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

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

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

.engineering-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);
}

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

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

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

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

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

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

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

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

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

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

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

/* --- tool: frequency-unit-conversion --- */
.frequency-converter {
    padding: 2rem 0;
}

.converter-card {
    background: #fff;
    border-radius: 15px;
    padding: 2rem;
    box-shadow: 0 8px 32px rgba(0,0,0,0.1);
    border: 1px solid rgba(255,255,255,0.2);
    backdrop-filter: blur(10px);
}

.conversion-arrow {
    position: relative;
}

.conversion-arrow::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 0;
    right: 0;
    height: 2px;
    background: linear-gradient(90deg, transparent, #007bff, transparent);
    transform: translateY(-50%);
}

.conversion-arrow i {
    background: #fff;
    padding: 0.5rem;
    border-radius: 50%;
    box-shadow: 0 4px 12px rgba(0,123,255,0.3);
}

.quick-conversions .btn {
    transition: all 0.3s ease;
    border-radius: 8px;
}

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

.unit-info-card {
    background: #f8f9fa;
    border-radius: 10px;
    padding: 1.5rem;
    height: 100%;
    border-left: 4px solid #007bff;
}

.unit-info-card h6 {
    color: #007bff;
    margin-bottom: 1rem;
}

.unit-info-card ul li {
    margin-bottom: 0.5rem;
    font-size: 0.9rem;
}

.conversion-table {
    background: #fff;
    border-radius: 15px;
    padding: 1.5rem;
    box-shadow: 0 4px 16px rgba(0,0,0,0.08);
}

.conversion-table .table {
    margin-bottom: 0;
}

.conversion-table .table th {
    background: #007bff;
    color: #fff;
    border: none;
    font-weight: 500;
}

.conversion-table .table td {
    vertical-align: middle;
    border-color: #e9ecef;
}

.conversion-table .table tbody tr:hover {
    background-color: #f8f9fa;
}

.form-floating > .form-control:focus,
.form-floating > .form-select:focus {
    border-color: #007bff;
    box-shadow: 0 0 0 0.2rem rgba(0,123,255,0.25);
}

.btn-primary {
    background: linear-gradient(135deg, #007bff, #0056b3);
    border: none;
    border-radius: 8px;
    padding: 0.75rem 1.5rem;
    font-weight: 500;
    transition: all 0.3s ease;
}

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

.btn-secondary {
    background: linear-gradient(135deg, #6c757d, #545b62);
    border: none;
    border-radius: 8px;
    padding: 0.75rem 1.5rem;
    font-weight: 500;
    transition: all 0.3s ease;
}

.btn-secondary:hover {
    background: linear-gradient(135deg, #545b62, #3d4449);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(108,117,125,0.3);
}

.btn-outline-primary {
    border-radius: 8px;
    padding: 0.75rem 1.5rem;
    font-weight: 500;
    transition: all 0.3s ease;
}

.btn-outline-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0,123,255,0.3);
}

@media (max-width: 768px) {
    .converter-card {
        padding: 1.5rem;
    }
    
    .unit-info-card {
        margin-bottom: 1rem;
    }
}