/**
 * PDE Solver Calculator - Polished styles
 * Heat, Wave, Laplace, Poisson, Transport, Schrodinger
 * Steps, reference table, export, animation, contour
 */

:root {
    --tool-primary: #0891b2;
    --tool-primary-dark: #0e7490;
    --tool-gradient: linear-gradient(135deg, #0891b2 0%, #06b6d4 100%);
    --tool-light: #ecfeff;
}
[data-theme="dark"] {
    --tool-light: rgba(8, 145, 178, 0.15);
}

/* ===== Mode Toggle - Single wrapped row ===== */
.pde-mode-toggle {
    display: flex;
    flex-wrap: wrap;
    gap: 0.375rem;
    margin-bottom: 1rem;
}
.pde-mode-toggle-row2 {
    display: none; /* merged into single row */
}
.pde-mode-btn {
    flex: 1 1 auto;
    min-width: 0;
    padding: 0.5rem 0.75rem;
    font-weight: 600;
    font-size: 0.8125rem;
    border: 1.5px solid var(--border, #e2e8f0);
    border-radius: var(--radius-full, 9999px);
    cursor: pointer;
    background: var(--bg-secondary);
    color: var(--text-secondary);
    transition: all 0.2s ease;
    font-family: var(--font-sans);
    text-align: center;
    white-space: nowrap;
}
.pde-mode-btn.active {
    background: var(--tool-gradient);
    color: #fff;
    border-color: var(--tool-primary);
    box-shadow: 0 2px 8px rgba(8, 145, 178, 0.25);
}
.pde-mode-btn:hover:not(.active) {
    background: var(--tool-light);
    border-color: var(--tool-primary);
    color: var(--tool-primary);
}
.pde-mode-btn:active {
    transform: scale(0.96);
}
[data-theme="dark"] .pde-mode-btn {
    background: var(--bg-tertiary);
    border-color: var(--border);
}
[data-theme="dark"] .pde-mode-btn.active {
    background: var(--tool-gradient);
    color: #fff;
    border-color: var(--tool-primary);
}
[data-theme="dark"] .pde-mode-btn:hover:not(.active) {
    background: rgba(255, 255, 255, 0.08);
    border-color: var(--tool-primary);
    color: #67e8f9;
}

/* ===== Form section wrappers - smooth reveal ===== */
#pde-heat-wrap, #pde-wave-wrap, #pde-laplace-wrap,
#pde-poisson-wrap, #pde-transport-wrap, #pde-schrodinger-wrap,
#pde-linear1-wrap {
    animation: pde-fadeIn 0.2s ease;
}
@keyframes pde-fadeIn {
    from { opacity: 0; transform: translateY(4px); }
    to { opacity: 1; transform: translateY(0); }
}

/* ===== Form inputs - focus ring ===== */
.pde-mode-toggle ~ div .tool-input:focus,
.pde-mode-toggle ~ div .tool-input-mono:focus {
    outline: none;
    border-color: var(--tool-primary);
    box-shadow: 0 0 0 3px rgba(8, 145, 178, 0.12);
}

/* ===== Preview ===== */
.pde-preview {
    background: var(--bg-secondary, #f8fafc);
    border: 1px solid var(--border, #e2e8f0);
    border-radius: var(--radius-md, 0.5rem);
    padding: 0.875rem 1rem;
    min-height: 52px;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow-x: auto;
    font-size: 1.1rem;
    margin-top: 1rem;
    transition: border-color 0.2s;
}
.pde-preview .katex-display { margin: 0; }
[data-theme="dark"] .pde-preview {
    background: var(--bg-tertiary);
    border-color: var(--border);
}

/* ===== Quick examples ===== */
.pde-examples {
    display: flex;
    flex-wrap: wrap;
    gap: 0.375rem;
}
.pde-example-chip {
    padding: 0.3rem 0.625rem;
    font-size: 0.75rem;
    font-family: var(--font-mono);
    background: var(--bg-secondary, #f8fafc);
    border: 1px solid var(--border, #e2e8f0);
    border-radius: var(--radius-full, 9999px);
    cursor: pointer;
    transition: all 0.15s;
    color: var(--text-secondary);
    white-space: nowrap;
}
.pde-example-chip:hover {
    background: var(--tool-primary);
    color: #fff;
    border-color: var(--tool-primary);
    transform: translateY(-1px);
}
.pde-example-chip:active {
    transform: translateY(0);
}
[data-theme="dark"] .pde-example-chip { background: var(--bg-tertiary); border-color: var(--border); }
[data-theme="dark"] .pde-example-chip:hover { background: var(--tool-primary); color: #fff; }

/* ===== Reference Table & Syntax Help ===== */
.pde-formulas-toggle, .pde-syntax-toggle {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0.625rem 0.75rem;
    background: var(--bg-secondary, #f8fafc);
    border: 1px solid var(--border, #e2e8f0);
    border-radius: var(--radius-md, 0.5rem);
    cursor: pointer;
    font-size: 0.8125rem;
    font-weight: 600;
    color: var(--text-secondary);
    margin-top: 0.625rem;
    transition: all 0.2s;
    user-select: none;
}
.pde-formulas-toggle:hover, .pde-syntax-toggle:hover {
    background: var(--tool-light);
    border-color: var(--tool-primary);
    color: var(--tool-primary);
}
[data-theme="dark"] .pde-formulas-toggle, [data-theme="dark"] .pde-syntax-toggle {
    background: var(--bg-tertiary);
    border-color: var(--border);
}
.pde-formulas-content, .pde-syntax-content {
    border: 1px solid var(--border, #e2e8f0);
    border-top: none;
    border-radius: 0 0 var(--radius-md, 0.5rem) var(--radius-md, 0.5rem);
    overflow: hidden;
    animation: pde-slideDown 0.2s ease;
}
@keyframes pde-slideDown {
    from { opacity: 0; max-height: 0; }
    to { opacity: 1; max-height: 600px; }
}
.pde-formulas-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.8125rem;
}
.pde-formulas-table th {
    background: var(--tool-light);
    color: var(--tool-primary);
    padding: 0.5rem 0.625rem;
    text-align: left;
    font-weight: 600;
    border-bottom: 1.5px solid var(--border, #e2e8f0);
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.03em;
}
.pde-formulas-table td {
    padding: 0.5rem 0.625rem;
    border-bottom: 1px solid var(--border, #e2e8f0);
    color: var(--text-primary);
    vertical-align: middle;
}
.pde-formulas-table tr:last-child td { border-bottom: none; }
.pde-formulas-table tr:hover td { background: var(--tool-light); }
[data-theme="dark"] .pde-formulas-table th { background: var(--tool-light); }
[data-theme="dark"] .pde-formulas-table td { border-bottom-color: var(--border); }

/* ===== Output Tabs ===== */
.pde-output-tabs {
    display: flex;
    border: 1.5px solid var(--border, #e2e8f0);
    border-radius: var(--radius-md, 0.5rem);
    overflow: hidden;
}
.pde-output-tab {
    flex: 1;
    padding: 0.5rem 0.25rem;
    font-weight: 600;
    font-size: 0.8125rem;
    border: none;
    cursor: pointer;
    background: var(--bg-secondary);
    color: var(--text-secondary);
    transition: all 0.2s;
    font-family: var(--font-sans);
    text-align: center;
    position: relative;
}
.pde-output-tab.active {
    background: var(--tool-gradient);
    color: #fff;
}
.pde-output-tab:hover:not(.active) {
    background: var(--tool-light);
    color: var(--tool-primary);
}
[data-theme="dark"] .pde-output-tab { background: var(--bg-tertiary); }
[data-theme="dark"] .pde-output-tab.active { background: var(--tool-gradient); color: #fff; }
[data-theme="dark"] .pde-output-tab:hover:not(.active) { background: rgba(255, 255, 255, 0.08); color: #67e8f9; }

/* ===== Panels ===== */
.pde-panel { display: none; flex: 1; min-height: 0; }
.pde-panel.active { display: flex; flex-direction: column; animation: pde-fadeIn 0.2s ease; }
#pde-panel-graph, #pde-panel-contour, #pde-panel-animate { min-height: 480px; }
#pde-panel-python { min-height: 540px; }
#pde-graph-container, #pde-contour-container, #pde-animate-container {
    width: 100%;
    min-height: 440px;
    border-radius: var(--radius-md);
}

/* ===== Action Row ===== */
.pde-action-row {
    display: flex;
    gap: 0.5rem;
    margin-top: 1rem;
}
.pde-action-row .pde-compute-btn {
    flex: 1;
    margin-top: 0;
}
.pde-compute-btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    pointer-events: none;
}
.pde-random-btn {
    flex: 0 0 auto;
    padding: 0.75rem 1rem;
    font-weight: 600;
    font-size: 0.8125rem;
    font-family: var(--font-sans);
    border: 1.5px solid var(--tool-primary);
    border-radius: var(--radius-md, 0.5rem);
    background: var(--bg-primary);
    color: var(--tool-primary);
    cursor: pointer;
    transition: all 0.2s;
    display: inline-flex;
    align-items: center;
    gap: 0.375rem;
}
.pde-random-btn:hover {
    background: var(--tool-primary);
    color: #fff;
}
.pde-random-btn:active {
    transform: scale(0.96);
}
[data-theme="dark"] .pde-random-btn { background: var(--bg-tertiary); border-color: var(--tool-primary); color: #67e8f9; }
[data-theme="dark"] .pde-random-btn:hover { background: var(--tool-primary); color: #fff; }

/* ===== Export Buttons - smooth reveal ===== */
.pde-export-row {
    display: flex;
    gap: 0.375rem;
    margin-top: 0.625rem;
    flex-wrap: wrap;
    animation: pde-fadeIn 0.3s ease;
}
.pde-export-btn {
    display: inline-flex;
    align-items: center;
    gap: 0.25rem;
    padding: 0.375rem 0.625rem;
    font-size: 0.75rem;
    font-weight: 600;
    font-family: var(--font-sans);
    border: 1px solid var(--border, #e2e8f0);
    border-radius: var(--radius-full, 9999px);
    background: var(--bg-secondary, #f8fafc);
    color: var(--text-secondary);
    cursor: pointer;
    transition: all 0.15s;
}
.pde-export-btn:hover {
    background: var(--tool-primary);
    color: #fff;
    border-color: var(--tool-primary);
    transform: translateY(-1px);
    box-shadow: 0 2px 6px rgba(8, 145, 178, 0.2);
}
.pde-export-btn:active {
    transform: translateY(0);
    box-shadow: none;
}
[data-theme="dark"] .pde-export-btn { background: var(--bg-tertiary); border-color: var(--border); }
[data-theme="dark"] .pde-export-btn:hover { background: var(--tool-primary); color: #fff; }

/* ===== Result Display ===== */
.pde-result-math {
    padding: 1.5rem;
    overflow-x: auto;
    max-width: 100%;
    min-width: 0;
}
.pde-result-math .katex-display {
    margin: 0.5rem 0;
    overflow-x: auto;
    overflow-y: hidden;
}
.pde-result-label {
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--tool-primary);
    margin-bottom: 0.75rem;
}
.pde-result-main {
    font-size: 1.1rem;
    color: var(--text-primary);
    overflow-x: auto;
    padding: 0.5rem 0;
    min-height: 2rem;
}
.pde-result-detail {
    display: flex;
    flex-wrap: wrap;
    gap: 0.375rem;
    margin-top: 0.75rem;
    align-items: center;
}

/* ===== Badges ===== */
.pde-method-badge {
    display: inline-flex;
    align-items: center;
    gap: 0.25rem;
    background: var(--tool-light);
    color: var(--tool-primary);
    padding: 0.2rem 0.625rem;
    border-radius: 9999px;
    font-size: 0.6875rem;
    font-weight: 600;
}
.pde-classify-badge {
    display: inline-block;
    background: #f0fdf4;
    color: #15803d;
    padding: 0.2rem 0.625rem;
    border-radius: 9999px;
    font-size: 0.6875rem;
    font-weight: 600;
}
[data-theme="dark"] .pde-classify-badge {
    background: rgba(22, 163, 74, 0.15);
    color: #4ade80;
}
.pde-verified-badge {
    display: inline-flex;
    align-items: center;
    gap: 0.2rem;
    background: #dcfce7;
    color: #16a34a;
    padding: 0.2rem 0.625rem;
    border-radius: 9999px;
    font-size: 0.6875rem;
    font-weight: 600;
}
[data-theme="dark"] .pde-verified-badge {
    background: rgba(22, 163, 74, 0.15);
    color: #4ade80;
}
.pde-error-badge {
    display: inline-block;
    background: #fef2f2;
    color: #dc2626;
    padding: 0.2rem 0.625rem;
    border-radius: 9999px;
    font-size: 0.6875rem;
    font-weight: 600;
}
[data-theme="dark"] .pde-error-badge {
    background: rgba(220, 38, 38, 0.15);
    color: #f87171;
}

/* ===== Numerical Metadata - with separators ===== */
.pde-meta-row {
    display: flex;
    flex-wrap: wrap;
    gap: 0;
    margin-top: 0.625rem;
    padding: 0.5rem 0.75rem;
    background: var(--bg-secondary, #f8fafc);
    border-radius: var(--radius-md, 0.5rem);
    border: 1px solid var(--border, #e2e8f0);
}
.pde-meta-item {
    font-size: 0.75rem;
    font-family: var(--font-mono);
    color: var(--text-secondary);
    white-space: nowrap;
    padding: 0.125rem 0;
}
.pde-meta-item:not(:last-child)::after {
    content: "\00b7";
    color: var(--border, #cbd5e1);
    margin: 0 0.5rem;
    font-weight: 700;
}
[data-theme="dark"] .pde-meta-row { background: var(--bg-tertiary); }

/* ===== Step-by-Step Solutions ===== */
.pde-steps-btn {
    display: inline-flex;
    align-items: center;
    gap: 0.375rem;
    margin-top: 1rem;
    padding: 0.5rem 1rem;
    font-size: 0.8125rem;
    font-weight: 600;
    font-family: var(--font-sans);
    border: 1.5px solid var(--tool-primary);
    border-radius: var(--radius-full, 9999px);
    background: transparent;
    color: var(--tool-primary);
    cursor: pointer;
    transition: all 0.15s;
}
.pde-steps-btn:hover {
    background: var(--tool-primary);
    color: #fff;
}
.pde-steps-container {
    margin-top: 1rem;
    border: 1px solid var(--border, #e2e8f0);
    border-radius: var(--radius-md, 0.5rem);
    overflow: hidden;
    animation: pde-fadeIn 0.3s ease;
}
.pde-steps-header {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.625rem 1rem;
    background: var(--tool-light);
    font-weight: 600;
    font-size: 0.8125rem;
    color: var(--tool-primary);
    border-bottom: 1px solid var(--border, #e2e8f0);
}
[data-theme="dark"] .pde-steps-header { background: var(--tool-light); }
.pde-steps-header span {
    font-weight: 400;
    font-size: 0.75rem;
    color: var(--text-muted);
}
.pde-steps-cas-badge {
    display: inline-block;
    background: var(--bg-secondary);
    color: var(--text-muted);
    padding: 0.125rem 0.5rem;
    border-radius: 9999px;
    font-size: 0.625rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-left: auto;
}
.pde-step {
    display: flex;
    gap: 0.75rem;
    padding: 0.875rem 1rem;
    border-bottom: 1px solid var(--border-light, #f1f5f9);
    align-items: flex-start;
}
.pde-step:last-child { border-bottom: none; }
[data-theme="dark"] .pde-step { border-bottom-color: var(--border); }
.pde-step-num {
    flex: 0 0 auto;
    width: 24px;
    height: 24px;
    border-radius: 50%;
    background: var(--tool-gradient);
    color: #fff;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.6875rem;
    font-weight: 700;
    margin-top: 0.125rem;
}
.pde-step-body {
    flex: 1;
    min-width: 0;
}
.pde-step-title {
    font-size: 0.6875rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.04em;
    color: var(--text-muted);
    margin-bottom: 0.25rem;
}
.pde-step-math {
    overflow-x: auto;
    overflow-y: hidden;
    font-size: 1rem;
    padding: 0.25rem 0;
}
.pde-step-math .katex-display {
    margin: 0;
    overflow-x: auto;
    overflow-y: hidden;
    white-space: nowrap;
    display: inline-block;
    min-width: min-content;
}

/* ===== Error ===== */
.pde-error {
    background: #fef3c7;
    border: 1px solid #fbbf24;
    border-radius: var(--radius-md);
    padding: 1.25rem;
    color: #92400e;
    animation: pde-fadeIn 0.2s ease;
}
.pde-error h4 {
    margin: 0 0 0.5rem;
    font-size: 0.9375rem;
    font-weight: 700;
}
.pde-error ul {
    margin: 0.5rem 0 0;
    padding-left: 1.25rem;
    font-size: 0.8125rem;
    line-height: 1.7;
}
[data-theme="dark"] .pde-error {
    background: rgba(251, 191, 36, 0.15);
    border-color: rgba(251, 191, 36, 0.3);
    color: #fbbf24;
}

/* ===== Spinner ===== */
@keyframes pde-spin {
    to { transform: rotate(360deg); }
}
.pde-spinner {
    width: 14px;
    height: 14px;
    border: 2px solid var(--border);
    border-top-color: var(--tool-primary);
    border-radius: 50%;
    animation: pde-spin 0.6s linear infinite;
}

/* ===== Separator ===== */
.pde-sep {
    border: none;
    border-top: 1px solid var(--border, #e2e8f0);
    margin: 0.75rem 0;
}

/* ===== Animation Controls - styled bar ===== */
.pde-anim-controls {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.625rem 0.75rem;
    background: var(--bg-secondary, #f8fafc);
    border: 1px solid var(--border, #e2e8f0);
    border-radius: var(--radius-md, 0.5rem);
    margin-top: 0.5rem;
}
[data-theme="dark"] .pde-anim-controls {
    background: var(--bg-tertiary);
    border-color: var(--border);
}
.pde-anim-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.25rem;
    padding: 0.35rem 0.625rem;
    font-size: 0.75rem;
    font-weight: 600;
    font-family: var(--font-sans);
    border: 1.5px solid var(--tool-primary);
    border-radius: var(--radius-full, 9999px);
    background: transparent;
    color: var(--tool-primary);
    cursor: pointer;
    transition: all 0.15s;
    flex-shrink: 0;
}
.pde-anim-btn:hover {
    background: var(--tool-primary);
    color: #fff;
}
.pde-anim-btn:active {
    transform: scale(0.95);
}
.pde-anim-slider {
    flex: 1;
    min-width: 0;
    accent-color: var(--tool-primary);
    height: 4px;
    cursor: pointer;
}
.pde-anim-time {
    font-size: 0.75rem;
    color: var(--text-muted);
    font-family: var(--font-mono);
    min-width: 4rem;
    text-align: right;
    flex-shrink: 0;
}

/* ===== Empty State Enhancement ===== */
.tool-empty-state .pde-empty-icon {
    font-size: 3rem;
    margin-bottom: 0.75rem;
    opacity: 0.35;
    line-height: 1;
}

/* ===== Scrollable result containment ===== */
#pde-result-content {
    min-width: 0;
    overflow-x: hidden;
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
    .pde-mode-toggle {
        gap: 0.25rem;
    }
    .pde-mode-btn {
        padding: 0.4rem 0.5rem;
        font-size: 0.75rem;
    }
}
@media (max-width: 600px) {
    .pde-mode-toggle {
        flex-wrap: wrap;
    }
    .pde-mode-btn {
        flex: 0 0 calc(50% - 0.25rem);
        padding: 0.45rem 0.5rem;
        font-size: 0.75rem;
    }
    .pde-output-tabs {
        flex-wrap: wrap;
    }
    .pde-output-tab {
        flex: 0 0 33.33%;
    }
    .pde-export-row {
        flex-wrap: wrap;
    }
    .pde-anim-controls {
        flex-wrap: wrap;
    }
}
@media (max-width: 400px) {
    .pde-mode-btn {
        flex: 0 0 calc(50% - 0.125rem);
        font-size: 0.6875rem;
    }
}