:root {
    --calc:#1e1f24;
    --screen:#e9edf1;
    --screen-text:#111827;
    --key:#2a2c33;
    --key-ghost:#3a3d47;
    --key-text:#e5e7eb;
    --key-ac:#f5c542;
    --key-del:#f5c542;
    --key-op:#394150;
    --accent:#ffd04d;
    --accent-2:#ffb200;
    --shadow:0 10px 24px rgba(0,0,0,.18);
    --radius:18px;
}

/* Calculator Container */
.calc {
    width: min(420px, 94vw);
    background: linear-gradient(135deg,#1f2026 0%,#1a1b20 60%,#17181c 100%);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 18px 16px 20px;
    position: relative;
    border: 1px solid rgba(255,255,255,.06);
}

/* Brand label inside calc */
.calc .brand {
    position: absolute;
    left: 18px;
    top: 12px;
    font-weight: 700;
    font-size: .9rem;
    letter-spacing: .08em;
    color: #fff;
}

/* Screen */
.calc .screen {
    margin-top: 26px;
    margin-bottom: 14px;
    background: var(--screen);
    color: var(--screen-text);
    border-radius: 12px;
    padding: 14px 14px 10px;
    box-shadow: inset 0 2px 8px rgba(0,0,0,.08);
}

.calc .screen .mini {
    min-height: 22px;
    font-size: .9rem;
    color: #6b7280;
    text-align: right;
    overflow: hidden;
    white-space: nowrap;
    text-overflow: ellipsis;
}

.calc .screen input {
    width: 100%;
    border: none;
    background: transparent;
    font-weight: 700;
    text-align: right;
    font-size: 1.8rem;
    outline: none;
    color: #111827;
    letter-spacing: .02em;
}

/* Meta Row */
.calc .meta-row {
    display: grid;
    grid-template-columns: repeat(6, 1fr);
    gap: 8px;
    margin: 10px 2px 12px;
}

.calc .kbd {
    font-size: .78rem;
    color: #a3a7b3;
}

/* Keys Layout */
.calc .keys {
    display: grid;
    grid-template-columns: repeat(6, 1fr);
    gap: 8px;
}

.calc button.key {
    appearance: none;
    border: none;
    background: var(--key);
    color: var(--key-text);
    padding: 12px 8px;
    border-radius: 10px;
    font-size: 1rem;
    font-weight: 600;
    box-shadow: 0 2px 0 rgba(0,0,0,.35);
    cursor: pointer;
    transition: transform .05s ease, background .15s ease, box-shadow .15s ease;
    user-select: none;
}

.calc button.key:active {
    transform: translateY(1px);
    box-shadow: 0 1px 0 rgba(0,0,0,.35);
}

/* Key Types */
.calc .op {
    background: var(--key-op);
}

.calc .ghost {
    background: var(--key-ghost);
}

.calc .ac,
.calc .del {
    background: var(--key-ac);
    color: #201a00;
}

.calc .equals {
    grid-column: span 2;
    background: #1b7cff;
}

.calc .wide {
    grid-column: span 2;
}

.calc .yellow {
    background: linear-gradient(180deg, var(--accent), var(--accent-2));
    color: #1b1300;
}

/* Pill buttons */
.calc .pill {
    background: #101216;
    color: #e5e7eb;
    border-radius: 999px;
    padding: 6px 10px;
    font-weight: 700;
    font-size: .8rem;
    border: 1px solid rgba(255,255,255,.08);
}

/* Toggle buttons */
.calc .toggle {
    display: flex;
    gap: 8px;
    align-items: center;
    justify-content: flex-end;
}

.calc .toggle button {
    background: #111418;
    color: #e5e7eb;
    border: 1px solid rgba(255,255,255,.12);
    padding: 6px 10px;
    border-radius: 999px;
    cursor: pointer;
    font-weight: 700;
    font-size: .8rem;
}

.calc .toggle .active {
    background: #23c55e;
    color: #071309;
    border-color: #23c55e;
}

/* Helper text */
.calc .note {
    color: #9aa0ad;
    font-size: .8rem;
    margin-top: 10px;
    text-align: right;
}

.calc .help {
    margin-top: 10px;
    color: #9aa0ad;
    font-size: .78rem;
}

/* Mobile responsiveness */
@media (max-width: 410px) {
    .calc .screen input {
        font-size: 1.5rem;
    }
    .calc .keys {
        gap: 6px;
    }
    .calc button.key {
        padding: 11px 6px;
        font-size: .95rem;
    }
}