/* ==========================================================================
    1. Global Variables & Root Styles
   ========================================================================== */

:root {
    /* Layout & Sizing */
    --global-border-radius: 6px;
    --panel-padding: 20px;
    --swatch-size: 45px;
    --control-panel-width: 580px;
    --side-panel-width: 300px;

    /* Core Color Palette */
    --text-default: hsl(0, 0%, 94%);
    --text-secondary: hsl(0, 0%, 80%);
    --text-tertiary: hsl(0, 0%, 70%);
    --text-dark: hsl(0, 0%, 10%);
    --text-highlight-on-dark: hsl(0, 0%, 90%); /* For text on dark animated buttons */
    --text-highlight-on-light: hsl(0, 0%, 10%); /* For text on light animated buttons (not currently used by animation) */

    --bg-panel: #282828;
    --bg-input-field: #3a3a3a;
    --bg-slider-track: #4a4a4a;
    --bg-output-panel: hsl(0, 0%, 0%, 0.3);
    --bg-swatch-empty: #444;
    --bg-slider-thumb: #999;

    --text-block-letter-on-dark: var(--text-highlight-on-dark);
    --text-block-letter-on-light: var(--text-dark);

    /* Borders */
    --border-color-default: #555;
    --border-color-strong: #777;
    --border-color-interactive-focus: purple;
    --border-color-input-range: hsl(0, 0%, 0%, 0.2);
    --border-color-thumb: #333;

    /* Shadows */
    --shadow-default: hsl(0, 0%, 0%, 0.3);
    --shadow-panel: 0 5px 15px hsl(0, 0%, 0%, 0.3);
    --shadow-interactive-focus: 0 0 8px hsl(271, 76%, 53%, 0.5);

    /* Button Specifics */
    --button-bg-default: #555555; /* Fallback for animated buttons if color is invalid */
    --button-bg-disabled: #404040;
    --button-text-disabled: #888;
    --button-animation-duration: 8s;

    /* Bin Specifics */
    --bin-border-color-default: var(--border-color-strong);
    --bin-border-color-drag-over: red;
    --bin-border-color-pending-clear: orange;
    --bin-icon-color-default: var(--border-color-strong);
    --bin-icon-color-drag-over: red;
    --bin-icon-color-pending-clear: orange;
    --bin-bg-drag-over: hsl(0 100% 50% / 0.2);

    /* Checkerboard Pattern (HTML Background & Opacity Slider) */
    --checkerboard-html-color1: #404040;
    --checkerboard-html-color2: #383838;
    --checkerboard-html-size: 20px;
    --checkerboard-html-offset: 10px;

    --checkerboard-slider-color1: #666;
    --checkerboard-slider-color2: #555;
    --checkerboard-slider-size: 10px; /* Size of each square in the checkerboard */
    --checkerboard-slider-offset: 5px; /* Offset for the second layer of checkerboard for slider */

    /* Base HSL components for CSS animations, to be set by JavaScript */
    --animation-base-hue: 0deg;
    --animation-base-saturation: 0%;
    --animation-base-lightness: 30%;


    --slider-label-width: 70px; /* For HSL, RGB, etc. labels */
    --slider-thumb-bg-color: var(--bg-slider-thumb);
    --slider-thumb-border-color: var(--border-color-thumb);
    --slider-thumb-border-radius: 4px;
    --slider-thumb-height: calc(var(--slider-track-height) + 8px);
    --slider-thumb-width: 12px;
    --slider-track-height: 28px;
    --slider-value-input-width: 40px; /* For HSL, RGB, etc. numeric inputs */
}

@property --block-letter-animated-saturation {
    syntax: "<percentage>";
    inherits: false;
    initial-value: 35%;
}

@property --button-animated-lightness {
    syntax: "<percentage>";
    inherits: false;
    initial-value: 15%;
}

@property --animation-base-lightness {
    /* Removed duplicate definition */
    syntax: "<percentage>";
    inherits: false;
    initial-value: 30%;
}

@property --animation-base-saturation {
    /* Removed duplicate definition */
    syntax: "<percentage>";
    inherits: false;
    initial-value: 0%;
}

/* ==========================================================================
    2. Base HTML & Body Styles
   ========================================================================== */

html {
    background-image: repeating-linear-gradient(45deg, var(--checkerboard-html-color1) 25%, transparent 25%, transparent 75%, var(--checkerboard-html-color1) 75%, var(--checkerboard-html-color1)), repeating-linear-gradient(45deg, var(--checkerboard-html-color1) 25%, var(--checkerboard-html-color2) 25%, var(--checkerboard-html-color2) 75%, var(--checkerboard-html-color1) 75%, var(--checkerboard-html-color1));
    background-position: 0 0, var(--checkerboard-html-offset) var(--checkerboard-html-offset);
    background-size: var(--checkerboard-html-size) var(--checkerboard-html-size);
    min-height: 100vh;
    margin: 0;
    font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, Cantarell, "Open Sans", "Helvetica Neue", sans-serif;
    transition: --animation-base-hue 1.2s ease-out, --animation-base-lightness 1.2s ease-out, --animation-base-saturation 1.2s ease-out;
}

body {
    color: var(--text-default);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    margin: 0;
    padding: 20px;
    box-sizing: border-box;
    transition: background-color 0.8s ease-out;
}

/* ==========================================================================
    3. Typography & Header
   ========================================================================== */

h1#mainHeader {
    text-align: center;
    margin-bottom: 20px;
    font-size: 1.9em;
    font-weight: bold;
    letter-spacing: 1px;
    line-height: 1.5;
}

.block-letter {
    animation: cycleBlockLetterSaturation var(--button-animation-duration) infinite alternate ease-in-out;
    background-color: hsl(var(--animation-base-hue), var(--block-letter-animated-saturation), var(--animation-base-lightness), 0.5);
    border-radius: var(--global-border-radius);
    box-shadow: 1px 1px 3px var(--shadow-default);
    color: var(--text-block-letter-on-light); /* JS will adjust */
    display: inline-block;
    font-weight: bold;
    line-height: 1.1;
    margin: 0.05em 0.1em;
    min-width: 1em;
    padding: 0.15em 0.35em;
    text-align: center;
    text-transform: uppercase;
    transition: color 0.8s ease-in-out;
    user-select: none;
    vertical-align: middle;
}

@keyframes cycleBlockLetterSaturation {
    from {
        --block-letter-animated-saturation: 35%;
    }
    to {
        --block-letter-animated-saturation: 85%;
    }
}

/* ==========================================================================
    4. Main Layout Wrappers & Panels
   ========================================================================== */

.main-content-wrapper {
    display: flex;
    flex-direction: row;
    flex-wrap: wrap; /* Allow wrapping on smaller screens */
    gap: 25px;
    align-items: flex-start;
    justify-content: center;
    max-width: 1100px;
    width: 100%;
}

#controlPanel {
    width: var(--control-panel-width);
    min-width: 300px; /* Minimum width for control panel */
    flex-shrink: 0;
}

.side-panels-column {
    display: flex;
    flex-direction: column;
    gap: 25px;
    width: var(--side-panel-width);
    min-width: 280px; /* Minimum width for side panels */
    flex-shrink: 0;
}

#controlPanel,
#colorTheoryPanel,
#paintboxPanel {
    background-color: var(--bg-panel);
    padding: var(--panel-padding);
    border-radius: var(--global-border-radius);
    box-shadow: var(--shadow-panel);
    display: flex;
    flex-direction: column;
    gap: 15px;
    box-sizing: border-box;
}

#colorTheoryPanel h2,
#paintboxPanel h2 {
    margin-top: 0;
    margin-bottom: 10px;
    color: var(--text-secondary);
    font-size: 1.2em;
    text-align: center;
}

/* ==========================================================================
    5. Interactive Elements: Buttons, Selects, Swatches
   ========================================================================== */

.animated-button,
.copy-btn {
    /* Base styles for buttons */
    padding: 7px 12px;
    color: var(--text-default);
    border: 1px solid var(--border-color-strong);
    border-radius: var(--global-border-radius);
    cursor: pointer;
    font-size: 0.8em;
    text-align: center;
    user-select: none;
    transition: filter 0.8s ease-out, background-color 0.8s, color 0.8s;
}

.animated-button {
    /* Specifics for animated buttons */
    background-color: hsl(var(--animation-base-hue), 90%, var(--button-animated-lightness));
    color: var(--text-highlight-on-dark);
    animation: cycleButtonLightness var(--button-animation-duration) infinite alternate ease-in-out;
}

@keyframes cycleButtonLightness {
    from {
        --button-animated-lightness: 15%;
    }
    to {
        --button-animated-lightness: 25%;
    }
}

.animated-button:hover:not(:disabled),
.copy-btn:hover:not(:disabled) {
    filter: brightness(1.15);
}

.animated-button:disabled,
.copy-btn:disabled {
    background-color: var(--button-bg-disabled) !important; /* !important to ensure override of animated bg */
    color: var(--button-text-disabled) !important;
    cursor: not-allowed;
    filter: grayscale(50%);
    opacity: 0.7;
    animation: none !important; /* Stop animation on disabled */
}

.animated-button.flash-red {
    animation: flashRedWarning 0.5s 3; /* Overrides cycleButtonLightness temporarily */
}

@keyframes flashRedWarning {
    0%,
    100% {
        background-color: red !important; /* !important to ensure override */
        color: var(--text-highlight-on-dark) !important;
    }
    50% {
        /* Mid-state can revert to its original animated color or a specific color */
        /* Default animated color will be used if not specified due to animation property */
    }
}

.theory-controls {
    display: flex;
    flex-direction: column;
    gap: 8px;
    margin-bottom: 10px;
    align-items: center;
}

.theory-controls select {
    padding: 7px 9px;
    background-color: var(--bg-input-field);
    border: 1px solid var(--border-color-default);
    border-radius: var(--global-border-radius);
    color: hsl(0, 0%, 88%);
    font-size: 0.85em;
    width: fit-content;
}

#copyTheoryToPaintboxBtn {
    margin-top: 8px;
    align-self: center;
    width: auto;
    display: inline-block;
}

#paletteSwatches {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
    justify-content: center;
    min-height: var(--swatch-size); /* Ensure container has height even when empty */
}
.palette-message {
    color: var(--text-tertiary);
    text-align: center;
    width: 100%;
    font-style: italic;
}

.swatch,
.paintbox-swatch,
#mainColorDraggable {
    /* Base styles for all swatch-like elements */
    width: var(--swatch-size);
    height: var(--swatch-size);
    border-radius: var(--global-border-radius);
    border: 1px solid hsl(0, 0%, 100%, 0.1);
    cursor: grab;
    transition: transform 0.6s ease-out, box-shadow 0.4s ease-out, background-color 0.8s ease-out;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.6em;
    color: transparent; /* Text shown on hover */
    overflow: hidden;
    text-align: center;
    user-select: none;
}

#mainColorDraggable {
    transition: background-color 0.6s ease-out;
    width: 64px;
}

.swatch:hover,
.paintbox-swatch:hover,
#mainColorDraggable:hover {
    transform: scale(1.1);
    box-shadow: 0 0 6px var(--shadow-default);
    color: var(--text-default); /* Show text on hover */
    text-shadow: 0 0 2px black, 0 0 2px black; /* Improve text visibility on diverse backgrounds */
}

.dragging {
    opacity: 0.5;
    border: 2px dashed #ccc !important; /* Use !important to override other border styles during drag */
    transform: scale(0.95); /* Slightly shrink dragged item */
}

#colorInput.drag-over-main-target,
#mainColorDraggable.drag-over-main-target {
    outline: 2px dashed var(--border-color-interactive-focus);
    outline-offset: 2px;
    box-shadow: var(--shadow-interactive-focus);
}

.paintbox-swatch.drag-over {
    border: 2px dashed var(--border-color-interactive-focus) !important; /* Ensure override */
    background-color: hsla(271, 76%, 53%, 0.1); /* Visual cue for droppable area */
}

/* ==========================================================================
    6. Paintbox Specific Styles
   ========================================================================== */

#paintboxGrid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(var(--swatch-size), 1fr)); /* Responsive columns */
    gap: 8px;
    margin-bottom: 10px;
}

.paintbox-swatch {
    width: auto; /* Let grid control width */
    aspect-ratio: 1 / 1; /* Maintain square shape */
}

#paintboxControls {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-top: 8px;
}

#exportPaintboxBtn {
    flex-grow: 1;
    font-size: 0.9em;
}

#paintboxBin {
    width: calc(var(--swatch-size) + 5px);
    height: calc(var(--swatch-size) + 5px);
    border: 2px dashed var(--bin-border-color-default);
    border-radius: var(--global-border-radius);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--bin-icon-color-default);
    cursor: default; /* Not draggable itself */
    transition: background-color 0.6s, border-color 0.6s, color 0.6s;
}

#paintboxBin svg {
    width: 60%;
    height: 60%;
    fill: currentColor;
}

#paintboxBin.drag-over-bin {
    background-color: var(--bin-bg-drag-over);
    border-color: var(--bin-border-color-drag-over);
    color: var(--bin-icon-color-drag-over);
}

#paintboxBin.pending-clear {
    border-color: var(--bin-border-color-pending-clear) !important; /* Ensure override */
    color: var(--bin-icon-color-pending-clear) !important;
}

.bin-click-notification {
    position: absolute;
    background-color: #222;
    color: var(--text-default);
    padding: 10px 15px;
    border-radius: var(--global-border-radius);
    box-shadow: 0 4px 12px hsl(0, 0%, 0%, 0.6);
    z-index: 1001;
    font-size: 0.9em;
    font-weight: 500;
    pointer-events: none;
    white-space: nowrap;
    border: 1px solid #444;
    transform: translateX(-50%);
    animation: fadeInBinNotification 0.4s ease-out;
    text-align: center;
}

@keyframes fadeInBinNotification {
    from {
        opacity: 0;
        transform: translateX(-50%) translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateX(-50%) translateY(0);
    }
}

/* ==========================================================================
    7. Form Controls: Text Inputs, Sliders
   ========================================================================== */

.color-input-container {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 10px;
}

.color-input-container label {
    font-size: 1em;
    color: var(--text-secondary);
    font-weight: normal;
    flex-shrink: 0;
}

.color-input-container input[type="text"] {
    flex-grow: 1;
    padding: 8px 10px;
    background-color: var(--bg-input-field);
    border: 1px solid var(--border-color-default);
    border-radius: var(--global-border-radius);
    color: var(--text-default);
    font-size: 0.9em;
    box-sizing: border-box;
    transition: border-color 0.6s, box-shadow 0.6s, background-color 0.6s;
}

.color-input-container input[type="text"].input-invalid {
    border-color: hsl(0, 90%, 65%);
    box-shadow: 0 0 0 3px hsl(0, 90%, 65%, 0.3), 0 0 8px hsl(0, 75%, 60%, 0.5) inset;
    background-color: hsl(0, 100%, 95%, 0.08);
    outline: 2px solid transparent; /* Prevents default browser outline from clashing */
    animation: pulseInvalidInput 1.5s infinite ease-in-out;
}

.color-input-container input[type="text"].input-invalid:focus {
    border-color: hsl(0, 95%, 55%);
    box-shadow: 0 0 0 3px hsl(0, 95%, 55%, 0.4), 0 0 10px hsl(0, 80%, 50%, 0.6) inset;
    animation: none; /* Stop pulsing on focus to allow user to correct */
}

#mainColorDraggable {
    /* Already styled with other swatches, specific margin */
    margin-left: 5px;
    flex-shrink: 0;
}

.slider-container {
    display: flex;
    align-items: center;
    gap: 10px;
}

.slider-container label {
    width: var(--slider-label-width);
    flex-shrink: 0;
    margin-right: 5px;
    font-size: 1em;
    color: var(--text-secondary);
    box-sizing: border-box;
}

.slider-container input[type="range"] {
    flex-grow: 1;
    flex-basis: 150px;
    min-width: 100px;
    margin-right: 10px; /* Spacing before numeric input */
}

.slider-container .value-input {
    width: var(--slider-value-input-width);
    min-width: var(--slider-value-input-width); /* Prevent shrinking */
    max-width: var(--slider-value-input-width); /* Prevent growing */
    padding: 4px 6px;
    background-color: var(--bg-input-field);
    border: 1px solid var(--border-color-default);
    border-radius: calc(var(--global-border-radius) - 2px);
    color: var(--text-secondary);
    font-size: 0.85em;
    text-align: right;
    box-sizing: border-box;
    -moz-appearance: textfield; /* Remove spinners in Firefox */
    appearance: textfield;
    flex-shrink: 0;
}

.slider-container .value-input::-webkit-outer-spin-button,
.slider-container .value-input::-webkit-inner-spin-button {
    -webkit-appearance: none; /* Remove spinners in Chrome/Safari/Edge */
    margin: 0;
}

.slider-container .unit-display {
    font-size: 0.9em;
    color: var(--text-tertiary);
    margin-left: 3px;
    user-select: none;
    flex-shrink: 0;
    width: 10px; /* Adjusted for ° symbol */
    text-align: left;
}

input[type="range"] {
    -webkit-appearance: none;
    appearance: none;
    width: 100%;
    height: var(--slider-track-height);
    padding: 0;
    border-radius: var(--global-border-radius);
    outline: none;
    opacity: 0.9;
    transition: opacity 0.6s;
    border: 1px solid var(--border-color-input-range);
    box-sizing: border-box;
    background-color: var(--bg-slider-track);
}

input[type="range"]:hover {
    opacity: 1;
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: var(--slider-thumb-width);
    height: var(--slider-thumb-height);
    background: var(--slider-thumb-bg-color); /* Dynamic background */
    border-radius: var(--slider-thumb-border-radius); /* Rectangular shape */
    cursor: pointer;
    border: 2px solid var(--slider-thumb-border-color); /* Dynamic border color */
    box-shadow: 0 0 6px var(--shadow-default);
    /* Adjusted margin-top for vertical centering of the TALLER thumb */
    margin-top: calc((var(--slider-thumb-height) - (var(--slider-track-height) - 2 * 1px)) / -2);
}

input[type="range"]::-moz-range-thumb {
    width: var(--slider-thumb-width);
    height: var(--slider-thumb-height);
    background: var(--slider-thumb-bg-color); /* Dynamic background */
    border-radius: var(--slider-thumb-border-radius); /* Rectangular shape */
    cursor: pointer;
    border: 2px solid var(--slider-thumb-border-color); /* Dynamic border color */
    box-shadow: 0 0 6px var(--shadow-default);
}

.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    margin: -1px;
    padding: 0;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    border: 0;
}

/* Common styles for Hue, Saturation, Lightness slider tracks (gradients) */
#hue,
#saturation.dynamic-gradient-slider,
#lightness.dynamic-gradient-slider {
    background-origin: border-box;
    background-position: center center;
    background-size: 100% 100%;
    background-clip: content-box;
    background-repeat: no-repeat;
}

/* Static background for Hue slider */
#hue {
    background-image: linear-gradient(to right, hsl(0, 100%, 50%), hsl(30, 100%, 50%), hsl(60, 100%, 50%), hsl(90, 100%, 50%), hsl(120, 100%, 50%), hsl(150, 100%, 50%), hsl(180, 100%, 50%), hsl(210, 100%, 50%), hsl(240, 100%, 50%), hsl(270, 100%, 50%), hsl(300, 100%, 50%), hsl(330, 100%, 50%), hsl(360, 100%, 50%));
}

/* Opacity slider background is fully managed by JS due to layering checkerboard and gradient */

/* ==========================================================================
    8. Color Output Display Panel
   ========================================================================== */

#colorOutput {
    background-color: var(--bg-output-panel);
    border-radius: var(--global-border-radius);
    color: var(--text-tertiary);
    display: flex;
    flex-direction: column;
    font-size: 0.9em;
    gap: 8px;
    margin-left: auto;
    margin-right: auto;
    margin-top: 10px;
    padding: 15px 20px;
    width: fit-content;
    min-width: 380px;
    box-sizing: border-box;
}

.output-line {
    display: flex;
    align-items: center;
    gap: 8px;
    justify-content: flex-start;
}

.output-line strong {
    color: var(--text-default);
    font-weight: 600;
    width: 60px; /* Consistent label width */
    flex-shrink: 0; /* Prevent label from shrinking */
}

.output-line span {
    font-family: "Source Code Pro", Consolas, "Courier New", Courier, monospace;
    flex-grow: 1; /* Allow value to take available space */
    min-width: 100px; /* Minimum space for value before wrapping */
    word-break: break-all; /* Break long color strings */
    margin-right: 5px; /* Spacing before copy button */
    text-align: left;
}

#colorOutput .copy-btn {
    /* Specifics for copy buttons in output panel */
    padding: 4px;
    font-size: 1em; /* Relative to parent #colorOutput's font-size */
    line-height: 1;
    width: 28px; /* Square button */
    height: 28px; /* Square button */
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    /* Animated button properties are inherited if class is also present */
}

#colorOutput .copy-btn svg {
    width: 18px;
    height: 18px;
    fill: currentColor;
    transition: fill 0.6s ease-in-out;
}

#colorOutput .copy-btn.copied-success svg {
    fill: hsl(120, 70%, 60%) !important;
}
#colorOutput .copy-btn.copied-fail svg {
    fill: hsl(0, 70%, 60%) !important;
}

#colorOutput .copy-btn:disabled svg {
    opacity: 0.5;
}

#colorOutput .copy-btn:hover:not(:disabled) {
    filter: brightness(1.25);
}