:root {
    /* Size / spacing — driven by the sliders */
    --inner-border-width: 2px;
    --outer-border-width: 5px;
    --title-size: 28px;
    --padding: 5px;
    --box-size: 50px;
    --margin: 10px;

    /* Card design — driven by the design presets (defaults = "Classic").
       Everything here is greyscale and shadow-free so the on-screen preview is
       an exact match for the black & white printout. Presets differ by shape:
       border width/style, corner radius and title treatment — not colour. */
    --card-bg: #ffffff;
    --card-border-color: #111111;
    --card-border-style: solid;
    --cell-border-color: #111111;
    --card-radius: 12px;
    --card-shadow: none;
    --title-color: #111111;
    --title-font: system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;
    --title-transform: none;
    --title-spacing: normal;
    --cell-bg: #ffffff;
    --cell-color: #111111;

    /* Theme palette */
    --accent: #4f46e5;
    --accent-hover: #4338ca;
    --accent-active: #3730a3;
    --bg-start: #eef2f7;
    --bg-end: #dde6f3;
    --panel: #ffffff;
    --panel-muted: #f6f8fc;
    --text: #1f2937;
    --text-muted: #6b7280;
    --border: #e2e8f0;
    --radius: 14px;
    --shadow-sm: 0 2px 6px rgba(15, 23, 42, 0.06);
    --shadow-md: 0 8px 24px rgba(15, 23, 42, 0.10);
}

html, body {
    height: 100%;
    margin: 0;
}

body {
    margin: 0;
    padding: 0;
    overflow-x: hidden;
    font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    color: var(--text);
    background: linear-gradient(160deg, var(--bg-start), var(--bg-end));
    min-height: 100%;
    display: flex;
    flex-direction: column;
}

@media print {
    #mainDiv,
    #footer {
        display: none !important;
    }

    /* The screen layout pins the body to one viewport height with a flex
       column. Firefox honours that when printing and clips everything onto a
       single page, so reset to normal block flow and let content grow. */
    html, body {
        height: auto;
        min-height: 0;
    }

    body {
        display: block;
        background: #ffffff;
    }

    #drawDiv {
        display: block;
        width: auto;
        margin: 0;
        text-align: center;
    }

    /* Cards stay inline-block (from the base rule) so several fit per row when
       there's space; break-inside: avoid keeps each card whole and pushes it to
       the next page rather than splitting it across the boundary. */
    .card {
        vertical-align: top;
        page-break-inside: avoid;
        break-inside: avoid;
        box-shadow: none;
    }

    .card:hover {
        transform: none;
    }

    @page {
        size: A4;
        margin: 10mm;
    }
}

#mainDiv {
    width: min(1100px, 96%);
    box-sizing: border-box;
    margin: 24px auto 0;
    padding: 28px 32px 32px;
    border: none;
    border-radius: 20px;
    background: linear-gradient(145deg, #ffffff, #f2f5fb);
    box-shadow: var(--shadow-md);
}

#mainDiv h1 {
    text-align: center;
    font-size: 52px;
    font-weight: 700;
    margin: 0 0 6px;
    letter-spacing: -0.02em;
    background: linear-gradient(135deg, var(--accent), #7c3aed);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    color: var(--accent);
}

#subtitle {
    text-align: center;
    margin: 0 0 22px;
    color: var(--text-muted);
    font-size: 16px;
    font-weight: 400;
}

/* Inline SVG icons inherit the surrounding text colour and scale with it. */
.icon {
    width: 1.15em;
    height: 1.15em;
    flex: 0 0 auto;
    vertical-align: -0.15em;
}

#settingsDiv {
    background: var(--panel);
    padding: 22px;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    box-shadow: var(--shadow-sm);
    margin-top: 16px;
    display: flex;
    flex-direction: column;
    gap: 18px;
    align-items: center;
}

#presetRow {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: center;
    gap: 10px;
}

#presetLabel {
    font-size: 14px;
    font-weight: 600;
    color: var(--text-muted);
    margin-right: 4px;
}

.preset-btn {
    padding: 8px 20px;
    border: 1px solid var(--border);
    border-radius: 999px;
    background: var(--panel-muted);
    color: var(--text);
    font-family: inherit;
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    transition: color 0.2s ease, border-color 0.2s ease, background 0.2s ease, box-shadow 0.2s ease;
}

.preset-btn:hover {
    border-color: var(--accent);
    color: var(--accent);
}

.preset-btn.active {
    background: var(--accent);
    border-color: var(--accent);
    color: #fff;
    box-shadow: 0 4px 12px rgba(79, 70, 229, 0.25);
}

#advancedToggle {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    background: transparent;
    border: none;
    color: var(--accent);
    font-family: inherit;
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    padding: 2px 6px;
}

#advancedToggle:hover {
    color: var(--accent-hover);
    text-decoration: underline;
}

#advancedDiv {
    display: flex;
    flex-wrap: wrap;
    gap: 16px;
    justify-content: center;
    width: 100%;
}

#settingsDiv label {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    font-size: 14px;
    font-weight: 500;
    color: var(--text);
    background: var(--panel-muted);
    padding: 14px 16px;
    border: 1px solid var(--border);
    border-radius: 10px;
    width: 200px;
    box-shadow: var(--shadow-sm);
}

#sizeSliderLabel {
    width: 340px;
    max-width: 100%;
    align-items: stretch;
    font-size: 15px;
    font-weight: 600;
}

#settingsDiv input[type="range"] {
    width: 100%;
    margin-top: 12px;
    appearance: none;
    -webkit-appearance: none;
    height: 6px;
    border-radius: 5px;
    background: #dbe2ec;
    outline: none;
    transition: background 0.3s ease;
}

#settingsDiv input[type="range"]::-webkit-slider-thumb {
    appearance: none;
    -webkit-appearance: none;
    width: 18px;
    height: 18px;
    border-radius: 50%;
    background: var(--accent);
    cursor: pointer;
    box-shadow: 0 0 0 4px rgba(79, 70, 229, 0.15);
    transition: background 0.2s ease, box-shadow 0.2s ease;
}

#settingsDiv input[type="range"]::-webkit-slider-thumb:hover {
    background: var(--accent-hover);
    box-shadow: 0 0 0 6px rgba(79, 70, 229, 0.20);
}

#settingsDiv input[type="range"]::-moz-range-thumb {
    width: 18px;
    height: 18px;
    border: none;
    border-radius: 50%;
    background: var(--accent);
    cursor: pointer;
}

#createDiv {
    background: var(--panel);
    padding: 24px;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    box-shadow: var(--shadow-sm);
    display: flex;
    flex-wrap: wrap;
    gap: 18px;
    justify-content: center;
    align-items: flex-start;
    margin-bottom: 0;
}

.field {
    display: flex;
    flex-direction: column;
    width: 200px;
}

.field label {
    font-size: 14px;
    font-weight: 600;
    color: var(--text);
    margin-bottom: 6px;
}

.field .optional {
    font-weight: 400;
    font-size: 12px;
    color: var(--text-muted);
}

.field .hint {
    margin-top: 6px;
    font-size: 12px;
    line-height: 1.35;
    color: var(--text-muted);
}

.field .checkbox-label {
    display: flex;
    flex-direction: row;
    align-self: flex-start;
    align-items: center;
    justify-content: flex-start;
    gap: 8px;
    margin-bottom: 6px;
    white-space: nowrap;
    cursor: pointer;
}

.field .checkbox-label input[type="checkbox"] {
    flex: 0 0 auto;
    width: 18px;
    height: 18px;
    margin: 0;
    accent-color: var(--accent);
    cursor: pointer;
}

#createDiv input,
#createDiv select,
#createDiv textarea {
    box-sizing: border-box;
    padding: 11px 15px;
    border: 1px solid var(--border);
    border-radius: 10px;
    font-family: inherit;
    font-size: 15px;
    color: var(--text);
    width: 100%;
    transition: border-color 0.2s ease, box-shadow 0.2s ease, background 0.2s ease;
    background: var(--panel-muted);
}

#createDiv input::placeholder,
#createDiv textarea::placeholder {
    color: var(--text-muted);
}

#createDiv input:focus,
#createDiv select:focus,
#createDiv textarea:focus {
    border-color: var(--accent);
    outline: none;
    background: #ffffff;
    box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.15);
}

.range-row {
    display: flex;
    align-items: center;
    gap: 8px;
}

.range-row input {
    flex: 1;
    min-width: 0;
    text-align: center;
}

.range-sep {
    color: var(--text-muted);
    font-size: 13px;
}

#selectText {
    flex-basis: 100%;
    width: 100%;
    max-width: 640px;
}

#selectText textarea {
    min-height: 110px;
    resize: vertical;
}

#createActions {
    flex-basis: 100%;
    display: flex;
    justify-content: center;
    gap: 12px;
    margin-top: 4px;
}

#createDiv button {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 12px 26px;
    background: var(--accent);
    color: #fff;
    border: none;
    border-radius: 10px;
    font-family: inherit;
    font-size: 15px;
    font-weight: 600;
    cursor: pointer;
    box-shadow: 0 4px 12px rgba(79, 70, 229, 0.25);
    transition: background-color 0.2s ease, transform 0.15s ease, box-shadow 0.2s ease;
}

#createDiv button:hover {
    background: var(--accent-hover);
    transform: translateY(-1px);
    box-shadow: 0 6px 16px rgba(79, 70, 229, 0.30);
}

#createDiv button:active {
    background: var(--accent-active);
    transform: translateY(0);
}

#createDiv button.secondary {
    background: var(--panel-muted);
    color: var(--accent);
    border: 1px solid var(--border);
    box-shadow: none;
}

#createDiv button.secondary:hover {
    background: #eef0f6;
    color: var(--accent-hover);
}

#formError {
    flex-basis: 100%;
    display: none;
    margin: 4px 0 0;
    text-align: center;
    color: #b91c1c;
    background: #fef2f2;
    border: 1px solid #fecaca;
    border-radius: 10px;
    padding: 10px 14px;
    font-size: 14px;
    font-weight: 500;
}

#settingsToggle {
    display: flex;
    width: fit-content;
    align-items: center;
    gap: 8px;
    margin: 18px auto 0;
    padding: 9px 16px;
    background: transparent;
    color: var(--text-muted);
    border: 1px solid var(--border);
    border-radius: 999px;
    font-family: inherit;
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    transition: color 0.2s ease, border-color 0.2s ease, background 0.2s ease;
}

#settingsToggle:hover {
    color: var(--accent);
    border-color: var(--accent);
    background: rgba(79, 70, 229, 0.06);
}

.error {
    border-color: #ef4444 !important;
    box-shadow: 0 0 0 3px rgba(239, 68, 68, 0.20) !important;
}

.card {
    border: var(--outer-border-width) var(--card-border-style) var(--card-border-color);
    background: var(--card-bg);
    box-shadow: var(--card-shadow);
    border-radius: var(--card-radius);
    padding: var(--padding);
    margin: var(--margin);
    display: inline-block;
    overflow: hidden;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.card:hover {
    transform: scale(1.5);
    box-shadow: 0 12px 28px rgba(15, 23, 42, 0.28);
    z-index: 5;
    position: relative;
}

.card h1 {
    text-align: center;
    font-size: var(--title-size);
    font-weight: 700;
    margin-bottom: 10px;
    color: var(--title-color);
    font-family: var(--title-font);
    text-transform: var(--title-transform);
    letter-spacing: var(--title-spacing);
}

.boxDiv {
    display: grid;
    row-gap: 0;
    border: var(--inner-border-width) solid var(--cell-border-color);
}

.boxDiv div.free {
    font-weight: 700;
    background: #eeeeee;
}

.card-number {
    text-align: center;
    margin-top: 8px;
    font-size: 12px;
    font-weight: 500;
    color: #555555;
    font-family: var(--title-font);
}

.boxDiv div {
    border: var(--inner-border-width) solid var(--cell-border-color);
    background: var(--cell-bg);
    color: var(--cell-color);
    width: var(--box-size);
    height: var(--box-size);
    display: flex;
    justify-content: center;
    align-items: center;
    text-align: center;
    padding: 5px;
    overflow-wrap: normal;
    word-break: break-word;
    hyphens: manual;
    hyphens: auto;
    line-height: 1.2;
    flex-direction: column;
    overflow: hidden;
    font-weight: 500;
}

/* ---- Card design presets --------------------------------------------------
   Selected by setting data-theme on #drawDiv. Each preset only overrides the
   greyscale design custom properties (border width/style, radius, title
   treatment), so what you see on screen is exactly what prints. The size and
   spacing sliders keep working on top of any preset. "classic" is the :root
   default and needs no overrides. */

/* Extra-round, soft grey grid. */
#drawDiv[data-theme="rounded"] {
    --card-radius: 24px;
    --card-border-color: #333333;
    --cell-border-color: #555555;
}

/* Crisp square edges with a formal, spaced-out uppercase title. */
#drawDiv[data-theme="sharp"] {
    --card-radius: 0;
    --card-border-color: #000000;
    --cell-border-color: #000000;
    --title-transform: uppercase;
    --title-spacing: 3px;
}

/* Double-line outer frame for a certificate-like look. */
#drawDiv[data-theme="double"] {
    --card-radius: 6px;
    --card-border-style: double;
    --card-border-color: #000000;
    --cell-border-color: #222222;
}

/* Dashed "cut-out" frame. */
#drawDiv[data-theme="dashed"] {
    --card-radius: 10px;
    --card-border-style: dashed;
    --card-border-color: #333333;
    --cell-border-color: #777777;
}

/* Airy and light: thin pale-grey lines, quiet uppercase title. */
#drawDiv[data-theme="minimal"] {
    --card-radius: 4px;
    --card-border-color: #cfcfcf;
    --cell-border-color: #e0e0e0;
    --title-color: #444444;
    --title-transform: uppercase;
    --title-spacing: 2px;
}

#drawDiv {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-around;
    align-content: flex-start;
    width: 210mm;
    max-width: 100%;
    margin: 20px auto 0;
    flex: 1;
}

#footer {
    text-align: center;
    padding: 20px;
    margin-top: auto;
    font-size: 16px;
    background: rgba(255, 255, 255, 0.7);
    backdrop-filter: blur(6px);
    border-top: 1px solid var(--border);
    width: 100%;
    box-sizing: border-box;
}

#footer a {
    text-decoration: none;
    color: var(--text-muted);
    display: inline-flex;
    align-items: center;
    gap: 8px;
    font-weight: 500;
    transition: color 0.2s ease;
}

#footer a:hover {
    color: var(--accent);
}

#footer .icon {
    width: 1.3em;
    height: 1.3em;
}