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

/* ── QR Code Modal ── */
#qr-modal {
    display: none;
    position: fixed;
    inset: 0;
    z-index: 1000;
    align-items: center;
    justify-content: center;
}
#qr-modal.qr-open {
    display: flex;
}
#qr-backdrop {
    position: absolute;
    inset: 0;
    background: rgba(10, 5, 50, 0.85);
    backdrop-filter: blur(8px);
    transition: backdrop-filter 0.3s ease;
}
#qr-box {
    position: relative;
    z-index: 1;
    background: linear-gradient(160deg, #1a0f80 0%, #2B11DB 100%);
    border: 1.5px solid rgba(200, 180, 255, 0.35);
    border-radius: 24px;
    padding: 36px 40px;
    text-align: center;
    box-shadow: 
        0 32px 80px rgba(0,0,0,0.75),
        0 0 40px rgba(120, 150, 255, 0.15),
        inset 0 1px 0 rgba(255,255,255,0.1);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 16px;
    animation: qr-pop 0.24s cubic-bezier(0.34,1.56,0.64,1) both;
}
@keyframes qr-pop {
    from { opacity: 0; transform: scale(0.85); }
    to   { opacity: 1; transform: scale(1);    }
}
.qr-title {
    font-size: 0.92rem;
    color: #c8ddf8;
    letter-spacing: 0.08em;
}
#qr-img {
    display: block;
    background: #fff;
    border-radius: 12px;
    padding: 0;
    box-shadow: 0 8px 24px rgba(0,0,0,0.4);
}
.qr-hint {
    font-size: 0.72rem;
    color: rgba(180, 210, 255, 0.38);
    letter-spacing: 0.1em;
    text-transform: uppercase;
}

body {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 8px 16px 56px;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', sans-serif;
    color: #f0f0f0;
    overflow-x: hidden;

    background-color: #0a0520;
    background-image:
        repeating-linear-gradient(
            135deg,
            transparent,
            transparent 40px,
            rgba(255,255,255,0.006) 40px,
            rgba(255,255,255,0.006) 41px
        ),
        radial-gradient(ellipse 140% 70% at 50% -8%,
            rgba(120, 80, 255, 0.6) 0%,
            rgba(60, 30, 200, 0.3)  40%,
            transparent              70%),
        radial-gradient(ellipse 100% 60% at 50% 120%,
            rgba(10, 5, 50, 0.95) 0%,
            transparent           60%),
        linear-gradient(160deg, #2B11DB 0%, #1a0899 50%, #0a0520 100%);
}

/* ── Header ── */
.site-header {
    text-align: center;
    margin-bottom: 8px;
    animation: slidedownin 0.3s cubic-bezier(0.34, 1.56, 0.64, 1) both;
}

@keyframes slidedownin {
    from { opacity: 0; transform: translateY(-20px); }
    to   { opacity: 1; transform: translateY(0);     }
}

.site-header .logo {
    display: block;
    margin: 0 auto;
    height: 60px;
    width: auto;
    margin-bottom: 8px;
    filter: brightness(0) invert(1) drop-shadow(0 3px 18px rgba(120,180,255,0.35));
    transition: filter 0.4s ease, transform 0.4s ease;
}

.site-header .logo:hover {
    filter: brightness(0) invert(1) drop-shadow(0 6px 24px rgba(140,200,255,0.55));
    transform: scale(1.02);
}

.header-title {
    animation: slidedownin 0.3s cubic-bezier(0.34, 1.56, 0.64, 1) both;
}

.header-title h1 {
    font-size: 2rem;
    font-weight: 700;
    letter-spacing: 0.02em;
    color: #ffffff;
    margin: 12px 0 8px;
    background: linear-gradient(135deg, #ffffff 0%, #c8ddf8 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.header-title .header-subtitle {
    font-size: 0.95rem;
    color: rgba(200, 221, 248, 0.75);
    letter-spacing: 0.05em;
    margin: 0;
    font-weight: 300;
}

/* ── Loading screen ── */
#loading {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 20px;
    padding: 24px 20px;
    animation: fadeindown 0.3s ease both;
}

@keyframes fadeindown {
    from { opacity: 0; transform: translateY(-10px); }
    to   { opacity: 1; transform: translateY(0);     }
}

.ring {
    width: 68px;
    height: 68px;
    border: 4px solid rgba(140, 180, 255, 0.12);
    border-top-color: #8accff;
    border-right-color: rgba(140, 180, 255, 0.3);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
    box-shadow: 
        0 0 28px rgba(140, 180, 255, 0.25),
        inset 0 0 16px rgba(140, 180, 255, 0.08);
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

.loading-label {
    font-size: 1.05rem;
    font-weight: 600;
    color: #f0f8ff;
    letter-spacing: 0.07em;
    text-shadow: 0 2px 8px rgba(0,0,0,0.3);
}

.loading-sub {
    font-size: 0.82rem;
    color: rgba(200, 221, 248, 0.6);
    letter-spacing: 0.07em;
    text-shadow: 0 1px 4px rgba(0,0,0,0.2);
}

/* ── Book clip (hides blank left page on cover) ── */
#book-clip {
    display: flex;
    justify-content: center;
}

/* ── Book wrapper ── */
#book-wrap {
    display: none;
    position: relative;
    flex-shrink: 0;
    filter:
        drop-shadow(0 60px 120px rgba(0, 0, 0, 0.9))
        drop-shadow(0 16px 40px rgba(0, 0, 0, 0.7))
        drop-shadow(0 0 100px rgba(100, 150, 255, 0.25));
    border-radius: 2px;
    animation: bookfadein 0.4s cubic-bezier(0.34, 1.56, 0.64, 1) 0.15s both;
    transition: filter 0.4s ease;
}

#book-wrap:hover {
    filter:
        drop-shadow(0 70px 140px rgba(0, 0, 0, 0.95))
        drop-shadow(0 20px 50px rgba(0, 0, 0, 0.8))
        drop-shadow(0 0 120px rgba(100, 200, 255, 0.35));
}

@keyframes bookfadein {
    from { opacity: 0; transform: scale(0.95); }
    to   { opacity: 1; transform: scale(1);     }
}

/* Booklet binding / spine */
#spine {
    display: none;
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 14px;
    pointer-events: none;
    z-index: 100;
    background: transparent;
}

/* ── Controls bar ── */
#controls {
    display: none;
    align-items: center;
    gap: 14px;
    margin-top: 36px;
    padding: 18px 36px;
    background: linear-gradient(135deg, rgba(25, 10, 100, 0.7) 0%, rgba(15, 5, 80, 0.6) 100%);
    border: 2px solid rgba(140, 200, 255, 0.3);
    border-radius: 60px;
    backdrop-filter: blur(24px);
    box-shadow: 
        0 12px 48px rgba(0,0,0,0.6),
        inset 0 1px 0 rgba(255,255,255,0.15),
        0 0 30px rgba(120, 180, 255, 0.2);
    animation: controsfadein 0.3s cubic-bezier(0.34, 1.56, 0.64, 1) 0.1s both;
    transition: all 0.4s ease;
}

#controls:hover {
    background: linear-gradient(135deg, rgba(40, 15, 120, 0.8) 0%, rgba(25, 10, 100, 0.7) 100%);
    border-color: rgba(160, 220, 255, 0.4);
    box-shadow: 
        0 14px 54px rgba(0,0,0,0.7),
        inset 0 1px 0 rgba(255,255,255,0.2),
        0 0 40px rgba(140, 200, 255, 0.25);
}

@keyframes controsfadein {
    from { opacity: 0; transform: translateY(20px); }
    to   { opacity: 1; transform: translateY(0);     }
}

.cbtn {
    background: linear-gradient(135deg, rgba(120, 180, 255, 0.12) 0%, rgba(100, 150, 255, 0.05) 100%);
    border: 1.3px solid rgba(140, 200, 255, 0.35);
    color: #d8e8ff;
    padding: 11px 22px;
    border-radius: 28px;
    cursor: pointer;
    font-size: 0.875rem;
    font-weight: 600;
    letter-spacing: 0.03em;
    transition: 
        background 0.28s cubic-bezier(0.34, 1.56, 0.64, 1),
        border-color 0.28s cubic-bezier(0.34, 1.56, 0.64, 1),
        color 0.28s ease,
        box-shadow 0.28s ease,
        transform 0.24s ease;
    position: relative;
    overflow: hidden;
    text-shadow: 0 1px 2px rgba(0,0,0,0.3);
}

.cbtn::before {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.1), transparent);
    transform: translateX(-100%);
    transition: transform 0.4s ease;
}

.cbtn:hover::before {
    transform: translateX(100%);
}

.cbtn:hover:not(:disabled) {
    background: linear-gradient(135deg, rgba(140, 200, 255, 0.28) 0%, rgba(120, 180, 255, 0.16) 100%);
    border-color: #8accff;
    color: #ffffff;
    box-shadow: 
        0 0 32px rgba(140, 180, 255, 0.45),
        inset 0 1px 0 rgba(255,255,255,0.2),
        0 4px 16px rgba(100, 140, 255, 0.3);
    transform: translateY(-3px);
}

.cbtn:active:not(:disabled) {
    transform: translateY(-1px);
}

.cbtn:disabled {
    opacity: 0.25;
    cursor: default;
}

#page-num {
    min-width: 170px;
    text-align: center;
    font-size: 0.92rem;
    font-weight: 700;
    color: #ffd700;
    letter-spacing: 0.05em;
    background: linear-gradient(135deg, rgba(120, 120, 255, 0.15) 0%, rgba(100, 100, 255, 0.08) 100%);
    padding: 8px 20px;
    border-radius: 24px;
    border: 1.5px solid rgba(255, 215, 0, 0.25);
    transition: all 0.3s ease;
    box-shadow: 0 0 16px rgba(255, 215, 0, 0.1);
}

/* ── Footer ── */
.site-footer {
    margin-top: 28px;
    font-size: 0.72rem;
    letter-spacing: 0.14em;
    color: rgba(180, 210, 255, 0.6);
    text-transform: uppercase;
    font-weight: 600;
    animation: fadeinslow 1s ease 0.8s both;
    text-shadow: 0 2px 8px rgba(0,0,0,0.5);
    transition: color 0.3s ease;
}

@keyframes fadeinslow {
    from { opacity: 0; }
    to   { opacity: 1; }
}

/* ════════════════════════════════════════
   RESPONSIVE — tablets & phones
   ════════════════════════════════════════ */
@media (max-width: 767px) {
    body {
        padding: 16px 8px 24px;
        overflow-x: hidden;
    }

    .site-header {
        margin-bottom: 20px;
    }

    .site-header .logo {
        height: 42px;
    }

    #book-wrap {
        /* tighten shadow on small screens to avoid clipping */
        filter:
            drop-shadow(0 32px 64px rgba(0, 0, 0, 0.8))
            drop-shadow(0 8px 20px rgba(0, 0, 0, 0.6))
            drop-shadow(0 0 50px rgba(100, 160, 255, 0.15));
    }

    #controls {
        margin-top: 18px;
        padding: 14px 18px;
        gap: 8px;
        flex-wrap: wrap;
        justify-content: center;
        border-radius: 48px;
        border: 1.5px solid rgba(140, 200, 255, 0.28);
    }

    #page-num {
        order: -1;
        width: 100%;
        min-width: unset;
        text-align: center;
        padding: 8px 16px;
        padding-bottom: 10px;
        border-bottom: 1.5px solid rgba(120, 180, 255, 0.2);
        margin-bottom: 8px;
        font-size: 0.88rem;
    }

    .cbtn {
        padding: 9px 18px;
        font-size: 0.84rem;
    }

    .site-footer {
        font-size: 0.64rem;
        text-align: center;
        letter-spacing: 0.12em;
        margin-top: 18px;
    }
}

/* very small phones (≤ 400 px wide) */
@media (max-width: 400px) {
    body {
        padding: 12px 4px 18px;
    }

    .site-header .logo {
        height: 36px;
        margin-bottom: 12px;
    }

    .header-title h1 {
        font-size: 1.4rem;
        margin: 8px 0 6px;
    }

    .header-title .header-subtitle {
        font-size: 0.82rem;
    }

    .cbtn {
        padding: 6px 12px;
        font-size: 0.76rem;
    }

    .ring {
        width: 52px;
        height: 52px;
        border-width: 3px;
    }
}