.calculator-container {
    --accent: #2563eb;
    --accent-dark: #1d4ed8;
    --surface: #ffffff;
    --surface-muted: #f6f8fb;
    --border: #dfe4ec;
    --text: #172033;
    --muted: #687386;
    width: min(100%, 720px);
    margin: 24px auto;
    overflow: hidden;
    color: var(--text);
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 18px;
    box-shadow: 0 14px 36px rgba(28, 39, 59, 0.1);
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

.mode-selector {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 4px;
    padding: 6px;
    background: #eef2f7;
    border-bottom: 1px solid var(--border);
}

.calculator-container .mode-btn {
    min-width: 0;
    min-height: 42px;
    padding: 8px 12px;
    color: var(--muted);
    background: transparent;
    border: 0;
    border-radius: 10px;
    font: inherit;
    font-size: 14px;
    font-weight: 650;
    cursor: pointer;
}

.calculator-container .mode-btn:hover { color: var(--text); background: rgba(255, 255, 255, 0.72); }
.calculator-container .mode-btn.active,
.calculator-container .mode-btn.active:hover,
.calculator-container .mode-btn.active:focus { color: #fff; background: var(--accent); box-shadow: 0 2px 7px rgba(37, 99, 235, 0.28); }

.display-container {
    min-height: 108px;
    box-sizing: border-box;
    padding: 20px 24px 18px;
    text-align: right;
    background: #fbfcfe;
    border-bottom: 1px solid var(--border);
}

.history {
    min-height: 22px;
    overflow: hidden;
    color: var(--muted);
    font-size: 14px;
    line-height: 22px;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.display {
    min-width: 0;
    overflow-x: auto;
    color: var(--text);
    font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
    font-size: clamp(30px, 6vw, 42px);
    font-weight: 600;
    line-height: 1.25;
    scrollbar-width: thin;
    white-space: nowrap;
}

.display.is-error { color: #c2413b; }

.calculator { display: none; padding: 16px; background: var(--surface-muted); }
.calculator.active { display: block; }
.standard .buttons { width: min(100%, 420px); margin: auto; }

.buttons {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 10px;
}

.btn,
.system-btn,
.size-btn {
    -webkit-tap-highlight-color: transparent;
    touch-action: manipulation;
}

.calculator-container .btn {
    min-width: 0;
    min-height: 58px;
    padding: 10px 6px;
    color: var(--text);
    background: #fff;
    border: 1px solid var(--border);
    border-radius: 11px;
    box-shadow: 0 1px 2px rgba(28, 39, 59, 0.06);
    font: inherit;
    font-size: 18px;
    font-weight: 620;
    cursor: pointer;
    transition: background-color 120ms ease, border-color 120ms ease, transform 80ms ease;
}

.calculator-container .btn:hover { color: var(--text); background: #f1f5f9; border-color: #b9c3d1; }
.calculator-container .btn:active {
    color: #173b78;
    background: #dbeafe;
    border-color: #93b4ec;
    transform: translateY(1px);
}
.btn:focus-visible,
.mode-btn:focus-visible,
.system-btn:focus-visible,
.size-btn:focus-visible { outline: 3px solid rgba(37, 99, 235, 0.25); outline-offset: 1px; }

.calculator-container .btn.function { color: #3f4b60; background: #edf1f6; }
.calculator-container .btn.function:active { color: #fff; background: #526174; border-color: #526174; }
.calculator-container .btn.operator { color: #fff; background: var(--accent); border-color: var(--accent); }
.calculator-container .btn.operator:hover { color: #fff; background: var(--accent-dark); border-color: var(--accent-dark); }
.calculator-container .btn.operator:active { color: #fff; background: #163fa4; border-color: #163fa4; }
.calculator-container .btn.equals { color: #fff; background: #087f5b; border-color: #087f5b; }
.calculator-container .btn.equals:hover { color: #fff; background: #066b4d; border-color: #066b4d; }
.calculator-container .btn.equals:active { color: #fff; background: #04543d; border-color: #04543d; }
.calculator-container .btn.hex { color: #5b21b6; background: #f2edff; border-color: #ded2ff; }
.calculator-container .btn.hex:hover { color: #4c1d95; background: #e9e0ff; border-color: #c9b7fb; }
.calculator-container .btn.hex:active { color: #fff; background: #6d3fd1; border-color: #6d3fd1; }
.calculator-container .btn:disabled { color: #a4acb9; background: #edf0f4; border-color: #e2e6ec; box-shadow: none; cursor: not-allowed; opacity: 0.72; }
.btn.zero { grid-column: span 2; }
.btn.active-option,
.calculator-container .btn.active-option:hover,
.calculator-container .btn.active-option:active { color: #fff; background: #526174; border-color: #526174; }

.scientific .buttons,
.programmer .buttons { grid-template-columns: repeat(6, minmax(0, 1fr)); }
.scientific .btn,
.programmer .btn { min-height: 50px; font-size: 14px; }
.scientific .zero { grid-column: span 1; }
.programmer-equals { grid-column: span 2; }
.programmer-zero { grid-column: span 5; }

.programmer-header {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 14px;
    margin-bottom: 12px;
}

.number-system,
.bit-size {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 5px;
    padding: 5px;
    background: #e8edf4;
    border-radius: 10px;
}

.calculator-container .system-btn,
.calculator-container .size-btn {
    min-width: 0;
    min-height: 36px;
    padding: 6px 4px;
    color: var(--muted);
    background: transparent;
    border: 0;
    border-radius: 7px;
    font: inherit;
    font-size: 12px;
    font-weight: 700;
    cursor: pointer;
}

.calculator-container .system-btn:hover,
.calculator-container .size-btn:hover { color: var(--text); background: rgba(255, 255, 255, 0.72); }

.calculator-container .system-btn.active,
.calculator-container .size-btn.active,
.calculator-container .system-btn.active:hover,
.calculator-container .size-btn.active:hover,
.calculator-container .system-btn.active:focus,
.calculator-container .size-btn.active:focus { color: #fff; background: var(--accent); box-shadow: 0 2px 6px rgba(37, 99, 235, 0.25); }

.programmer-display {
    display: grid;
    gap: 2px;
    margin-bottom: 12px;
    padding: 8px 12px;
    background: #fff;
    border: 1px solid var(--border);
    border-radius: 10px;
}

.base-value {
    display: grid;
    grid-template-columns: 44px minmax(0, 1fr);
    align-items: baseline;
    min-height: 28px;
    color: var(--muted);
    font-size: 11px;
    font-weight: 700;
}

.base-value output {
    overflow-x: auto;
    color: #263247;
    font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
    font-size: 13px;
    font-weight: 500;
    line-height: 28px;
    scrollbar-width: thin;
    white-space: nowrap;
}

@media (max-width: 640px) {
    .calculator-container { margin: 12px auto; border-radius: 14px; }
    .display-container { min-height: 94px; padding: 16px; }
    .calculator { padding: 10px; }
    .buttons { gap: 7px; }
    .btn { min-height: 54px; border-radius: 9px; }
    .scientific .btn,
    .programmer .btn { min-height: 46px; padding: 6px 2px; font-size: 12px; }
    .programmer-header { grid-template-columns: 1fr; gap: 7px; }
    .programmer-display { padding: 6px 8px; }
}

@media (max-width: 380px) {
    .mode-btn { padding-inline: 4px; font-size: 13px; }
    .scientific .buttons,
    .programmer .buttons { gap: 5px; }
    .scientific .btn,
    .programmer .btn { min-height: 43px; font-size: 11px; }
    .base-value { grid-template-columns: 38px minmax(0, 1fr); }
}

@media (prefers-reduced-motion: reduce) {
    .btn { transition: none; }
}