:root {
    --primary-color: #0052CC;
    --primary-hover: #0065FF;
    --secondary-color: #42526E;
    --success-color: #00875A;
    --warning-color: #FF991F;
    --error-color: #DE350B;
    --background: #FFFFFF;
    --surface: #F4F5F7;
    --border: #DFE1E6;
    --text-primary: #172B4D;
    --text-secondary: #6B778C;
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.12);
    --shadow-md: 0 4px 6px rgba(0,0,0,0.1);
    --shadow-lg: 0 10px 20px rgba(0,0,0,0.15);
    --radius: 8px;
    --transition: all 0.3s ease;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Fira Sans', 'Droid Sans', 'Helvetica Neue', sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    color: var(--text-primary);
    line-height: 1.6;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
}

header {
    background: var(--background);
    border-radius: var(--radius);
    padding: 2rem;
    margin-bottom: 2rem;
    box-shadow: var(--shadow-lg);
    text-align: center;
}

h1 {
    font-size: 2.5rem;
    font-weight: 700;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    margin-bottom: 0.5rem;
}

.subtitle {
    color: var(--text-secondary);
    font-size: 1.1rem;
}

.language-switcher {
    display: flex;
    gap: 0.5rem;
    justify-content: center;
    margin-top: 1rem;
}

.lang-btn {
    padding: 0.5rem 1rem;
    background: var(--surface);
    border: 2px solid var(--border);
    border-radius: var(--radius);
    cursor: pointer;
    transition: var(--transition);
    font-weight: 500;
}

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

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

.main-content {
    display: grid;
    gap: 2rem;
}

.card {
    background: var(--background);
    border-radius: var(--radius);
    padding: 2rem;
    box-shadow: var(--shadow-md);
}

.card-title {
    font-size: 1.3rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.card-title::before {
    content: '';
    width: 4px;
    height: 24px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border-radius: 2px;
}

.input-group {
    display: grid;
    grid-template-columns: 1fr auto;
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.input-field {
    padding: 0.75rem 1rem;
    border: 2px solid var(--border);
    border-radius: var(--radius);
    font-size: 1rem;
    transition: var(--transition);
    background: var(--surface);
}

.input-field:focus {
    outline: none;
    border-color: var(--primary-color);
    background: var(--background);
}

.select-field {
    padding: 0.75rem 1rem;
    border: 2px solid var(--border);
    border-radius: var(--radius);
    font-size: 1rem;
    background: var(--surface);
    cursor: pointer;
    transition: var(--transition);
}

.select-field:focus {
    outline: none;
    border-color: var(--primary-color);
    background: var(--background);
}

.button-group {
    display: flex;
    gap: 1rem;
}

.btn {
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: var(--radius);
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

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

.btn-primary:hover {
    background: var(--primary-hover);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background: var(--surface);
    color: var(--text-primary);
    border: 2px solid var(--border);
}

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

.results-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1rem;
}

.result-card {
    background: var(--surface);
    padding: 1.5rem;
    border-radius: var(--radius);
    border: 2px solid var(--border);
    transition: var(--transition);
}

.result-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
    border-color: var(--primary-color);
}

.result-label {
    display: block;
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 0.5rem;
    font-weight: 500;
}

.result-value-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.result-value {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--text-primary);
    font-family: 'Courier New', monospace;
}

.copy-btn {
    padding: 0.25rem 0.75rem;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.85rem;
    transition: var(--transition);
}

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

.bit-container {
    display: flex;
    flex-wrap: wrap;
    gap: 0.25rem;
    padding: 1rem;
    background: var(--surface);
    border-radius: var(--radius);
    justify-content: center;
}

.bit {
    width: 30px;
    height: 50px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    border-radius: 4px;
    transition: var(--transition);
}

.bit-on {
    background: var(--success-color);
    color: white;
}

.bit-off {
    background: var(--surface);
    border: 2px solid var(--border);
    color: var(--text-secondary);
}

.bit-value {
    font-size: 1.2rem;
    font-weight: bold;
}

.bit-position {
    font-size: 0.7rem;
    opacity: 0.7;
}

.bit-separator {
    width: 2px;
    height: 50px;
    background: var(--border);
    margin: 0 0.5rem;
}

.bit-info {
    text-align: center;
    margin-top: 1rem;
    padding: 1rem;
    background: var(--background);
    border-radius: var(--radius);
    font-family: 'Courier New', monospace;
    color: var(--text-primary);
}

.steps-container {
    display: grid;
    gap: 1rem;
}

.step-card {
    background: var(--surface);
    border-radius: var(--radius);
    overflow: hidden;
    border: 2px solid var(--border);
}

.step-header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 0.75rem 1rem;
    font-weight: 500;
}

.step-content {
    padding: 1rem;
}

.conversion-math {
    font-family: 'Courier New', monospace;
    line-height: 2;
}

.conversion-math div {
    padding: 0.25rem 0;
}

.conversion-result {
    margin-top: 0.5rem;
    padding-top: 0.5rem;
    border-top: 2px solid var(--border);
    font-weight: bold;
    color: var(--primary-color);
}

.bitwise-section {
    margin-top: 2rem;
}

.bitwise-inputs {
    display: grid;
    grid-template-columns: 1fr 1fr auto;
    gap: 1rem;
    margin-bottom: 1rem;
}

.bitwise-visualization {
    background: var(--surface);
    padding: 1.5rem;
    border-radius: var(--radius);
    font-family: 'Courier New', monospace;
}

.bitwise-row {
    padding: 0.5rem 0;
    display: flex;
    align-items: center;
}

.bitwise-label {
    display: inline-block;
    width: 80px;
    font-weight: bold;
    color: var(--text-secondary);
}

.bitwise-operator {
    border-top: 2px solid var(--border);
    border-bottom: 2px solid var(--border);
    margin: 0.5rem 0;
    padding-left: 80px;
    font-weight: bold;
}

.bitwise-result {
    background: var(--background);
    margin-top: 0.5rem;
    padding: 0.5rem;
    border-radius: 4px;
}

.bit-char {
    padding: 0 2px;
}

.bit-one {
    color: var(--success-color);
    font-weight: bold;
}

.bit-zero {
    color: var(--text-secondary);
}

.bitwise-result-card {
    background: var(--surface);
    padding: 1.5rem;
    border-radius: var(--radius);
    border: 2px solid var(--primary-color);
}

.result-header {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.result-formats {
    display: flex;
    gap: 2rem;
    margin-bottom: 1rem;
}

.result-formats span {
    font-family: 'Courier New', monospace;
}

.bitwise-explanation {
    margin-top: 1rem;
}

.toast {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    background: var(--success-color);
    color: white;
    padding: 1rem 1.5rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow-lg);
    opacity: 0;
    transform: translateY(20px);
    transition: var(--transition);
    z-index: 1000;
}

.toast.show {
    opacity: 1;
    transform: translateY(0);
}

#errorMessage {
    display: none;
    background: var(--error-color);
    color: white;
    padding: 1rem;
    border-radius: var(--radius);
    margin-bottom: 1rem;
}

.history-list {
    max-height: 200px;
    overflow-y: auto;
}

.history-item {
    padding: 0.75rem;
    background: var(--surface);
    border-radius: var(--radius);
    margin-bottom: 0.5rem;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    transition: var(--transition);
}

.history-item:hover {
    background: var(--border);
}

.history-time {
    color: var(--text-secondary);
    font-size: 0.85rem;
}

.no-history {
    text-align: center;
    color: var(--text-secondary);
    padding: 2rem;
}

@media (max-width: 768px) {
    .container {
        padding: 1rem;
    }
    
    h1 {
        font-size: 1.8rem;
    }
    
    .input-group {
        grid-template-columns: 1fr;
    }
    
    .bitwise-inputs {
        grid-template-columns: 1fr;
    }
    
    .results-grid {
        grid-template-columns: 1fr;
    }
    
    .bit-container {
        padding: 0.5rem;
    }
    
    .bit {
        width: 25px;
        height: 40px;
    }
    
    .result-formats {
        flex-direction: column;
        gap: 0.5rem;
    }
}