.substitution-tool {
    --sub-sidebar-width: 340px;
    --sub-bg: #e9e9ea;
    --sub-panel: #f8f8f9;
    --sub-panel-strong: #ffffff;
    --sub-line: #d8dbe0;
    --sub-line-strong: #c9ced6;
    --sub-text: #152033;
    --sub-muted: #687385;
    --sub-blue: #dbe7f5;
    --sub-blue-strong: #b8c6da;
    --sub-red: #f3e4e4;
    --sub-red-strong: #e9d3d3;
    --sub-green: #eef8ef;
    --sub-green-strong: #cfe2d1;
    --sub-hover-filter: brightness(0.97);
    --sub-shadow: 0 12px 30px rgba(19, 28, 40, 0.08);
    --sub-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", monospace;
    color: var(--sub-text);
    font-family: "Inter", var(--font-sans);
}

html[data-theme="dark"] .substitution-tool {
    --sub-bg: #171a1f;
    --sub-panel: #20242a;
    --sub-panel-strong: #252a31;
    --sub-line: #323944;
    --sub-line-strong: #424b58;
    --sub-text: #f1f5f9;
    --sub-muted: #a1adbd;
    --sub-blue: #213147;
    --sub-blue-strong: #39526f;
    --sub-red: #3a2528;
    --sub-red-strong: #684147;
    --sub-green: #203629;
    --sub-green-strong: #3f684c;
    --sub-hover-filter: brightness(1.1);
    --sub-shadow: none;
}

.substitution-tool * {
    box-sizing: border-box;
}

.substitution-tool .sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

.tool-template.tool-template-substitution-wide {
    max-width: min(1480px, calc(100vw - 56px));
}

.container.tool-page-container-substitution {
    width: min(1360px, calc(100% - 48px));
}

.tool-template-substitution-wide .tool-template-card {
    overflow: hidden;
}

.substitution-shell {
    max-width: 100%;
    overflow: hidden;
    padding: 8px;
}

html[data-theme="dark"] .substitution-shell {
    background: transparent;
}

.substitution-topbar,
.substitution-actions,
.substitution-io-head,
.substitution-io-footer,
.substitution-chips {
    display: flex;
    gap: 12px;
    align-items: center;
    flex-wrap: wrap;
}

.substitution-topbar {
    justify-content: space-between;
    margin-bottom: 20px;
}

.substitution-topbar .tool-topbar-start {
    width: fit-content;
    justify-self: start;
}

.substitution-mode {
    display: inline-flex;
    flex: 0 0 auto;
    justify-self: start;
    gap: 4px;
    padding: 5px;
    border: 1px solid var(--sub-line);
    border-radius: 999px;
    background: #f1f2f4;
}

html[data-theme="dark"] .substitution-mode {
    background: #1c2026;
}

.substitution-segment-btn {
    min-height: 42px;
    padding: 10px 24px;
    border: 0;
    border-radius: 999px;
    background: transparent;
    color: #6f7786;
    cursor: pointer;
    font: inherit;
    font-size: 0.95rem;
    font-weight: 700;
    transition: background-color 0.18s ease, color 0.18s ease;
}

.substitution-segment-btn[aria-pressed="true"] {
    background: var(--sub-blue);
    color: var(--sub-text);
    box-shadow: inset 0 0 0 1px rgba(180, 194, 214, 0.7);
}

.substitution-actions {
    gap: 8px;
}

.substitution-btn,
.substitution-tool-btn,
.substitution-mini-btn,
.substitution-stepper-btn {
    border: 1px solid var(--sub-line);
    background: var(--sub-panel-strong);
    color: var(--sub-text);
    cursor: pointer;
    font: inherit;
    font-weight: 700;
    transition: background-color 0.16s ease, border-color 0.16s ease, filter 0.16s ease, opacity 0.16s ease;
}

.substitution-btn {
    min-height: 40px;
    padding: 10px 16px;
    border-radius: 12px;
    font-size: 0.9rem;
    white-space: nowrap;
}

.substitution-btn-danger {
    border-color: var(--sub-red-strong);
    background: var(--sub-red);
    color: #5e4848;
}

html[data-theme="dark"] .substitution-btn-danger {
    color: #ffd7d7;
}

.substitution-btn:hover,
.substitution-tool-btn:hover,
.substitution-mini-btn:hover,
.substitution-stepper-btn:hover {
    border-color: var(--sub-line-strong);
    filter: var(--sub-hover-filter);
}

.substitution-grid {
    display: grid;
    grid-template-columns: minmax(260px, var(--sub-sidebar-width)) minmax(0, 1fr);
    gap: 20px;
    align-items: start;
    min-width: 0;
}

.substitution-sidebar {
    position: sticky;
    top: 24px;
    display: flex;
    flex-direction: column;
    gap: 16px;
    min-width: 0;
}

.substitution-workspace {
    display: grid;
    gap: 20px;
    min-width: 0;
}

.substitution-section,
.substitution-io {
    min-width: 0;
    border: 1px solid var(--sub-line);
    border-radius: 16px;
    background: rgba(255, 255, 255, 0.72);
    padding: 18px;
}

html[data-theme="dark"] .substitution-section,
html[data-theme="dark"] .substitution-io {
    background: rgba(32, 36, 42, 0.78);
}

.substitution-section-title {
    margin: 0 0 14px;
    color: var(--sub-text);
    font-size: 0.95rem;
    font-weight: 800;
    line-height: 1.2;
}

.substitution-collapse-toggle {
    display: contents;
    border: 0;
    background: transparent;
    color: inherit;
    cursor: default;
    font: inherit;
    text-align: left;
}

.substitution-collapse-icon {
    display: none;
}

.substitution-collapse-action {
    display: none;
}

.substitution-control-stack,
.substitution-field {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.substitution-field {
    gap: 7px;
}

.substitution-label {
    display: flex;
    justify-content: space-between;
    gap: 12px;
    color: var(--sub-text);
    font-size: 0.8rem;
    font-weight: 800;
}

.substitution-label span:last-child {
    color: var(--sub-muted);
    font-family: var(--sub-mono);
    font-size: 0.74rem;
    font-weight: 700;
}

.substitution-input,
.substitution-io textarea {
    width: 100%;
    min-width: 0;
    border: 1px solid var(--sub-line);
    border-radius: 14px;
    background: var(--sub-panel-strong);
    color: var(--sub-text);
    font: inherit;
    outline: none;
    transition: border-color 0.16s ease, box-shadow 0.16s ease, background 0.16s ease;
}

.substitution-input {
    min-height: 46px;
    padding: 10px 12px;
    font-family: var(--sub-mono);
    font-size: 0.92rem;
}

.substitution-alphabet-input {
    letter-spacing: 0.04em;
    text-transform: uppercase;
}

.substitution-input:focus,
.substitution-io textarea:focus,
.substitution-btn:focus-visible,
.substitution-tool-btn:focus-visible,
.substitution-mini-btn:focus-visible,
.substitution-stepper-btn:focus-visible {
    border-color: rgba(78, 127, 210, 0.42);
    box-shadow: 0 0 0 3px rgba(78, 127, 210, 0.14);
}

.substitution-input.is-invalid {
    border-color: var(--sub-red-strong);
    background: var(--sub-red);
}

.substitution-help {
    margin: 0;
    color: var(--sub-muted);
    font-size: 0.8rem;
    font-weight: 600;
    line-height: 1.45;
}

.substitution-tool-buttons {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 8px;
}

.substitution-tool-btn {
    min-height: 42px;
    padding: 9px 10px;
    border-radius: 12px;
    font-size: 0.8rem;
}

.substitution-tool-btn-primary {
    grid-column: 1 / -1;
    background: var(--sub-blue);
    border-color: var(--sub-blue-strong);
}

.substitution-validation {
    padding: 10px 12px;
    border: 1px solid var(--sub-red-strong);
    border-radius: 14px;
    background: var(--sub-red);
    color: #5e4848;
    font-size: 0.82rem;
    font-weight: 800;
    line-height: 1.4;
}

.substitution-validation.is-good {
    border-color: var(--sub-green-strong);
    background: var(--sub-green);
    color: #435944;
}

html[data-theme="dark"] .substitution-validation {
    color: #ffd7d7;
}

html[data-theme="dark"] .substitution-validation.is-good {
    color: #d9f5de;
}

.substitution-option-list {
    display: grid;
    gap: 12px;
    padding: 2px 0;
}

.substitution-option-row {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    min-height: 32px;
    padding: 2px 0;
}

.substitution-option-row.is-disabled {
    opacity: 0.52;
}

.substitution-option-left {
    display: flex;
    align-items: center;
    gap: 10px;
    min-width: 0;
    color: var(--sub-text);
    font-size: 0.88rem;
    font-weight: 700;
}

.substitution-option-left input {
    width: 18px;
    height: 18px;
    flex: 0 0 auto;
    accent-color: #6d91c4;
}

.substitution-stepper {
    display: inline-flex;
    align-items: center;
    overflow: hidden;
    border: 1px solid var(--sub-line);
    border-radius: 999px;
    background: #f3f4f6;
}

html[data-theme="dark"] .substitution-stepper {
    background: #1c2026;
}

.substitution-stepper.is-disabled {
    opacity: 0.45;
}

.substitution-stepper-btn {
    width: 34px;
    height: 32px;
    border: 0;
    background: transparent;
}

.substitution-stepper-value {
    min-width: 34px;
    color: var(--sub-text);
    font-family: var(--sub-mono);
    font-size: 0.86rem;
    font-weight: 800;
    text-align: center;
}

.substitution-io-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 20px;
    min-width: 0;
}

.substitution-io {
    display: flex;
    flex-direction: column;
    gap: 12px;
    padding: 16px;
}

.substitution-io-head,
.substitution-io-footer {
    justify-content: space-between;
}

.substitution-io-head h3 {
    margin: 0;
    color: var(--sub-text);
    font-size: 0.95rem;
    font-weight: 800;
}

.substitution-mini-btn {
    min-height: 32px;
    padding: 0 12px;
    border-radius: 999px;
    color: var(--sub-muted);
    font-size: 0.76rem;
}

.substitution-mini-btn.is-done {
    border-color: var(--sub-green-strong);
    background: var(--sub-green);
    color: #435944;
}

.substitution-mini-btn.is-error {
    border-color: var(--sub-red-strong);
    background: var(--sub-red);
    color: #5e4848;
}

.substitution-mini-btn:disabled,
.substitution-stepper-btn:disabled {
    cursor: not-allowed;
    opacity: 0.55;
    transform: none;
}

.substitution-io textarea {
    min-height: 410px;
    height: clamp(410px, 46.5vh, 600px);
    padding: 14px;
    resize: vertical;
    font-family: var(--sub-mono);
    font-size: 0.92rem;
    line-height: 1.55;
}

.tool-template.tool-template-substitution-wide .substitution-io textarea {
    min-height: 410px;
    height: clamp(410px, 46.5vh, 600px);
    resize: vertical;
    padding: 14px;
    font-size: 0.92rem;
    line-height: 1.55;
}

.substitution-output {
    background: var(--sub-panel);
}

.substitution-io-footer {
    gap: 8px;
    color: var(--sub-muted);
    font-size: 0.78rem;
    font-weight: 700;
}

.substitution-stat strong {
    color: var(--sub-text);
}

.substitution-map-section {
    padding: 18px;
}

.substitution-map-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(52px, 1fr));
    gap: 8px;
}

.substitution-map-pair {
    display: grid;
    grid-template-rows: auto auto auto;
    gap: 3px;
    place-items: center;
    min-height: 76px;
    padding: 8px 4px;
    border: 1px solid var(--sub-line);
    border-radius: 12px;
    background: var(--sub-panel-strong);
}

.substitution-plain-letter,
.substitution-cipher-letter {
    font-family: var(--sub-mono);
    font-size: 0.94rem;
    font-weight: 900;
    line-height: 1;
}

.substitution-cipher-letter {
    color: #4b6f9e;
}

html[data-theme="dark"] .substitution-cipher-letter {
    color: #93b5e5;
}

.substitution-arrow {
    color: var(--sub-muted);
    font-size: 0.72rem;
    font-weight: 800;
}

.substitution-chips {
    gap: 8px;
}

.substitution-properties-section {
    padding: 14px 16px;
}

.substitution-properties-section .substitution-section-title {
    margin-bottom: 10px;
    color: var(--sub-muted);
    font-size: 0.78rem;
    font-weight: 800;
    letter-spacing: 0.06em;
    text-transform: uppercase;
}

.substitution-properties-section .substitution-chips {
    gap: 6px;
}

.substitution-chip {
    gap: 4px;
    border-color: var(--sub-line);
}

@media (min-width: 1101px) {
    .substitution-topbar .tool-topbar-start {
        width: var(--sub-sidebar-width);
    }

    .substitution-mode {
        width: 100%;
    }

    .substitution-mode .substitution-segment-btn {
        flex: 1 1 0;
        text-align: center;
    }

    .substitution-map-grid {
        grid-template-columns: repeat(13, minmax(46px, 1fr));
    }
}

@media (min-width: 1500px) {
    .substitution-io-grid {
        grid-template-columns: repeat(2, minmax(340px, 1fr));
    }
}

@media (max-width: 1100px) {
    .substitution-grid {
        display: flex;
        flex-direction: column;
        align-items: stretch;
        gap: 18px;
    }

    .substitution-sidebar,
    .substitution-workspace {
        display: contents;
    }

    .substitution-io-grid {
        order: 1;
    }

    .substitution-config-section {
        order: 2;
    }

    .substitution-sidebar .substitution-section:nth-child(2) {
        order: 3;
    }

    .substitution-map-section {
        order: 4;
    }

    .substitution-properties-section {
        order: 5;
    }

    .substitution-io-grid {
        grid-template-columns: 1fr;
    }
}

@media (min-width: 761px) and (max-width: 1100px) {
    .substitution-topbar {
        flex-direction: row;
        justify-content: center;
        align-items: center;
        gap: 14px 16px;
    }

    .substitution-topbar .tool-topbar-start,
    .substitution-topbar .tool-topbar-end {
        width: auto;
        max-width: 100%;
    }

    .substitution-topbar .tool-topbar-start,
    .substitution-topbar .tool-topbar-end {
        display: flex;
        justify-content: center;
    }

    .substitution-actions {
        width: fit-content;
        max-width: 100%;
        justify-content: center;
    }

    .substitution-actions .substitution-btn {
        flex: 0 0 auto;
    }

    .substitution-sidebar .substitution-section:nth-child(2) {
        width: min(100%, 560px);
        align-self: center;
    }

    .substitution-map-grid {
        grid-template-columns: repeat(13, minmax(42px, 1fr));
    }

    .substitution-properties-section .substitution-chips {
        justify-content: center;
    }
}

@media (min-width: 900px) and (max-width: 1100px) {
    .substitution-io-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }
}

@media (max-width: 760px) {
    .tool-template.tool-template-substitution-wide {
        max-width: min(100%, calc(100vw - 24px));
    }

    .container.tool-page-container-substitution {
        width: min(100%, calc(100% - 24px));
    }

    .substitution-shell {
        padding: 0;
    }

    .substitution-grid {
        gap: 16px;
    }

    .substitution-sidebar,
    .substitution-io-grid {
        position: static;
    }

    .substitution-topbar {
        align-items: stretch;
    }

    .substitution-actions {
        width: 100%;
    }

    .substitution-mode {
        width: fit-content;
        max-width: 100%;
    }

    .substitution-segment-btn,
    .substitution-actions .substitution-btn {
        flex: 1 1 0;
    }

    .substitution-mode .substitution-segment-btn {
        flex: 0 0 auto;
    }

    .substitution-sidebar,
    .substitution-io-grid {
        grid-template-columns: 1fr;
    }

    .substitution-io textarea {
        min-height: 250px;
        height: clamp(250px, 38vh, 420px);
    }

    .tool-template.tool-template-substitution-wide .substitution-io textarea {
        min-height: 250px;
        height: clamp(250px, 38vh, 420px);
        resize: vertical;
    }

    .substitution-section-title {
        margin-bottom: 12px;
    }

    .substitution-collapse-toggle {
        display: flex;
        width: 100%;
        align-items: center;
        justify-content: space-between;
        gap: 12px;
        padding: 0;
        cursor: pointer;
    }

    .substitution-collapse-toggle:focus-visible {
        outline: 3px solid rgba(43, 110, 246, 0.22);
        outline-offset: 6px;
        border-radius: 12px;
    }

    .substitution-collapse-action {
        display: inline-flex;
        align-items: center;
        gap: 8px;
        color: var(--sub-muted);
        font-size: 0.75rem;
        font-weight: 800;
        line-height: 1;
        text-transform: uppercase;
    }

    .substitution-collapse-action-text::before {
        content: "Hide";
    }

    .substitution-section.is-collapsed .substitution-collapse-action-text::before {
        content: "Show";
    }

    .substitution-collapse-icon {
        position: relative;
        display: inline-grid;
        width: 28px;
        height: 28px;
        flex: 0 0 auto;
        place-items: center;
        border: 1px solid var(--sub-line);
        border-radius: 999px;
        background: var(--sub-panel-strong);
        box-shadow: 0 8px 18px rgba(15, 23, 42, 0.06);
        transition: background 0.16s ease, border-color 0.16s ease, color 0.16s ease;
    }

    .substitution-collapse-icon::before,
    .substitution-collapse-icon::after {
        content: "";
        position: absolute;
        width: 10px;
        height: 2px;
        border-radius: 999px;
        background: currentColor;
        transition: opacity 0.16s ease, transform 0.16s ease;
    }

    .substitution-collapse-icon::after {
        transform: rotate(90deg);
    }

    .substitution-section:not(.is-collapsed) .substitution-collapse-icon::after {
        opacity: 0;
        transform: rotate(90deg) scaleX(0);
    }

    .substitution-section.is-collapsed {
        padding-top: 15px;
        padding-bottom: 15px;
    }

    .substitution-section.is-collapsed .substitution-section-title {
        margin-bottom: 0;
    }

    .substitution-section.is-collapsed [data-substitution-collapsible-panel] {
        display: none;
    }

    .substitution-map-grid {
        grid-template-columns: repeat(13, minmax(0, 1fr));
        gap: 4px;
    }

    .substitution-map-section {
        padding: 14px;
    }

    .substitution-map-pair {
        min-height: 38px;
        gap: 0;
        padding: 4px 2px;
        border-radius: 8px;
    }

    .substitution-plain-letter,
    .substitution-cipher-letter {
        font-size: 0.68rem;
    }

    .substitution-arrow {
        font-size: 0.52rem;
    }

    .substitution-tool-buttons {
        grid-template-columns: 1fr;
    }

    .substitution-tool-btn-primary {
        grid-column: auto;
    }

    .substitution-properties-section {
        padding: 14px;
    }

    .substitution-properties-section .substitution-section-title {
        margin-bottom: 8px;
    }

    .substitution-properties-section .substitution-chips {
        display: grid;
        grid-template-columns: repeat(2, minmax(0, 1fr));
        gap: 8px;
    }

    .substitution-chip {
        justify-content: flex-start;
        min-height: 34px;
        padding: 7px 9px;
        font-size: 0.72rem;
        line-height: 1.1;
    }

    .substitution-chip strong {
        font-size: 0.72rem;
        line-height: 1.1;
    }
}

@media (min-width: 461px) and (max-width: 679px) {
    .substitution-topbar {
        flex-direction: column;
        justify-content: center;
        align-items: center;
        gap: 14px;
    }

    .substitution-topbar .tool-topbar-start,
    .substitution-topbar .tool-topbar-end,
    .substitution-actions {
        display: flex;
        width: fit-content;
        max-width: 100%;
        justify-content: center;
    }

    .substitution-actions .substitution-btn {
        flex: 0 0 auto;
    }

    .substitution-sidebar .substitution-section:nth-child(2) {
        width: min(100%, 560px);
        align-self: center;
    }
}

@media (min-width: 680px) and (max-width: 760px) {
    .substitution-topbar {
        flex-direction: row;
        justify-content: center;
        align-items: center;
        gap: 14px 16px;
    }

    .substitution-topbar .tool-topbar-start,
    .substitution-topbar .tool-topbar-end,
    .substitution-actions {
        display: flex;
        width: auto;
        max-width: 100%;
        justify-content: center;
    }

    .substitution-actions .substitution-btn {
        flex: 0 0 auto;
    }

    .substitution-sidebar .substitution-section:nth-child(2) {
        width: min(100%, 560px);
        align-self: center;
    }
}

@media (min-width: 680px) and (max-width: 1100px) {
    .tool-template.tool-template-substitution-wide .substitution-topbar .tool-topbar-start,
    .tool-template.tool-template-substitution-wide .substitution-topbar .tool-topbar-end {
        flex: 0 0 auto;
        justify-self: center;
        width: auto;
        max-width: max-content;
        margin-bottom: 0;
        order: 0;
    }
}

@media (max-width: 460px) {
    .substitution-section,
    .substitution-io {
        padding: 14px;
        border-radius: 14px;
    }

    .substitution-segment-btn,
    .substitution-btn {
        padding-right: 12px;
        padding-left: 12px;
        font-size: 0.82rem;
    }

    .substitution-mode {
        width: 100%;
    }

    .substitution-mode .substitution-segment-btn {
        flex: 1 1 0;
    }

    .substitution-option-row {
        align-items: flex-start;
        flex-direction: column;
    }

    .substitution-stepper {
        align-self: flex-start;
    }

    .substitution-map-grid {
        grid-template-columns: repeat(7, minmax(0, 1fr));
    }

    .substitution-map-pair {
        min-height: 40px;
    }

    .substitution-properties-section .substitution-chips {
        grid-template-columns: 1fr;
    }
}