/* Lesson Board: a dark slate chalkboard with light writing and Steel & Code
 * blue accents. Shares the --wb-blue and grayscale tokens from workbench.css.
 */

.board-page {
    --wb-blue: #4d8fd6;
    --wb-chalk: #e8eef2;
    --wb-slate: #1c2733;
    --wb-slate-deep: #16202a;
    --wb-frame: #3a3a3a;

    padding: 48px 6% 72px;
    max-width: 1400px;
    min-width: 0;
}

.board-header { margin-bottom: 26px; }
.board-header h1 {
    margin: 10px 0 10px;
    font-size: clamp(32px, 4.5vw, 48px);
    line-height: 1.1;
}
.board-header .eyebrow { margin: 0 0 8px; }
.board-tagline { margin: 0; max-width: 60ch; color: #aaa; font-size: 17px; line-height: 1.6; }

/* Toolbar */
.board-toolbar {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 18px;
    padding: 16px 18px;
    background: #181818;
    border: 1px solid var(--wb-frame);
}
.board-tool-group { display: flex; align-items: center; gap: 10px; }
/* Push the save/navigation actions to the trailing edge on wide screens. */
.board-actions { margin-left: auto; }

.board-toolbar .btn {
    padding: 10px 18px;
    background: #303030;
    color: #f3f3f3;
    border: 1px solid #777;
    cursor: pointer;
}
/* The active tool is filled with the Steel & Code blue. */
.board-tool[aria-pressed="true"] {
    background: var(--wb-blue);
    border-color: var(--wb-blue);
    color: #0d1117;
    font-weight: bold;
}
.board-toolbar .btn:hover { background: #404040; color: #fff; }
.board-toolbar .btn:focus-visible,
.board-width-group input:focus-visible {
    outline: 2px solid var(--wb-blue);
    outline-offset: 3px;
}

.board-width-group label {
    color: #aaa;
    font-size: 14px;
    white-space: nowrap;
}
.board-width-group input[type="range"] { width: 130px; accent-color: var(--wb-blue); }
.board-width-group output {
    min-width: 2.5ch;
    color: #f3f3f3;
    font: 15px Consolas, monospace;
}

#boardStatus { margin: 14px 0 12px; color: #aaa; font-size: 15px; }

/* Chalkboard surface */
.board-surface {
    background: var(--wb-slate-deep);
    border: 2px solid var(--wb-frame);
    /* Fullscreen promotes only the surface, so the canvas fills the screen. */
    box-shadow: inset 0 0 60px rgba(0, 0, 0, 0.45);
}
.board-surface:fullscreen {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 100%;
    height: 100%;
    background: var(--wb-slate-deep);
    border: 0;
}
.board-surface:fullscreen .board-canvas { width: 100%; height: 100%; }

.board-canvas {
    display: block;
    width: 100%;
    /* Keeps a usable drawing area on desktop without a fixed pixel height. */
    height: 62vh;
    min-height: 380px;
    background: var(--wb-slate);
    cursor: crosshair;
    /* The canvas owns its own pointer events; avoid page scroll hijacking. */
    touch-action: none;
}
.board-canvas:focus-visible { outline: 3px solid var(--wb-blue); outline-offset: -3px; }
/* Eraser reads as a blocky tool rather than a drawing nib. */
.board-page[data-tool="eraser"] .board-canvas { cursor: cell; }

/* Fullscreen: the board fills the viewport and the toolbar stays reachable. */
.board-page:has(.board-surface:fullscreen) { padding: 0; max-width: none; }

@media (max-width: 760px) {
    .board-page { padding: 32px 4% 56px; }
    .board-toolbar { gap: 14px; }
    .board-actions { margin-left: 0; width: 100%; }
    .board-canvas { height: 56vh; min-height: 300px; }
}