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

body {
    font-family: 'Inter', sans-serif;
    background-color: #f8fafc;
    color: #374151;
    line-height: 1.6;
}

.header {
    background: linear-gradient(135deg, #1e3a8a, #1e293b);
    color: white;
    text-align: center;
    padding: 2rem;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
}

.header h1 {
    font-family: 'STIX Two Math', serif;
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
}

.header p {
    font-size: 1.125rem;
    opacity: 0.9;
}

.main-container {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: 2rem;
    max-width: 1400px;
    margin: 2rem auto;
    padding: 0 1rem;
}

.input-panel {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    height: fit-content;
}

.function-input-section {
    margin-bottom: 2rem;
}

.function-input-section label {
    display: block;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: #1e293b;
}

#function-input {
    width: 100%;
    padding: 0.75rem;
    border: 2px solid #e5e7eb;
    border-radius: 8px;
    font-family: 'Courier New', monospace;
    font-size: 1rem;
    transition: border-color 0.2s;
}

#function-input:focus {
    outline: none;
    border-color: #3b82f6;
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

.helper-buttons {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin: 1rem 0;
}

.helper-btn {
    padding: 0.375rem 0.75rem;
    background: #f3f4f6;
    border: 1px solid #d1d5db;
    border-radius: 6px;
    cursor: pointer;
    font-family: 'STIX Two Math', serif;
    font-size: 0.875rem;
    transition: all 0.2s;
}

.helper-btn:hover {
    background: #e5e7eb;
    transform: translateY(-1px);
}

.syntax-guide {
    color: #6b7280;
    font-size: 0.875rem;
}

.limits-section {
    margin-bottom: 2rem;
    padding: 1rem;
    background: #f9fafb;
    border-radius: 8px;
    border: 1px solid #e5e7eb;
}

.limit-input {
    margin-bottom: 1rem;
}

.limit-input label {
    display: block;
    font-weight: 500;
    margin-bottom: 0.25rem;
    color: #374151;
}

.limit-input input {
    width: 100%;
    padding: 0.5rem;
    border: 1px solid #d1d5db;
    border-radius: 6px;
    font-size: 0.875rem;
}

.limit-input input:focus {
    outline: none;
    border-color: #3b82f6;
    box-shadow: 0 0 0 2px rgba(59, 130, 246, 0.1);
}

.limit-indicator {
    text-align: center;
    font-family: 'STIX Two Math', serif;
    font-size: 1rem;
    color: #6b7280;
    font-style: italic;
}

.control-buttons {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

#calculate-btn {
    background: linear-gradient(135deg, #3b82f6, #1e40af);
    color: white;
    border: none;
    padding: 0.875rem 1.5rem;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
}

#calculate-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 20px -5px rgba(59, 130, 246, 0.3);
}

#clear-btn {
    background: #f3f4f6;
    color: #374151;
    border: 1px solid #d1d5db;
    padding: 0.75rem 1.5rem;
    border-radius: 8px;
    font-size: 0.875rem;
    cursor: pointer;
    transition: all 0.2s;
}

#clear-btn:hover {
    background: #e5e7eb;
}

#examples-dropdown {
    padding: 0.75rem;
    border: 1px solid #d1d5db;
    border-radius: 8px;
    background: white;
    cursor: pointer;
    font-size: 0.875rem;
}

.visualization-panel {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
}

.canvas-container {
    border: 2px solid #e5e7eb;
    border-radius: 8px;
    overflow: hidden;
    margin-bottom: 1rem;
}

#graph-canvas {
    display: block;
    width: 100%;
    height: auto;
    max-width: 600px;
}

.graph-controls {
    display: flex;
    gap: 0.5rem;
    justify-content: center;
}

.graph-controls button {
    padding: 0.5rem 1rem;
    background: #f3f4f6;
    border: 1px solid #d1d5db;
    border-radius: 6px;
    cursor: pointer;
    font-size: 0.875rem;
    transition: all 0.2s;
}

.graph-controls button:hover {
    background: #e5e7eb;
}

.results-panel {
    background: white;
    margin: 2rem auto;
    max-width: 1400px;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 2rem;
}

.calculation-output {
    text-align: center;
}

#integral-notation {
    font-family: 'STIX Two Math', serif;
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: #1e293b;
}

#result-value {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    font-family: 'STIX Two Math', serif;
}

#method-info {
    color: #6b7280;
    font-size: 0.875rem;
}

.additional-info {
    padding: 1rem;
    background: #f9fafb;
    border-radius: 8px;
    border: 1px solid #e5e7eb;
}

#function-info {
    font-size: 0.875rem;
    color: #374151;
}

/* Responsive Design */
@media (max-width: 1024px) {
    .main-container {
        grid-template-columns: 1fr;
    }
    
    .results-panel {
        grid-template-columns: 1fr;
        text-align: center;
    }
}

@media (max-width: 768px) {
    .header h1 {
        font-size: 2rem;
    }
    
    .header p {
        font-size: 1rem;
    }
    
    .input-panel,
    .visualization-panel,
    .results-panel {
        margin: 1rem;
        padding: 1rem;
    }
    
    .helper-buttons {
        justify-content: center;
    }
    
    .graph-controls {
        flex-wrap: wrap;
    }
}

/* Smooth animations */
* {
    transition: all 0.2s ease;
}

button:active {
    transform: translateY(0) scale(0.98);
}

input:focus,
select:focus {
    animation: focusGlow 0.3s ease;
}

@keyframes focusGlow {
    0% { box-shadow: 0 0 0 0 rgba(59, 130, 246, 0.3); }
    50% { box-shadow: 0 0 0 4px rgba(59, 130, 246, 0.2); }
    100% { box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1); }
}

/* Mathematical expressions */
sub, sup {
    font-size: 0.75em;
}

sup {
    vertical-align: super;
}

sub {
    vertical-align: sub;
}