/* ===== CSS Variables & Reset ===== */
:root {
    --bg-primary: #0a0e1a;
    --bg-secondary: #111827;
    --bg-card: rgba(17, 24, 39, 0.7);
    --bg-glass: rgba(30, 41, 59, 0.55);
    --border-glass: rgba(139, 92, 246, 0.25);
    --accent-primary: #8b5cf6;
    --accent-secondary: #06b6d4;
    --accent-tertiary: #ec4899;
    --accent-glow: rgba(139, 92, 246, 0.4);
    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;
    --success: #10b981;
    --warning: #f59e0b;
    --radius: 12px;
    --radius-sm: 8px;
    --radius-lg: 16px;
    --transition: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
    --font: 'Inter', system-ui, -apple-system, sans-serif;
}

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

html {
    font-size: 16px;
    -webkit-text-size-adjust: 100%;
}

body {
    font-family: var(--font);
    background: var(--bg-primary);
    color: var(--text-primary);
    min-height: 100vh;
    overflow-x: hidden;
    line-height: 1.5;
}

/* ===== Background Glow ===== */
body::before {
    content: '';
    position: fixed;
    top: -40%;
    left: -20%;
    width: 80%;
    height: 80%;
    background: radial-gradient(ellipse, rgba(139, 92, 246, 0.08) 0%, transparent 70%);
    pointer-events: none;
    z-index: 0;
}

body::after {
    content: '';
    position: fixed;
    bottom: -30%;
    right: -20%;
    width: 70%;
    height: 70%;
    background: radial-gradient(ellipse, rgba(6, 182, 212, 0.06) 0%, transparent 70%);
    pointer-events: none;
    z-index: 0;
}

/* ===== Header ===== */
.header {
    position: sticky;
    top: 0;
    z-index: 100;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 14px 24px;
    background: rgba(10, 14, 26, 0.85);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-bottom: 1px solid var(--border-glass);
}

.header-title {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 1.15rem;
    font-weight: 700;
    letter-spacing: -0.02em;
}

.header-title .icon {
    font-size: 1.3rem;
}

.header-title .accent {
    background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.back-btn {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 8px 16px;
    background: var(--bg-glass);
    border: 1px solid var(--border-glass);
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    font-size: 0.85rem;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    text-decoration: none;
    font-family: var(--font);
    backdrop-filter: blur(8px);
}

.back-btn:hover {
    background: rgba(139, 92, 246, 0.15);
    color: var(--text-primary);
    border-color: var(--accent-primary);
}

/* ===== Main Layout ===== */
.app-container {
    position: relative;
    z-index: 1;
    max-width: 1400px;
    margin: 0 auto;
    padding: 20px;
    display: grid;
    grid-template-columns: 1fr 240px;
    grid-template-rows: auto auto 1fr;
    gap: 20px;
}

.controls-panel {
    grid-column: 1 / -1;
}

.main-display {
    grid-column: 1 / 2;
}

.sidebar {
    grid-column: 2 / 3;
    grid-row: 2 / 4;
}

/* ===== Glass Card ===== */
.glass-card {
    background: var(--bg-glass);
    border: 1px solid var(--border-glass);
    border-radius: var(--radius-lg);
    padding: 20px;
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    transition: var(--transition);
}

.glass-card:hover {
    border-color: rgba(139, 92, 246, 0.4);
}

.card-title {
    font-size: 0.8rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--text-muted);
    margin-bottom: 14px;
    display: flex;
    align-items: center;
    gap: 6px;
}

.card-title .dot {
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: var(--accent-primary);
    box-shadow: 0 0 8px var(--accent-glow);
}

/* ===== Controls Panel ===== */
.controls-row {
    display: flex;
    flex-wrap: wrap;
    gap: 16px;
    align-items: flex-end;
}

.control-group {
    display: flex;
    flex-direction: column;
    gap: 6px;
    flex: 1;
    min-width: 180px;
}

.control-group label {
    font-size: 0.78rem;
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.06em;
}

.control-group select {
    appearance: none;
    background: var(--bg-secondary);
    border: 1px solid rgba(139, 92, 246, 0.2);
    border-radius: var(--radius-sm);
    padding: 10px 36px 10px 14px;
    color: var(--text-primary);
    font-size: 0.9rem;
    font-family: var(--font);
    cursor: pointer;
    transition: var(--transition);
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='%2394a3b8' stroke-width='2'%3E%3Cpath d='M6 9l6 6 6-6'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 12px center;
}

.control-group select:hover,
.control-group select:focus {
    border-color: var(--accent-primary);
    outline: none;
    box-shadow: 0 0 0 3px rgba(139, 92, 246, 0.15);
}

/* ===== Threshold Slider ===== */
.slider-container {
    display: flex;
    align-items: center;
    gap: 12px;
}

.slider-container input[type="range"] {
    flex: 1;
    -webkit-appearance: none;
    appearance: none;
    height: 8px;
    border-radius: 4px;
    background: linear-gradient(90deg, var(--accent-secondary), var(--accent-primary));
    outline: none;
    cursor: pointer;
}

.slider-container input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 28px;
    height: 28px;
    border-radius: 50%;
    background: var(--text-primary);
    border: 3px solid var(--accent-primary);
    box-shadow: 0 0 12px var(--accent-glow), 0 2px 6px rgba(0, 0, 0, 0.3);
    cursor: grab;
    transition: transform 0.15s ease, box-shadow 0.15s ease;
}

.slider-container input[type="range"]::-webkit-slider-thumb:hover {
    transform: scale(1.15);
    box-shadow: 0 0 20px var(--accent-glow), 0 2px 8px rgba(0, 0, 0, 0.4);
}

.slider-container input[type="range"]::-webkit-slider-thumb:active {
    cursor: grabbing;
    transform: scale(1.1);
}

.slider-container input[type="range"]::-moz-range-thumb {
    width: 28px;
    height: 28px;
    border-radius: 50%;
    background: var(--text-primary);
    border: 3px solid var(--accent-primary);
    box-shadow: 0 0 12px var(--accent-glow), 0 2px 6px rgba(0, 0, 0, 0.3);
    cursor: grab;
}

.slider-value {
    min-width: 44px;
    text-align: center;
    font-weight: 700;
    font-size: 1.05rem;
    color: var(--accent-secondary);
    font-variant-numeric: tabular-nums;
}

/* ===== Upload Area ===== */
.upload-area {
    display: none;
    margin-top: 10px;
}

.upload-area.visible {
    display: block;
}

.upload-label {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 14px 20px;
    border: 2px dashed rgba(139, 92, 246, 0.3);
    border-radius: var(--radius);
    color: var(--text-secondary);
    font-size: 0.88rem;
    cursor: pointer;
    transition: var(--transition);
}

.upload-label:hover {
    border-color: var(--accent-primary);
    background: rgba(139, 92, 246, 0.08);
    color: var(--text-primary);
}

.upload-label input {
    display: none;
}

/* ===== Operation Buttons ===== */
.operations-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 10px;
    margin-top: 4px;
}

.op-btn {
    position: relative;
    padding: 14px 8px;
    background: var(--bg-secondary);
    border: 2px solid rgba(139, 92, 246, 0.15);
    border-radius: var(--radius);
    color: var(--text-secondary);
    font-size: 0.82rem;
    font-weight: 600;
    font-family: var(--font);
    cursor: pointer;
    transition: var(--transition);
    text-align: center;
    overflow: hidden;
}

.op-btn .op-label {
    display: block;
    font-size: 0.88rem;
    font-weight: 700;
    margin-bottom: 2px;
}

.op-btn .op-desc {
    display: block;
    font-size: 0.68rem;
    font-weight: 400;
    color: var(--text-muted);
    opacity: 0.8;
}

.op-btn:hover {
    border-color: var(--accent-primary);
    background: rgba(139, 92, 246, 0.1);
    color: var(--text-primary);
    transform: translateY(-1px);
}

.op-btn.active {
    background: linear-gradient(135deg, rgba(139, 92, 246, 0.25), rgba(6, 182, 212, 0.15));
    border-color: var(--accent-primary);
    color: var(--text-primary);
    box-shadow: 0 0 20px rgba(139, 92, 246, 0.2), inset 0 1px 0 rgba(255, 255, 255, 0.05);
}

.op-btn.active::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: linear-gradient(90deg, var(--accent-primary), var(--accent-secondary));
}

/* ===== Visualization ===== */
.canvas-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
}

.canvas-wrapper {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
}

.canvas-label {
    font-size: 0.78rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: var(--text-muted);
}

.canvas-label.input-label {
    color: var(--accent-secondary);
}

.canvas-label.output-label {
    color: var(--accent-tertiary);
}

.canvas-wrapper canvas {
    width: 100%;
    max-width: 450px;
    aspect-ratio: 1;
    border-radius: var(--radius);
    border: 1px solid rgba(139, 92, 246, 0.2);
    background: #000;
    image-rendering: pixelated;
    transition: border-color var(--transition);
}

.canvas-wrapper canvas:hover {
    border-color: var(--accent-primary);
}

/* ===== Structuring Element Grid ===== */
.se-grid {
    display: grid;
    grid-template-columns: repeat(7, 1fr);
    gap: 4px;
    margin-bottom: 16px;
}

.se-cell {
    aspect-ratio: 1;
    border-radius: 4px;
    border: 1.5px solid rgba(139, 92, 246, 0.2);
    background: var(--bg-secondary);
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.65rem;
    min-width: 0;
    min-height: 0;
    padding: 0;
    font-family: var(--font);
    color: var(--text-muted);
}

.se-cell:hover {
    border-color: var(--accent-primary);
    transform: scale(1.05);
}

.se-cell.active {
    background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
    border-color: transparent;
    box-shadow: 0 0 14px var(--accent-glow);
    color: white;
}

.se-cell.center {
    border-color: var(--accent-tertiary);
}

.se-cell.center.active {
    border-color: transparent;
}

.se-presets {
    display: flex;
    flex-direction: column;
    gap: 6px;
}

.se-preset-label {
    font-size: 0.72rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: var(--text-muted);
}

.se-presets select {
    appearance: none;
    background: var(--bg-secondary);
    border: 1px solid rgba(139, 92, 246, 0.2);
    border-radius: var(--radius-sm);
    padding: 10px 36px 10px 12px;
    color: var(--text-primary);
    font-size: 0.85rem;
    font-family: var(--font);
    cursor: pointer;
    transition: var(--transition);
    width: 100%;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='%2394a3b8' stroke-width='2'%3E%3Cpath d='M6 9l6 6 6-6'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 10px center;
}

.se-presets select:hover,
.se-presets select:focus {
    border-color: var(--accent-primary);
    outline: none;
    box-shadow: 0 0 0 3px rgba(139, 92, 246, 0.15);
}


/* ===== SE Description ===== */
.se-info {
    margin-top: 14px;
    padding: 10px 12px;
    background: rgba(6, 182, 212, 0.08);
    border-radius: var(--radius-sm);
    border-left: 3px solid var(--accent-secondary);
    font-size: 0.78rem;
    color: var(--text-secondary);
    line-height: 1.5;
}

/* ===== Info Banner ===== */
.info-banner {
    grid-column: 1 / 2;
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 12px 16px;
    background: rgba(6, 182, 212, 0.08);
    border: 1px solid rgba(6, 182, 212, 0.2);
    border-radius: var(--radius);
    font-size: 0.82rem;
    color: var(--text-secondary);
    line-height: 1.4;
}

.info-banner .info-icon {
    font-size: 1.2rem;
    flex-shrink: 0;
}

/* ===== Responsive: Tablet ===== */
@media (max-width: 960px) {
    .app-container {
        grid-template-columns: 1fr;
        padding: 14px;
        gap: 14px;
    }

    .sidebar {
        grid-column: 1;
        grid-row: auto;
    }

    .se-grid {
        max-width: 260px;
        margin-left: auto;
        margin-right: auto;
    }

    .operations-grid {
        grid-template-columns: repeat(3, 1fr);
    }
}

/* ===== Responsive: Mobile ===== */
@media (max-width: 600px) {
    .header {
        padding: 10px 14px;
    }

    .header-title {
        font-size: 0.95rem;
    }

    .back-btn {
        padding: 8px 10px;
        font-size: 0.8rem;
    }

    .app-container {
        padding: 10px;
        gap: 12px;
    }

    .glass-card {
        padding: 14px;
        border-radius: var(--radius);
    }

    .controls-row {
        flex-direction: column;
        gap: 12px;
    }

    .control-group {
        min-width: 100%;
    }

    .canvas-container {
        grid-template-columns: 1fr;
        gap: 12px;
    }

    .canvas-wrapper canvas {
        max-width: 100%;
    }

    .operations-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 8px;
    }

    .op-btn {
        padding: 12px 6px;
    }

    .se-grid {
        max-width: 220px;
    }

    .operations-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

/* ===== Scrollbar ===== */
::-webkit-scrollbar {
    width: 6px;
}

::-webkit-scrollbar-track {
    background: transparent;
}

::-webkit-scrollbar-thumb {
    background: rgba(139, 92, 246, 0.3);
    border-radius: 3px;
}

::-webkit-scrollbar-thumb:hover {
    background: rgba(139, 92, 246, 0.5);
}

/* ===== Loading Indicator ===== */
.processing-indicator {
    display: none;
    align-items: center;
    gap: 6px;
    font-size: 0.78rem;
    color: var(--accent-secondary);
}

.processing-indicator.show {
    display: inline-flex;
}

.spinner {
    width: 14px;
    height: 14px;
    border: 2px solid rgba(6, 182, 212, 0.2);
    border-top-color: var(--accent-secondary);
    border-radius: 50%;
    animation: spin 0.6s linear infinite;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}