:root {
    --primary-color: #007BFF;   /* Electric Blue */
    --secondary-color: #E0FFF1; /* Soft Mint */
    --accent-color: #FF007F;    /* Neon Pink */
    --success-color: #32CD32;   /* Lime Green */
    --warning-color: #FFD700;   /* Bright Yellow */
    --error-color: #8A2BE2;     /* Deep Purple */
    --text-color: #1E1E1E;      /* Near Black */
    --widget-bg: #ffffff;
    --widget-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.05), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --border-radius: 0.75rem; /* 12px */
}

body {
    font-family: 'Pretendard', sans-serif;
}

.bg-primary { background-color: var(--primary-color); }
.bg-secondary { background-color: var(--secondary-color); }
.bg-accent { background-color: var(--accent-color); }
.bg-success { background-color: var(--success-color); }
.bg-warning { background-color: var(--warning-color); }
.bg-error { background-color: var(--error-color); }
.text-primary { color: var(--primary-color); }
.text-accent { color: var(--accent-color); }
.text-text { color: var(--text-color); }

.add-button {
    display: flex;
    align-items: center;
    padding: 0.6rem 1.2rem;
    background-color: var(--primary-color);
    color: white;
    font-weight: 700;
    border-radius: var(--border-radius);
    transition: all 0.3s ease;
    box-shadow: 0 4px 12px rgba(0, 123, 255, 0.3);
}
.add-button:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 20px rgba(0, 123, 255, 0.4);
}

.nav-button {
    display: flex;
    align-items: center;
    padding: 0.6rem 1.2rem;
    background-color: transparent;
    border: 2px solid var(--primary-color);
    color: var(--primary-color);
    font-weight: 700;
    border-radius: var(--border-radius);
    transition: all 0.3s ease;
}
.nav-button:hover {
    background-color: var(--primary-color);
    color: white;
    transform: translateY(-2px);
}


.dashboard-widget {
    background-color: var(--widget-bg);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    box-shadow: var(--widget-shadow);
    transition: all 0.3s ease-in-out;
}

.dashboard-widget:hover {
    transform: translateY(-5px);
    box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.08), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
}

.widget-title {
    font-size: 1.1rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text-color);
}

.start-learning-button {
    display: inline-flex;
    align-items: center;
    padding: 1rem 2.5rem;
    background-color: var(--accent-color);
    color: white;
    font-size: 1.25rem;
    font-weight: 900;
    border-radius: 50px;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px rgba(255, 0, 127, 0.4);
}

.start-learning-button:hover {
    transform: translateY(-3px) scale(1.05);
    box-shadow: 0 10px 25px rgba(255, 0, 127, 0.5);
}

.perspective-1000 { perspective: 1000px; }
.transform-style-3d { transform-style: preserve-3d; }
.transform-rotate-y-180 { transform: rotateY(180deg); }
.backface-hidden { backface-visibility: hidden; }

.card-face {
    backface-visibility: hidden;
    background-color: var(--widget-bg);
    border-radius: var(--border-radius);
    box-shadow: var(--widget-shadow);
    cursor: pointer;
}

.card-back-face {
    display: flex;
    flex-direction: column;
}

.card-topic-badge {
    position: absolute;
    top: 1rem;
    right: 1rem;
    background-color: var(--secondary-color);
    color: var(--primary-color);
    padding: 0.25rem 0.75rem;
    border-radius: 9999px;
    font-size: 0.75rem;
    font-weight: bold;
}

#learn-card.is-flipped {
    transform: rotateY(180deg);
}

.rating-button {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 1rem;
    border-radius: var(--border-radius);
    color: white;
    font-weight: 700;
    transition: transform 0.2s ease, box-shadow 0.2s ease;
    cursor: pointer;
    border: none;
    line-height: 1.2;
}

.rating-button:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 15px rgba(0, 0, 0, 0.2);
}

.form-widget {
    background-color: var(--widget-bg);
    border-radius: var(--border-radius);
    padding: 2rem;
    box-shadow: var(--widget-shadow);
    max-width: 600px;
    margin: 0 auto;
}

.form-input {
    width: 100%;
    border: 1px solid #d1d5db;
    border-radius: 0.5rem;
    padding: 0.75rem 1rem;
    transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.form-input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(0, 123, 255, 0.2);
}

.save-button, .cancel-button {
    padding: 0.6rem 1.5rem;
    font-weight: 700;
    border-radius: var(--border-radius);
    transition: all 0.2s ease;
    border: none;
    cursor: pointer;
}
.save-button {
    background-color: var(--primary-color);
    color: white;
}
.save-button:hover {
    opacity: 0.9;
}
.cancel-button {
    background-color: #e5e7eb;
    color: var(--text-color);
}
.cancel-button:hover {
    background-color: #d1d5db;
}

.card-manage-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background-color: var(--widget-bg);
    padding: 1rem 1.5rem;
    border-radius: var(--border-radius);
    box-shadow: var(--widget-shadow);
}

.card-manage-item .content p {
    margin: 0;
    padding: 0;
}

.card-manage-item .actions {
    display: flex;
    gap: 0.5rem;
}

.edit-btn, .delete-btn {
    padding: 0.5rem;
    border: none;
    border-radius: 0.5rem;
    cursor: pointer;
    transition: background-color 0.2s ease;
    display: flex;
    align-items: center;
    justify-content: center;
}

.edit-btn {
    background-color: #e0f2fe;
    color: #0c4a6e;
}

.edit-btn:hover {
    background-color: #bae6fd;
}

.delete-btn {
    background-color: #fee2e2;
    color: #991b1b;
}

.delete-btn:hover {
    background-color: #fecaca;
}