/* style.css - Physics & Chemistry Mind Map
   FIXED: No flash on reload, smooth transitions
*/

/* ===== PREVENT FLASH ON LOAD ===== */
html.js-loading {
    visibility: hidden;
    opacity: 0;
}

html.js-loaded {
    visibility: visible;
    opacity: 1;
    transition: opacity 0.2s ease;
}

/* Transitions disabled by default */
.sidebar {
    transition: none !important;
}

.sidebar-content,
.sidebar-title {
    transition: none !important;
}

/* Transitions enabled after page load */
.sidebar.transitions-ready {
    transition: width 0.3s ease !important;
}

.sidebar.transitions-ready .sidebar-content,
.sidebar.transitions-ready .sidebar-title {
    transition: opacity 0.2s ease !important;
}

/* ===== CSS VARIABLES ===== */
:root {
    /* Colors - Chemistry Theme (Default) */
    --color-primary: #0969da;
    --color-primary-light: #4d7dc1;
    --color-primary-dark: #0a58ca;
    --color-accent: #e6b800;
    --color-accent-light: #ffd966;
    --color-accent-dark: #b38f00;
    
    /* Neutral Colors */
    --color-bg-primary: #eef2f7;
    --color-bg-secondary: #ffffff;
    --color-bg-tertiary: #f6f8fa;
    --color-bg-elevated: #ffffff;
    --color-bg-hover: #f3f4f6;
    --color-bg-sidebar: #f6f8fa;
    
    /* Text Colors */
    --color-text-primary: #24292f;
    --color-text-secondary: #57606a;
    --color-text-muted: #6e7781;
    --color-text-disabled: #8c959f;
    
    /* Border Colors */
    --color-border: #d0d7de;
    --color-border-light: #d0d7de;
    --color-border-hover: #6e7781;
    
    /* Status Colors */
    --color-success: #4CAF50;
    --color-warning: #ffd966;
    --color-error: #ff6b6b;
    --color-info: #0969da;
    
    /* Node Colors */
    --node-subject: #ff6b6b;
    --node-chapter: #4ecdc4;
    --node-topic: #45b7d1;
    --node-concept: #96ceb4;
    --node-description: #ffeaa7;
    
    /* Spacing */
    --spacing-xs: 4px;
    --spacing-sm: 8px;
    --spacing-md: 12px;
    --spacing-lg: 16px;
    --spacing-xl: 20px;
    --spacing-xxl: 24px;
    
    /* Typography */
    --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
    --font-family-hindi: 'Noto Sans Devanagari', -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
    --font-size-xs: 11px;
    --font-size-sm: 12px;
    --font-size-md: 13px;
    --font-size-lg: 14px;
    --font-size-xl: 16px;
    --font-size-xxl: 18px;
    
    /* Border Radius */
    --radius-sm: 4px;
    --radius-md: 6px;
    --radius-lg: 8px;
    --radius-xl: 12px;
    --radius-full: 9999px;
    
    /* Shadows */
    --shadow-sm: 0 1px 0 rgba(0,0,0,0.04);
    --shadow-md: 0 4px 12px rgba(0,0,0,0.08);
    --shadow-lg: 0 4px 12px rgba(0,0,0,0.15);
    --shadow-xl: 0 8px 24px rgba(0,0,0,0.12);
    
    /* Layout */
    --sidebar-width: 320px;
    --sidebar-collapsed-width: 50px;
    --header-height: 60px;
}

/* Physics Theme Variables */
[data-theme="physics"] {
    --color-primary: #e6b800;
    --color-primary-light: #ffd966;
    --color-primary-dark: #b38f00;
    --color-accent: #0969da;
    --color-accent-light: #4d7dc1;
    --color-accent-dark: #0a58ca;
}

/* ===== RESET & BASE STYLES ===== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

*::before,
*::after {
    box-sizing: inherit;
}

html {
    font-size: 16px;
    height: 100%;
}

body {
    font-family: var(--font-family);
    display: flex;
    height: 100vh;
    overflow: hidden;
    background: var(--color-bg-primary);
    color: var(--color-text-primary);
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Hindi font support */
body.hindi-active,
body.hindi-active .sidebar,
body.hindi-active .instructions,
body.hindi-active .content-info,
body.hindi-active .footer,
body.hindi-active .tab-btn,
body.hindi-active .node text {
    font-family: var(--font-family-hindi);
}

/* ===== SCIENCE PAGE LAYOUT ===== */
.science-page {
    display: flex;
    height: 100vh;
    overflow: hidden;
    position: relative;
}

/* ===== SIDEBAR STYLES ===== */
.sidebar {
    width: var(--sidebar-width);
    background: var(--color-bg-sidebar);
    border-right: 1px solid var(--color-border);
    display: flex;
    flex-direction: column;
    position: relative;
    overflow: hidden;
    flex-shrink: 0;
    z-index: 20;
}

.sidebar.collapsed {
    width: var(--sidebar-collapsed-width);
}

.sidebar.collapsed .sidebar-content,
.sidebar.collapsed .sidebar-title {
    opacity: 0;
    pointer-events: none;
}

.sidebar:not(.collapsed) .sidebar-content,
.sidebar:not(.collapsed) .sidebar-title {
    opacity: 1;
    pointer-events: auto;
}

/* Sidebar Header */
.sidebar-header {
    padding: var(--spacing-lg);
    background: var(--color-bg-secondary);
    border-bottom: 1px solid var(--color-border);
    display: flex;
    align-items: center;
    justify-content: space-between;
    min-height: var(--header-height);
}

.sidebar.collapsed .sidebar-header {
    padding: var(--spacing-lg) var(--spacing-sm);
}

.sidebar-title {
    font-size: var(--font-size-xl);
    font-weight: 600;
    color: var(--color-text-primary);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

/* ===== SQUARE BUTTON STYLE - LIKE ELECTRICAL ===== */
.sidebar-toggle {
    width: 30px;
    height: 30px;
    background: var(--color-bg-tertiary);
    border: 1px solid var(--color-border);
    border-radius: 4px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 18px;
    color: var(--color-text-primary);
    box-shadow: var(--shadow-sm);
    transition: all 0.3s ease;
    flex-shrink: 0;
    line-height: 1;
    font-weight: bold;
}

.sidebar-toggle:hover {
    background: var(--color-bg-hover);
    transform: scale(1.05);
    border-color: var(--color-border-hover);
}

.sidebar.collapsed .sidebar-toggle {
    background: var(--color-bg-hover);
    border-radius: 4px;
}
/* ===== END SQUARE BUTTON STYLE ===== */

/* Sidebar Content */
.sidebar-content {
    flex: 1;
    overflow-y: auto;
    padding: var(--spacing-xl);
    scrollbar-width: thin;
    scrollbar-color: var(--color-border) var(--color-bg-tertiary);
}

/* Section Styles */
.section {
    margin-bottom: var(--spacing-xxl);
}

.section h3 {
    font-size: var(--font-size-lg);
    font-weight: 600;
    margin-bottom: var(--spacing-md);
    color: var(--color-text-primary);
    border-bottom: 1px solid var(--color-border);
    padding-bottom: var(--spacing-sm);
}

hr {
    border: none;
    border-top: 1px solid var(--color-border);
    margin: var(--spacing-xl) 0;
}

/* Radio Group */
.radio-group {
    margin-bottom: var(--spacing-md);
}

.radio-label {
    display: block;
    margin-bottom: var(--spacing-sm);
    cursor: pointer;
    font-size: var(--font-size-lg);
    color: var(--color-text-primary);
}

.radio-label input {
    margin-right: var(--spacing-sm);
    cursor: pointer;
}

/* Instructions */
.instructions {
    font-size: var(--font-size-md);
    line-height: 1.6;
    color: var(--color-text-secondary);
    background: var(--color-bg-secondary);
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
    border: 1px solid var(--color-border);
}

/* Content Info */
.content-info {
    font-size: var(--font-size-md);
    line-height: 1.6;
    color: var(--color-text-secondary);
    background: var(--color-bg-secondary);
    padding: var(--spacing-lg);
    border-radius: var(--radius-md);
    border: 1px solid var(--color-border);
    box-shadow: var(--shadow-sm);
}

.content-info strong {
    color: var(--color-text-primary);
    font-weight: 600;
}

.content-info hr {
    margin: var(--spacing-sm) 0;
}

/* Legend */
.legend {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.legend-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    padding: var(--spacing-xs) 0;
}

.legend-color {
    width: 16px;
    height: 16px;
    border-radius: var(--radius-sm);
    filter: drop-shadow(var(--shadow-sm));
}

.legend-color.subject { background: var(--node-subject); }
.legend-color.chapter { background: var(--node-chapter); }
.legend-color.topic { background: var(--node-topic); }
.legend-color.concept { background: var(--node-concept); }
.legend-color.description { background: var(--node-description); }

/* Status Badge */
.status-badge {
    background: var(--color-bg-secondary);
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: var(--font-size-sm);
    border: 1px solid var(--color-border);
}

.status-dot {
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background: var(--color-success);
    animation: pulse 2s infinite;
    box-shadow: 0 0 0 2px rgba(76, 175, 80, 0.2);
}

/* Keyboard Shortcut */
.shortcut-info {
    background: var(--color-bg-tertiary);
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
    font-size: var(--font-size-xs);
    color: var(--color-text-muted);
    border: 1px solid var(--color-border);
}

.shortcut-info kbd {
    background: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    padding: 2px 6px;
    font-family: 'SF Mono', Monaco, 'Cascadia Code', 'Roboto Mono', monospace;
    color: var(--color-text-primary);
    font-size: var(--font-size-xs);
    box-shadow: var(--shadow-sm);
}

/* Footer */
.footer {
    font-size: var(--font-size-xs);
    color: var(--color-text-muted);
    text-align: center;
    border-top: 1px solid var(--color-border);
    padding-top: var(--spacing-lg);
    margin-top: var(--spacing-xxl);
}

/* ===== NAVIGATION STYLES ===== */
.navigation-container {
    width: 100%;
}

.nav-links-wrapper {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

.nav-category {
    background: var(--color-bg-secondary);
    border-radius: var(--radius-md);
    padding: var(--spacing-lg);
    border: 1px solid var(--color-border);
    margin-bottom: var(--spacing-xs);
    transition: all var(--transition-fast);
    box-shadow: var(--shadow-sm);
}

.nav-category:hover {
    box-shadow: var(--shadow-md);
}

.nav-category h4 {
    color: var(--color-text-primary);
    font-size: var(--font-size-lg);
    margin-bottom: var(--spacing-md);
    padding-bottom: var(--spacing-sm);
    border-bottom: 1px solid var(--color-border);
    font-weight: 600;
}

.nav-link {
    display: inline-block;
    padding: var(--spacing-sm) var(--spacing-lg);
    background: var(--color-primary);
    color: white;
    text-decoration: none;
    border-radius: var(--radius-md);
    font-size: var(--font-size-lg);
    font-weight: 500;
    margin-right: var(--spacing-sm);
    margin-bottom: var(--spacing-sm);
    transition: all var(--transition-fast);
    border: 1px solid var(--color-primary-dark);
}

.nav-link:hover {
    background: var(--color-primary-dark);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.nav-link.active {
    background: var(--color-primary-dark);
    border-color: var(--color-primary-dark);
    font-weight: 600;
}

/* ===== MAIN CONTENT ===== */
.main-content {
    flex: 1;
    position: relative;
    overflow: hidden;
    display: flex;
    flex-direction: column;
    background: var(--color-bg-secondary);
}

/* Header Controls - Like Electrical */
.header-controls {
    position: absolute;
    top: 15px;
    left: 25px;
    right: 25px;
    z-index: 1000;
    display: flex;
    justify-content: space-between;
    align-items: center;
    pointer-events: none;
}

.header-controls .tabs {
    position: static;
    pointer-events: auto;
    display: flex;
    gap: var(--spacing-sm);
}

.header-controls .badge {
    background: var(--color-bg-tertiary);
    color: var(--color-text-primary);
    padding: 8px 20px;
    border-radius: 30px;
    font-size: 14px;
    font-weight: 600;
    box-shadow: var(--shadow-md);
    border: 1px solid var(--color-border);
    pointer-events: auto;
}

/* Tabs */
.tabs {
    display: flex;
    gap: var(--spacing-sm);
}

.tab-btn {
    padding: var(--spacing-sm) var(--spacing-lg);
    background: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    cursor: pointer;
    font-weight: 500;
    font-size: var(--font-size-lg);
    color: var(--color-text-primary);
    transition: all var(--transition-fast);
    box-shadow: var(--shadow-sm);
}

.tab-btn:hover {
    background: var(--color-bg-hover);
    border-color: var(--color-border-hover);
}

.tab-btn.active {
    background: var(--color-primary);
    color: white;
    border-color: var(--color-primary);
}

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

/* Container */
#container {
    flex: 1;
    overflow: auto;
    position: relative;
    background: var(--color-bg-secondary);
    padding: var(--spacing-xl);
}

/* SVG Styles */
svg {
    display: block;
    margin: 0 auto;
    background: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
}

/* Node styling */
.node rect {
    filter: drop-shadow(var(--shadow-sm));
    transition: filter var(--transition-fast);
    cursor: pointer;
}

.node:hover rect {
    filter: drop-shadow(var(--shadow-lg));
}

.node text {
    user-select: none;
    font-family: inherit;
    pointer-events: none;
    fill: var(--color-text-primary);
    font-weight: 500;
}

/* Connection paths */
.connection path {
    stroke: var(--color-text-muted);
    stroke-width: 2;
    fill: none;
    stroke-linecap: round;
    opacity: 0.8;
    transition: stroke var(--transition-fast);
    pointer-events: none;
}

.connection:hover path {
    stroke: var(--color-primary);
}

/* ===== SCROLLBAR STYLES ===== */
::-webkit-scrollbar {
    width: 12px;
    height: 12px;
}

::-webkit-scrollbar-track {
    background: var(--color-bg-tertiary);
}

::-webkit-scrollbar-thumb {
    background: #c0c7cf;
    border-radius: var(--radius-md);
    border: 3px solid var(--color-bg-tertiary);
}

::-webkit-scrollbar-thumb:hover {
    background: #a0a9b3;
}

::-webkit-scrollbar-corner {
    background: var(--color-bg-tertiary);
}

/* ===== ANIMATIONS ===== */
@keyframes pulse {
    0% { opacity: 1; }
    50% { opacity: 0.8; }
    100% { opacity: 1; }
}

.start-state {
    animation: pulse 2s infinite;
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateX(-20px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Apply animations */
.sidebar-content,
.content-info,
.instructions,
.legend {
    animation: fadeIn var(--transition-base);
}

/* ===== RESPONSIVE DESIGN ===== */
@media (max-width: 1024px) {
    :root {
        --sidebar-width: 300px;
    }
}

@media (max-width: 768px) {
    :root {
        --sidebar-width: 280px;
        --sidebar-collapsed-width: 50px;
        --header-height: 50px;
        --spacing-xl: 16px;
        --spacing-xxl: 20px;
    }
    
    .header-controls {
        left: 15px;
        right: 15px;
    }
    
    .header-controls .badge {
        padding: 6px 15px;
        font-size: var(--font-size-sm);
    }
    
    .tab-btn {
        padding: 6px 12px;
        font-size: var(--font-size-sm);
    }
    
    #container {
        padding: var(--spacing-md);
    }
    
    .nav-link {
        padding: 6px 12px;
        font-size: var(--font-size-sm);
    }
}

@media (max-width: 480px) {
    :root {
        --sidebar-width: 250px;
    }
    
    .header-controls {
        top: 10px;
        left: 10px;
        right: 10px;
    }
    
    .header-controls .badge {
        padding: 4px 10px;
        font-size: var(--font-size-xs);
    }
    
    .tab-btn {
        padding: 4px 8px;
        font-size: var(--font-size-xs);
    }
    
    .sidebar-header {
        padding: var(--spacing-md);
    }
    
    .sidebar-content {
        padding: var(--spacing-md);
    }
}

/* ===== HIGH CONTRAST MODE ===== */
@media (prefers-contrast: high) {
    :root {
        --color-bg-primary: #ffffff;
        --color-bg-secondary: #ffffff;
        --color-text-primary: #000000;
        --color-text-secondary: #000000;
        --color-border: #000000;
        --color-primary: #0000ff;
    }
    
    .node rect {
        stroke-width: 2px;
        stroke: #000000;
    }
    
    .connection path {
        stroke-width: 2px;
        stroke: #000000;
    }
}

/* ===== REDUCED MOTION ===== */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }
}

/* ===== PRINT STYLES ===== */
@media print {
    .sidebar,
    .header-controls {
        display: none !important;
    }
    
    .main-content {
        margin: 0;
        padding: 0;
        background: white;
    }
    
    #container svg {
        background: white;
        border: 1px solid #000;
        box-shadow: none;
    }
    
    .node text {
        fill: black;
    }
    
    .connection path {
        stroke: #666 !important;
    }
}

/* ===== LOADING STATE ===== */
.loading {
    display: flex;
    align-items: center;
    justify-content: center;
    height: 100%;
    color: var(--color-text-muted);
    font-size: var(--font-size-lg);
}

.loading::after {
    content: '';
    width: 20px;
    height: 20px;
    margin-left: var(--spacing-sm);
    border: 2px solid var(--color-border);
    border-top-color: var(--color-primary);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* ===== ERROR STATE ===== */
.error-message {
    color: var(--color-error);
    background: rgba(255, 107, 107, 0.1);
    border: 1px solid var(--color-error);
    padding: var(--spacing-xl);
    border-radius: var(--radius-lg);
    margin: var(--spacing-xl);
    text-align: center;
}

/* ===== FOCUS STATES ===== */
.sidebar-toggle:focus-visible,
.tab-btn:focus-visible,
.nav-link:focus-visible,
.radio-label input:focus-visible {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}