/* =========================================================
   DIFFICULTY SELECTION SCREEN (MODERN 4-CARD STAGE SELECT)
   1920x1080 Native Canvas Layout
========================================================= */

#difficulty-selection {
    display: none;
    position: relative;
    width: 100%;
    min-height: 100vh;
    box-sizing: border-box;
    background-image:
        linear-gradient(rgba(10, 6, 22, 0.75), rgba(5, 3, 14, 0.92)),
        url("bgassets/mainmenu.png");
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
    overflow-y: auto;
    overflow-x: hidden;
    padding: clamp(14px, 2.5vh, 36px) clamp(16px, 2.5vw, 40px);
    font-family: 'Inter', sans-serif;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
}

#difficulty-selection:not([style*="display: none"]),
#difficulty-selection[style*="display: flex"],
#difficulty-selection[style*="display: block"] {
    display: flex !important;
}

/* Background vignette */
#difficulty-selection::before {
    content: "";
    position: absolute;
    inset: 0;
    background: radial-gradient(circle at center, transparent 40%, rgba(0, 0, 0, 0.75) 100%);
    pointer-events: none;
    z-index: 1;
}

/* --- Header Row --- */
.diff-header-row {
    position: relative;
    z-index: 5;
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: clamp(10px, 1.8vh, 26px);
    max-width: 1550px;
    width: 100%;
    margin-left: auto;
    margin-right: auto;
    flex-shrink: 0;
}

.diff-back-btn {
    background: rgba(28, 18, 48, 0.9);
    border: 1px solid #7c3aed;
    color: #e9d5ff;
    font-family: 'Inter', sans-serif;
    font-size: clamp(14px, 1.3vmin + 2px, 16.5px);
    font-weight: 700;
    padding: clamp(8px, 1vh, 12px) clamp(14px, 1.5vw, 24px);
    border-radius: 10px;
    cursor: pointer;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.4);
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    gap: 8px;
}

.diff-back-btn:hover {
    background: #7c3aed;
    color: #ffffff;
    transform: translateX(-4px);
    box-shadow: 0 6px 20px rgba(124, 58, 237, 0.4);
}

.diff-title-wrap {
    text-align: center;
}

.diff-title-wrap h2 {
    margin: 0 0 clamp(2px, 0.5vh, 6px) 0;
    font-family: 'Inter', sans-serif;
    font-size: clamp(24px, 3vmin + 6px, 40px);
    font-weight: 800;
    color: #ffffff;
    letter-spacing: 1px;
    text-shadow: 0 4px 15px rgba(0, 0, 0, 0.6), 0 0 30px rgba(168, 85, 247, 0.4);
}

.diff-subtitle {
    margin: 0;
    font-family: 'Inter', sans-serif;
    font-size: clamp(14.5px, 1.2vmin + 2px, 17px);
    color: #c4b5fd;
    letter-spacing: 0.3px;
}

.diff-header-spacer {
    width: clamp(70px, 8vw, 140px);
}

/* =========================================================
   DIFFICULTY 4-CARD STAGE GRID
========================================================= */

.difficulty-cards-grid {
    position: relative;
    z-index: 5;
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr)) !important;
    gap: clamp(10px, 1.5vw, 24px);
    min-height: 0;
    flex: 1;
    max-width: 1550px;
    width: 100%;
    margin: auto auto;
    align-items: center;
}

.diff-stage-card {
    background: linear-gradient(180deg, rgba(25, 18, 48, 0.94) 0%, rgba(12, 8, 26, 0.98) 100%);
    border: 2px solid #5a388a;
    border-radius: 18px;
    padding: clamp(12px, 1.8vh, 22px) clamp(12px, 1.4vw, 22px);
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    box-shadow: 0 15px 40px rgba(0, 0, 0, 0.65), 0 0 25px rgba(120, 60, 200, 0.15);
    backdrop-filter: blur(10px);
    transition: transform 0.25s ease, border-color 0.25s ease, box-shadow 0.25s ease;
    box-sizing: border-box;
    position: relative;
    overflow: hidden;
    min-height: clamp(360px, 56vh, 510px);
    max-height: clamp(390px, 60vh, 540px);
}

.diff-stage-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 22px 55px rgba(0, 0, 0, 0.75), 0 0 35px rgba(168, 85, 247, 0.35);
}

/* Color thematic accents per card */
.diff-stage-card.card-easy {
    border-top: 5px solid #10b981;
}
.diff-stage-card.card-easy:hover {
    border-color: #10b981;
    box-shadow: 0 22px 55px rgba(0, 0, 0, 0.75), 0 0 35px rgba(16, 185, 129, 0.3);
}

.diff-stage-card.card-normal {
    border-top: 5px solid #3b82f6;
}
.diff-stage-card.card-normal:hover {
    border-color: #3b82f6;
    box-shadow: 0 22px 55px rgba(0, 0, 0, 0.75), 0 0 35px rgba(59, 130, 246, 0.3);
}

.diff-stage-card.card-hard {
    border-top: 5px solid #f59e0b;
}
.diff-stage-card.card-hard:hover {
    border-color: #f59e0b;
    box-shadow: 0 22px 55px rgba(0, 0, 0, 0.75), 0 0 35px rgba(245, 158, 11, 0.3);
}

.diff-stage-card.card-hell {
    border-top: 5px solid #ef4444;
}
.diff-stage-card.card-hell:hover {
    border-color: #ef4444;
    box-shadow: 0 22px 55px rgba(0, 0, 0, 0.75), 0 0 40px rgba(239, 68, 68, 0.4);
}

/* Card Header Badges */
.card-badge-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: clamp(10px, 1.4vmin, 20px);
}

.card-star-badge {
    font-family: 'JetBrains Mono', monospace;
    font-size: clamp(12px, 1.1vmin, 13.5px);
    font-weight: 700;
    color: #ffd166;
    background: rgba(255, 209, 102, 0.15);
    padding: 4px 10px;
    border-radius: 20px;
    border: 1px solid rgba(255, 209, 102, 0.4);
}

.card-powerup-badge {
    font-family: 'Inter', sans-serif;
    font-size: clamp(12px, 1.1vmin, 13.5px);
    font-weight: 700;
    color: #6ee7b7;
    background: rgba(16, 185, 129, 0.15);
    padding: 4px 10px;
    border-radius: 20px;
    border: 1px solid rgba(16, 185, 129, 0.4);
}

.card-powerup-badge.hardcore {
    color: #fca5a5;
    background: rgba(239, 68, 68, 0.15);
    border: 1px solid rgba(239, 68, 68, 0.4);
}

.card-powerup-badge.paid {
    color: #fde047;
    background: rgba(234, 179, 8, 0.15);
    border: 1px solid rgba(234, 179, 8, 0.4);
}

/* Card Monster / Boss Preview Spotlight */
.diff-card-preview {
    display: flex;
    align-items: center;
    justify-content: center;
    height: clamp(80px, 12vh, 120px);
    margin: clamp(4px, 0.8vh, 10px) 0;
    position: relative;
    pointer-events: none;
}

.diff-card-preview::after {
    content: "";
    position: absolute;
    bottom: 2px;
    width: clamp(70px, 65%, 130px);
    height: 16px;
    border-radius: 50%;
    background: radial-gradient(ellipse at center, rgba(168, 85, 247, 0.4) 0%, transparent 75%);
    filter: blur(4px);
    z-index: 1;
}

.card-easy .diff-card-preview::after {
    background: radial-gradient(ellipse at center, rgba(16, 185, 129, 0.5) 0%, transparent 75%);
}
.card-normal .diff-card-preview::after {
    background: radial-gradient(ellipse at center, rgba(59, 130, 246, 0.5) 0%, transparent 75%);
}
.card-hard .diff-card-preview::after {
    background: radial-gradient(ellipse at center, rgba(245, 158, 11, 0.5) 0%, transparent 75%);
}
.card-hell .diff-card-preview::after {
    background: radial-gradient(ellipse at center, rgba(239, 68, 68, 0.55) 0%, transparent 75%);
}

.diff-boss-preview-img {
    max-height: 100%;
    max-width: 90%;
    object-fit: contain;
    position: relative;
    z-index: 2;
    filter: drop-shadow(0 8px 16px rgba(0, 0, 0, 0.75));
    transition: transform 0.3s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.diff-stage-card:hover .diff-boss-preview-img {
    transform: scale(1.12) translateY(-4px);
}

/* Card Titles */
.card-title {
    margin: 0 0 2px 0;
    font-family: 'Inter', sans-serif;
    font-size: clamp(20px, 2.4vmin, 30px);
    font-weight: 800;
    letter-spacing: 0.5px;
    color: #ffffff;
}

.card-easy .card-title { color: #34d399; }
.card-normal .card-title { color: #60a5fa; }
.card-hard .card-title { color: #fbbf24; }
.card-hell .card-title { color: #f87171; }

.card-domain {
    margin: 0 0 clamp(4px, 0.8vh, 12px) 0;
    font-size: clamp(13px, 1.1vmin + 2px, 15px);
    color: #c4b5fd;
    line-height: 1.35;
    min-height: auto;
}

/* Card Vitals Info Box */
.card-info-box {
    background: rgba(12, 8, 24, 0.7);
    border: 1px solid rgba(120, 80, 180, 0.25);
    border-radius: 12px;
    padding: clamp(8px, 1.2vh, 14px) clamp(10px, 1.2vw, 16px);
    display: flex;
    flex-direction: column;
    gap: clamp(6px, 0.8vh, 10px);
    margin-bottom: clamp(6px, 1vh, 16px);
}

.card-info-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: clamp(13px, 1vmin + 2px, 15px);
    color: #cbd5e1;
}

.card-info-row span {
    color: #94a3b8;
}

.card-info-row strong {
    color: #ffffff;
    font-family: 'JetBrains Mono', monospace;
    font-weight: 600;
}

/* Play Button */
.diff-play-btn {
    width: 100%;
    height: clamp(42px, 5vh, 54px);
    border-radius: 10px;
    font-family: 'Inter', sans-serif;
    font-size: clamp(14.5px, 1.3vmin + 2px, 17px);
    font-weight: 700;
    cursor: pointer;
    border: none;
    color: #ffffff;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    transition: all 0.2s ease;
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.4);
}

.card-easy .diff-play-btn {
    background: linear-gradient(135deg, #059669, #10b981);
    box-shadow: 0 6px 20px rgba(16, 185, 129, 0.35);
}
.card-easy .diff-play-btn:hover {
    background: linear-gradient(135deg, #10b981, #34d399);
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(16, 185, 129, 0.55);
}

.card-normal .diff-play-btn {
    background: linear-gradient(135deg, #2563eb, #3b82f6);
    box-shadow: 0 6px 20px rgba(59, 130, 246, 0.35);
}
.card-normal .diff-play-btn:hover {
    background: linear-gradient(135deg, #3b82f6, #60a5fa);
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(59, 130, 246, 0.55);
}

.card-hard .diff-play-btn {
    background: linear-gradient(135deg, #d97706, #f59e0b);
    box-shadow: 0 6px 20px rgba(245, 158, 11, 0.35);
}
.card-hard .diff-play-btn:hover {
    background: linear-gradient(135deg, #f59e0b, #fbbf24);
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(245, 158, 11, 0.55);
}

.card-hell .diff-play-btn {
    background: linear-gradient(135deg, #dc2626, #ef4444);
    box-shadow: 0 6px 20px rgba(239, 68, 68, 0.4);
}
.card-hell .diff-play-btn:hover {
    background: linear-gradient(135deg, #ef4444, #f87171);
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(239, 68, 68, 0.6);
}

/* Locked Card State */
.diff-stage-card.is-locked {
    opacity: 0.65;
    filter: grayscale(40%);
}

.diff-stage-card.is-locked .diff-play-btn {
    background: #332747;
    color: #948aa8;
    box-shadow: none;
    cursor: pointer;
}

.diff-stage-card.is-locked .diff-play-btn:hover {
    background: #463463;
    color: #ff88a3;
    transform: none;
}

/* =========================================================
   LOCKED DIFFICULTY MODAL & SHAKE PROMPT
========================================================= */

@keyframes lockCardShake {
    0%, 100% { transform: translateX(0); }
    20%, 60% { transform: translateX(-8px) rotate(-1deg); }
    40%, 80% { transform: translateX(8px) rotate(1deg); }
}

.lock-shake {
    animation: lockCardShake 0.45s cubic-bezier(0.36, 0.07, 0.19, 0.97) both !important;
}

.diff-locked-modal-wrap {
    position: absolute;
    inset: 0;
    z-index: 99999;
    display: flex;
    align-items: center;
    justify-content: center;
    animation: modalFadeIn 0.25s ease-out;
}

@keyframes modalFadeIn {
    0% { opacity: 0; }
    100% { opacity: 1; }
}

.diff-locked-modal-backdrop {
    position: absolute;
    inset: 0;
    background: rgba(6, 2, 14, 0.88);
    backdrop-filter: blur(8px);
}

.diff-locked-modal-box {
    position: relative;
    z-index: 10;
    width: 720px;
    max-width: 95%;
    background: linear-gradient(180deg, #240a28 0%, #0d0115 100%);
    border: 2px solid #ef4444;
    border-top: 5px solid #ff3366;
    border-radius: 18px;
    box-shadow: 0 25px 60px rgba(0, 0, 0, 0.95), 0 0 35px rgba(239, 68, 68, 0.35);
    overflow: hidden;
    animation: modalPopIn 0.28s cubic-bezier(0.18, 0.89, 0.32, 1.28);
}

@keyframes modalPopIn {
    0% { opacity: 0; transform: scale(0.92) translateY(15px); }
    100% { opacity: 1; transform: scale(1) translateY(0); }
}

.diff-locked-header {
    display: flex;
    align-items: center;
    gap: 16px;
    padding: 22px 28px;
    border-bottom: 1px solid rgba(255, 68, 102, 0.3);
    background: rgba(45, 8, 30, 0.65);
}

.diff-locked-icon {
    font-size: 34px;
    line-height: 1;
    filter: drop-shadow(0 0 10px rgba(255, 68, 102, 0.7));
}

.diff-locked-titles {
    flex: 1;
}

.diff-locked-title {
    font-family: 'Inter', sans-serif;
    font-size: 20px;
    font-weight: 800;
    color: #ff5577;
    margin: 0 0 4px 0;
    letter-spacing: 0.5px;
    text-shadow: 0 0 12px rgba(255, 85, 119, 0.6);
}

.diff-locked-subtitle {
    font-family: 'Inter', sans-serif;
    font-size: 13.5px;
    color: #cbd5e1;
    margin: 0;
}

.diff-locked-close-x {
    background: rgba(60, 10, 25, 0.85);
    border: 1px solid #ff4466;
    color: #ff99bb;
    font-size: 16px;
    width: 36px;
    height: 36px;
    border-radius: 8px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s ease;
}

.diff-locked-close-x:hover {
    background: #ff4466;
    color: #ffffff;
    box-shadow: 0 0 15px rgba(255, 68, 102, 0.8);
    transform: scale(1.05);
}

.diff-locked-body {
    padding: 26px 28px;
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.diff-target-pill-wrap {
    display: flex;
    align-items: center;
    gap: 12px;
    background: rgba(20, 6, 30, 0.75);
    border: 1px solid rgba(168, 85, 247, 0.3);
    border-radius: 10px;
    padding: 10px 16px;
}

.diff-target-label {
    font-family: 'JetBrains Mono', monospace;
    font-size: 13.5px;
    font-weight: 700;
    color: #94a3b8;
    letter-spacing: 1px;
}

.diff-target-name {
    font-family: 'JetBrains Mono', monospace;
    font-size: 15.5px;
    font-weight: 800;
    color: #fca5a5;
    letter-spacing: 1px;
}

.diff-requirement-card {
    display: flex;
    align-items: flex-start;
    gap: 16px;
    background: rgba(30, 10, 20, 0.85);
    border: 1px solid rgba(239, 68, 68, 0.4);
    border-left: 5px solid #ef4444;
    border-radius: 12px;
    padding: 16px 20px;
}

.diff-req-icon {
    font-size: 26px;
    line-height: 1;
    margin-top: 2px;
}

.diff-req-content {
    flex: 1;
}

.diff-req-heading {
    display: block;
    font-family: 'Inter', sans-serif;
    font-size: 13.5px;
    font-weight: 800;
    color: #f87171;
    letter-spacing: 1px;
    margin-bottom: 6px;
}

.diff-req-text {
    margin: 0;
    font-family: 'Inter', sans-serif;
    font-size: 15.5px;
    line-height: 1.5;
    color: #e2e8f0;
}

.diff-roadmap-box {
    background: rgba(14, 5, 22, 0.8);
    border: 1px solid rgba(147, 51, 234, 0.3);
    border-radius: 12px;
    padding: 16px 20px;
}

.roadmap-title {
    font-family: 'Inter', sans-serif;
    font-size: 13.5px;
    font-weight: 700;
    color: #c084fc;
    letter-spacing: 0.5px;
    margin-bottom: 14px;
    display: block;
}

.roadmap-tiers {
    display: flex;
    align-items: center;
    gap: 10px;
}

.roadmap-step {
    flex: 1;
    background: rgba(25, 8, 38, 0.8);
    border: 1px solid rgba(147, 51, 234, 0.35);
    border-radius: 10px;
    padding: 10px 8px;
    text-align: center;
    display: flex;
    flex-direction: column;
    gap: 4px;
    transition: all 0.2s ease;
}

.roadmap-step.cleared {
    border-color: #10b981;
    background: rgba(6, 40, 25, 0.85);
    box-shadow: 0 0 12px rgba(16, 185, 129, 0.25);
}

.roadmap-step.active {
    border-color: #38bdf8;
    background: rgba(8, 45, 65, 0.85);
    box-shadow: 0 0 12px rgba(56, 189, 248, 0.25);
}

.roadmap-step.locked {
    opacity: 0.5;
    border-style: dashed;
}

.roadmap-step.target-tier {
    opacity: 0.95;
    border: 2px dashed #f87171;
    background: rgba(45, 10, 20, 0.8);
    box-shadow: 0 0 15px rgba(248, 113, 113, 0.3);
}

.step-badge {
    font-family: 'JetBrains Mono', monospace;
    font-size: 12px;
    font-weight: 700;
    color: #94a3b8;
}

.step-name {
    font-family: 'Inter', sans-serif;
    font-size: 15px;
    font-weight: 700;
    color: #ffffff;
}

.step-status {
    font-size: 13px;
    font-weight: 600;
}

.roadmap-step.cleared .step-status { color: #34d399; }
.roadmap-step.active .step-status { color: #38bdf8; }
.roadmap-step.locked .step-status { color: #f87171; }

.roadmap-arrow {
    color: #a855f7;
    font-size: 15px;
    font-weight: bold;
}

.diff-locked-footer {
    display: flex;
    justify-content: flex-end;
    align-items: center;
    gap: 14px;
    padding: 18px 28px;
    border-top: 1px solid rgba(255, 68, 102, 0.2);
    background: rgba(22, 4, 30, 0.85);
}

.diff-locked-play-btn {
    background: linear-gradient(135deg, #9333ea, #c026d3) !important;
    border: 1px solid rgba(255, 255, 255, 0.3) !important;
    color: #ffffff !important;
    font-family: 'Inter', sans-serif !important;
    font-size: 15.5px !important;
    font-weight: 700 !important;
    padding: 12px 24px !important;
    border-radius: 10px !important;
    cursor: pointer !important;
    box-shadow: 0 4px 15px rgba(168, 85, 247, 0.4) !important;
    transition: all 0.2s ease !important;
}

.diff-locked-play-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 22px rgba(192, 38, 211, 0.6) !important;
}

.diff-locked-dismiss-btn {
    background: rgba(45, 15, 55, 0.8) !important;
    border: 1px solid rgba(168, 85, 247, 0.4) !important;
    color: #e2e8f0 !important;
    font-family: 'Inter', sans-serif !important;
    font-size: 15.5px !important;
    font-weight: 600 !important;
    padding: 12px 22px !important;
    border-radius: 10px !important;
    cursor: pointer !important;
    transition: all 0.2s ease !important;
}

.diff-locked-dismiss-btn:hover {
    background: rgba(88, 28, 110, 0.9) !important;
    color: #ffffff !important;
}