:root {
    --duo-green: #58cc02;
    --duo-green-dark: #46a302;
    --duo-red: #ea2b2b;
    --duo-blue: #1cb0f6;
    --duo-gray: #e5e5e5;
    --duo-dark-gray: #afafaf;
    --text-color: #4b4b4b;
    --bg-color: #ffffff;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'din-round', sans-serif;
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    overflow: hidden;
    height: 100vh;
    display: flex;
    flex-direction: column;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    width: 100%;
    padding: 0 20px;
}

/* Noise Overlay */
.noise-overlay {
    position: fixed;
    top: 0; left: 0; width: 100%; height: 100%;
    pointer-events: none; z-index: 1000; opacity: 0.03;
    background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 200 200' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.65'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
}

/* Nav & Progress */
.top-nav {
    padding: 20px 0;
}

.nav-content {
    display: flex;
    align-items: center;
    gap: 20px;
}

.icon-btn {
    background: none;
    border: none;
    font-size: 24px;
    color: var(--duo-dark-gray);
    cursor: pointer;
}

.progress-wrapper {
    flex-grow: 1;
    height: 16px;
    background-color: var(--duo-gray);
    border-radius: 10px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background-color: var(--duo-green);
    border-radius: 10px;
    transition: width 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

.lives {
    display: flex;
    align-items: center;
    gap: 8px;
    color: #ff4b4b;
    font-weight: bold;
    font-size: 20px;
}

/* Main Content */
.lesson-container {
    flex-grow: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
}

.question-card {
    width: 100%;
    max-width: 600px;
}

.question-title {
    font-size: 28px;
    font-weight: bold;
    margin-bottom: 30px;
    color: #3c3c3c;
}

/* Options / Buttons */
.options-grid {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.option-btn {
    background: white;
    border: 2px solid var(--duo-gray);
    border-bottom: 5px solid var(--duo-gray);
    padding: 15px 20px;
    border-radius: 12px;
    font-size: 18px;
    text-align: left;
    cursor: pointer;
    transition: all 0.1s;
    display: flex;
    align-items: center;
}

.option-btn:hover {
    background-color: #f7f7f7;
}

.option-btn.selected {
    border-color: var(--duo-blue);
    background-color: #ddf4ff;
    color: var(--duo-blue);
    border-bottom: 5px solid var(--duo-blue);
}

/* Word Jumble */
.word-pool {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-top: 30px;
}

.word-tile {
    padding: 10px 15px;
    border: 2px solid var(--duo-gray);
    border-bottom: 4px solid var(--duo-gray);
    border-radius: 8px;
    cursor: pointer;
    background: white;
    font-weight: 500;
}

.word-tile.used {
    background: var(--duo-gray);
    color: var(--duo-gray);
    border-color: var(--duo-gray);
}

.answer-slots {
    min-height: 60px;
    border-bottom: 2px solid var(--duo-gray);
    margin-bottom: 20px;
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    padding: 10px 0;
}

/* Footer Feedback */
.feedback-footer {
    padding: 30px 0;
    transition: transform 0.3s ease-out;
    background-color: white;
    border-top: 2px solid var(--duo-gray);
}

.feedback-footer.correct {
    background-color: #d7ffb8;
    color: #58a700;
    border-top: none;
}

.feedback-footer.incorrect {
    background-color: #ffdfe0;
    color: #ea2b2b;
    border-top: none;
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.feedback-info {
    display: flex;
    align-items: center;
    gap: 20px;
}

.feedback-icon {
    width: 60px;
    height: 60px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 30px;
    background: white;
}

.correct .feedback-icon::after { content: "✔"; }
.incorrect .feedback-icon::after { content: "✖"; }

.continue-btn {
    padding: 15px 40px;
    border-radius: 12px;
    border: none;
    font-size: 18px;
    font-weight: bold;
    text-transform: uppercase;
    cursor: pointer;
    box-shadow: 0 4px 0 rgba(0,0,0,0.1);
}

.feedback-footer.correct .continue-btn {
    background-color: var(--duo-green);
    color: white;
}

.feedback-footer.incorrect .continue-btn {
    background-color: var(--duo-red);
    color: white;
}

.hidden {
    display: none !important;
}

/* Overlay */
.overlay {
    position: fixed;
    top: 0; left: 0; width: 100%; height: 100%;
    background: white;
    z-index: 2000;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
}

.start-btn {
    margin-top: 20px;
    padding: 15px 60px;
    background-color: var(--duo-blue);
    color: white;
    border: none;
    border-bottom: 5px solid #1899d6;
    border-radius: 12px;
    font-size: 20px;
    font-weight: bold;
    cursor: pointer;
}

.start-btn:active {
    border-bottom: 0;
    transform: translateY(4px);
}