:root {
    --bg-color: #0e2715;
    --card-bg: #1e293b;
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --accent-color: #38bdf8;
    --border-color: #334155;
    --input-bg: #0f172a;
    --radius-xl: 32px;
    --radius-lg: 24px;
    --radius-md: 12px;
    --warning-color: #fbbf24;
}

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

body {
    font-family: 'Source Code Pro', monospace;
    background-color: var(--bg-color);
    color: var(--text-primary);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    padding: 20px;
}

.container {
    width: 100%;
    max-width: 1400px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 90vh;
}

header {
    text-align: center;
    margin-bottom: 40px;
    display: flex;
    flex-direction: column;
    align-items: center;
}

header h1 {
    font-weight: 800;
    font-size: clamp(2rem, 8vw, 3rem);
    line-height: 1;
    letter-spacing: -0.05em;
    color: #fff;
    margin-bottom: 0;
    display: inline-block;
    transform: scaleX(-1); /* Mirrored Title */
    transition: transform 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}

header p {
    color: var(--text-secondary);
    font-size: clamp(0.7rem, 2.5vw, 0.9rem);
    font-weight: 400;
    margin-top: 4px;
    letter-spacing: 0.2em;
    text-transform: uppercase;
}

.calculator-layout {
    display: flex;
    flex-direction: column;
    align-items: center;
    width: 100%;
}

.visual-composition {
    display: flex;
    align-items: center; /* Center vertically */
    justify-content: center;
    gap: clamp(30px, 8vw, 60px);
    flex-wrap: wrap;
}

.composition-part {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.target-part {
    justify-content: center; 
}

.label-top {
    font-size: clamp(0.7rem, 2.5vw, 0.9rem);
    text-transform: uppercase;
    letter-spacing: 0.15em;
    color: var(--text-secondary);
    margin-bottom: 16px;
    font-weight: 600;
    height: 1.2em;
}

.target-visual-wrapper {
    /* Removed fixed height and flex centering to allow natural flow */
    position: relative;
}

.target-box {
    width: clamp(140px, 40vw, 200px);
    height: clamp(140px, 40vw, 200px);
    border-radius: var(--radius-lg);
    position: relative;
    overflow: hidden;
    cursor: pointer;
    transition: transform 0.2s;
}

.target-box:hover {
    transform: scale(1.02);
}

.target-box:disabled {
    cursor: not-allowed;
    opacity: 0.6;
}

.input-bottom {
    margin-top: 20px;
    font-size: 1.1rem;
}

/* Operator & Opacity Group */
.operator-group {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
    justify-content: center;
    /* Removed fixed height and margin-top */
}

.operator {
    font-size: clamp(4rem, 15vw, 8rem);
    color: #e2e8f0;
    font-weight: 100;
    opacity: 0.9;
    line-height: 1;
}

.opacity-controls-central {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 12px;
    width: clamp(150px, 40vw, 180px);
}

#opacityDisplay {
    font-size: clamp(1.25rem, 5vw, 2rem);
    font-family: 'Source Code Pro', monospace;
    color: #fff;
    font-weight: 700;
    letter-spacing: -0.02em;
}

input[type="range"] {
    width: 100%;
    height: 8px;
    background: var(--border-color);
    border-radius: 4px;
    -webkit-appearance: none;
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 24px;
    height: 24px;
    background: var(--accent-color);
    border-radius: 50%;
    cursor: pointer;
    border: 4px solid var(--bg-color);
}

/* Matte Surrounds Source */
.matte-surround-group {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 12px;
}

.label-matte-top {
    font-size: clamp(0.7rem, 2.5vw, 0.9rem);
    text-transform: uppercase;
    letter-spacing: 0.15em;
    color: var(--text-secondary);
    font-weight: 600;
    height: 1.2em;
}

/* Matte Wrapper Structure */
.matte-wrapper {
    width: clamp(280px, 85vw, 420px);
    height: clamp(280px, 85vw, 420px);
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
}

.matte-background {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border-radius: var(--radius-xl);
    transition: transform 0.2s;
    z-index: 1;
    cursor: pointer;
    background-color: #fff;
    background-image: url(https://tomippe.jp/img/apps-logo.svg);
    background-repeat: no-repeat;
    background-position: center bottom 55%;
    background-size: 80%;
    background-blend-mode: exclusion;
}

.matte-background:hover {
    transform: scale(1.02);
}

.source-group {
    position: relative;
    z-index: 2;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 20px;
    pointer-events: none;
}

.source-group > * {
    pointer-events: auto;
}

.label-source {
    font-size: clamp(0.7rem, 2.5vw, 0.9rem);
    text-transform: uppercase;
    letter-spacing: 0.15em;
    color: rgba(0,0,0,0.4);
    font-weight: 700;
}

.source-box {
    width: clamp(140px, 40vw, 200px);
    height: clamp(140px, 40vw, 200px);
    border-radius: var(--radius-lg);
    overflow: hidden;
    display: flex;
    position: relative;
    cursor: default;
    transition: transform 0.2s, opacity 0.2s;
}

.source-box:hover {
    transform: scale(1.02);
}

.source-box.clickable {
    cursor: pointer;
}

.half-transparent {
    flex: 1;
    height: 100%;
    background-color: #ccc;
    opacity: 0.4;
    pointer-events: none;
}

.half-solid {
    flex: 1;
    height: 100%;
    background-color: #ccc;
    pointer-events: none;
}

.error-icon-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: none;
    align-items: center;
    justify-content: center;
    z-index: 10;
    pointer-events: none;
}

.error-icon-overlay svg {
    /* No shadow for cleaner appearance */
}

.source-hex {
    background: transparent;
    padding: 0;
    margin-top: 10px;
    display: flex;
    align-items: center;
    gap: 12px;
    min-height: 48px;
}

.source-hex .hex-text {
    color: #333;
    font-size: clamp(1.75rem, 6vw, 2.5rem);
    font-weight: 800;
    letter-spacing: -0.03em;
}

.source-hex-input {
    font-size: clamp(1.75rem, 6vw, 2.5rem) !important;
    font-weight: 800 !important;
    letter-spacing: -0.03em !important;
    width: auto !important;
    max-width: 100%;
    background: transparent !important;
    border: none !important;
    border-bottom: 2px solid transparent !important;
    padding: 0 8px !important;
    text-align: center;
}

.source-hex-input:focus {
    outline: none;
    border-bottom-color: currentColor !important;
    opacity: 0.7;
}

.source-hex .icon-btn {
    opacity: 0.6;
    transition: opacity 0.2s;
    background: transparent;
    border: none;
    padding: 0;
}

.source-hex .icon-btn:hover {
    opacity: 1;
}

.matte-controls-bottom-outside {
    margin-top: 4px;
}

.matte-controls-bottom-outside .hex-input {
    color: var(--text-primary);
    border-bottom-color: var(--border-color);
    font-size: 1.1rem;
}

/* Hex Inputs & Displays */
.hex-input {
    background: transparent;
    border: none;
    border-bottom: 2px solid var(--border-color);
    color: var(--text-primary);
    padding: 8px;
    font-family: 'Source Code Pro', monospace;
    text-align: center;
    width: clamp(90px, 25vw, 110px);
    font-size: clamp(0.9rem, 3vw, 1.1rem);
    font-weight: 600;
    transition: border-color 0.2s;
}

.hex-input:focus {
    outline: none;
    border-color: var(--accent-color);
}

.hidden-picker {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    opacity: 0;
    cursor: pointer;
    z-index: 15;
    pointer-events: auto;
}

/* Responsive - Row layout for wide screens */
@media (min-width: 1201px) {
    .composition-part {
        margin-bottom: 45px;
    }
}

/* Responsive - Column layout for narrow screens */
@media (max-width: 1200px) {
    .visual-composition {
        flex-direction: column;
    }
    
    .operator-group {
        margin-top: -30px;
    }
    
    .operator {
        transform: rotate(90deg);
    }
}

/* Fine-tune for very small screens */
@media (max-width: 360px) {
    body {
        padding: 10px;
    }
}