.tool-fullwidth {
    width: 100%;
    max-width: 100%;
    margin: 0;
    padding: 0;
}

/* Tool shell */
.academic-tool {
    max-width: 100%;
    margin: 0 auto;
}

.academic-tool.editor-section,
.editor-section.academic-tool {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.academic-tool .card:not(.result-card) {
    border: 1px solid var(--color-border, #e5e7eb);
    box-shadow: var(--shadow-sm, 0 1px 3px rgba(0, 0, 0, 0.06));
    border-radius: var(--radius, 12px);
    background: var(--color-surface, #fff);
}

.academic-tool .card-body {
    padding: 1.25rem 1.35rem;
}

.academic-tool .card-title {
    color: var(--color-text, #1f2937);
    font-weight: 700;
    font-size: 1.05rem;
}

.academic-tool .form-control,
.academic-tool .form-select,
.academic-tool .select-input,
.academic-tool textarea {
    border-radius: 8px;
    border: 1px solid var(--color-border, #e5e7eb);
}

.academic-tool .form-control:focus,
.academic-tool .form-select:focus,
.academic-tool textarea:focus {
    border-color: var(--color-primary, #0d9488);
    box-shadow: 0 0 0 3px rgba(13, 148, 136, 0.15);
}

.academic-tool .btn-primary {
    background: var(--color-primary, #0d9488);
    border-color: var(--color-primary, #0d9488);
}

.academic-tool .btn-primary:hover {
    background: var(--color-primary-hover, #0f766e);
    border-color: var(--color-primary-hover, #0f766e);
}

.academic-tool .alert {
    border-radius: 10px;
}

[data-theme="dark"] .academic-tool .card:not(.result-card) {
    background: var(--color-surface, #1f2937);
    border-color: var(--color-border, #374151);
}

[data-theme="dark"] .academic-tool .card-title,
[data-theme="dark"] .academic-tool .form-label,
[data-theme="dark"] .academic-tool {
    color: var(--color-text, #f9fafb);
}

[data-theme="dark"] .academic-tool .text-muted,
[data-theme="dark"] .academic-tool .form-text {
    color: var(--color-text-secondary, #9ca3af) !important;
}

[data-theme="dark"] .academic-tool .form-control,
[data-theme="dark"] .academic-tool .form-select,
[data-theme="dark"] .academic-tool textarea {
    background: #111827;
    color: var(--color-text, #f9fafb);
    border-color: var(--color-border, #374151);
}

/* --- tool: variance-calculator --- */
.variance-calculator {
    background: #fff;
    border-radius: 10px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    padding: 20px;
}

.result-box {
    background: #f8f9fa;
    border: 1px solid #dee2e6;
    border-radius: 8px;
    padding: 20px;
    margin-top: 20px;
}

.calculation-steps {
    background: #fff;
    border: 1px solid #e9ecef;
    border-radius: 6px;
    padding: 15px;
    margin-top: 15px;
    font-family: 'Courier New', monospace;
    font-size: 14px;
    line-height: 1.6;
}

.stat-result {
    background: #e3f2fd;
    border: 1px solid #2196f3;
    border-radius: 6px;
    padding: 12px;
    margin: 8px 0;
    font-weight: 500;
}

.data-points {
    background: #f5f5f5;
    border-radius: 4px;
    padding: 8px;
    margin: 5px 0;
    font-family: 'Courier New', monospace;
}

.step-item {
    margin: 8px 0;
    padding: 8px;
    border-left: 3px solid #007bff;
    background: #f8f9fa;
}

.formula {
    background: #fff3cd;
    border: 1px solid #ffc107;
    border-radius: 4px;
    padding: 10px;
    margin: 10px 0;
    font-family: 'Times New Roman', serif;
    font-style: italic;
}

.error-message {
    background: #f8d7da;
    border: 1px solid #f5c6cb;
    color: #721c24;
    border-radius: 4px;
    padding: 10px;
    margin: 10px 0;
}

.success-message {
    background: #d4edda;
    border: 1px solid #c3e6cb;
    color: #155724;
    border-radius: 4px;
    padding: 10px;
    margin: 10px 0;
}

.input-group-text {
    background: #e9ecef;
    border: 1px solid #ced4da;
}

.btn-calculate {
    background: linear-gradient(45deg, #007bff, #0056b3);
    border: none;
    color: white;
    font-weight: 500;
    transition: all 0.3s ease;
}

.btn-calculate:hover {
    background: linear-gradient(45deg, #0056b3, #004085);
    transform: translateY(-1px);
    box-shadow: 0 4px 8px rgba(0,0,0,0.2);
}

.btn-clear {
    background: linear-gradient(45deg, #6c757d, #545b62);
    border: none;
    color: white;
    font-weight: 500;
    transition: all 0.3s ease;
}

.btn-clear:hover {
    background: linear-gradient(45deg, #545b62, #3d4449);
    transform: translateY(-1px);
    box-shadow: 0 4px 8px rgba(0,0,0,0.2);
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 15px;
    margin-top: 20px;
}

.stat-card {
    background: #fff;
    border: 1px solid #dee2e6;
    border-radius: 8px;
    padding: 15px;
    text-align: center;
    transition: transform 0.2s ease;
}

.stat-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0,0,0,0.15);
}

.stat-value {
    font-size: 1.5rem;
    font-weight: bold;
    color: #007bff;
    margin-bottom: 5px;
}

.stat-label {
    font-size: 0.9rem;
    color: #6c757d;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

@media (max-width: 768px) {
    .stats-grid {
        grid-template-columns: 1fr;
    }
    
    .calculation-steps {
        font-size: 12px;
    }
}