*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

/* ─── Tokens ────────────────────────────────────────────────────────────────── */

:root {
    --bg: #f4f4f5;
    --fg: #18181b;
    --card-bg: #ffffff;
    --card-shadow: 0 1px 4px rgba(0, 0, 0, .08), 0 4px 24px rgba(0, 0, 0, .06);
    --heading: #52525b;
    --muted: #636369;
    --divider: #f1f1f1;
    --green: #15803d;

    --error-bg: #fef2f2;
    --error-border: #fecaca;
    --error-fg: #b91c1c;
    --error-code-bg: #fee2e2;

    --input-bg: #fafafa;
    --input-fg: #18181b;
    --input-border: #e4e4e7;
    --input-focus-bg: #ffffff;
    --input-focus-border: #a1a1aa;
    --input-focus-shadow: rgba(0, 0, 0, .06);
    --placeholder: #d4d4d8;

    --btn-bg: #fafafa;
    --btn-fg: #3f3f46;
    --btn-border: #e4e4e7;
    --btn-hover-bg: #f1f1f1;
    --btn-hover-border: #d4d4d8;
    --btn-active-bg: #e9e9ea;
    --btn-success-fg: #16a34a;
    --btn-success-border: #bbf7d0;
    --btn-success-bg: #f0fdf4;
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg: #09090b;
        --fg: #fafafa;
        --card-bg: #18181b;
        --card-shadow: 0 1px 4px rgba(0, 0, 0, .4), 0 4px 24px rgba(0, 0, 0, .3);
        --heading: #a1a1aa;
        --muted: #a1a1aa;
        --divider: #27272a;
        --green: #4ade80;

        --error-bg: #450a0a;
        --error-border: #7f1d1d;
        --error-fg: #fca5a5;
        --error-code-bg: #3b0404;

        --input-bg: #27272a;
        --input-fg: #fafafa;
        --input-border: #3f3f46;
        --input-focus-bg: #3f3f46;
        --input-focus-border: #71717a;
        --input-focus-shadow: rgba(255, 255, 255, .04);
        --placeholder: #52525b;

        --btn-bg: #27272a;
        --btn-fg: #d4d4d8;
        --btn-border: #3f3f46;
        --btn-hover-bg: #3f3f46;
        --btn-hover-border: #52525b;
        --btn-active-bg: #52525b;
        --btn-success-fg: #4ade80;
        --btn-success-border: #166534;
        --btn-success-bg: #052e16;
    }
}

/* ─── Base ──────────────────────────────────────────────────────────────────── */

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    background: var(--bg);
    color: var(--fg);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

main {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 2rem;
}

footer {
    padding: 1rem 2rem;
    text-align: center;
}

/* ─── Card ──────────────────────────────────────────────────────────────────── */

.card {
    background: var(--card-bg);
    border-radius: 12px;
    box-shadow: var(--card-shadow);
    padding: 2rem 2.5rem;
    max-width: 480px;
    width: 100%;
}

.card--wide {
    max-width: 640px;
}

h1 {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--heading);
    text-transform: uppercase;
    letter-spacing: .08em;
    margin-bottom: 1.5rem;
    text-align: center;
}

/* ─── QR ────────────────────────────────────────────────────────────────────── */

#qr-wrap {
    display: flex;
    justify-content: center;
    margin-bottom: 1.75rem;
}

#qr-wrap canvas {
    border-radius: 6px;
}

/* ─── Info table ────────────────────────────────────────────────────────────── */

.info-table {
    width: 100%;
    border-collapse: collapse;
    font-size: .88rem;
}

.info-table tr + tr td {
    border-top: 1px solid var(--divider);
}

.info-table td {
    padding: .45rem .25rem;
    vertical-align: top;
}

.info-table td:first-child {
    color: var(--muted);
    white-space: nowrap;
    padding-right: 1rem;
    width: 1%;
}

.info-table td:last-child {
    font-weight: 500;
    display: flex;
    align-items: flex-start;
    gap: .5rem;
}

.info-table td:last-child > span:first-child {
    flex: 1;
    word-break: break-all;
}

.copy-wrap {
    position: relative;
    flex-shrink: 0;
    display: inline-flex;
    align-items: center;
}

.copy-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: .25rem;
    border: 1px solid transparent;
    background: transparent;
    color: var(--muted);
    border-radius: 6px;
    cursor: pointer;
    transition: color .15s, background .15s, border-color .15s;
    line-height: 1;
}

.copy-btn svg {
    width: 13px;
    height: 13px;
    fill: currentColor;
}

/* checkmark uses stroke, not fill */
.copy-btn--success svg {
    fill: none;
}

.copy-btn:hover {
    color: var(--fg);
    background: var(--divider);
}

.copy-btn:focus-visible {
    outline: 3px solid;
    outline-offset: 2px;
    border-radius: 2px;
    opacity: 1;
}

.copy-btn--success {
    color: var(--green);
    border-color: var(--green);
}

/* ─── Copy feedback badge (tooltip) ─────────────────────────────────────────── */

.copy-feedback {
    position: absolute;
    right: calc(100% + .4rem);
    top: 50%;
    transform: translateY(-50%);
    z-index: 10;
    font-size: .75rem;
    font-weight: 600;
    color: var(--fg);
    background: var(--card-bg);
    border: 1px solid var(--btn-border);
    border-radius: 6px;
    padding: .15rem .45rem;
    white-space: nowrap;
    opacity: 0;
    pointer-events: none;
    transition: opacity .15s;
    box-shadow: var(--card-shadow);
}

.copy-feedback--visible {
    opacity: 1;
}

.amount-row td:last-child {
    font-size: 1.15rem;
    font-weight: 700;
    color: var(--green);
}

/* ─── Error ─────────────────────────────────────────────────────────────────── */

#error {
    display: none;
    background: var(--error-bg);
    border: 1px solid var(--error-border);
    border-radius: 8px;
    padding: 1rem;
    color: var(--error-fg);
    font-size: .875rem;
    margin-bottom: 1rem;
}

#error code {
    display: block;
    margin-top: .5rem;
    font-size: .78rem;
    background: var(--error-code-bg);
    padding: .4rem .6rem;
    border-radius: 4px;
    word-break: break-all;
}

/* ─── Form ──────────────────────────────────────────────────────────────────── */

.form-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: .75rem 1rem;
    margin-bottom: 1.5rem;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: .3rem;
}

.form-group--full {
    grid-column: 1 / -1;
}

label {
    font-size: .8rem;
    font-weight: 500;
    color: var(--muted);
    text-transform: uppercase;
    letter-spacing: .05em;
}

input {
    padding: .5rem .65rem;
    border: 1px solid var(--input-border);
    border-radius: 6px;
    font-size: .9rem;
    font-family: inherit;
    color: var(--input-fg);
    background: var(--input-bg);
    transition: border-color .15s, box-shadow .15s;
    outline: none;
}

input:focus {
    border-color: var(--input-focus-border);
    background: var(--input-focus-bg);
    box-shadow: 0 0 0 3px var(--input-focus-shadow);
}

input::placeholder {
    color: var(--placeholder);
}

/* ─── Buttons ───────────────────────────────────────────────────────────────── */

.actions {
    display: flex;
    gap: .75rem;
    margin-top: 1.25rem;
}

.btn {
    flex: 1;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: .4rem;
    padding: .55rem 1rem;
    border: 1px solid var(--btn-border);
    border-radius: 7px;
    font-size: .85rem;
    font-family: inherit;
    font-weight: 500;
    color: var(--btn-fg);
    background: var(--btn-bg);
    cursor: pointer;
    transition: background .15s, border-color .15s;
}

.btn:hover {
    background: var(--btn-hover-bg);
    border-color: var(--btn-hover-border);
}

.btn:active {
    background: var(--btn-active-bg);
}

.btn:disabled {
    opacity: .4;
    cursor: not-allowed;
}

.btn--success {
    color: var(--btn-success-fg);
    border-color: var(--btn-success-border);
    background: var(--btn-success-bg);
}

/* ─── Secondary action row (anchor label + copy button) ─────────────────────── */

.actions--secondary {
    margin-top: .5rem;
}

.anchor-input {
    flex: 1;
}

.btn--anchor {
    flex: 0 0 auto;
}

/* ─── Responsive ─────────────────────────────────────────────────────────────── */

@media (max-width: 520px) {
    main {
        padding: 1rem;
    }

    .card {
        padding: 1.5rem 1.25rem;
    }

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

    .actions {
        flex-direction: column;
    }

    .actions--secondary {
        flex-direction: column;
        margin-top: .75rem;
    }

    .btn,
    .btn--anchor,
    .anchor-input {
        width: 100%;
        flex: none;
    }
}

/* ─── Footer link ───────────────────────────────────────────────────────────── */

.footer-link {
    display: inline-block;
    font-size: .8rem;
    color: var(--muted);
    text-decoration: underline;
    letter-spacing: .02em;
    transition: color .15s;
}

.footer-link:hover {
    color: var(--fg);
}

.footer-link:focus-visible {
    outline: 3px solid;
    outline-offset: 4px;
    border-radius: 2px;
    opacity: 1;
}