@font-face {
    font-family: "Gunken";
    src: url("../assets/fonts/Gunken.woff2") format("woff2"),
         url("../assets/fonts/Gunken.woff") format("woff");
    font-display: swap;
}

@font-face {
    font-family: "Syne";
    src: url("../assets/fonts/Syne.woff2") format("woff2"),
         url("../assets/fonts/Syne.woff") format("woff");
    font-display: swap;
}

:root {
    --background: #0d0d0d;
    --surface: #1a1a1a;
    --title-color: #ffffff;
    --desc-color: #000000;
    --title: Gunken, sans-serif;
    --desc: Syne, sans-serif;
    --background-calculator: #111111;
    --border: 18px;
    --shadow: 0 0 25px rgba(255, 208, 0, 0.15);
    --display-background: #e5e5e5;
    --button-back: #2a2a2a;
    --op-back: #ffd000;
    --border-display: 12px;
    --border-buttons: 10px;
    --border-hover: #b3b3b3;
    --clear-btn: #ef4444;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

/* ---> HEADER <--- */

header {
    background-color: var(--background);
    min-width: 100vw;
    height: auto;
    padding: 15px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

header img {
    height: 55px;
    width: 55px;
}

header h1 {
    font-family: var(--title);
    color: var(--title-color);
    font-size: 48px;
}

/* ---> MAIN <--- */

body {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

main {
    flex: 1;
    width: 100%;
    height: 100%;
    background-color: var(--surface);
    display: flex;
    justify-content: center;
    align-items: center;
}

.calculator {
    height: auto;
    width: 35%;
    padding: 20px;
    background-color: var(--background-calculator);
    border-radius: var(--border);
    box-shadow: var(--shadow);
    display: flex;
    flex-direction: column;
    gap: 30px;
}

.display {
    height: auto;
    width: 100%;
    background-color: var(--display-background);
    border-radius: var(--border-display);
    box-shadow: var(--shadow);
    margin: 0;
    padding: 10px;
    display: flex;
    align-items: center;
    justify-content: flex-end;
}

.display p {
    font-family: var(--desc);
    color: var(--desc-color);
    font-size: 52px;
}

.calculator-buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 25px;
}

.numbers-btn {  
    background-color: var(--button-back);
    display: flex;
    align-items: center;
    justify-content: center;
    font-family: var(--desc);
    color: var(--title-color);
    font-size: 24px;
    padding: 15px;
    border: none;
    border-radius: var(--border-buttons);
    border: 1px solid transparent;
    transition: all ease 0.2s;
}

.operators-btn {
    background-color: var(--op-back);
    display: flex;
    align-items: center;
    justify-content: center;
    font-family: var(--desc);
    color: var(--desc-color);
    font-size: 24px;
    padding: 15px;
    border: none;
    border-radius: var(--border-buttons);
    border: 1px solid transparent;
    transition: all ease 0.2s;
}

.clear-btn {
    background-color: var(--clear-btn);
    display: flex;
    align-items: center;
    justify-content: center;
    font-family: var(--desc);
    color: var(--desc-color);
    font-size: 24px;
    padding: 15px;
    border: none;
    border-radius: var(--border-buttons);
    border: 1px solid transparent;
    transition: all ease 0.2s;
}

.operators-btn:hover,
.numbers-btn:hover,
.clear-btn:hover {
    border-color: var(--border-hover);
}

.operators-btn:active,
.numbers-btn:active,
.clear-btn:active {
    transform: scale(0.96);
    filter: brightness(0.9);
}