:root {
    --bg1: #f6f8fb;
    --bg2: #eef5ff;
    --glass: rgba(255, 255, 255, 0.72);
    --muted: #6b7280;
    --accent: #6ee7b7;
    /* gentle mint accent */
    --card: rgba(255, 255, 255, 0.85);
    --shadow-lg: 0 10px 30px rgba(14, 20, 30, 0.12);
    --shadow-sm: 0 6px 18px rgba(14, 20, 30, 0.06);
    --glass-border: rgba(255, 255, 255, 0.6);
    --glass-blur: 10px;
    font-family: Inter, ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial;
}

* {
    box-sizing: border-box
}

html,
body {
    height: auto;
    min-height: 100%;
    overflow-y: auto;
}

body {
    margin: 0;
    background: linear-gradient(180deg, var(--bg1), var(--bg2));
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    color: #0f172a;
    display: flex;
    justify-content: center;
    padding: 32px;
}

/* shell */
.app {
    width: 100%;
    max-width: 1100px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 1fr 420px;
    gap: 28px;
    align-items: start;
}

@media (max-width:980px) {
    .app {
        grid-template-columns: 1fr;
        padding: 12px
    }

    .right-panel {
        order: -1;
    }
}

/* header */
.header {
    grid-column: 1 / -1;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    margin-bottom: 6px;
}

.logo {
    display: flex;
    gap: 12px;
    align-items: center;
}

.logo-mark {

    width: 70px;
    height: 70px;
    border-radius: 10px;
    background: linear-gradient(135deg, #eef9f1, #dff7f0);
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-sm);
    font-weight: 700;
    color: #06384a;
    font-size: 70px;
}

.title {
    font-size: 20px;
    font-weight: 700;
    letter-spacing: -0.3px;
}

.subtitle {
    font-size: 13px;
    color: var(--muted)
}

/* glass card */
.glass {
    background: var(--card);
    border-radius: 14px;
    padding: 20px;
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--glass-border);
    backdrop-filter: blur(var(--glass-blur));
}

/* left column layout */
.left {
    display: flex;
    flex-direction: column;
    gap: 18px;
}

/* continent picker */
.continent-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 12px;
}

@media (max-width:640px) {
    .continent-grid {
        grid-template-columns: repeat(2, 1fr)
    }
}

.continent-btn {
    border-radius: 12px;
    padding: 14px;
    background: linear-gradient(180deg, rgba(255, 255, 255, 0.7), rgba(245, 247, 250, 0.7));
    border: 1px solid rgba(15, 23, 42, 0.04);
    display: flex;
    flex-direction: column;
    gap: 6px;
    cursor: pointer;
    transition: transform .18s ease, box-shadow .18s ease;
    text-align: left;
}

.continent-btn:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-sm)
}

.continent-btn.active {
    background: linear-gradient(180deg, #f0fbf8, #e7f8f0);
    box-shadow: 0 12px 30px rgba(13, 49, 44, 0.06);
    border: 1px solid rgba(17, 131, 116, 0.12);
}

.continent-name {
    font-weight: 600;
    color: #06384a
}

.continent-count {
    font-size: 12px;
    color: var(--muted)
}

/* center card (quiz) */
.card-wrap {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 320px;
}

.card-scene {
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
}

.card {
    width: 100%;
    max-width: 540px;
    height: 320px;
    perspective: 1200px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.card-inner {
    width: 100%;
    height: 100%;
    border-radius: 16px;
    position: relative;
    transform-style: preserve-3d;
    transition: transform .72s cubic-bezier(.2, .9, .3, 1);
    box-shadow: var(--shadow-lg);
}

.card-inner.flipped {
    transform: rotateY(180deg) translateY(-4px)
}

.card-face {
    position: absolute;
    inset: 0;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    padding: 28px;
    border-radius: 16px;
    backface-visibility: hidden;
    -webkit-backface-visibility: hidden;
    overflow: hidden;
}

.card-front {
    background: linear-gradient(180deg, rgba(255, 255, 255, 0.95), rgba(250, 250, 252, 0.96));
    border: 1px solid rgba(15, 23, 42, 0.03);
}

.card-back {
    background: linear-gradient(180deg, #eafdf6, #ecfbf8);
    transform: rotateY(180deg);
    border: 1px solid rgba(15, 23, 42, 0.03);
}

.city {
    font-size: 28px;
    font-weight: 700;
    color: #082c32;
    letter-spacing: -0.4px;
}

.hint {
    font-size: 13px;
    color: var(--muted);
}

/* options list */
.options {
    display: grid;
    gap: 10px;
    grid-template-columns: 1fr 1fr;
    margin-top: 8px;
}

@media (max-width:520px) {
    .options {
        grid-template-columns: 1fr
    }
}

.opt-btn {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 10px;
    padding: 12px 14px;
    border-radius: 12px;
    background: white;
    border: 1px solid rgba(10, 15, 25, 0.04);
    cursor: pointer;
    transition: transform .15s ease, box-shadow .15s ease, background .18s ease;
    font-weight: 600;
    color: #0b1720;
    box-shadow: var(--shadow-sm);
}

.opt-btn:hover {
    transform: translateY(-4px)
}

.opt-btn[disabled] {
    opacity: 0.5;
    cursor: default;
    transform: none;
    box-shadow: none
}

.opt-correct {
    background: linear-gradient(90deg, #eafff3, #dffbe9);
    border: 1px solid rgba(16, 185, 129, 0.14);
    color: #044d3b;
}

.opt-wrong {
    background: linear-gradient(90deg, #fff3f3, #fff1f1);
    border: 1px solid rgba(255, 99, 99, 0.07);
    color: #7a1f1f
}

/* right panel */
.right-panel {
    display: flex;
    flex-direction: column;
    gap: 12px
}

.stats {
    display: flex;
    gap: 8px;
    align-items: center;
    justify-content: space-between
}

.stat {
    background: linear-gradient(180deg, rgba(255, 255, 255, 0.9), rgba(248, 249, 251, 0.9));
    border-radius: 12px;
    padding: 10px 12px;
    font-weight: 700;
    font-size: 14px;
    box-shadow: var(--shadow-sm);
    border: 1px solid rgba(15, 23, 42, 0.02);
    text-align: center;
}

.controls {
    display: flex;
    gap: 10px;
    margin-top: 6px
}

.btn {
    padding: 10px 12px;
    border-radius: 10px;
    border: 0;
    background: #0f172a;
    color: white;
    font-weight: 600;
    cursor: pointer;
    box-shadow: var(--shadow-sm);
}

.btn.ghost {
    background: transparent;
    border: 1px solid rgba(15, 23, 42, 0.06);
    color: #0f172a
}

.btn.mint {
    background: linear-gradient(90deg, #00d1a8, #26e3b6);
    color: #04302b
}

.footer-note {
    font-size: 12px;
    color: var(--muted);
    text-align: center;
    margin-top: 10px
}

/* micro animations */
.fade-in {
    animation: fadeIn .45s ease both
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(6px)
    }

    to {
        opacity: 1;
        transform: none
    }
}