.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: vertical-multiplication-calculator --- */
/* 竖式乘法计算器样式 */
.vertical-multiplication-calculator {
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
}

.input-section {
    background: #f8f9fa;
    border-radius: 10px;
    padding: 25px;
    margin-bottom: 30px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.input-group-custom {
    display: flex;
    align-items: center;
    gap: 20px;
    margin-bottom: 20px;
    flex-wrap: wrap;
}

.input-group-custom .form-control {
    font-size: 1.2rem;
    text-align: center;
    font-weight: bold;
    border: 2px solid #dee2e6;
    border-radius: 8px;
    padding: 12px;
    min-width: 120px;
}

.input-group-custom .form-control:focus {
    border-color: #0d6efd;
    box-shadow: 0 0 0 0.2rem rgba(13, 110, 253, 0.25);
}

.multiply-symbol {
    font-size: 2rem;
    font-weight: bold;
    color: #0d6efd;
    margin: 0 10px;
}

.calculate-btn {
    background: linear-gradient(135deg, #0d6efd, #0b5ed7);
    border: none;
    color: white;
    padding: 12px 30px;
    border-radius: 8px;
    font-size: 1.1rem;
    font-weight: bold;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px rgba(13, 110, 253, 0.3);
}

.calculate-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(13, 110, 253, 0.4);
}

.result-section {
    background: white;
    border-radius: 10px;
    padding: 25px;
    margin-bottom: 30px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    border: 1px solid #e9ecef;
}

.vertical-calculation {
    font-family: 'Courier New', monospace;
    font-size: 1.2rem;
    line-height: 1.8;
    background: #f8f9fa;
    padding: 20px;
    border-radius: 8px;
    border: 1px solid #dee2e6;
    margin: 20px 0;
    overflow-x: auto;
}

.calculation-step {
    margin: 8px 0;
    padding: 5px 0;
}

.calculation-step.highlight {
    background: #fff3cd;
    border-radius: 4px;
    padding: 8px;
    border-left: 4px solid #ffc107;
}

.result-highlight {
    background: #d1ecf1;
    border-radius: 4px;
    padding: 8px;
    border-left: 4px solid #17a2b8;
    font-weight: bold;
    margin-top: 10px;
}

.error-message {
    background: #f8d7da;
    color: #721c24;
    padding: 15px;
    border-radius: 8px;
    border: 1px solid #f5c6cb;
    margin: 15px 0;
}

.clear-btn {
    background: #6c757d;
    border: none;
    color: white;
    padding: 8px 20px;
    border-radius: 6px;
    font-size: 0.9rem;
    margin-left: 10px;
}

.clear-btn:hover {
    background: #5a6268;
}

.examples-section {
    background: #e7f3ff;
    border-radius: 10px;
    padding: 20px;
    margin-top: 20px;
}

.example-btn {
    background: #17a2b8;
    border: none;
    color: white;
    padding: 8px 15px;
    border-radius: 6px;
    font-size: 0.9rem;
    margin: 5px;
    cursor: pointer;
}

.example-btn:hover {
    background: #138496;
}

@media (max-width: 768px) {
    .input-group-custom {
        flex-direction: column;
        gap: 15px;
    }
    
    .multiply-symbol {
        transform: rotate(90deg);
        margin: 10px 0;
    }
    
    .vertical-calculation {
        font-size: 1rem;
    }
}