/* Standard calculator panel (header overlay) */
.tool-calc {
    position: relative;
    width: 100%;
    user-select: none;
    -webkit-user-select: none;
    font-family: "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
    color: #1f2a44;
}

/* 透明输入层叠在显示区：保证可聚焦，稳定接收数字键（含中文输入法） */
.tool-calc-keytrap {
    position: absolute;
    left: 0;
    right: 0;
    top: 0;
    height: 78px;
    z-index: 2;
    margin: 0;
    padding: 0;
    border: 0;
    opacity: 0;
    color: transparent;
    caret-color: transparent;
    background: transparent;
    outline: none;
}

.tool-calc-display {
    background: #f4f8ff;
    border: 1px solid #d8e5ff;
    border-radius: 8px;
    padding: 10px 12px 8px;
    margin-bottom: 10px;
    min-height: 72px;
    display: flex;
    flex-direction: column;
    justify-content: flex-end;
    align-items: flex-end;
    gap: 2px;
    box-sizing: border-box;
}

.tool-calc-expr {
    min-height: 18px;
    font-size: 13px;
    line-height: 18px;
    color: #6f7d96;
    width: 100%;
    text-align: right;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    word-break: keep-all;
}

.tool-calc-value {
    font-size: 32px;
    font-weight: 600;
    line-height: 1.15;
    letter-spacing: -0.02em;
    width: 100%;
    text-align: right;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    color: #1f2a44;
}

.tool-calc-value.is-error {
    font-size: 22px;
    color: #c0392b;
}

.tool-calc-pad {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 6px;
}

.tool-calc-btn {
    appearance: none;
    border: 1px solid #d8e5ff;
    border-radius: 8px;
    background: #edf3ff;
    color: #1f2a44;
    font-size: 16px;
    font-weight: 600;
    height: 44px;
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    line-height: 1;
    transition: background 0.12s ease, border-color 0.12s ease, color 0.12s ease;
}

.tool-calc-btn:hover {
    background: #e0ebff;
    border-color: #c5d7ff;
}

.tool-calc-btn:active,
.tool-calc-btn.is-pressed {
    background: #d0e0ff;
    border-color: #a8c4ff;
}

.tool-calc-btn:focus-visible {
    outline: 2px solid #2f6bff;
    outline-offset: 1px;
}

.tool-calc-btn.fn {
    background: #f7f9fc;
    color: #3c4f78;
    font-size: 14px;
    font-weight: 600;
}

.tool-calc-btn.fn:hover {
    background: #eef3fb;
}

.tool-calc-btn.op {
    background: #e8f0ff;
    color: #2f6bff;
    font-size: 18px;
}

.tool-calc-btn.op:hover,
.tool-calc-btn.op.is-active {
    background: #d9e7ff;
    border-color: #a8c4ff;
    color: #1f5ae6;
}

.tool-calc-btn.eq {
    background: linear-gradient(135deg, #2f6bff, #5b8dff);
    border-color: transparent;
    color: #fff;
    font-size: 20px;
}

.tool-calc-btn.eq:hover {
    background: linear-gradient(135deg, #2860e8, #4f82f0);
    border-color: transparent;
    color: #fff;
}

.tool-calc-btn.digit {
    background: #fff;
    font-size: 18px;
}

.tool-calc-btn.digit:hover {
    background: #f4f8ff;
}

.tool-calc-hint {
    margin-top: 8px;
    font-size: 11px;
    color: #8a97b0;
    text-align: center;
    line-height: 1.4;
}