/* ============================================
   UI Buttons — 汎用ボタン・コントロールボタン
   ============================================ */

.diff-btn {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 24px 40px;
    cursor: pointer;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
    min-width: 100px;
    transition: all var(--transition-normal);
    position: relative;
    overflow: hidden;
}

.diff-btn:hover {
    border-color: var(--green-neon);
    transform: translateY(-4px);
    box-shadow: 0 8px 32px var(--green-glow);
}

.diff-btn.-mode {
    flex: 1;
    width: 100%;
    padding: 15px;
    display: flex;
    flex-direction: row;
    align-items: center;
    justify-content: center;
    gap: 8px;
    min-height: 48px;
}

.diff-btn.-mode.selected.daily-mode {
    border-color: var(--color-daily);
    background: rgba(3, 169, 244, 0.05);
    box-shadow: 0 0 10px rgba(3, 169, 244, 0.3);
}

.diff-btn.-mode.selected.permanent-mode {
    border-color: var(--color-permanent);
    background: rgba(76, 175, 80, 0.05);
    box-shadow: 0 0 10px rgba(76, 175, 80, 0.3);
}

.nav-btn,
.header-btn,
.back-btn,
.secondary-btn,
.control-btn {
    background: rgba(255, 255, 255, 0.8);
    border: 2px solid var(--green-neon);
    color: var(--green-dark);
    padding: 8px 16px;
    border-radius: 8px;
    cursor: pointer;
    font-weight: bold;
    transition: all 0.2s;
}

.control-btn.active {
    background: var(--green-neon) !important;
    color: #000 !important;
}

.control-btn.memo1.active {
    background: var(--green-neon) !important;
    color: #000 !important;
}

.control-btn.memo2.active {
    background: var(--danger) !important;
    color: #fff !important;
    border-color: var(--danger) !important;
    box-shadow: 0 0 15px rgba(255, 82, 82, 0.4);
}


.nav-btn.guest-disabled {
    opacity: 0.5;
    background: #e0e0e0 !important;
    border-color: #9e9e9e !important;
    color: #757575 !important;
    cursor: not-allowed;
    box-shadow: none !important;
}

.nav-btn.guest-disabled:hover {
    background: #e0e0e0 !important;
    box-shadow: none !important;
}

/* Hint Button in game header */
.hint-btn {
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid var(--warning);
    color: var(--warning);
    padding: 6px 14px;
    border-radius: 8px;
    cursor: pointer;
    font-weight: bold;
    font-size: 0.85rem;
    transition: all 0.2s;
    display: flex;
    align-items: center;
    gap: 5px;
}

.hint-btn:hover {
    background: rgba(255, 152, 0, 0.15);
    box-shadow: 0 0 12px rgba(255, 152, 0, 0.3);
}

/* Assist button */
.assist-btn {
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid var(--green-neon);
    color: var(--green-neon);
    padding: 6px 14px;
    border-radius: 8px;
    cursor: pointer;
    font-weight: bold;
    font-size: 0.85rem;
    transition: all 0.2s;
    display: flex;
    align-items: center;
    gap: 5px;
}

/* --- Stage Select Button (Card) --- */
.stage-btn {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 16px;
    padding: 20px 15px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 8px;
    cursor: pointer;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
    backdrop-filter: blur(5px);
}

.stage-btn:hover {
    transform: translateY(-6px);
    border-color: var(--green-neon);
    box-shadow: 0 12px 24px var(--green-glow-strong);
    background: #fff;
}

.stage-btn:active {
    transform: translateY(-2px);
}

.stage-number {
    font-family: var(--font-title);
    font-size: 2rem;
    font-weight: 900;
    color: var(--green-dark);
    line-height: 1;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
}

.stage-label {
    font-size: 0.75rem;
    font-weight: 700;
    color: var(--text-muted);
    letter-spacing: 1px;
    text-transform: uppercase;
}

/* Cleared State (Optional but recommended) */
.stage-btn.cleared {
    background: rgba(0, 172, 193, 0.18);
    border-color: var(--green-neon);
    box-shadow: 0 4px 10px rgba(0, 172, 193, 0.1);
}

.stage-btn.cleared:hover {
    background: rgba(0, 172, 193, 0.28);
    border-color: var(--green-neon);
    box-shadow: 0 8px 24px rgba(0, 172, 193, 0.2);
}

.stage-btn.cleared .stage-number {
    color: var(--green-neon);
}