/* ═══════════════════════════════════════════
   LPC Image Prediction – Styles
   ═══════════════════════════════════════════ */

:root {
    --bg: #0d1117;
    --surface: #161b22;
    --surface2: #1c2333;
    --border: #30363d;
    --text: #e6edf3;
    --text2: #8b949e;
    --accent: #58a6ff;
    --accent2: #388bfd;
    --green: #3fb950;
    --orange: #d29922;
    --red: #f85149;
    --radius: 12px;
    --font: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    --mono: 'JetBrains Mono', 'Fira Code', monospace;
}

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

html {
    font-size: 14px;
}

body {
    font-family: var(--font);
    background: var(--bg);
    color: var(--text);
    min-height: 100vh;
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
}

/* ─── Navigation ─── */
#top-nav {
    position: sticky;
    top: 0;
    z-index: 100;
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 0.6rem 1.5rem;
    background: rgba(13, 17, 23, 0.85);
    backdrop-filter: blur(16px);
    border-bottom: 1px solid var(--border);
}

#back-btn {
    display: flex;
    align-items: center;
    gap: 0.3rem;
    background: none;
    border: 1px solid var(--border);
    color: var(--text2);
    padding: 0.35rem 0.7rem;
    border-radius: 8px;
    cursor: pointer;
    font-size: 0.85rem;
    transition: all 0.2s;
}

#back-btn:hover {
    color: var(--text);
    border-color: var(--accent);
}

#nav-title {
    font-size: 1.1rem;
    font-weight: 600;
    flex: 1;
    white-space: nowrap;
}

#image-selector {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

#image-selector label {
    color: var(--text2);
    font-size: 0.85rem;
    font-weight: 500;
}

select,
input[type="range"] {
    font-family: var(--font);
}

select {
    background: var(--surface);
    color: var(--text);
    border: 1px solid var(--border);
    padding: 0.35rem 0.6rem;
    border-radius: 8px;
    font-size: 0.85rem;
    cursor: pointer;
    outline: none;
    transition: border-color 0.2s;
}

select:focus {
    border-color: var(--accent);
}

/* ─── Main Content ─── */
#main-content {
    max-width: 1400px;
    margin: 0 auto;
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

/* ─── Cards ─── */
.card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1.2rem;
    transition: border-color 0.3s;
}

.card:hover {
    border-color: rgba(88, 166, 255, 0.3);
}

.card h3 {
    font-size: 0.95rem;
    font-weight: 600;
    margin-bottom: 0.8rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.tag {
    font-size: 0.7rem;
    font-weight: 500;
    color: var(--accent);
    background: rgba(88, 166, 255, 0.1);
    padding: 0.15rem 0.5rem;
    border-radius: 99px;
}

.subtitle {
    font-size: 0.8rem;
    color: var(--text2);
    margin-bottom: 0.6rem;
}

/* ─── Layout: Top Row ─── */
#top-row {
    display: grid;
    grid-template-columns: auto auto 1fr;
    gap: 1.5rem;
    align-items: start;
}

/* ─── Source Image ─── */
#source-wrap {
    position: relative;
    width: 256px;
    height: 256px;
    border: 1px solid var(--border);
    border-radius: 4px;
    overflow: hidden;
}

#source-canvas,
#overlay-canvas {
    position: absolute;
    top: 0;
    left: 0;
    width: 256px;
    height: 256px;
    image-rendering: pixelated;
}

#overlay-canvas {
    pointer-events: none;
}

/* ─── Zoomed Window ─── */
#zoom-canvas {
    border: 1px solid var(--border);
    border-radius: 4px;
    image-rendering: pixelated;
    display: block;
}

.zoom-legend {
    display: flex;
    gap: 1rem;
    margin-top: 0.5rem;
    font-size: 0.75rem;
    color: var(--text2);
}

.legend-item {
    display: flex;
    align-items: center;
    gap: 0.3rem;
}

.swatch {
    display: inline-block;
    width: 12px;
    height: 12px;
    border-radius: 3px;
}

.swatch-current {
    background: var(--green);
    border: 1px solid rgba(63, 185, 80, 0.5);
}

.swatch-predictor {
    background: var(--orange);
    border: 1px solid rgba(210, 153, 34, 0.5);
}

/* ─── Controls ─── */
.control-row {
    display: flex;
    align-items: center;
    gap: 0.6rem;
    margin-bottom: 0.7rem;
}

.control-row label {
    font-size: 0.85rem;
    color: var(--text2);
    min-width: 80px;
    font-weight: 500;
}

input[type="range"] {
    flex: 1;
    accent-color: var(--accent);
    height: 4px;
}

.control-row span,
#mu-value,
#speed-value {
    font-family: var(--mono);
    font-size: 0.8rem;
    color: var(--accent);
    min-width: 80px;
    text-align: right;
}

.button-row {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
    margin-top: 0.3rem;
}

.btn {
    font-family: var(--font);
    font-size: 0.82rem;
    font-weight: 500;
    padding: 0.4rem 0.9rem;
    border-radius: 8px;
    border: 1px solid var(--border);
    background: var(--surface2);
    color: var(--text);
    cursor: pointer;
    transition: all 0.2s;
}

.btn:hover:not(:disabled) {
    border-color: var(--accent);
    background: rgba(88, 166, 255, 0.08);
}

.btn:disabled {
    opacity: 0.4;
    cursor: not-allowed;
}

.btn-accent {
    background: var(--accent2);
    border-color: var(--accent);
    color: #fff;
}

.btn-accent:hover:not(:disabled) {
    background: var(--accent);
}

.btn-secondary {
    color: var(--text2);
}

/* ─── Coefficient Grid ─── */
#coeff-grid {
    display: flex;
    flex-direction: column;
    gap: 3px;
    margin-top: 0.4rem;
}

.coeff-row {
    display: flex;
    gap: 3px;
}

.coeff-cell {
    width: 56px;
    height: 42px;
    border-radius: 6px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    font-family: var(--mono);
    font-size: 0.72rem;
    transition: background 0.3s;
}

.coeff-cell.empty {
    background: transparent;
}

.coeff-cell.labeled {
    background: var(--surface2);
    border: 1px solid var(--border);
}

.coeff-cell .coeff-name {
    font-size: 0.65rem;
    color: var(--orange);
    font-weight: 500;
}

.coeff-cell .coeff-val {
    color: var(--text);
    font-weight: 500;
}

.current-cell {
    background: rgba(63, 185, 80, 0.15);
    border: 1px solid rgba(63, 185, 80, 0.4);
    color: var(--green);
    font-size: 1rem;
}

/* ─── Math Section ─── */
.matrix {
    display: inline-grid;
    border-left: 2px solid var(--text2);
    border-right: 2px solid var(--text2);
    border-radius: 4px;
    padding: 2px 4px;
    gap: 2px 8px;
    text-align: right;
    align-items: center;
}

.matrix-cell {
    padding: 2px;
}

/* ─── Bottom Row ─── */
#bottom-row {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
}

#pred-canvas,
#error-canvas,
#full-error-canvas {
    border: 1px solid var(--border);
    border-radius: 4px;
    image-rendering: pixelated;
    display: block;
    width: 100%;
    max-width: 300px;
}

/* ─── Stats ─── */
.stat-row {
    display: flex;
    gap: 0.8rem;
    margin-top: 0.6rem;
    flex-wrap: wrap;
}

.stat-chip {
    display: flex;
    flex-direction: column;
    background: var(--surface2);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 0.4rem 0.8rem;
    min-width: 90px;
}

.stat-label {
    font-size: 0.7rem;
    color: var(--text2);
    text-transform: uppercase;
    letter-spacing: 0.04em;
}

.stat-value {
    font-family: var(--mono);
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--accent);
}

/* ─── Responsive ─── */
@media (max-width: 1100px) {
    #top-row {
        grid-template-columns: auto 1fr;
    }

    #controls-card {
        grid-column: span 2;
    }
}

@media (max-width: 750px) {
    #top-nav {
        flex-wrap: wrap;
        gap: 0.5rem;
    }

    #nav-title {
        order: -1;
        width: 100%;
        font-size: 1rem;
    }

    #top-row {
        grid-template-columns: 1fr;
    }

    #controls-card {
        grid-column: span 1;
    }

    #bottom-row {
        grid-template-columns: 1fr;
    }

    #source-wrap {
        width: 100%;
        max-width: 256px;
    }

    #source-canvas,
    #overlay-canvas {
        width: 100%;
        height: auto;
    }

    .card {
        padding: 1rem;
    }
}