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

:root {
    --bg-color: #f0f2f5;
    --text-color: #333;
    --container-bg: white;
    --header-border: #eaeaea;
    --date-color: #666;
    --title-color: #1a1a1a;
    --button-bg: #f0f0f0;
    --button-hover: #e0e0e0;
    --puzzle-bg: #f7f9fc;
    --puzzle-border: #e0e6ed;
    --bracket-color: #1a1a1a;
    --solved-bg: #e6f7e6;
    --solved-color: #2c662d;
    --active-color: #0066cc;
    --slot-border: #999;
    --slot-color: #666;
    --slot-hover: #f0f0f0;
    --input-border: #ddd;
    --input-focus: #0066cc;
    --submit-bg: #0066cc;
    --submit-color: white;
    --submit-hover: #0052a3;
    --incorrect-color: #cc3232;
    --hint-color: #0066cc;
    --hint-bg: #e6f0fa;
    --instructions-bg: #f8f9fa;
    --instructions-border: #e0e6ed;
    --font-size-base: 16px;
}

[data-theme="dark"] {
    --bg-color: #121212;
    --text-color: #e0e0e0;
    --container-bg: #1e1e1e;
    --header-border: #333;
    --date-color: #aaa;
    --title-color: #ffffff;
    --button-bg: #333;
    --button-hover: #444;
    --puzzle-bg: #2a2a2a;
    --puzzle-border: #444;
    --bracket-color: #ffffff;
    --solved-bg: #2c4c2c;
    --solved-color: #8cd98d;
    --active-color: #5599ff;
    --slot-border: #666;
    --slot-color: #aaa;
    --slot-hover: #333;
    --input-border: #444;
    --input-focus: #5599ff;
    --submit-bg: #0066cc;
    --submit-color: white;
    --submit-hover: #0078f0;
    --incorrect-color: #ff6b6b;
    --hint-color: #5599ff;
    --hint-bg: #1a3049;
    --instructions-bg: #2a2a2a;
    --instructions-border: #444;
}

body {
    font-family: 'Arial', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    padding: 20px;
    font-size: var(--font-size-base);
    transition: background-color 0.3s, color 0.3s;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    background-color: var(--container-bg);
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
    transition: background-color 0.3s;
}

header {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
    padding-bottom: 15px;
    border-bottom: 1px solid var(--header-border);
}

.date-display {
    font-size: 1rem;
    color: var(--date-color);
    margin-bottom: 10px;
    width: 100%;
    text-align: center;
}

h1 {
    text-align: center;
    color: var(--title-color);
    font-size: 2rem;
    font-weight: bold;
    letter-spacing: 1px;
    width: 100%;
    margin-bottom: 10px;
}

.button-container {
    display: flex;
    width: 100%;
    justify-content: space-between;
}

.nav-buttons {
    display: flex;
    gap: 10px;
}

.action-buttons {
    display: flex;
    gap: 10px;
}

.nav-btn, .settings-btn, .info-btn {
    background-color: var(--button-bg);
    border: none;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    font-size: 1.2rem;
    cursor: pointer;
    transition: all 0.2s;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-color);
}

.nav-btn:hover, .settings-btn:hover, .info-btn:hover {
    background-color: var(--button-hover);
}

.puzzle-container {
    margin: 20px 0;
}

.puzzle {
    font-size: 1.4rem;
    line-height: 1.8;
    padding: 20px;
    background-color: var(--puzzle-bg);
    border-radius: 8px;
    margin-bottom: 20px;
    min-height: 120px;
    text-align: center;
    border: 1px solid var(--puzzle-border);
    word-wrap: break-word;
    transition: background-color 0.3s;
}

.bracket {
    font-weight: bold;
    color: var(--bracket-color);
}

.solved {
    background-color: var(--solved-bg);
    color: var(--solved-color);
    padding: 2px 6px;
    border-radius: 4px;
    font-weight: bold;
}

.active {
    color: var(--active-color);
    font-weight: bold;
}

.slot {
    border-bottom: 2px dashed var(--slot-border);
    padding: 0 2px;
    margin: 0 3px;
    color: var(--slot-color);
    min-width: 40px;
    display: inline-block;
    cursor: pointer;
}

.slot:hover {
    background-color: var(--slot-hover);
}

.input-area {
    display: flex;
    margin-bottom: 20px;
    flex-direction: column;
}

@media (min-width: 480px) {
    .input-area {
        flex-direction: row;
    }
}

#answer-input {
    flex: 1;
    padding: 12px 15px;
    border: 2px solid var(--input-border);
    border-radius: 8px;
    font-size: 1.1rem;
    transition: border-color 0.3s;
    margin-bottom: 10px;
    width: 100%;
}

@media (min-width: 480px) {
    #answer-input {
        border-radius: 8px 0 0 8px;
        margin-bottom: 0;
    }
}

#answer-input:focus {
    border-color: var(--input-focus);
    outline: none;
}

#submit-btn {
    padding: 12px 25px;
    background-color: var(--submit-bg);
    color: var(--submit-color);
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 1.1rem;
    font-weight: bold;
    transition: background-color 0.3s;
    width: 100%;
}

@media (min-width: 480px) {
    #submit-btn {
        border-radius: 0 8px 8px 0;
        width: auto;
    }
}

#submit-btn:hover {
    background-color: var(--submit-hover);
}

.messages {
    min-height: 60px;
    margin: 15px 0;
    font-size: 1.1rem;
    text-align: center;
    padding: 10px;
}

.correct {
    color: var(--solved-color);
    font-weight: bold;
}

.incorrect {
    color: var(--incorrect-color);
}

.hint {
    color: var(--hint-color);
    font-style: italic;
    background-color: var(--hint-bg);
    padding: 8px 12px;
    border-radius: 6px;
    border-left: 4px solid var(--hint-color);
}

.instructions {
    background-color: var(--instructions-bg);
    padding: 20px;
    border-radius: 8px;
    border: 1px solid var(--instructions-border);
    transition: background-color 0.3s;
}

.complete {
    background-color: var(--solved-bg);
    color: var(--solved-color);
    padding: 20px;
    border-radius: 8px;
    text-align: center;
    font-size: 1.3rem;
    margin-top: 20px;
    font-weight: bold;
}

/* Modal Styles */
.modal {
    display: none;
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    align-items: center;
    justify-content: center;
}

.modal-content {
    background-color: var(--container-bg);
    margin: 10% auto;
    padding: 20px;
    border-radius: 10px;
    width: 90%;
    max-width: 500px;
    position: relative;
    transition: background-color 0.3s;
}

.close-btn {
    position: absolute;
    right: 15px;
    top: 10px;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-color);
}

.settings-section {
    margin-bottom: 20px;
}

.settings-section h3 {
    margin-bottom: 10px;
    color: var(--title-color);
}

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

.font-btn {
    padding: 8px 15px;
    border: none;
    background-color: var(--button-bg);
    color: var(--text-color);
    border-radius: 4px;
    cursor: pointer;
}

.font-btn:hover {
    background-color: var(--button-hover);
}

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

.theme-btn {
    padding: 8px 15px;
    border: none;
    background-color: var(--button-bg);
    color: var(--text-color);
    border-radius: 4px;
    cursor: pointer;
}

.theme-btn:hover {
    background-color: var(--button-hover);
}

.theme-btn.active {
    background-color: var(--active-color);
    color: white;
}