:root {
    /** BACKGROUND / BG*/
    --bg-primary: #1e1e2e;
    --bg-secondary: #252536;
    --bg-tertiary: #2d2d44;

    /** TEXT */
    --text-primary: #ffffff;
    --text-secondary: #a9a9b2;
    --text-muted: #6c757d;

    /** OTHER COLORS*/
    --primary: #6c5ce7;
    --primary-hovers: #5d4fd6;
    --secondary: #a29bfe;
    --success: #00b894;
    --warning: #fdcb6e;
    --danger: #d63031;
    --border: #3d3d5c;
    --shadow: rgba(0, 0, 0, 0.3);
    --card-bg: #2a2a40;
    --button-bg: #3a3a5a;
    --button-hovers: #4a4a6a;
    --accent: #fd79a8;
}
.light-theme {
    --bg-primary: #f8f9fa;
    --bg-secondary: #e9ecef;
    --bg-tertiary: #ffffff;
    --text-primary: #212529;
    --text-secondary: #5d4fd6;
    --text-muted: #6c757d;
    --primary: #6c5ce7;
    --primary-hovers: #5d4fd6;
    --secondary: #a29bfe;
    --success: #00b894;
    --warning: #fdcb6e;
    --danger: #d63031;
    --border: #dee2e6;
    --shadow: rgba(0, 0, 0, 0.1);
    --card-bg: #ffffff;
    --button-bg: #ffffff;
    --button-hover: #e9ecef;
    --accent: #fd79a8
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
body {
    font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    transition: background-color 0.3s, color 0.3s;
}
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem;
}
header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 0;
    margin-bottom: 2rem;
}
.app-title {
    font-size: 1.8rem;
    font-weight: 700;
    color: var(--primary);
}
.settings-bar {
    display: flex;
    gap: 1rem;
}
.btn {
    background: var(--button-bg);
    color: var(--text-primary);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 0.5rem 1rem;
    cursor: pointer;
    font-size: 0.9rem;
    transition: all 0.2s;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}
.btn:hover {
    background: var(--button-hover);
}
.btn-primary {
    background: var(--primary);
    color: white;
}
.btn-primary:hover {
    background: var(--primary-hovers);
}
.btn-icon {
    padding: 0.5rem;
    border-radius: 50%;
}
.main-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
    margin-bottom: 2rem;
}
@media (max-width: 900px) {
    .main-content {
        grid-template-columns: 1fr;
    }
}
.calculator-container {
    perspective: 1000px;
}
.calculator-3d {
    width: 100%;
    transition: transform 0.3s;
    transform-style: preserve-3d;
}
.calculator-card {
    background: var(--card-bg);
    border-radius: 16px;
    padding: 1.5rem;
    box-shadow: 0 10px 30px var(--shadow);
    transform-style: preserve-3d;
    transition: transform 0.3s, box-shadow 0.3s;
    border: 1px solid var(--border);
}
.enhanced-3d .calculator-card {
    transform: translateZ(20px);
    box-shadow: 0 15px 35px var(--shadow), 0 5px 15px rgba(0, 0, 0, 0.07);
}
.enhanced-3d .calc-btn {
    transform: translateZ(10px);
    box-shadow: 0 4px 8px var(--shadow), 0 2px 4px rgba(0, 0, 0, 0.1);
}
.calc-display {
    background: var(--bg-secondary);
    border-radius: 8px;
    padding: 1rem;
    margin-bottom: 1rem;
    font-family: 'Courier New', monospace;
    text-align: right;
    min-height: 80px;
    display: flex;
    flex-direction: column;
    justify-content: flex-end;
    border: 1px solid var(--border);
}
.calc-expression {
    font-size: 0.9rem;
    color: var(--text-secondary);
    min-height: 1.2rem;
    margin-bottom: 0.5rem;
    word-break: break-all;
}
.calc-result {
    font-size: 1.8rem;
    font-weight: bold;
    word-break: break-all;
}
.calc-buttons {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 0.5rem;
}
@media (max-width: 600px) {
    .calc-buttons {
        grid-template-columns: repeat(4, 1fr);
    }
}
.calc-btn {
    background: var(--button-bg);
    color: var(--text-primary);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 0.8rem 0;
    font-size: 1.1rem;
    cursor: pointer;
    transition: all 0.1s;
    position: relative;
    transform: translateZ(0);
}
.calc-btn:active {
    transform: translateY(2px);
}
.calc-btn.operator {
    background: var(--primary);
    color: white;
}
.calc-btn.function {
    background: var(--secondary);
    color: var(--text-primary);
}
.calc-btn.memory {
    background: var(--accent);
    color: white;
}
.calc-btn.equals {
    background: var(--success);
    color: white;
}
.calc-btn.clear {
    background: var(--danger);
    color: white;
}
.calc-history {
    margin-top: 1rem;
    background: var(--bg-secondary);
    border-radius: 8px;
    padding: 1rem;
    max-height: 200px;
    overflow-y: auto;
    border: 1px solid var(--border);
}
.history-title {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}
.history-item {
    padding: 0.5rem 0;
    border-bottom: 1px solid var(--border);
    font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
}
.history-item:last-child {
    border-bottom: none;
}
.currency-converter {
    background: var(--card-bg);
    border-radius: 16px;
    padding: 1.5rem;
    box-shadow: 0 10px 30px var(--shadow);
    border: 1px solid var(--border);
}
.converter-title {
    font-size: 1.2rem;
    margin-bottom: 1rem;
    color: var(--primary);
}
.currency-form {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}
.form-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}
.form-row {
    display: flex;
    gap: 1rem;
    align-items: center;
}
.form-label {
    font-size: 0.9rem;
    color: var(--text-secondary);
}
.form-input, .form-select {
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 0.8rem;
    color: var(--text-primary);
    flex: 1;
}
.currency-result {
    margin-top: 1rem;
    padding: 1rem;
    background: var(--bg-secondary);
    border-radius: 8px;
    text-align: center;
    font-size: 1.2rem;
    font-weight: bold;
    border: 1px solid var(--border);
}
.rate-info {
    font-size: 0.8rem;
    color: var(--text-muted);
    margin-top: 0.5rem;
}
.help-panel {
    background: var(--card-bg);
    border-radius: 16px;
    padding: 1.5rem;
    margin-top: 2rem;
    border: 1px solid var(--border);
}
a {
    color: white;
}
.help-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
    cursor: pointer;
}
.help-title {
    font-size: 1.2rem;
    color: var(--primary);
}
.help-content {
    max-height: 0;
    overflow: hidde;
    transition: max-height 0.3s ease-out;
}
.help-content.expanded {
    max-height: 500px;
}
.help-section {
    margin-bottom: 1.5rem;
}
.help-section-title {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
    color: var(--secondary);
}
.keyboard-shortcuts {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
    gap: 1rem;
}
.shortcut-item {
    display: flex;
    justify-content: space-between;
    padding: 0.5rem;
    background: var(--bg-secondary);
    border-radius: 8px;
}
.key {
    background: var(--button-bg);
    padding: 0.2rem 0.5rem;
    border-radius: 4px;
    font-family: monospace;
    border: 1px solid var(--border);
}
footer {
    margin-top: auto;
    padding: 1rem 0;
    color: var(--text-muted);
    font-size: 0.9rem;
}
.tooltip {
    position: relative;
    display: inline-block;
}
.tooltip .tooltip-text {
    visibility: hidden;
    width: 200px;
    background-color: var(--bg-tertiary);
    color: var(--text-primary);
    text-align: center;
    border-radius: 6px;
    padding: 5px;
    position: absolute;
    z-index: 1;
    bottom: 125%;
    left: 50%;
    transform: translateX(-50%);
    opacity: 0;
    transition: opacity 0.3s;
    font-size: 0.8rem;
    border: 1px solid var(--border);
}
.tooltip:hover .tooltip-text {
    visibility: visible;
    opacity: 1;
}
@keyframes buttonPress {
    0% {
        transform: scale(1);
    }
    50% {
        transform: scale(0.95);
    }
    100% {
        transform: scale(1);
    }
}
.button-press {
    animation: buttonPress 0.1s;
}