:root {
    --bg: #f6f8fb;
    --surface: #ffffff;
    --surface-2: #edf2f7;
    --text: #172033;
    --muted: #667085;
    --border: #d9e1ec;
    --accent: #2563eb;
    --accent-strong: #1d4ed8;
    --danger: #c2410c;
    --danger-bg: #fff1e8;
    --shadow: 0 18px 50px rgba(32, 44, 72, 0.11);
}

[data-theme="dark"] {
    --bg: #111827;
    --surface: #182235;
    --surface-2: #223049;
    --text: #eef4ff;
    --muted: #9fb0c8;
    --border: #334155;
    --accent: #60a5fa;
    --accent-strong: #93c5fd;
    --danger: #fb923c;
    --danger-bg: #3a2118;
    --shadow: 0 18px 50px rgba(0, 0, 0, 0.25);
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    min-height: 100vh;
    background:
        radial-gradient(circle at 20% 0%, rgba(37, 99, 235, 0.13), transparent 32rem),
        var(--bg);
    color: var(--text);
    font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

button,
input,
select,
textarea {
    font: inherit;
}

.topbar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
    padding: 1.25rem clamp(1rem, 4vw, 3rem);
}

.label {
    margin: 0 0 0.25rem;
    color: var(--accent);
    font-size: 0.78rem;
    font-weight: 800;
    letter-spacing: 0;
    text-transform: uppercase;
}

h1,
h2,
h3,
p {
    margin-top: 0;
}

h1 {
    margin-bottom: 0;
    font-size: clamp(1.65rem, 3vw, 2.6rem);
    line-height: 1.08;
}

h2 {
    margin-bottom: 1rem;
    font-size: 1.12rem;
}

h3 {
    margin-bottom: 0.65rem;
    font-size: 0.95rem;
}

.layout {
    display: grid;
    grid-template-columns: minmax(15rem, 19rem) minmax(0, 1fr);
    gap: 1.25rem;
    padding: 0 clamp(1rem, 4vw, 3rem) 2rem;
}

.sidebar,
.workspace,
.cipher-form,
.result-panel,
.calculation-panel,
.empty-state,
.history-panel {
    border: 1px solid var(--border);
    background: color-mix(in srgb, var(--surface) 94%, transparent);
    box-shadow: var(--shadow);
}

.sidebar {
    align-self: start;
    display: grid;
    gap: 1rem;
    padding: 1rem;
    border-radius: 8px;
}

.workspace {
    display: grid;
    gap: 1rem;
    padding: 1rem;
    border-radius: 8px;
}

.cipher-tabs {
    display: grid;
    gap: 0.45rem;
}

.tab-button,
.theme-toggle,
.ghost-button,
.primary-button {
    border: 1px solid var(--border);
    border-radius: 8px;
    cursor: pointer;
    transition: transform 160ms ease, border-color 160ms ease, background 160ms ease;
}

.tab-button {
    width: 100%;
    padding: 0.78rem 0.9rem;
    background: transparent;
    color: var(--text);
    text-align: left;
    font-weight: 700;
}

.tab-button:hover,
.tab-button.active {
    border-color: var(--accent);
    background: color-mix(in srgb, var(--accent) 13%, transparent);
    color: var(--accent-strong);
}

.theme-toggle {
    display: inline-flex;
    align-items: center;
    gap: 0.45rem;
    padding: 0.72rem 0.9rem;
    background: var(--surface);
    color: var(--text);
    font-weight: 700;
}

.theme-icon {
    font-size: 1.1rem;
}

.cipher-form,
.result-panel,
.calculation-panel,
.empty-state,
.history-panel {
    padding: 1rem;
    border-radius: 8px;
}

.form-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 1rem;
}

label {
    display: grid;
    gap: 0.45rem;
    color: var(--muted);
    font-size: 0.84rem;
    font-weight: 700;
}

input,
select,
textarea {
    width: 100%;
    border: 1px solid var(--border);
    border-radius: 8px;
    background: var(--surface);
    color: var(--text);
    padding: 0.75rem 0.85rem;
    outline: none;
}

input:focus,
select:focus,
textarea:focus {
    border-color: var(--accent);
    box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 18%, transparent);
}

textarea {
    margin-top: 1rem;
    resize: vertical;
    min-height: 9rem;
}

.cipher-field {
    display: none;
}

.cipher-field.active {
    display: grid;
}

.affine-fields {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 0.75rem;
}

.hill-fields {
    grid-column: 1 / -1;
}

.matrix-inputs {
    display: grid;
    gap: 0.35rem;
    max-width: min(100%, 32rem);
}

.matrix-row {
    display: grid;
    gap: 0.35rem;
}

.matrix-row input {
    padding: 0.6rem;
    text-align: center;
}

.actions,
.panel-heading {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
    flex-wrap: wrap;
}

.primary-button {
    border-color: var(--accent);
    background: var(--accent);
    color: #ffffff;
    padding: 0.82rem 1.2rem;
    font-weight: 800;
}

.primary-button:hover,
.theme-toggle:hover,
.ghost-button:hover,
.tab-button:hover {
    transform: translateY(-1px);
}

.ghost-button {
    background: transparent;
    color: var(--muted);
    padding: 0.45rem 0.7rem;
    font-size: 0.82rem;
}

.muted {
    color: var(--muted);
}

code {
    display: inline-block;
    border-radius: 6px;
    background: var(--surface-2);
    color: var(--text);
    padding: 0.28rem 0.45rem;
    font-size: 0.86rem;
}

output {
    display: block;
    overflow-wrap: anywhere;
    border-radius: 8px;
    background: var(--surface-2);
    padding: 1rem;
    color: var(--accent-strong);
    font-size: clamp(1.2rem, 2.4vw, 1.8rem);
    font-weight: 800;
}

.error-panel {
    border-color: var(--danger);
    background: var(--danger-bg);
}

.error-panel h2,
.error-panel p {
    color: var(--danger);
}

.matrix-summary {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(13rem, 1fr));
    gap: 1rem;
    margin-bottom: 1rem;
}

.matrix-table {
    border-collapse: collapse;
    width: auto;
    min-width: 12rem;
    overflow: hidden;
    border-radius: 8px;
}

.matrix-table td {
    border: 1px solid var(--border);
    background: var(--surface-2);
    padding: 0.72rem;
    text-align: center;
    font-weight: 800;
}

.playfair-table td {
    color: var(--accent-strong);
}

.step-list {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(15rem, 1fr));
    gap: 0.8rem;
}

.step-card {
    border: 1px solid var(--border);
    border-radius: 8px;
    background: var(--surface);
    padding: 0.9rem;
}

.step-card code {
    display: block;
    margin: 0.25rem 0;
}

.step-table-wrap {
    overflow-x: auto;
}

.step-table {
    width: 100%;
    min-width: 42rem;
    border-collapse: collapse;
}

.step-table th,
.step-table td {
    border-bottom: 1px solid var(--border);
    padding: 0.75rem;
    text-align: left;
}

.step-table th {
    color: var(--muted);
    font-size: 0.78rem;
    text-transform: uppercase;
}

.pair-line {
    overflow-wrap: anywhere;
    font-weight: 800;
}

.history-list {
    display: grid;
    gap: 0.6rem;
}

.history-item {
    border: 1px solid var(--border);
    border-radius: 8px;
    background: var(--surface-2);
    padding: 0.75rem;
}

.history-item div {
    display: flex;
    justify-content: space-between;
    gap: 0.5rem;
}

.history-item p {
    margin: 0.55rem 0;
    overflow-wrap: anywhere;
    font-weight: 800;
}

.history-item small {
    color: var(--muted);
}

.empty-state {
    min-height: 13rem;
    display: grid;
    align-content: center;
}

.reveal {
    animation: reveal 260ms ease both;
}

@keyframes reveal {
    from {
        opacity: 0;
        transform: translateY(8px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@media (max-width: 860px) {
    .layout {
        grid-template-columns: 1fr;
    }

    .cipher-tabs {
        grid-template-columns: repeat(5, minmax(7rem, 1fr));
        overflow-x: auto;
    }
}

@media (max-width: 640px) {
    .topbar,
    .actions,
    .panel-heading {
        align-items: stretch;
        flex-direction: column;
    }

    .form-grid,
    .affine-fields {
        grid-template-columns: 1fr;
    }

    .cipher-tabs {
        grid-template-columns: 1fr 1fr;
    }
}