:root {
    --dark-bg: rgb(24, 26, 42);
    --tile-bg: rgb(45, 52, 71);
    --border-color: rgb(68, 76, 95);
    --text-light: rgb(224, 224, 224);
    --text-main: rgb(255, 255, 255);
    --accent: rgb(52, 152, 219); /* Flat UI Sky Blue */
    --green: rgb(22, 163, 74);
}

body {
    font-family: 'Helvetica', 'Arial', sans-serif;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: flex-start;
    padding: 20px;
    height: 100vh;
    margin: 0;
    background-color: var(--dark-bg);
    color: var(--text-main);
    text-transform: lowercase;
}

#title-container {
    text-align: center;
    margin-bottom: 20px; /* Increased spacing */
}

h1 {
    color: var(--text-main);
    margin-bottom: 5px;
    font-weight: bold;
    font-size: 2.5em;
}

.subheader {
    font-size: 1.1em;
    color: var(--text-light);
    font-weight: 600; /* semibold */
    margin: 0;
}

#game-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 10px;
    width: 90%;
    max-width: 450px;
    margin-top: 20px; /* Increased spacing */
}

/* Start Screen */
#start-container {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    padding: 20px;
    margin-top: 5vh; 
}

#instructions {
    margin-bottom: 30px;
    color: var(--text-light);
    max-width: 400px;
    line-height: 1.4;
}

#instructions h2 {
    margin-bottom: 15px;
    color: var(--text-main);
}

#instructions p {
    margin: 5px 0;
}

#start-btn {
    font-size: 1.5em;
    padding: 15px 30px;
    border: none;
    border-radius: 8px;
    background-color: var(--accent);
    color: var(--text-main);
    cursor: pointer;
    transition: transform 0.2s;
}

#start-btn:hover {
    transform: scale(1.05);
}

/* Post Game Screen */
#post-game-container {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    padding: 20px;
    margin-top: 5vh; /* Adjust vertical position */
    border: 2px solid var(--border-color);
    border-radius: 12px;
}

#post-game-message {
    font-size: 1.5em;
    color: var(--text-main);
    margin-bottom: 20px;
}

#post-game-stats {
    margin-bottom: 20px;
    font-size: 1.1em;
    color: var(--text-light); /* Ensure stats are readable */
}

#post-game-stats .stat {
    margin: 5px 0;
}

#post-game-solution {
    margin-bottom: 20px;
    color: var(--text-light);
}

#post-game-footer {
    margin-top: 20px;
    font-size: 1em;
    color: var(--text-light);
}

#share-result-btn {
    font-size: 1.2em;
    padding: 15px 30px;
    border: none;
    border-radius: 8px;
    background-color: var(--green);
    color: var(--text-main);
    cursor: pointer;
    transition: opacity 0.2s;
    margin-top: 20px; /* Add spacing */
}

#share-result-btn:hover {
    opacity: 0.9;
}


.hidden {
    display: none !important;
}

#game-header {
    display: grid;
    grid-template-columns: 1fr auto 1fr; /* Center is auto, sides take up rest */
    gap: 10px;
    width: 100%;
    margin-bottom: 25px; /* Increased spacing */
    align-items: center;
    text-align: center;
    padding: 0 10px;
}

#puzzle-number {
    justify-self: start;
    font-weight: bold;
    font-size: 1.1em;
    color: var(--text-light);
}
#streak-counter {
    justify-self: center;
    font-weight: bold;
    font-size: 1.1em;
    color: var(--text-light);
}
#timer {
    justify-self: end;
    font-weight: bold;
    font-size: 1.1em;
    color: var(--text-light);
}


#target-number-container {
    font-size: 1.3em;
    font-weight: bold;
    perspective: 1000px;
    transition: transform 0.6s;
    transform-style: preserve-3d;
    margin-bottom: 30px; /* Increased spacing */
}

#target-number {
    font-size: 2.2em;
    padding: 8px 20px;
    border: 2px solid var(--accent);
    border-radius: 8px;
    background-color: var(--tile-bg);
    color: var(--accent);
}

#equation-builder {
    display: flex;
    flex-wrap: nowrap;
    align-items: center;
    justify-content: center;
    width: 100%;
    min-height: 70px;
    margin-bottom: 25px; /* Increased spacing */
    gap: 5px;
}

.slot {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 50px;
    height: 50px;
    border: 2px solid var(--border-color);
    border-radius: 5px;
    font-size: 1.6em;
    font-weight: bold;
    color: var(--text-main);
    transition: all 0.2s ease-in-out;
    user-select: none;
}

.number-slot {
    background-color: transparent; /* Keep number slots transparent by default */
    border-style: dashed;
}

.number-slot.filled {
    background-color: var(--tile-bg);
    border-style: solid;
    border-color: var(--border-color);
}

.operator-slot {
    background-color: transparent;
    border-style: solid;
    border-color: transparent;
    cursor: pointer;
}

.operator-slot.filled {
    background-color: var(--tile-bg);
    border-color: var(--border-color);
}

.slot.operator-slot.active {
    border-color: var(--accent);
    color: var(--accent);
}

.slot.correct {
    background-color: var(--green);
    border-color: var(--green);
    color: var(--text-main);
}

#current-result-display {
    font-size: 1.8em;
    font-weight: bold;
    color: var(--text-light);
    margin: 15px 0 25px 0; /* Increased spacing */
    min-height: 40px;
}

#feedback {
    min-height: 20px;
    margin-bottom: 20px; /* Increased spacing */
    color: var(--accent);
    font-weight: bold;
    font-size: 0.9em;
}

#number-pool {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 10px;
    margin-top: 20px;
    padding: 10px;
    width: 100%;
}

.pool-number {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 60px;
    height: 60px;
    font-size: 1.8em;
    font-weight: bold;
    background-color: var(--tile-bg);
    color: var(--text-main);
    border: 2px solid var(--border-color);
    border-radius: 8px;
    cursor: grab;
    perspective: 1000px;
    transition: transform 0.6s, background-color 0.3s;
    transform-style: preserve-3d;
    user-select: none;
}


.pool-number.used {
    background-color: var(--dark-bg);
    border-color: var(--tile-bg);
    color: var(--tile-bg);
    cursor: not-allowed;
}

#control-buttons {
    display: flex;
    justify-content: center;
    gap: 15px;
    margin-top: 30px; /* Increased spacing */
    width: 100%;
}

#control-buttons button {
    padding: 10px 20px;
    font-size: 1.1em;
    font-weight: bold;
    border-radius: 8px;
    border: none;
    background-color: var(--tile-bg);
    color: var(--text-main);
    cursor: pointer;
}

#control-buttons button:hover {
    background-color: rgb(68, 76, 95);
}

#control-buttons button:disabled, #reset-btn:disabled, #give-up-btn:disabled {
    background-color: var(--dark-bg);
    color: var(--border-color);
    cursor: not-allowed;
    opacity: 0.5;
}

#reset-btn {
    background-color: var(--accent);
}

#give-up-btn {
    background-color: transparent;
    border: 2px solid var(--border-color);
}

/* Modal Styles */
.modal {
    display: none;
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    overflow: auto;
    background-color: rgba(18, 18, 19, 0.8);
    backdrop-filter: blur(5px);
}


.modal-content {
    background-color: var(--tile-bg);
    color: var(--text-main);
    margin: 15% auto;
    padding: 30px;
    border: 1px solid var(--border-color);
    width: 85%;
    max-width: 350px;
    text-align: center;
    border-radius: 15px;
}

.close-btn {
    color: var(--text-light);
    position: absolute;
    top: 10px;
    right: 20px;
    font-size: 28px;
    font-weight: bold;
    cursor: pointer;
}

#result-title {
    color: var(--text-main);
    font-size: 1.8em;
}

#result-message {
    font-size: 1.1em;
    color: var(--text-light);
    margin-bottom: 25px;
}

#community-stats {
    margin-top: 20px;
    padding-top: 20px;
    border-top: 1px solid var(--border-color);
}

#community-stats p {
    margin: 5px 0;
    color: var(--text-light);
}

#share-btn {
    background-color: var(--accent);
    color: var(--text-main);
    padding: 10px 20px;
    font-size: 1.1em;
    border-radius: 8px;
    border: none;
    cursor: pointer;
    margin-top: 15px;
}

#share-btn:hover {
    opacity: 0.9;
}

/* Animation */
.face-down {
    transform: rotateY(180deg);
}

/* Responsive Design for Mobile */
@media (max-width: 480px) {
    body {
        padding-top: 10px;
    }
    #title-container {
        margin-bottom: 10px;
    }
    h1 {
        font-size: 1.8em;
    }
    .subheader {
        font-size: 1em;
    }
    #game-container {
        padding: 10px;
        margin-top: 10px;
    }
    #start-container, #post-game-container {
        margin-top: 5vh;
    }
    #game-header {
        gap: 10px;
        margin-bottom: 15px;
    }
    #timer, #puzzle-number, #streak-counter {
        font-size: 1em;
    }
    #target-number-container {
        font-size: 1.2em;
        margin-bottom: 15px;
    }
    #target-number {
        font-size: 1.8em;
        padding: 3px 10px;
    }
    #equation-builder {
        gap: 3px;
        min-height: auto;
        margin-bottom: 15px;
    }
    .slot {
        width: 40px;
        height: 40px;
        font-size: 1.2em;
    }
    .operator-slot {
        width: 30px;
    }
    #current-result-display {
        font-size: 1.5em;
        margin-bottom: 20px;
    }
    #feedback {
        margin-bottom: 10px;
    }
    #number-pool {
        gap: 5px;
        padding: 5px;
        margin-top: 10px;
    }
    .pool-number {
        width: 45px;
        height: 45px;
        font-size: 1.5em;
    }
    #control-buttons {
        gap: 10px;
        margin-top: 20px;
    }
    #control-buttons button {
        padding: 8px 16px;
        font-size: 0.9em;
    }
    .modal-content {
        margin-top: 25%;
        padding: 20px;
    }
    #result-title {
        font-size: 1.5em;
    }
    #result-message {
        font-size: 1em;
    }
    #share-btn {
        padding: 8px 16px;
        font-size: 0.9em;
    }
}