.date-calculator-app {
    max-width: 1000px;
    margin: 0 auto;
    padding: 20px;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
}

.calculator-section {
    background: #ffffff;
    border: 1px solid #e0e0e0;
    border-radius: 12px;
    padding: 25px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    transition: box-shadow 0.3s ease;
}

.calculator-section:hover {
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.15);
}

.calculator-section h2 {
    margin: 0 0 20px 0;
    color: #333;
    font-size: 1.4em;
    font-weight: 600;
    border-bottom: 2px solid #007bff;
    padding-bottom: 10px;
}

.input-group {
    margin-bottom: 20px;
}

.input-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
    color: #555;
    font-size: 0.95em;
}

.date-input,
.number-input,
.select-input {
    width: 100%;
    padding: 12px 16px;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    font-size: 1em;
    transition: all 0.3s ease;
    background: #ffffff;
}

.date-input:focus,
.number-input:focus,
.select-input:focus {
    outline: none;
    border-color: #007bff;
    box-shadow: 0 0 0 3px rgba(0, 123, 255, 0.1);
}

.number-input {
    -moz-appearance: textfield;
}

.number-input::-webkit-outer-spin-button,
.number-input::-webkit-inner-spin-button {
    -webkit-appearance: none;
    margin: 0;
}

.btn {
    padding: 12px 24px;
    border: none;
    border-radius: 8px;
    font-size: 1em;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
    width: 100%;
    margin-bottom: 20px;
}

.btn-primary {
    background: linear-gradient(135deg, #007bff, #0056b3);
    color: white;
}

.btn-primary:hover {
    background: linear-gradient(135deg, #0056b3, #004085);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 123, 255, 0.3);
}

.btn-primary:active {
    transform: translateY(0);
}

.result-section {
    background: #f8f9fa;
    border: 1px solid #e9ecef;
    border-radius: 8px;
    padding: 15px;
    min-height: 50px;
    font-family: 'Courier New', monospace;
    font-size: 0.95em;
    line-height: 1.5;
    color: #495057;
    white-space: pre-wrap;
    word-wrap: break-word;
}

.result-section:empty {
    display: none;
}

.result-section.has-content {
    display: block;
    background: #e8f5e8;
    border-color: #28a745;
    color: #155724;
}

.result-section .result-title {
    font-weight: bold;
    color: #333;
    margin-bottom: 10px;
    font-family: inherit;
}

.result-section .result-value {
    font-size: 1.1em;
    color: #007bff;
    font-weight: 600;
}

.result-section .result-details {
    margin-top: 10px;
    font-size: 0.9em;
    color: #666;
}

.message {
    grid-column: 1 / -1;
    padding: 15px;
    border-radius: 8px;
    margin-top: 20px;
    text-align: center;
    font-weight: 500;
    display: none;
}

.message.success {
    background: #d4edda;
    border: 1px solid #c3e6cb;
    color: #155724;
    display: block;
}

.message.error {
    background: #f8d7da;
    border: 1px solid #f5c6cb;
    color: #721c24;
    display: block;
}

/* Responsive Design */
@media (max-width: 768px) {
    .date-calculator-app {
        grid-template-columns: 1fr;
        padding: 15px;
        gap: 20px;
    }
    
    .calculator-section {
        padding: 20px;
    }
    
    .calculator-section h2 {
        font-size: 1.2em;
    }
    
    .date-input,
    .number-input,
    .select-input {
        padding: 10px 14px;
    }
    
    .btn {
        padding: 10px 20px;
    }
}

@media (max-width: 480px) {
    .date-calculator-app {
        padding: 10px;
    }
    
    .calculator-section {
        padding: 15px;
    }
    
    .calculator-section h2 {
        font-size: 1.1em;
    }
    
    .input-group label {
        font-size: 0.9em;
    }
    
    .date-input,
    .number-input,
    .select-input {
        padding: 8px 12px;
        font-size: 0.95em;
    }
}