.builder {
    display: grid;
    grid-template-columns: minmax(0, 1.4fr) minmax(300px, 0.72fr);
    gap: 28px;
    align-items: start;
    padding: 8px 0 88px;
}
.choices { display: grid; gap: 28px; }
.choices fieldset {
    border: 0;
    margin: 0;
    padding: 0 0 26px;
    border-bottom: 1px solid var(--line);
}
.choices fieldset:last-child { border-bottom: 0; padding-bottom: 0; }
.choices legend {
    font-size: 15px;
    font-weight: 560;
    color: var(--night);
    margin-bottom: 12px;
}
.choice-row, .os-grid { display: flex; flex-wrap: wrap; gap: 8px; }
.choice, .gateway {
    position: relative;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    min-height: 46px;
    padding: 8px 14px;
    border-radius: 14px;
    border: 1px solid var(--line);
    background: #fff;
    color: var(--ink);
    cursor: pointer;
    box-shadow: 0 8px 22px rgba(16, 32, 64, 0.04);
    transition: border-color 180ms ease, background 180ms ease, color 180ms ease, transform 180ms ease, box-shadow 180ms ease;
}
.choice input, .gateway input {
    position: absolute;
    opacity: 0;
    inset: 0;
    margin: 0;
}
.choice:focus-within, .gateway:focus-within {
    outline: 2px solid var(--accent);
    outline-offset: 2px;
}
.choice:has(input:checked), .gateway:has(input:checked) {
    border-color: var(--night);
    background: var(--night);
    color: #fff;
    box-shadow: 0 12px 28px rgba(16, 32, 64, 0.16);
}
.choice:active { transform: scale(0.98); }
.choice b { font-weight: 500; color: var(--ink-soft); font-variant-numeric: tabular-nums; }
.choice:has(input:checked) b { color: rgba(255, 255, 255, 0.78); }
.models { display: grid; grid-template-columns: 1fr 1fr; }
.models .choice {
    min-height: 108px;
    padding: 18px 18px 16px;
    flex-direction: column;
    align-items: flex-start;
    justify-content: flex-end;
    border-radius: 18px;
    overflow: hidden;
}
.models .choice span {
    font-size: 28px;
    font-weight: 520;
    letter-spacing: -0.04em;
    color: var(--night);
}
.models .choice b { margin-top: 4px; font-size: 15px; }
.models .choice:has(input:checked) {
    background:
        radial-gradient(140px 80px at 100% 0%, rgba(255, 255, 255, 0.28), transparent 70%),
        linear-gradient(165deg, #102040, #1a4f8c);
}
.models .choice:has(input:checked) span { color: #fff; }
.seg { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); }
.seg-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
.seg .choice {
    justify-content: center;
    flex-direction: column;
    gap: 2px;
    min-height: 64px;
}
.seg .choice span { font-size: 16px; font-weight: 560; }
.os-label {
    margin: 4px 0 8px;
    color: var(--ink-soft);
    font-size: 13px;
}
.os-grid { display: grid; grid-template-columns: 1fr 1fr; }
.os-grid + .os-label { margin-top: 14px; }
.os-grid .choice { justify-content: flex-start; }
.ip-field { display: flex; align-items: center; gap: 8px; }
.ip-field button {
    width: 46px;
    height: 46px;
    border-radius: 14px;
    border: 1px solid var(--line);
    background: #fff;
    color: var(--night);
    font-size: 22px;
    line-height: 1;
    box-shadow: 0 8px 22px rgba(16, 32, 64, 0.04);
    transition: background 180ms ease, transform 180ms ease;
}
.ip-field button:hover { background: var(--ice); }
.ip-field button:active { transform: scale(0.96); }
.ip-field input {
    width: 88px;
    height: 46px;
    border-radius: 14px;
    border: 1px solid var(--line);
    padding: 0 12px;
    background: #fff;
    text-align: center;
    font-variant-numeric: tabular-nums;
    font-size: 18px;
    color: var(--night);
}
.choices .fine { margin-top: 10px; }
.slip {
    position: sticky;
    top: calc(var(--header) + 16px);
    padding: 8px 8px 18px;
    border-radius: 22px;
    background: #fff;
    box-shadow: var(--shadow);
}
.slip-head {
    padding: 18px 16px 16px;
    border-radius: 16px;
    color: #fff;
    background:
        radial-gradient(160px 80px at 100% 0%, rgba(255, 255, 255, 0.24), transparent 70%),
        linear-gradient(165deg, #102040, #1a4f8c);
}
.slip-place { font-size: 13px; letter-spacing: 0.04em; color: rgba(255, 255, 255, 0.72); }
.slip-kicker { margin-top: 14px; color: rgba(255, 255, 255, 0.72); font-size: 14px; }
.due {
    margin: 4px 0 0;
    font-size: clamp(48px, 5vw, 64px);
    letter-spacing: -0.05em;
    line-height: 0.95;
    color: #fff;
    font-variant-numeric: tabular-nums;
    font-weight: 520;
}
.due.is-tick { animation: tick 420ms cubic-bezier(0.22, 1, 0.36, 1); }
@keyframes tick {
    from { opacity: 0.25; transform: translateY(8px); }
    to { opacity: 1; transform: none; }
}
.slip-row, .quote-lines li {
    display: flex;
    justify-content: space-between;
    gap: 12px;
    color: var(--ink-soft);
    font-variant-numeric: tabular-nums;
}
.slip-row { margin: 14px 12px 0; padding-bottom: 8px; color: var(--night); }
.slip-row strong { font-size: 18px; }
.quote-lines {
    list-style: none;
    margin: 0 12px;
    padding: 8px 0 0;
    border-top: 1px solid var(--line);
}
.quote-lines li { padding: 7px 0; font-size: 14px; }
.quote-lines li span:last-child { color: var(--night); }
#gateway-list { display: grid; gap: 8px; margin: 14px 12px; }
.gateway { color: var(--ink); background: var(--ice); box-shadow: none; }
#checkout-btn {
    width: calc(100% - 24px);
    margin: 0 12px;
    min-height: 48px;
    background: var(--night);
    color: #fff;
    border-color: var(--night);
    box-shadow: none;
}
#checkout-btn:hover { background: var(--accent-press); color: #fff; border-color: var(--accent-press); }
.slip > .fine { margin: 12px 12px 0; }
.pay-dialog p { margin: 8px 0 20px; color: var(--ink-soft); line-height: 1.6; }
.pay-actions { display: flex; gap: 8px; }
.pay-actions .btn { flex: 1; min-height: 44px; }
@media (max-width: 980px) {
    .builder, .os-grid, .models { grid-template-columns: 1fr; }
    .slip { position: static; }
    .seg-4 { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 640px) {
    .seg, .os-grid { grid-template-columns: 1fr; }
}
@media (prefers-reduced-motion: reduce) {
    .due.is-tick { animation: none; }
    .choice, .ip-field button, #checkout-btn { transition: none; }
}