/* Kaprekar's Constant - Clean Modern Styling */

.kaprekars-container {
    max-width: 600px;
    margin: 2rem auto;
    padding: 2rem;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background: #ffffff;
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

.kaprekars-header {
    text-align: center;
    margin-bottom: 2rem;
}

.kaprekars-title {
    font-size: 1.75rem;
    font-weight: 600;
    color: #1a1a1a;
    margin: 0 0 0.5rem 0;
    letter-spacing: -0.02em;
}

.kaprekars-description {
    font-size: 0.95rem;
    color: #666;
    margin: 0;
    line-height: 1.5;
}

.kaprekars-input-section {
    display: flex;
    gap: 0.75rem;
    margin-bottom: 1rem;
}

.kaprekars-input {
    flex: 1;
    padding: 0.875rem 1rem;
    font-size: 1.125rem;
    font-weight: 500;
    letter-spacing: 0.1em;
    text-align: center;
    border: 2px solid #e0e0e0;
    border-radius: 6px;
    outline: none;
    transition: all 0.2s ease;
    font-family: 'Courier New', monospace;
}

.kaprekars-input:focus {
    border-color: #2563eb;
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.kaprekars-input::placeholder {
    color: #bbb;
    letter-spacing: normal;
    font-weight: normal;
}

.kaprekars-button {
    padding: 0.875rem 1.75rem;
    font-size: 1rem;
    font-weight: 600;
    color: #ffffff;
    background: #2563eb;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.2s ease;
    white-space: nowrap;
}

.kaprekars-button:hover {
    background: #1d4ed8;
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.3);
}

.kaprekars-button:active {
    transform: translateY(0);
}

.kaprekars-error {
    display: none;
    padding: 0.875rem;
    margin-bottom: 1rem;
    background: #fef2f2;
    border: 1px solid #fecaca;
    border-radius: 6px;
    color: #dc2626;
    font-size: 0.9rem;
    text-align: center;
}

.kaprekars-results {
    margin-top: 2rem;
}

.kaprekars-step {
    margin-bottom: 1.5rem;
    padding: 1.25rem;
    background: #f9fafb;
    border-radius: 6px;
    border-left: 3px solid #e5e7eb;
    opacity: 0;
    transform: translateY(20px);
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

.kaprekars-step.visible {
    opacity: 1;
    transform: translateY(0);
}

.kaprekars-start {
    background: #eff6ff;
    border-left-color: #3b82f6;
}

.step-label {
    font-size: 0.8rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: #6b7280;
    margin-bottom: 0.5rem;
}

.step-number {
    font-size: 1.5rem;
    font-weight: 700;
    font-family: 'Courier New', monospace;
    color: #1a1a1a;
    letter-spacing: 0.15em;
}

.step-calculation {
    margin-top: 0.75rem;
}

.calc-line {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.5rem 0;
    font-family: 'Courier New', monospace;
}

.calc-line.calc-result {
    margin-top: 0.5rem;
    padding-top: 0.75rem;
    border-top: 2px solid #e5e7eb;
}

.calc-label {
    font-size: 0.85rem;
    color: #6b7280;
    min-width: 90px;
    font-weight: 600;
}

.calc-number {
    font-size: 1.125rem;
    font-weight: 600;
    letter-spacing: 0.15em;
    color: #1a1a1a;
}

.calc-number.subtract {
    position: relative;
}

.calc-number.subtract::before {
    content: '−';
    position: absolute;
    left: -1.25rem;
    color: #dc2626;
    font-weight: 700;
}

.calc-value {
    font-size: 0.9rem;
    color: #9ca3af;
    margin-left: auto;
}

.result-number {
    color: #2563eb;
}

.result-number.constant {
    color: #16a34a;
    font-weight: 700;
}

.kaprekars-final {
    margin-top: 2rem;
    padding: 1.75rem;
    background: linear-gradient(135deg, #ecfdf5 0%, #d1fae5 100%);
    border-radius: 8px;
    border: 2px solid #86efac;
    text-align: center;
    opacity: 0;
    transform: scale(0.95);
    transition: all 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}

.kaprekars-final.visible {
    opacity: 1;
    transform: scale(1);
}

.final-message {
    font-size: 1rem;
    color: #065f46;
    margin-bottom: 1rem;
}

.final-constant {
    font-size: 3rem;
    font-weight: 700;
    font-family: 'Courier New', monospace;
    color: #16a34a;
    letter-spacing: 0.2em;
    text-shadow: 0 2px 4px rgba(22, 163, 74, 0.2);
}

/* Responsive Design */
@media (max-width: 640px) {
    .kaprekars-container {
        padding: 1.5rem;
        margin: 1rem;
    }
    
    .kaprekars-title {
        font-size: 1.5rem;
    }
    
    .kaprekars-input-section {
        flex-direction: column;
    }
    
    .kaprekars-button {
        width: 100%;
    }
    
    .calc-line {
        flex-wrap: wrap;
    }
    
    .calc-value {
        width: 100%;
        text-align: right;
        margin-left: 0;
    }
    
    .final-constant {
        font-size: 2.5rem;
    }
}

/* Dark mode support */
@media (prefers-color-scheme: dark) {
    .kaprekars-container {
        background: #1a1a1a;
        box-shadow: 0 2px 8px rgba(0, 0, 0, 0.3);
    }
    
    .kaprekars-title {
        color: #f5f5f5;
    }
    
    .kaprekars-description {
        color: #a3a3a3;
    }
    
    .kaprekars-input {
        background: #262626;
        border-color: #404040;
        color: #f5f5f5;
    }
    
    .kaprekars-input:focus {
        border-color: #3b82f6;
    }
    
    .kaprekars-step {
        background: #262626;
        border-left-color: #404040;
    }
    
    .kaprekars-start {
        background: #1e3a5f;
        border-left-color: #3b82f6;
    }
    
    .step-number,
    .calc-number {
        color: #f5f5f5;
    }
    
    .calc-line.calc-result {
        border-top-color: #404040;
    }
    
    .kaprekars-final {
        background: linear-gradient(135deg, #064e3b 0%, #065f46 100%);
        border-color: #10b981;
    }
    
    .final-message {
        color: #d1fae5;
    }
    
    .final-constant {
        color: #34d399;
    }
}