/*
 * ============================================================
 *  TNT | Sudoku Saga — Rules & Strategies
 *  File:    sudokuRulesStrategiesStyles.css
 *  Coder:   KLP + GitHub Copilot
 *  Created: 2026-07-15
 *
 *  Reference page palette — readable, clear, content-first.
 *  Requires CSS custom properties from tnt-base-styles.css.
 * ============================================================
 */


/* ── Shared tokens ── */
:root {
    --sudoku-green:      #2e7d32;
    --sudoku-green-lt:   #e8f5e9;
    --sudoku-green-mid:  #c8e6c9;
    --sudoku-ink:        #1a1a2e;
    --badge-bg-begin:    #2e7d32;
    --badge-bg-inter:    #e65100;
    --badge-bg-adv:      #4a148c;
}


/* ─────────────────────────────────────────────────────────
   HERO — content/reference page: taller than the game hero,
   using the same Einstein background and blue-green gradient.
   A reference page earns a longer hero than a game page
   because the reader pauses here rather than clicking through.
───────────────────────────────────────────────────────── */
#hero {
    min-height: 190px;
    background-image:
        linear-gradient(135deg,
            rgba(10, 14, 50, 0.74)  0%,
            rgba(20, 80, 30, 0.60) 100%),
        url('../images/einsteinSudoku.jpg');
    background-size: cover;
    background-position: center 30%;
    padding: 2rem 1rem 1.8rem;
    border-bottom: 4px solid var(--tnt-red);
}

#hero .hero-title {
    font-size: clamp(2.2rem, 5vw, 3.2rem);
    margin-bottom: 0.5rem;
    color: #fff;
    text-shadow: 0 3px 14px rgba(0, 0, 0, 0.9);
}

#hero .hero-eyebrow { color: var(--tnt-amber); }

#hero .hero-subtitle {
    color: rgba(255, 255, 255, 0.88);
    font-size: clamp(0.88rem, 2vw, 1.1rem);
}

.hero-sudoku-icon {
    height: 2.4rem;
    vertical-align: middle;
    margin-right: 0.4rem;
    filter: brightness(0) invert(1);
}


/* ─────────────────────────────────────────────────────────
   PAGE BACKGROUND & CONTENT CONTAINER
───────────────────────────────────────────────────────── */
#contentSection {
    background: #f8faf8;
    padding: 2rem 0 4rem;
}

.rules-container {
    max-width: 860px;
    margin: 0 auto;
    padding: 0 1rem;
}


/* ─────────────────────────────────────────────────────────
   SECTION HEADERS
───────────────────────────────────────────────────────── */
.section-header {
    display: flex;
    align-items: center;
    gap: 0.7rem;
    margin: 2.5rem 0 1rem;
    padding-bottom: 0.5rem;
    border-bottom: 3px solid var(--sudoku-green);
}

.section-header .section-icon {
    font-size: 1.5rem;
    color: var(--sudoku-green);
    flex-shrink: 0;
}

.section-header h2 {
    font-family: var(--boogaloo);
    font-size: clamp(1.5rem, 3.5vw, 2rem);
    color: var(--sudoku-ink);
    margin: 0;
    line-height: 1.1;
}


/* ─────────────────────────────────────────────────────────
   RULE CARDS — the six numbered rules
───────────────────────────────────────────────────────── */
.rule-card {
    display: flex;
    align-items: flex-start;
    gap: 1rem;
    background: #fff;
    border: 1px solid var(--sudoku-green-mid);
    border-left: 5px solid var(--sudoku-green);
    border-radius: 0 8px 8px 0;
    padding: 0.85rem 1rem;
    margin-bottom: 0.6rem;
}

.rule-number {
    flex-shrink: 0;
    width: 2rem;
    height: 2rem;
    background: var(--sudoku-green);
    color: #fff;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 0.95rem;
    margin-top: 0.05rem;
}

.rule-card p { margin: 0; font-size: 0.95rem; line-height: 1.6; }
.rule-card strong { color: var(--sudoku-ink); }


/* ─────────────────────────────────────────────────────────
   BOARD DIAGRAM — ASCII-style 3×3 grid illustration
───────────────────────────────────────────────────────── */
.board-diagram {
    background: #fff;
    border: 1px solid #dee2e6;
    border-radius: 8px;
    padding: 1rem 1.2rem;
    margin: 1rem 0;
    font-size: 0.88rem;
}

.board-diagram table.mini-board {
    border-collapse: collapse;
    margin: 0 auto;
}

.board-diagram table.mini-board td {
    width: 30px;
    height: 30px;
    text-align: center;
    font-size: 0.85rem;
    border: 1px solid #b0bec5;
    color: #37474f;
}

.board-diagram table.mini-board td.box-right  { border-right:  2px solid var(--sudoku-green); }
.board-diagram table.mini-board tr.box-bottom  { border-bottom: 2px solid var(--sudoku-green); }
.board-diagram table.mini-board td.given       { font-weight: 700; color: var(--sudoku-ink); background: var(--sudoku-green-lt); }
.board-diagram table.mini-board td.alt         { background: #fff; }
.board-diagram table.mini-board td.conflict    { background: #ffcdd2; color: #c62828; }
.board-diagram table.mini-board td.active-cell { background: var(--sudoku-green-mid); }
.board-diagram table.mini-board td.marked      { color: #1565c0; font-style: italic; text-decoration: underline; }


/* ─────────────────────────────────────────────────────────
   STRATEGY CARDS
───────────────────────────────────────────────────────── */
.strategy-card {
    background: #fff;
    border: 1px solid #dee2e6;
    border-radius: 10px;
    padding: 1rem 1.1rem;
    margin-bottom: 0.9rem;
    box-shadow: 0 1px 4px rgba(0,0,0,0.05);
}

.strategy-card-header {
    display: flex;
    align-items: center;
    gap: 0.6rem;
    margin-bottom: 0.5rem;
    flex-wrap: wrap;
}

.strategy-card-header h3 {
    font-family: var(--boogaloo);
    font-size: 1.15rem;
    color: var(--sudoku-ink);
    margin: 0;
}

.difficulty-badge {
    font-size: 0.68rem;
    font-weight: 700;
    letter-spacing: 1.5px;
    text-transform: uppercase;
    padding: 2px 8px;
    border-radius: 20px;
    color: #fff;
    flex-shrink: 0;
}

.badge-beginner     { background: var(--badge-bg-begin); }
.badge-intermediate { background: var(--badge-bg-inter); }
.badge-advanced     { background: var(--badge-bg-adv); }

.strategy-card p   { font-size: 0.9rem; line-height: 1.65; margin-bottom: 0.4rem; }
.strategy-card p:last-child { margin-bottom: 0; }
.strategy-card .tip {
    background: var(--sudoku-green-lt);
    border-left: 3px solid var(--sudoku-green);
    padding: 0.4rem 0.7rem;
    border-radius: 0 4px 4px 0;
    font-size: 0.85rem;
    margin-top: 0.5rem;
}


/* ─────────────────────────────────────────────────────────
   APP CONTROLS REFERENCE
───────────────────────────────────────────────────────── */
.controls-grid {
    display: grid;
    grid-template-columns: auto 1fr;
    gap: 0.4rem 1rem;
    background: #fff;
    border: 1px solid #dee2e6;
    border-radius: 8px;
    padding: 1rem 1.2rem;
    margin: 0.5rem 0;
    align-items: start;
}

.ctrl-key {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-width: 2.2rem;
    padding: 0.2rem 0.5rem;
    background: var(--sudoku-ink);
    color: #fff;
    border-radius: 5px;
    font-family: 'Noto Sans Mono', monospace, 'Courier New';
    font-size: 0.82rem;
    font-weight: 700;
    white-space: nowrap;
    box-shadow: 0 2px 0 rgba(0,0,0,0.35);
    justify-self: start;
}

.ctrl-key.green  { background: var(--sudoku-green); }
.ctrl-key.red    { background: #c62828; }
.ctrl-key.amber  { background: var(--tnt-amber-dark); }
.ctrl-key.blue   { background: #1565c0; }
.ctrl-key.number { background: #37474f; }

.ctrl-desc { font-size: 0.88rem; line-height: 1.5; padding: 0.2rem 0; }
.ctrl-desc strong { color: var(--sudoku-ink); }


/* ─────────────────────────────────────────────────────────
   BACK BAR
───────────────────────────────────────────────────────── */
.back-bar {
    background: var(--tnt-dark);
    padding: 0.6rem 1rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.back-bar a {
    color: var(--tnt-amber);
    font-weight: 700;
    font-size: 0.88rem;
    text-decoration: none;
}

.back-bar a:hover { text-decoration: underline; }
.back-bar span { color: rgba(255,255,255,0.5); font-size: 0.8rem; }


/* ─────────────────────────────────────────────────────────
   CALLOUT BOX (general-purpose aside)
───────────────────────────────────────────────────────── */
.callout {
    background: #fffbf2;
    border: 2px solid var(--tnt-amber);
    border-radius: 8px;
    padding: 0.85rem 1rem;
    margin: 1rem 0;
    font-size: 0.88rem;
    line-height: 1.65;
}

.callout strong { color: #a06010; }