:root {
    --bg-grad: linear-gradient(135deg, #070b19, #101836);
    --card-bg: #151e3f;
    --card-border: #23305c;
    --text-main: #e2e8f0;
    --text-sec: #a5b4fc;
    --primary: #6366f1;
    --primary-hover: #818cf8;
    --success: #dcfce7;
    --success-border: #86efac;
    --error: #fee2e2;
    --error-border: #f87171;
    --input-bg: #0b0f24;
    --example-bg: #1e2954;
    --hover-bg: #1e2954;
    font-family: "Poppins", system-ui, -apple-system, Segoe UI, Roboto, "Helvetica Neue", Arial, sans-serif;
}

[data-theme="light"] {
    --bg-grad: linear-gradient(135deg, #dbeafe, #eff6ff);
    --card-bg: #ffffff;
    --card-border: #c7d2fe;
    --text-main: #0f172a;
    --text-sec: #1e3a8a;
    --primary: #3b82f6;
    --primary-hover: #2563eb;
    --input-bg: #ffffff;
    --example-bg: #f1f5f9;
    --hover-bg: #e0e7ff;
}

[data-theme="dark"] {
    --bg-grad: linear-gradient(135deg, #0f172a, #1e293b);
    --card-bg: #1e293b;
    --card-border: #334155;
    --text-main: #f8fafc;
    --text-sec: #93c5fd;
    --primary: #3b82f6;
    --primary-hover: #60a5fa;
    --input-bg: #0f172a;
    --example-bg: #334155;
    --hover-bg: #334155;
}

[data-theme="space"] {
    --bg-grad: linear-gradient(135deg, #070b19, #101836);
    --card-bg: #151e3f;
    --card-border: #23305c;
    --text-main: #e2e8f0;
    --text-sec: #a5b4fc;
    --primary: #6366f1;
    --primary-hover: #818cf8;
    --input-bg: #0b0f24;
    --example-bg: #1e2954;
    --hover-bg: #1e2954;
}

[data-theme="submarine"] {
    --bg-grad: linear-gradient(135deg, #0f172a, #083344);
    --card-bg: #164e63;
    --card-border: #0ea5e9;
    --text-main: #f0fdfa;
    --text-sec: #4ade80;
    --primary: #f97316;
    --primary-hover: #ea580c;
    --input-bg: #082f49;
    --example-bg: #155e75;
    --hover-bg: #115e59;
    --success: #f97316;
    --success-border: #16a34a;
}

[data-theme="ice"] {
    --bg-grad: linear-gradient(135deg, #f0f9ff, #dbeafe);
    --card-bg: #ffffff;
    --card-border: #93c5fd;
    --text-main: #1e3a8a;
    --text-sec: #3b82f6;
    --primary: #60a5fa;
    --primary-hover: #3b82f6;
    --input-bg: #ffffff;
    --example-bg: #eff6ff;
    --hover-bg: #dbeafe;
}

[data-theme="ocean"] {
    --bg-grad: linear-gradient(135deg, #cffafe, #bae6fd);
    --card-bg: #f0fdfa;
    --card-border: #67e8f9;
    --text-main: #083344;
    --text-sec: #0891b2;
    --primary: #06b6d4;
    --primary-hover: #0891b2;
    --input-bg: #ffffff;
    --example-bg: #cffafe;
    --hover-bg: #bae6fd;
}

[data-theme="nature"] {
    --bg-grad: linear-gradient(135deg, #ecfdf5, #d1fae5);
    --card-bg: #ffffff;
    --card-border: #a7f3d0;
    --text-main: #064e3b;
    --text-sec: #047857;
    --primary: #10b981;
    --primary-hover: #059669;
    --input-bg: #ffffff;
    --example-bg: #ecfdf5;
    --hover-bg: #a7f3d0;
}

[data-theme="carrot"] {
    --bg-grad: linear-gradient(135deg, #fff7ed, #ffedd5);
    --card-bg: #ffffff;
    --card-border: #fb923c;
    --text-main: #14532d;
    --text-sec: #16a34a;
    --primary: #f97316;
    --primary-hover: #ea580c;
    --input-bg: #ffffff;
    --example-bg: #ffedd5;
    --hover-bg: #fdba74;
    --success: #22c55e;
    --success-border: #16a34a;
}

[data-theme="cotton"] {
    --bg-grad: linear-gradient(135deg, #ffe4f1, #ffd6ec);
    --card-bg: #fff7fb;
    --card-border: #ffb6d9;
    --text-main: #7a1f52;
    --text-sec: #d9468f;
    --primary: #ff69b4;
    --primary-hover: #ec4899;
    --input-bg: #ffffff;
    --example-bg: #ffe4f1;
    --hover-bg: #ffd6ec;
}

body {
    margin: 0;
    padding: 24px;
    background: var(--bg-grad);
    color: var(--text-main);
    transition: background 0.3s, color 0.3s;
}

.progress-bar-container { 
    width: 100%; 
    height: 16px; 
    background: var(--card-border); 
    border-radius: 8px; 
    margin-bottom: 18px; 
    overflow: hidden; 
}
.progress-bar { 
    height: 100%; 
    width: 0%; 
    background: var(--primary); 
    transition: width 0.3s; 
}

.container {
    max-width: 960px;
    margin: 0 auto;
    background: var(--card-bg);
    padding: 28px;
    border-radius: 16px;
    box-shadow: 0 8px 32px rgba(37, 99, 235, 0.15);
    transition: background 0.3s;
}

h1 { 
    font-size: 24px; 
    margin: 0 0 18px; 
    text-align: center; 
    color: var(--text-sec); 
}

.controls { 
    display: flex; 
    gap: 10px; 
    flex-wrap: wrap; 
    justify-content: center; 
    margin-bottom: 18px; 
    align-items: center; 
}

button, input, select { 
    font-size: 15px; 
    padding: 10px 14px; 
    border-radius: 10px; 
    border: 1px solid var(--card-border); 
    background: var(--input-bg); 
    color: var(--text-main); 
    cursor: pointer; 
    transition: 0.25s; 
    font-family: inherit;
}

button:hover, select:hover, input[type=file]:hover { 
    background: var(--hover-bg);
    border-color: var(--primary); 
}

button.primary-btn { 
    background: var(--primary); 
    color: white; 
    border: none; 
    font-weight: 500;
}
button.primary-btn:hover { 
    background: var(--primary-hover); 
}

.progress { 
    margin: 10px 0 20px 0; 
    font-size: 14px; 
    color: var(--text-sec); 
    text-align: center; 
}

.card { 
    border-radius: 12px; 
    padding: 22px; 
    border: 1px solid var(--card-border); 
    margin-bottom: 14px; 
    background: var(--card-bg); 
    transition: 0.3s; 
}

.definition { 
    font-size: 20px; 
    margin-bottom: 14px; 
    text-align: center; 
    font-weight: 500; 
    color: var(--text-sec); 
}

.options { 
    display: grid; 
    grid-template-columns: 1fr 1fr; 
    gap: 12px; 
}

.opt-btn { 
    padding: 12px; 
    border-radius: 10px; 
    border: 1px solid var(--card-border); 
    background: var(--input-bg); 
    color: var(--text-main); 
    cursor: pointer; 
    font-size: 15px; 
    transition: 0.25s; 
}
.opt-btn:hover:not(:disabled) { 
    background: var(--hover-bg); 
}
.opt-btn.correct { 
    background: var(--success) !important; 
    border-color: var(--success-border) !important; 
    color: #166534; 
}
.opt-btn.wrong { 
    background: var(--error) !important; 
    border-color: var(--error-border) !important; 
    color: #991b1b; 
}

.field { 
    display: flex; 
    gap: 10px; 
    margin-top: 14px; 
    justify-content: center; 
}
.input-typed { 
    flex: 1; 
    padding: 12px; 
    border-radius: 10px; 
    border: 1px solid var(--card-border); 
    font-size: 15px; 
    outline: none; 
    transition: 0.3s; 
}
.input-typed:focus { 
    border-color: var(--primary); 
}

.small { 
    font-size: 13px; 
    color: var(--text-sec); 
}

.footer { 
    display: flex; 
    justify-content: space-between; 
    align-items: center; 
    gap: 12px; 
    margin-top: 16px; 
}
.footer .note { 
    flex: 1; 
    min-height: 1.2em; 
    font-size: 14px; 
    color: var(--text-sec); 
}
.footer .progress { 
    margin: 0; 
    white-space: nowrap; 
    line-height: 1.2; 
}

.switch { 
    display: flex; 
    align-items: center; 
    gap: 8px; 
    cursor: pointer;
}
.switch input { 
    display: none; 
}
.slider { 
    width: 40px; 
    height: 20px; 
    background: #ccc; 
    border-radius: 20px; 
    position: relative; 
    transition: 0.3s;
}
.slider:before { 
    content: ""; 
    position: absolute; 
    width: 16px; 
    height: 16px; 
    background: #fff; 
    border-radius: 50%; 
    top: 2px; 
    left: 2px; 
    transition: 0.2s; 
}
.switch input:checked + .slider { 
    background: var(--primary); 
}
.switch input:checked + .slider:before { 
    transform: translateX(20px); 
}
.label { 
    font-size: 13px; 
}

#continueBtn, #hintBtn, #correctBtn, #dontKnowBtn { 
    display: none; 
    margin-top: 14px; 
    background: var(--primary); 
    color: #fff; 
    border: none; 
    padding: 10px 16px; 
    border-radius: 10px; 
    cursor: pointer; 
    font-size: 15px; 
    transition: opacity 0.3s ease, background 0.25s; 
}
#continueBtn:hover, #hintBtn:hover, #correctBtn:hover, #dontKnowBtn:hover { 
    background: var(--primary-hover); 
}

#switchBox { 
    display: flex; 
    flex-direction: column; 
    gap: 8px; 
    align-items: flex-start; 
}
#switchBox.single > * { 
    margin-top: auto; 
    margin-bottom: auto; 
    align-self: center; 
}

.fc-area { 
    display: flex; 
    flex-direction: column; 
    align-items: center; 
}
.fc-box { 
    width: 100%; 
    box-sizing: border-box;
    padding: 40px 20px; 
    text-align: center; 
    border: 2px dashed var(--primary); 
    border-radius: 16px; 
    cursor: pointer; 
    transition: 0.3s; 
    background: var(--input-bg); 
}
.fc-box:hover { 
    background: var(--example-bg); 
}
.fc-word { 
    font-size: 32px; 
    font-weight: 700; 
    color: var(--text-sec); 
    margin-bottom: 10px;
}
.fc-instruction { 
    font-size: 14px; 
    color: #64748b; 
    font-style: italic; 
}
.fc-details { 
    display: none; 
    margin-top: 20px; 
    text-align: left; 
    animation: fadeIn 0.4s ease; 
    border-top: 1px solid var(--card-border); 
    padding-top: 20px;
}
.fc-def { 
    font-size: 22px; 
    font-weight: 600; 
    color: var(--primary); 
    margin-bottom: 15px; 
    text-align: center;
}
.fc-examples { 
    background: var(--example-bg); 
    padding: 16px 20px; 
    border-radius: 10px; 
    list-style-type: none; 
    margin: 0; 
}
.fc-examples li { 
    margin-bottom: 10px; 
    font-size: 15px; 
    position: relative; 
    padding-left: 20px;
}
.fc-examples li::before { 
    content: "•"; 
    position: absolute; 
    left: 0; 
    color: var(--primary); 
    font-weight: bold; 
    font-size: 18px;
}
.fc-examples li:last-child { 
    margin-bottom: 0; 
}

@keyframes fadeIn { 
    from { opacity: 0; transform: translateY(-5px); } 
    to { opacity: 1; transform: translateY(0); } 
}