacing-sm);
}

/* Utility Classes */
.hidden { 
    display: none; 
}

/* ============================================
   RESPONSIVE DESIGN
   ============================================ */
@media (max-width: 768px) {
    /* Navigation */
    nav {
        flex-direction: column;
        gap: var(--spacing-md);
        padding: var(--spacing-md);
    }
    
    .nav-links {
        flex-direction: column;
        width: 100%;
        gap: var(--spacing-sm);
    }
    
    .nav-links a {
        width: 100%;
        text-align: center;
    }
    
    .lang-selector {
        width: 100%;
        justify-content: center;
    }
    
    /* Typography */
    h1 {
        font-size: 2em;
    }
    
    h2 {
        font-size: 1.5em;
    }
    
    /* Layout */
    .main-content {
        padding: var(--spacing-md);
    }
    
    .container {
        padding: 0 var(--spacing-md);
    }
    
    header {
        padding: var(--spacing-xl) var(--spacing-md);
    }
    
    .section {
        padding: var(--spacing-lg);
        margin: var(--spacing-md) 0;
    }
}

/* Tablet */
@media (min-width: 769px) and (max-width: 1024px) {
    .container {
        max-width: 100%;
        padding: 0 var(--spacing-lg);
    }
}

/* Small mobile */
@media (max-width: 480px) {
    h1 {
        font-size: 1.75em;
    }
    
    .section {
        padding: var(--spacing-md);
    }
    
    .main-content {
        padding: var(--spacing-sm);
    }
}