#app {
    --calc-screen-bg: #ffffff;
    --calc-key-bg: #ffffff;
    --calc-key-func: #e8eaf0;
    --calc-key-op: #e8eaf0;
    --calc-key-equal: #4a6cf7;
    --calc-key-equal-text: #ffffff;
    --calc-key-ac: #ffaa33;
    --calc-key-ac-text: #ffffff;
    --calc-key-del: #ffd4a3;
    --calc-key-del-text: #333333;
    --calc-border: #d1d5e3;
    --calc-radius: 14px;
    --calc-active: #c7cbd6;
}

#app .calculator-card {
    padding: 18px;
    background: var(--bg);
    border: 1px solid var(--border);
}

#app .app-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text);
    display: flex;
    align-items: center;
    gap: 10px;
    margin: 0 0 6px;
}

#app .app-title .svg-icon {
    color: var(--calc-key-equal);
}

#app .calc-screen {
    background: var(--calc-screen-bg);
    border-radius: var(--calc-radius);
    padding: 16px 18px;
    margin-bottom: 14px;
    min-height: 90px;
    display: flex;
    flex-direction: column;
    justify-content: flex-end;
    align-items: flex-end;
    box-shadow: inset 0 1px 3px rgba(0,0,0,0.04);
    word-break: break-all;
}

#app .calc-expr {
    font-size: 0.95rem;
    color: var(--text-secondary);
    min-height: 1.4em;
    text-align: right;
    width: 100%;
}

#app .calc-result {
    font-size: 2.6rem;
    font-weight: 700;
    color: var(--text);
    line-height: 1.2;
    text-align: right;
    width: 100%;
}

#app .calc-result.error {
    color: var(--danger);
    font-size: 1.4rem;
}

#app .calc-toolbar {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr 1fr 1fr 1fr 1fr;
    gap: 10px;
    margin-bottom: 10px;
}

#app .calc-mode {
    grid-column: span 2;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    border: none;
    background: var(--calc-key-func);
    color: var(--text);
    border-radius: var(--calc-radius);
    padding: 10px 0;
    font-size: 0.95rem;
    font-weight: 500;
    cursor: pointer;
    transition: background 0.15s, transform 0.05s;
    user-select: none;
}

#app .calc-mode.active {
    background: var(--calc-active);
    box-shadow: inset 0 1px 3px rgba(0,0,0,0.12);
}

#app .calc-keypad {
    display: grid;
    grid-template-columns: repeat(7, 1fr);
    gap: 10px;
}

#app .calc-btn {
    border: 1px solid transparent;
    border-radius: var(--calc-radius);
    padding: 0;
    height: 52px;
    font-size: 1.05rem;
    font-weight: 500;
    cursor: pointer;
    transition: background 0.15s, transform 0.05s, box-shadow 0.15s;
    user-select: none;
    display: flex;
    align-items: center;
    justify-content: center;
}

#app .calc-btn:active {
    transform: scale(0.96);
}

#app .calc-btn sup {
    font-size: 0.7em;
    margin-left: 1px;
}

#app .calc-num {
    background: var(--calc-key-bg);
    color: var(--text);
    border-color: var(--calc-border);
    box-shadow: 0 1px 2px rgba(0,0,0,0.04);
}

#app .calc-num:hover {
    background: #f8f9fb;
}

#app .calc-func,
#app .calc-const,
#app .calc-mem {
    background: var(--calc-key-func);
    color: var(--text);
    border-color: transparent;
}

#app .calc-func:hover,
#app .calc-const:hover,
#app .calc-mem:hover {
    background: #dde0e8;
}

#app .calc-op {
    background: var(--calc-key-op);
    color: var(--text);
    border-color: transparent;
}

#app .calc-op:hover {
    background: #dde0e8;
}

#app .calc-equal {
    background: var(--calc-key-equal);
    color: var(--calc-key-equal-text);
    border-color: transparent;
    font-size: 1.4rem;
    font-weight: 700;
}

#app .calc-equal:hover {
    background: #3b5de0;
}

#app .calc-ac {
    grid-column: span 2;
    background: var(--calc-key-ac);
    color: var(--calc-key-ac-text);
    border-color: transparent;
}

#app .calc-ac:hover {
    background: #f59e28;
}

#app .calc-del {
    background: var(--calc-key-del);
    color: var(--calc-key-del-text);
    border-color: transparent;
}

#app .calc-del:hover {
    background: #ffc48a;
}

#app .calc-btn.active-mode {
    background: var(--calc-active) !important;
    box-shadow: inset 0 1px 3px rgba(0,0,0,0.12);
}

#app .calc-help {
    display: flex;
    flex-direction: column;
    gap: 8px;
    font-size: 0.86rem;
    color: var(--text-secondary);
    line-height: 1.7;
}

#app .calc-help p {
    margin: 0;
}

@media (max-width: 640px) {
    #app .calc-btn {
        height: 44px;
        font-size: 0.95rem;
    }
    #app .calc-result {
        font-size: 2rem;
    }
    #app .calc-expr {
        font-size: 0.85rem;
    }
    #app .calculator-card {
        padding: 12px;
    }
    #app .calc-keypad,
    #app .calc-toolbar {
        gap: 6px;
    }
}