/* ===== RESET ===== */

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

/* ===== VARIABLES ===== */

:root {
    --background: #f5f5f5;
    --surface: #ffffff;
    --text: #222222;
    --accent: #4f8cff;
    --border: #dddddd;
    --radius: 12px;
    --shadow: 0 8px 20px rgba(0, 0, 0, 0.12);
    --tile_size: 10vmin;
    --tile_margin: 5px;
}

/* ===== PAGE ===== */

body {
    font-family:
        system-ui,
        -apple-system,
        BlinkMacSystemFont,
        "Segoe UI",
        sans-serif;
    background: var(--background);
    color: var(--text);

    min-height: 100vh;
}

header {
    text-align: center;
}

nav {
    text-align: center;

    font-size: 2vmin;
    background-color: rgb(210, 210, 210);
    padding-bottom: 10px;
    margin: 10px;
    border-radius: 10px;
}

.main-header {
    font-size: 2vmin;
    background-color: rgb(210, 210, 210);
    padding-bottom: 10px;
    margin: 10px;
    border-radius: 10px;
}

a {
    text-decoration: none;
    color: var(--text);
}

.game_board {
    display: grid;
    grid-template-columns: repeat(3, calc(var(--tile_size) + var(--tile_margin)));

    width: fit-content;
    margin: 0 auto;
}

.tile {
    font-size: calc(var(--tile_size) * 0.75);

    user-select: none;
    outline: none;
}

.level_select, .tile{
    width: var(--tile_size);
    height: var(--tile_size);
    border: 2px solid rgb(180, 180, 180);
    margin: calc(var(--tile_margin) / 2);
    border-radius: calc(var(--tile_size) / 6);
    background-color: rgb(210, 210, 210);

    display: flex;
    justify-content: center;
    align-items: center;
}

.level_select:hover {
    cursor: pointer;
}

.next_button {
    width: 75vmin;
    height: var(--tile_size);
    border: 2px solid rgb(180, 180, 180);
    margin: calc(var(--tile_margin) / 2);
    border-radius: 20px;
    background-color: rgb(240, 255, 240);

    display: flex;
    justify-content: center;
    align-items: center;
    justify-self: center;
}

.next_button:hover {
    cursor: pointer;
}

#fullscreen {
    position: fixed;
    top: 15px;
    right: 15px;

    width: 35px;
    height: 35px;

    padding: 0;
    border: none;
    background: transparent;

    font-size: 25px;
    cursor: pointer;

    user-select: none;
    outline: none;

    z-index: 1000;
}