:root {
    --bg: #f4efe4;
    --text-primary: #2b2419;
    --text-secondary: rgba(75, 62, 40, 0.55);
    --gold: #9c7c2c;
    --gold-strong: #86691f;
    --hairline: rgba(156, 124, 44, 0.4);
    --hairline-soft: rgba(156, 124, 44, 0.22);
    --panel: linear-gradient(160deg, rgba(255, 253, 246, 0.9), rgba(250, 245, 233, 0.84));
    --screen-bg: rgba(255, 254, 249, 0.75);
    --key-bg: linear-gradient(180deg, rgba(255, 254, 250, 0.94), rgba(249, 244, 232, 0.92));
    --key-op-bg: rgba(255, 253, 246, 0.4);
    --clear: #a04a40;
    --radius: 34px;
    --shadow: 0 30px 60px -20px rgba(90, 70, 30, 0.35), inset 0 1px 0 rgba(255, 255, 255, 0.9);
    --key-shadow: 0 3px 10px -3px rgba(90, 70, 30, 0.28), inset 0 1px 0 rgba(255, 255, 255, 0.85);
    --eq-bg: linear-gradient(160deg, #dcc57e, #c9a94e);
    --eq-text: #241c08;
    --eq-shadow: 0 6px 16px -6px rgba(168, 132, 44, 0.4), inset 0 1px 0 rgba(255, 245, 210, 0.5);
    --display-font: 'Didot', 'Bodoni MT', 'Playfair Display', 'Hiragino Mincho ProN', 'Yu Mincho', Georgia, serif;
    --blob-1: rgba(205, 166, 61, 0.2);
    --blob-2: rgba(160, 74, 64, 0.1);
    --blob-3: rgba(120, 110, 80, 0.12);
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg: #060507;
        --text-primary: #e9d9a6;
        --text-secondary: rgba(212, 181, 106, 0.55);
        --gold: #d4af37;
        --gold-strong: #e9cf7a;
        --hairline: rgba(212, 175, 55, 0.42);
        --hairline-soft: rgba(212, 175, 55, 0.2);
        --panel: linear-gradient(160deg, rgba(22, 19, 14, 0.88), rgba(12, 11, 9, 0.92));
        --screen-bg: rgba(0, 0, 0, 0.5);
        --key-bg: linear-gradient(180deg, rgba(33, 29, 21, 0.88), rgba(24, 21, 16, 0.9));
        --key-op-bg: rgba(212, 175, 55, 0.06);
        --clear: #c96f60;
        --shadow: 0 30px 70px -20px rgba(0, 0, 0, 0.85), inset 0 1px 0 rgba(212, 175, 55, 0.22);
        --key-shadow: 0 4px 12px -4px rgba(0, 0, 0, 0.7), inset 0 1px 0 rgba(212, 175, 55, 0.16);
        --eq-bg: linear-gradient(160deg, #dcc274, #b3933c);
        --eq-text: #1c1504;
        --eq-shadow: 0 6px 16px -6px rgba(212, 175, 55, 0.28), inset 0 1px 0 rgba(255, 240, 190, 0.45);
        --blob-1: rgba(212, 175, 55, 0.1);
        --blob-2: rgba(120, 70, 40, 0.08);
        --blob-3: rgba(60, 50, 30, 0.12);
    }
}

* {
    box-sizing: border-box;
}

html {
    height: 100%;
}

body {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    min-height: 100dvh;
    margin: 0;
    padding: 24px;
    padding: max(24px, env(safe-area-inset-top)) max(24px, env(safe-area-inset-right)) max(24px, env(safe-area-inset-bottom)) max(24px, env(safe-area-inset-left));
    font-family: -apple-system, BlinkMacSystemFont, 'SF Pro Text', 'Segoe UI', 'Hiragino Sans', sans-serif;
    color: var(--text-primary);
    background: var(--bg);
    overflow-x: hidden;
    -webkit-tap-highlight-color: transparent;
}

/* Ambient glow */
.bg {
    position: fixed;
    inset: 0;
    z-index: -1;
    overflow: hidden;
    filter: blur(80px);
}

.blob {
    position: absolute;
    width: 45vmax;
    height: 45vmax;
    border-radius: 50%;
}

.blob-1 { background: var(--blob-1); top: -14vmax; left: -8vmax; animation: drift-1 30s ease-in-out infinite alternate; }
.blob-2 { background: var(--blob-2); bottom: -16vmax; right: -10vmax; animation: drift-2 36s ease-in-out infinite alternate; }
.blob-3 { background: var(--blob-3); top: 42%; left: 55%; width: 28vmax; height: 28vmax; animation: drift-3 26s ease-in-out infinite alternate; }

@keyframes drift-1 { to { transform: translate(8vmax, 6vmax) scale(1.12); } }
@keyframes drift-2 { to { transform: translate(-6vmax, -8vmax) scale(1.08); } }
@keyframes drift-3 { to { transform: translate(-10vmax, 5vmax) scale(0.88); } }

@media (prefers-reduced-motion: reduce) {
    .blob { animation: none; }
}

.calculator {
    background: var(--panel);
    -webkit-backdrop-filter: blur(30px) saturate(140%);
    backdrop-filter: blur(30px) saturate(140%);
    border: 1px solid var(--hairline);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 26px 24px 24px;
    width: 380px;
    max-width: 100%;
    position: relative;
}

/* Fine double-border detail */
.calculator::before {
    content: "";
    position: absolute;
    inset: 6px;
    border: 1px solid var(--hairline-soft);
    border-radius: calc(var(--radius) - 6px);
    pointer-events: none;
}

.screen {
    border: 1px solid var(--hairline-soft);
    border-radius: 18px;
    background: var(--screen-bg);
    padding: 14px 18px 16px;
    margin-bottom: 20px;
    overflow: hidden;
}

.expression {
    min-height: 1.4em;
    font-size: 15px;
    font-family: var(--display-font);
    color: var(--text-secondary);
    text-align: right;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    font-variant-numeric: tabular-nums lining-nums;
    letter-spacing: 0.02em;
}

.display {
    display: block;
    width: 100%;
    font-size: 40px;
    font-weight: 500;
    font-family: var(--display-font);
    line-height: 1.25;
    text-align: right;
    color: var(--text-primary);
    font-variant-numeric: tabular-nums lining-nums;
    letter-spacing: 0.02em;
    white-space: nowrap;
    overflow-x: auto;
    scrollbar-width: none;
}

.display sup,
.expression sup {
    font-size: 0.58em;
    vertical-align: super;
    line-height: 0;
}

.display::-webkit-scrollbar {
    display: none;
}

.display.error {
    color: var(--clear);
}

.keys {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
    touch-action: manipulation;
}

.key {
    font-size: 23px;
    font-weight: 500;
    font-family: var(--display-font);
    aspect-ratio: 1 / 1;
    width: 100%;
    border: 1px solid var(--hairline-soft);
    border-radius: 50%;
    cursor: pointer;
    color: var(--text-primary);
    background: var(--key-bg);
    box-shadow: var(--key-shadow);
    transition: transform 0.1s, filter 0.15s, border-color 0.15s;
    user-select: none;
    -webkit-user-select: none;
}

.key:hover {
    filter: brightness(1.05);
    border-color: var(--hairline);
}

.key:active {
    transform: scale(0.92);
}

.key.op {
    background: var(--key-op-bg);
    color: var(--gold);
    border-color: var(--hairline-soft);
}

.key.op:hover {
    color: var(--gold-strong);
}

/* Equals: polished gold */
.key.eq {
    background: var(--eq-bg);
    color: var(--eq-text);
    border-color: rgba(255, 240, 190, 0.4);
    box-shadow: var(--eq-shadow);
    font-weight: 600;
}

/* Clear: outlined, not filled */
.key.cl {
    background: transparent;
    color: var(--clear);
    border: 1.5px solid var(--clear);
    box-shadow: none;
}

.key.cl:hover {
    filter: none;
    background: rgba(160, 74, 64, 0.08);
    border-color: var(--clear);
}

/* Zero key stretches across two columns */
.key.zero {
    grid-column: span 2;
    aspect-ratio: auto;
    border-radius: 999px;
}

@media (max-width: 420px) {
    body {
        padding: 12px;
        padding: max(12px, env(safe-area-inset-top)) max(12px, env(safe-area-inset-right)) max(12px, env(safe-area-inset-bottom)) max(12px, env(safe-area-inset-left));
    }

    .calculator {
        padding: 18px 16px 16px;
        border-radius: 28px;
        width: 100%;
    }

    .calculator::before {
        inset: 5px;
        border-radius: 23px;
    }

    .screen {
        padding: 10px 14px 12px;
        border-radius: 15px;
        margin-bottom: 14px;
    }

    .display {
        font-size: 32px;
    }

    .keys {
        gap: 8px;
    }

    .key {
        font-size: clamp(17px, 5.5vw, 22px);
    }
}

/* Short landscape screens (phones rotated) */
@media (max-height: 620px) and (orientation: landscape) {
    body {
        padding: 10px;
    }

    .calculator {
        width: 340px;
        padding: 14px;
    }

    .screen {
        margin-bottom: 10px;
        padding: 8px 14px;
    }

    .display {
        font-size: 26px;
    }

    .keys {
        gap: 6px;
    }

    .key {
        aspect-ratio: auto;
        height: 44px;
        border-radius: 22px;
        font-size: 18px;
    }
}