/* CSS Variables for Theme Management */
:root {
    /* Light Theme Colors */
    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fa;
    --bg-tertiary: #e9ecef;
    --text-primary: #212529;
    --text-secondary: #6c757d;
    --accent-primary: #007bff;
    --accent-secondary: #6c757d;
    --border-color: #dee2e6;
    --shadow: rgba(0, 0, 0, 0.1);
    --shadow-hover: rgba(0, 0, 0, 0.15);
    
    /* Button Colors */
    --btn-number: #ffffff;
    --btn-number-text: #212529;
    --btn-operator: #007bff;
    --btn-operator-text: #ffffff;
    --btn-equals: #28a745;
    --btn-equals-text: #ffffff;
    --btn-function: #6f42c1;
    --btn-function-text: #ffffff;
    --btn-memory: #fd7e14;
    --btn-memory-text: #ffffff;
    --btn-clear: #dc3545;
    --btn-clear-text: #ffffff;
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    
    /* Border Radius */
    --radius-sm: 0.25rem;
    --radius-md: 0.5rem;
    --radius-lg: 1rem;
    
    /* Transitions */
    --transition-fast: 0.15s ease;
    --transition-normal: 0.3s ease;
}

/* Dark Theme */
[data-theme="dark"] {
    --bg-primary: #1a1a1a;
    --bg-secondary: #2d2d2d;
    --bg-tertiary: #404040;
    --text-primary: #ffffff;
    --text-secondary: #b3b3b3;
    --accent-primary: #4dabf7;
    --accent-secondary: #868e96;
    --border-color: #495057;
    --shadow: rgba(0, 0, 0, 0.3);
    --shadow-hover: rgba(0, 0, 0, 0.4);
    
    --btn-number: #2d2d2d;
    --btn-number-text: #ffffff;
    --btn-operator: #4dabf7;
    --btn-operator-text: #ffffff;
    --btn-equals: #51cf66;
    --btn-equals-text: #ffffff;
    --btn-function: #9775fa;
    --btn-function-text: #ffffff;
    --btn-memory: #ff922b;
    --btn-memory-text: #ffffff;
    --btn-clear: #ff6b6b;
    --btn-clear-text: #ffffff;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background-color: var(--bg-secondary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color var(--transition-normal), color var(--transition-normal);
}

/* Calculator Container */
.calculator-container {
    max-width: 800px;
    margin: 0 auto;
    padding: var(--spacing-md);
    display: grid;
    grid-template-columns: 1fr;
    grid-template-rows: auto auto auto 1fr;
    grid-template-areas: 
        "header"
        "voice"
        "modes"
        "main";
    gap: var(--spacing-md);
    min-height: 100vh;
}

/* Header */
.calculator-header {
    grid-area: header;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-lg);
    background: linear-gradient(135deg, var(--accent-primary), #6c5ce7, #a29bfe);
    border-radius: var(--radius-lg);
    box-shadow: 0 8px 32px rgba(0, 123, 255, 0.3);
    position: relative;
    overflow: hidden;
    animation: headerGlow 3s ease-in-out infinite alternate;
}

.calculator-header::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: linear-gradient(45deg, transparent, rgba(255, 255, 255, 0.1), transparent);
    animation: shimmer 3s linear infinite;
    pointer-events: none;
}

.header-left {
    display: flex;
    align-items: center;
}

.logo-container {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    animation: logoFloat 4s ease-in-out infinite;
}

.logo-icon {
    background: rgba(255, 255, 255, 0.2);
    border-radius: 50%;
    width: 60px;
    height: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.8rem;
    color: white;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.2);
    animation: iconSpin 8s linear infinite;
}

.title-container {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.calculator-title {
    font-size: 2.2rem;
    font-weight: 800;
    color: white;
    margin: 0;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.3);
    animation: titlePulse 2s ease-in-out infinite alternate;
}

.calculator-subtitle {
    font-size: 0.9rem;
    color: rgba(255, 255, 255, 0.8);
    margin: 0;
    font-weight: 500;
    letter-spacing: 1px;
    text-transform: uppercase;
}

.header-controls {
    display: flex;
    gap: var(--spacing-sm);
}

.control-btn {
    background: rgba(255, 255, 255, 0.2);
    border: 1px solid rgba(255, 255, 255, 0.3);
    border-radius: var(--radius-md);
    padding: var(--spacing-sm) var(--spacing-md);
    color: white;
    cursor: pointer;
    transition: all var(--transition-normal);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-xs);
    min-width: 70px;
    height: 60px;
    backdrop-filter: blur(10px);
    position: relative;
    overflow: hidden;
}

.control-btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.4), transparent);
    transition: left 0.5s;
}

.control-btn:hover::before {
    left: 100%;
}

.control-btn:hover {
    background: rgba(255, 255, 255, 0.3);
    transform: translateY(-3px) scale(1.05);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.3);
}

.control-btn i {
    font-size: 1.2rem;
    transition: transform var(--transition-fast);
}

.control-btn:hover i {
    transform: scale(1.2);
}

.control-btn.listening {
    background: linear-gradient(45deg, #28a745, #20c997);
    animation: listeningPulse 1.5s ease-in-out infinite;
}

.control-btn.listening i {
    color: white;
    animation: microphonePulse 0.8s ease-in-out infinite alternate;
}

.btn-label {
    font-size: 0.7rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    opacity: 0.9;
}

/* Voice Status Indicator */
.voice-status {
    grid-area: voice;
    background: linear-gradient(135deg, #28a745, #20c997);
    border-radius: var(--radius-md);
    padding: var(--spacing-sm) var(--spacing-md);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-weight: 600;
    box-shadow: 0 4px 15px rgba(40, 167, 69, 0.3);
    animation: voicePulse 1.5s ease-in-out infinite;
}

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

.voice-indicator i {
    font-size: 1.2rem;
    animation: microphonePulse 0.8s ease-in-out infinite alternate;
}

/* Language Modal */
.language-modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    backdrop-filter: blur(5px);
}

.modal-content {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    max-width: 400px;
    width: 90%;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
    animation: modalSlideIn 0.3s ease-out;
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-lg);
}

.modal-header h3 {
    color: var(--text-primary);
    font-size: 1.5rem;
    font-weight: 700;
}

.close-btn {
    background: none;
    border: none;
    font-size: 1.5rem;
    color: var(--text-secondary);
    cursor: pointer;
    padding: var(--spacing-xs);
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
}

.close-btn:hover {
    background: var(--bg-tertiary);
    color: var(--text-primary);
}

.language-options {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.language-option {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: var(--spacing-md);
    cursor: pointer;
    transition: all var(--transition-fast);
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    color: var(--text-primary);
    font-weight: 600;
}

.language-option:hover {
    background: var(--accent-primary);
    color: white;
    transform: translateY(-2px);
    box-shadow: 0 4px 15px rgba(0, 123, 255, 0.3);
}

.language-option i {
    font-size: 1.2rem;
}

/* Voice Settings Modal */
.voice-settings-modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    backdrop-filter: blur(5px);
}

.voice-settings-content {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

.setting-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md);
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
    border: 1px solid var(--border-color);
}

.setting-label {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    color: var(--text-primary);
    font-weight: 600;
}

.setting-label i {
    color: var(--accent-primary);
    width: 20px;
}

.toggle-switch {
    position: relative;
    width: 50px;
    height: 24px;
    cursor: pointer;
}

.toggle-switch input {
    opacity: 0;
    width: 0;
    height: 0;
}

.toggle-slider {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: 24px;
    transition: all var(--transition-fast);
}

.toggle-slider:before {
    position: absolute;
    content: "";
    height: 18px;
    width: 18px;
    left: 2px;
    bottom: 2px;
    background: white;
    border-radius: 50%;
    transition: all var(--transition-fast);
    box-shadow: 0 2px 4px rgba(0,0,0,0.2);
}

.toggle-switch input:checked + .toggle-slider {
    background: var(--accent-primary);
}

.toggle-switch input:checked + .toggle-slider:before {
    transform: translateX(26px);
}

.setting-description {
    background: var(--bg-secondary);
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
    border-left: 3px solid var(--accent-primary);
}

.setting-description p {
    color: var(--text-secondary);
    font-size: 0.9rem;
    line-height: 1.5;
    margin-bottom: var(--spacing-xs);
}

.setting-description p:last-child {
    margin-bottom: 0;
}

/* Mode Selector */
.mode-selector {
    grid-area: modes;
    display: flex;
    gap: var(--spacing-xs);
    background: var(--bg-primary);
    padding: var(--spacing-sm);
    border-radius: var(--radius-lg);
    box-shadow: 0 4px 20px var(--shadow);
    overflow-x: auto;
    position: relative;
    animation: slideInUp 0.6s ease-out 0.2s both;
}

.mode-selector::before {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--accent-primary), #6c5ce7, #a29bfe);
    border-radius: 0 0 var(--radius-lg) var(--radius-lg);
    animation: progressBar 2s ease-in-out infinite;
}

.mode-btn {
    background: var(--bg-tertiary);
    border: none;
    border-radius: var(--radius-md);
    padding: var(--spacing-sm) var(--spacing-md);
    color: var(--text-primary);
    cursor: pointer;
    transition: all var(--transition-normal);
    white-space: nowrap;
    font-weight: 600;
    position: relative;
    overflow: hidden;
    animation: fadeInScale 0.5s ease-out;
}

.mode-btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, var(--accent-primary), transparent);
    transition: left 0.3s ease;
}

.mode-btn:hover::before {
    left: 100%;
}

.mode-btn:hover {
    background: var(--accent-primary);
    color: white;
    transform: translateY(-2px) scale(1.05);
    box-shadow: 0 6px 20px rgba(0, 123, 255, 0.4);
}

.mode-btn.active {
    background: var(--accent-primary);
    color: white;
    box-shadow: 0 4px 15px rgba(0, 123, 255, 0.5);
    transform: scale(1.05);
    animation: activeGlow 2s ease-in-out infinite alternate;
}

/* Main Calculator Area */
.calculator-main {
    grid-area: main;
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    box-shadow: 0 8px 32px var(--shadow);
    padding: var(--spacing-lg);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
    position: relative;
    animation: slideInUp 0.8s ease-out 0.4s both;
    overflow: hidden;
}

.calculator-main::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: linear-gradient(90deg, var(--accent-primary), #6c5ce7, #a29bfe, var(--accent-primary));
    background-size: 200% 100%;
    animation: gradientMove 3s linear infinite;
}

/* Display */
.display-container {
    background: linear-gradient(135deg, var(--bg-secondary), var(--bg-tertiary));
    border-radius: var(--radius-md);
    padding: var(--spacing-lg);
    text-align: right;
    position: relative;
    min-height: 120px;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    box-shadow: inset 0 2px 10px rgba(0, 0, 0, 0.1);
    border: 1px solid var(--border-color);
    animation: displayGlow 0.3s ease-out;
    overflow: hidden;
}

.display-container::after {
    content: '';
    position: absolute;
    top: 0;
    right: 0;
    width: 100px;
    height: 100px;
    background: radial-gradient(circle, rgba(0, 123, 255, 0.1), transparent);
    border-radius: 50%;
    animation: displayPulse 4s ease-in-out infinite;
}

.display-secondary {
    font-size: 0.9rem;
    color: var(--text-secondary);
    min-height: 1.2em;
    word-break: break-all;
}

.display-primary {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--text-primary);
    word-break: break-all;
    line-height: 1.2;
    transition: all var(--transition-fast);
    animation: numberEntry 0.2s ease-out;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.display-memory {
    position: absolute;
    top: var(--spacing-sm);
    left: var(--spacing-sm);
    font-size: 0.8rem;
    color: var(--accent-primary);
    font-weight: 600;
}

/* Button Grids */
.button-grid {
    display: grid;
    gap: var(--spacing-sm);
    flex: 1;
}

.standard-grid {
    grid-template-columns: repeat(4, 1fr);
    grid-template-rows: repeat(6, 1fr);
}

.scientific-grid {
    grid-template-columns: repeat(5, 1fr);
    grid-template-rows: repeat(6, 1fr);
}

.programming-grid {
    grid-template-columns: repeat(4, 1fr);
    grid-template-rows: repeat(8, 1fr);
}

/* Buttons */
.btn {
    border: none;
    border-radius: var(--radius-md);
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);
    min-height: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
    user-select: none;
    position: relative;
    overflow: hidden;
}

.btn:hover {
    transform: translateY(-3px) scale(1.05);
    box-shadow: 0 8px 25px var(--shadow-hover);
    background: linear-gradient(135deg, var(--bg-tertiary), var(--accent-primary));
    color: white;
    animation: buttonHover 0.3s ease-out;
}

@keyframes buttonHover {
    0% {
        background: var(--bg-tertiary);
    }
    100% {
        background: linear-gradient(135deg, var(--bg-tertiary), var(--accent-primary));
    }
}

.btn:active {
    transform: translateY(0);
    box-shadow: 0 2px 5px var(--shadow);
    animation: buttonPress 0.1s ease-out;
}

.btn::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    background: rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    transform: translate(-50%, -50%);
    transition: width 0.3s, height 0.3s;
}

.btn:active::before {
    width: 300px;
    height: 300px;
}

/* Button Types */
.number-btn {
    background: var(--btn-number);
    color: var(--btn-number-text);
    border: 1px solid var(--border-color);
}

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

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

.function-btn {
    background: var(--btn-function);
    color: var(--btn-function-text);
    font-size: 0.9rem;
}

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

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

.hex-btn {
    background: var(--btn-function);
    color: var(--btn-function-text);
}

.hex-btn.disabled {
    background: var(--bg-tertiary);
    color: var(--text-secondary);
    cursor: not-allowed;
    opacity: 0.5;
}

.base-btn {
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    padding: var(--spacing-xs) var(--spacing-sm);
    color: var(--text-primary);
    cursor: pointer;
    transition: all var(--transition-fast);
    font-weight: 600;
    font-size: 0.9rem;
}

.base-btn.active {
    background: var(--accent-primary);
    color: white;
}

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

/* Programming Controls */
.programming-controls {
    margin-bottom: var(--spacing-md);
}

.base-selector {
    display: flex;
    gap: var(--spacing-xs);
    background: var(--bg-secondary);
    padding: var(--spacing-xs);
    border-radius: var(--radius-md);
}

/* Unit Converter */
.unit-converter {
    padding: var(--spacing-lg);
}

.unit-category {
    margin-bottom: var(--spacing-lg);
}

.unit-category select {
    width: 100%;
    padding: var(--spacing-md);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--bg-primary);
    color: var(--text-primary);
    font-size: 1rem;
}

.unit-conversion-row {
    display: flex;
    align-items: center;
    gap: var(--spacing-lg);
}

.unit-input-group {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.unit-input-group input,
.unit-input-group select {
    padding: var(--spacing-md);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--bg-primary);
    color: var(--text-primary);
    font-size: 1rem;
}

.conversion-arrow {
    font-size: 1.5rem;
    color: var(--accent-primary);
}

/* Financial Calculator */
.financial-calculator {
    padding: var(--spacing-lg);
}

.financial-tabs {
    display: flex;
    gap: var(--spacing-xs);
    margin-bottom: var(--spacing-lg);
    border-bottom: 1px solid var(--border-color);
}

.financial-tab {
    background: none;
    border: none;
    padding: var(--spacing-md);
    color: var(--text-secondary);
    cursor: pointer;
    border-bottom: 2px solid transparent;
    transition: all var(--transition-fast);
    font-weight: 600;
}

.financial-tab.active {
    color: var(--accent-primary);
    border-bottom-color: var(--accent-primary);
}

.financial-tab:hover {
    color: var(--accent-primary);
}

.financial-content {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.input-group {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.input-group label {
    font-weight: 600;
    color: var(--text-primary);
}

.input-group input {
    padding: var(--spacing-md);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--bg-primary);
    color: var(--text-primary);
    font-size: 1rem;
}

.calculate-btn {
    background: var(--accent-primary);
    color: white;
    border: none;
    border-radius: var(--radius-md);
    padding: var(--spacing-md);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.calculate-btn:hover {
    background: #0056b3;
    transform: translateY(-2px);
    box-shadow: 0 4px 15px rgba(0, 123, 255, 0.3);
}

.results {
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
    padding: var(--spacing-md);
    margin-top: var(--spacing-md);
}

/* Graphing Calculator */
.graphing-calculator {
    padding: var(--spacing-lg);
}

.graph-controls {
    display: flex;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-lg);
    flex-wrap: wrap;
}

.graph-controls input {
    flex: 1;
    min-width: 200px;
    padding: var(--spacing-md);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--bg-primary);
    color: var(--text-primary);
    font-size: 1rem;
}

.graph-controls button {
    background: var(--accent-primary);
    color: white;
    border: none;
    border-radius: var(--radius-md);
    padding: var(--spacing-sm) var(--spacing-md);
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.graph-controls button:hover {
    background: #0056b3;
    transform: translateY(-2px);
}

#graph-canvas {
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--bg-primary);
    width: 100%;
    max-width: 600px;
}

/* Statistics Calculator */
.statistics-calculator {
    padding: var(--spacing-lg);
}

.stats-input {
    margin-bottom: var(--spacing-lg);
}

#stats-data {
    width: 100%;
    min-height: 120px;
    padding: var(--spacing-md);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--bg-primary);
    color: var(--text-primary);
    font-size: 1rem;
    resize: vertical;
    margin-bottom: var(--spacing-md);
}

.stats-results {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: var(--spacing-md);
}

.stat-item {
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
    padding: var(--spacing-md);
    text-align: center;
}

.stat-label {
    font-size: 0.9rem;
    color: var(--text-secondary);
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
}

.stat-value {
    font-size: 1.5rem;
    color: var(--accent-primary);
    font-weight: 700;
}

/* Compact History Panel */
.history-panel-compact {
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
    border: 1px solid var(--border-color);
    margin-bottom: var(--spacing-md);
    overflow: hidden;
    animation: slideInUp 0.4s ease-out;
}

.history-toggle {
    width: 100%;
    background: var(--bg-secondary);
    border: none;
    padding: var(--spacing-sm) var(--spacing-md);
    display: flex;
    align-items: center;
    justify-content: space-between;
    cursor: pointer;
    color: var(--text-primary);
    font-weight: 600;
    transition: all var(--transition-fast);
}

.history-toggle:hover {
    background: var(--bg-tertiary);
}

.history-toggle .toggle-icon {
    transition: transform var(--transition-fast);
}

.history-toggle.active .toggle-icon {
    transform: rotate(180deg);
}

.history-content {
    border-top: 1px solid var(--border-color);
    background: var(--bg-primary);
    max-height: 200px;
    overflow-y: auto;
    animation: slideDown 0.3s ease-out;
}

.history-content.hidden {
    display: none;
}

.history-header {
    display: flex;
    justify-content: flex-end;
    align-items: center;
    padding: var(--spacing-sm) var(--spacing-md);
}

.btn.small {
    padding: var(--spacing-xs) var(--spacing-sm);
    font-size: 0.8rem;
    min-height: 30px;
}

.history-header h3 {
    color: var(--text-primary);
    font-size: 1.3rem;
    font-weight: 700;
}

.history-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
    max-height: 400px;
    overflow-y: auto;
}

.history-item {
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
    padding: var(--spacing-md);
    cursor: pointer;
    transition: all var(--transition-fast);
    border: 1px solid var(--border-color);
}

.history-item:hover {
    background: var(--bg-tertiary);
    transform: translateX(5px);
    box-shadow: 0 2px 10px var(--shadow);
}

.history-expression {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xs);
}

.history-result {
    font-size: 1.1rem;
    color: var(--text-primary);
    font-weight: 600;
}

/* 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: 0;
}

/* Animations */
@keyframes headerGlow {
    0% {
        box-shadow: 0 8px 32px rgba(0, 123, 255, 0.3);
    }
    100% {
        box-shadow: 0 8px 32px rgba(0, 123, 255, 0.5);
    }
}

@keyframes shimmer {
    0% {
        transform: translateX(-200%);
    }
    100% {
        transform: translateX(200%);
    }
}

@keyframes logoFloat {
    0%, 100% {
        transform: translateY(0);
    }
    50% {
        transform: translateY(-5px);
    }
}

@keyframes iconSpin {
    0% {
        transform: rotate(0deg);
    }
    100% {
        transform: rotate(360deg);
    }
}

@keyframes titlePulse {
    0% {
        text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.3);
    }
    100% {
        text-shadow: 2px 2px 8px rgba(0, 0, 0, 0.5);
    }
}

@keyframes slideInUp {
    0% {
        opacity: 0;
        transform: translateY(30px);
    }
    100% {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes slideInRight {
    0% {
        opacity: 0;
        transform: translateX(30px);
    }
    100% {
        opacity: 1;
        transform: translateX(0);
    }
}

@keyframes fadeInScale {
    0% {
        opacity: 0;
        transform: scale(0.9);
    }
    100% {
        opacity: 1;
        transform: scale(1);
    }
}

@keyframes progressBar {
    0% {
        width: 0%;
    }
    50% {
        width: 70%;
    }
    100% {
        width: 100%;
    }
}

@keyframes activeGlow {
    0% {
        box-shadow: 0 4px 15px rgba(0, 123, 255, 0.5);
    }
    100% {
        box-shadow: 0 4px 15px rgba(0, 123, 255, 0.8);
    }
}

@keyframes gradientMove {
    0% {
        background-position: 0% 50%;
    }
    100% {
        background-position: 200% 50%;
    }
}

@keyframes displayGlow {
    0% {
        box-shadow: inset 0 2px 10px rgba(0, 0, 0, 0.1);
    }
    100% {
        box-shadow: inset 0 2px 10px rgba(0, 123, 255, 0.2);
    }
}

@keyframes displayPulse {
    0%, 100% {
        opacity: 0.3;
        transform: scale(1);
    }
    50% {
        opacity: 0.6;
        transform: scale(1.1);
    }
}

@keyframes numberEntry {
    0% {
        transform: scale(1.1);
    }
    100% {
        transform: scale(1);
    }
}

@keyframes buttonPress {
    0% {
        transform: scale(1);
    }
    50% {
        transform: scale(0.95);
    }
    100% {
        transform: scale(1);
    }
}

@keyframes voicePulse {
    0%, 100% {
        box-shadow: 0 4px 15px rgba(40, 167, 69, 0.3);
        transform: scale(1);
    }
    50% {
        box-shadow: 0 4px 25px rgba(40, 167, 69, 0.6);
        transform: scale(1.02);
    }
}

@keyframes microphonePulse {
    0% {
        transform: scale(1);
    }
    100% {
        transform: scale(1.2);
    }
}

@keyframes modalSlideIn {
    0% {
        opacity: 0;
        transform: translateY(-30px) scale(0.9);
    }
    100% {
        opacity: 1;
        transform: translateY(0) scale(1);
    }
}

@keyframes slideDown {
    0% {
        max-height: 0;
        opacity: 0;
    }
    100% {
        max-height: 200px;
        opacity: 1;
    }
}

@keyframes listeningPulse {
    0% {
        box-shadow: 0 0 0 0 rgba(40, 167, 69, 0.7);
    }
    70% {
        box-shadow: 0 0 0 10px rgba(40, 167, 69, 0);
    }
    100% {
        box-shadow: 0 0 0 0 rgba(40, 167, 69, 0);
    }
}

/* Responsive Design */
@media (max-width: 768px) {
    .calculator-container {
        grid-template-columns: 1fr;
        grid-template-areas: 
            "header"
            "voice"
            "modes"
            "main";
        padding: var(--spacing-sm);
    }
    
    .calculator-header {
        flex-direction: column;
        gap: var(--spacing-md);
        text-align: center;
    }
    
    .header-controls {
        justify-content: center;
    }
    
    .mode-selector {
        justify-content: center;
    }
    
    .calculator-main {
        min-height: auto;
    }
    

    
    .unit-conversion-row {
        flex-direction: column;
        align-items: stretch;
    }
    
    .conversion-arrow {
        transform: rotate(90deg);
        align-self: center;
    }
    
    .graph-controls {
        flex-direction: column;
    }
    
    .graph-controls input {
        min-width: auto;
    }
    
    .stats-results {
        grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
    }
}

@media (max-width: 480px) {
    .calculator-title {
        font-size: 1.8rem;
    }
    
    .display-primary {
        font-size: 2rem;
    }
    
    .btn {
        min-height: 50px;
        font-size: 1rem;
    }
    
    .mode-btn {
        padding: var(--spacing-xs) var(--spacing-sm);
        font-size: 0.9rem;
    }
    
    .calculator-main {
        padding: var(--spacing-md);
    }
}