@font-face {
    font-family: 'Digital-7';
    src: url('../fonts/digital-7/digital-7.woff2') format('woff2'),
        url('../fonts/digital-7/digital-7.ttf') format('truetype');
    font-weight: normal;
    font-style: normal;
}

:root {
    --bg-body: #fcfcfc;
    --text-light: #F9FAF8;
    --text-dark: #1F2937;

    --btn-primary: #0d6efd;
    --btn-primary-hover: #0b5ed7;
    --btn-primary-active: #0a58ca;

    --btn-secondary: #6c757d;
    --btn-secondary-hover: #5c636a;
    --btn-secondary-active: #565e64;

    --btn-danger: #dc3545;
    --btn-danger-hover: #bb2d3b;
    --btn-danger-active: #b02a37;

    --bg-secondary-400: #ced4da;
    --bg-screen: #c7ffa4;

    --keyboard-navigation: #777cff;
}

@media (max-width: 320px) {
    html, .container {
        min-width: 250px;
        resize: none;
    }
}

*, *::before, *::after {
    box-sizing: border-box;
}

html, body {
    height: 100%;
}

body {
    margin: 0;
    background: var(--bg-body);
    font-family: system-ui, -apple-system, Segoe UI, Roboto, Arial, sans-serif;
    line-height: 1.5;
}

header, footer {
    text-align: center;
    background: var(--text-dark);
    color: var(--text-light);
    padding-block: 24px;
}


h1 {
    margin: 0;
    font-size: clamp(20px, 2vw + 1rem, 32px);
}

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0 0 0 0);
    white-space: nowrap;
    border: 0;
}

.calculator-inner {
    min-height: 91.8vh;
    display: flex;
    align-items: center;
}

.container {
    width: min(120vw, 22rem);
    margin-inline: auto;
    padding: 20px 20px 28px;
    border: 3px solid var(--btn-secondary);
    background: var(--bg-secondary-400);
    border-radius: 14px;
}

.calc-display {
    display: block;
    width: 280px;
    height: 82px;
    padding: 14px 12px 10px 12px;
    background: var(--bg-screen);
    border: 1px solid var(--btn-secondary);
    border-radius: 12px;
    text-align: end;
    appearance: textfield;
    caret-color: transparent;
    font-family: Digital-7;
}

.calc-display:focus-visible {
    outline: 2px solid var(--keyboard-navigation);
    outline-offset: 2px;
}

.calc-keys {
    display: flex;
    flex-direction: column;
    gap: 10px;
    margin-top: 12px;
    align-items: center;
}

.calc-grid {
    display: flex;
    gap: 6px;
}

.key {
    padding: 17px;
    border-radius: 8px;
    border: 1px solid var(--btn-primary);
    color: var(--text-light);
    background: var(--btn-primary);
    font-size: 22px;
    width: 54px;
    height: auto;
    line-height: 1;
    cursor: pointer;
    transition: background-color .12s ease, border-color .12s ease, transform .06s ease;
    user-select: none;
}

.key:hover {
    background-color: var(--btn-primary-hover);
    border-color: var(--btn-primary-hover);
}

.key:active {
    background-color: var(--btn-primary-active);
    border-color: var(--btn-primary-active);
    transform: translateY(1px);
}

.key:focus-visible {
    outline: 2px solid var(--keyboard-navigation);
    outline-offset: 2px;
}

.key--op, .key--func {
    color: var(--text-light);
}

.key--func[data-action="clear"] {
    background: var(--btn-danger);
    border-color: var(--btn-danger);
}

.key--func[data-action="clear"]:hover {
    background: var(--btn-danger-hover);
    border-color: var(--btn-danger-hover);
}

.key--func[data-action="clear"]:active {
    background: var(--btn-danger-active);
    border-color: var(--btn-danger-active);
}

.key--func[data-action="backspace"], .key--equals[data-action="equals"] {
    background: var(--btn-secondary);
    border-color: var(--btn-secondary);
}

.key--func[data-action="backspace"]:hover, .key--equals[data-action="equals"]:hover {
    background: var(--btn-secondary-hover);
    border-color: var(--btn-secondary-hover);
}

.key--func[data-action="backspace"]:active, .key--equals[data-action="equals"]:active {
    background: var(--btn-secondary-active);
    border-color: var(--btn-secondary-active);
}

.key--zero {
    width: calc(52px * 2 + 10px);
}

.key--func[data-action="clear"], .key--func[data-action="backspace"] {
    width: calc(40px * 2 + 4px);
}

.display-wrap {
    position: relative;
}

.display-wrap::after {
    content: "";
    position: absolute;
    top: 50%;
    right: 11px;
    transform: translateY(-50%);
    width: 1.7px;
    height: 40px;
    background: var(--text-dark);
    animation: cursor-blink .8s steps(2, end) infinite;
    pointer-events: none;
}

@media (max-width: 1400px) {
    .container {
        width: min(90vw, 18rem);
        padding: 16px 16px 24px;
    }

    .key {
        width: 50px;
        font-size: 20px;
        padding: 14px;
    }

    .display-wrap::after{
        height: 30px;
    }

    .calc-display {
        width: 240px;
    }

    .key--zero {
        width: calc(50px * 2 + 6px);
    }

    .key--func[data-action="clear"], .key--func[data-action="backspace"] {
        width: calc(35px * 2 + 8px);
    }
}

@media (max-width: 380px) {
    .container {
        width: min(94vw, 16rem);
        padding: 12px 6px 24px;
    }

    .key {
        width: 44px;
        font-size: 18px;
        padding: 12px;
    }

    .calc-display {
        width: 210px;
    }

    .key--zero {
        width: calc(44px * 2 + 6px);
    }

    .key--func[data-action="clear"], .key--func[data-action="backspace"] {
        width: calc(30px * 2 + 9px);
    }
}

.history-display {
    position: absolute;
    font-size: 1.45rem;
    bottom: 56%;
    width: 90%;
    transform: translateX(12px);
    pointer-events: none;
    font-family: Digital-7;
    text-overflow: ellipsis;
    overflow: hidden;
    white-space: nowrap;
}

@keyframes cursor-blink {
    0%, 50% {
        opacity: 1;
    }

    50.01%, 100% {
        opacity: 0;
    }
}