:root {
    --bg-color: #0f172a;
    --text-color: #f8fafc;
    --card-bg: rgba(255, 255, 255, 0.05);
    --card-border: rgba(255, 255, 255, 0.1);
    --primary-color: #8b5cf6;
    --secondary-color: #ec4899;
    --accent-color: #06b6d4;
    --font-family: 'Outfit', sans-serif;
    --glass-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.37);
}

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

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    font-family: var(--font-family);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    overflow-x: hidden;
    position: relative;
}

/* Background Animation */
.background-blobs {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
    overflow: hidden;
}

.blob {
    position: absolute;
    border-radius: 50%;
    filter: blur(80px);
    opacity: 0.6;
    animation: move 20s infinite alternate;
}

.blob-1 {
    width: 400px;
    height: 400px;
    background: var(--primary-color);
    top: -100px;
    left: -100px;
}

.blob-2 {
    width: 500px;
    height: 500px;
    background: var(--secondary-color);
    bottom: -150px;
    right: -150px;
    animation-delay: -5s;
}

.blob-3 {
    width: 300px;
    height: 300px;
    background: var(--accent-color);
    top: 40%;
    left: 40%;
    filter: blur(60px);
    animation-delay: -10s;
}

@keyframes move {
    from {
        transform: translate(0, 0) scale(1);
    }

    to {
        transform: translate(50px, -50px) scale(1.1);
    }
}

/* App Container */
.app-container {
    width: 90%;
    max-width: 800px;
    padding: 2rem 0;
    z-index: 1;
}

header {
    text-align: center;
    margin-bottom: 2rem;
}

header h1 {
    font-size: 3rem;
    font-weight: 700;
    background: linear-gradient(to right, #c084fc, #f472b6);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    margin-bottom: 0.5rem;
}

header p {
    font-size: 1.1rem;
    opacity: 0.8;
}

/* Semester Tabs */
.semester-tabs-container {
    margin-bottom: 1.5rem;
    overflow-x: auto;
    padding-bottom: 10px;
    /* Hide scrollbar aesthetics if needed */
}

.semester-tabs {
    display: flex;
    gap: 0.5rem;
    /* justify-content: center;  Allow wrapping or scrolling */
}

.tab-btn {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--card-border);
    color: var(--text-color);
    padding: 0.75rem 1.5rem;
    border-radius: 50px;
    cursor: pointer;
    transition: all 0.3s ease;
    white-space: nowrap;
    font-family: var(--font-family);
    font-weight: 500;
}

.tab-btn:hover {
    background: rgba(255, 255, 255, 0.15);
    transform: translateY(-2px);
}

.tab-btn.active {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    border-color: transparent;
    box-shadow: 0 4px 15px rgba(139, 92, 246, 0.4);
}

/* Glass Card */
.glass-card {
    background: var(--card-bg);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border: 1px solid var(--card-border);
    border-radius: 20px;
    padding: 2rem;
    box-shadow: var(--glass-shadow);
}

/* Courses List */
.courses-header {
    display: grid;
    grid-template-columns: 1fr 100px 150px;
    gap: 1rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--card-border);
    margin-bottom: 1rem;
    font-weight: 600;
    opacity: 0.9;
}

.course-item {
    display: grid;
    grid-template-columns: 1fr 100px 150px;
    gap: 1rem;
    align-items: center;
    margin-bottom: 1rem;
    animation: fadeIn 0.5s ease forwards;
}

.course-info h3 {
    font-size: 1.1rem;
    font-weight: 500;
    margin-bottom: 0.2rem;
}

.course-info p {
    font-size: 0.85rem;
    opacity: 0.6;
}

.credit-hours {
    text-align: center;
    font-weight: 600;
    opacity: 0.8;
}

select.grade-select {
    width: 100%;
    padding: 0.6rem;
    border-radius: 8px;
    background: rgba(0, 0, 0, 0.3);
    border: 1px solid var(--card-border);
    color: white;
    font-family: var(--font-family);
    cursor: pointer;
    outline: none;
    transition: border-color 0.3s;
}

select.grade-select:focus {
    border-color: var(--primary-color);
}

/* Calculator Button */
.actions {
    margin-top: 2rem;
    display: flex;
    justify-content: flex-end;
}

.premium-btn {
    background: linear-gradient(135deg, var(--secondary-color), var(--primary-color));
    color: white;
    border: none;
    padding: 1rem 2.5rem;
    border-radius: 50px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px rgba(236, 72, 153, 0.4);
    font-family: var(--font-family);
}

.premium-btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 25px rgba(236, 72, 153, 0.6);
}

/* Result Modal */
.result-modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.6);
    backdrop-filter: blur(5px);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 100;
    opacity: 1;
    transition: opacity 0.3s ease;
}

.result-modal.hidden {
    opacity: 0;
    pointer-events: none;
}

.result-content {
    background: #1e293b;
    /* Fallback */
    background: linear-gradient(135deg, rgba(30, 41, 59, 0.9), rgba(15, 23, 42, 0.9));
    border: 1px solid rgba(255, 255, 255, 0.2);
    padding: 3rem;
    text-align: center;
    position: relative;
    width: 90%;
    max-width: 400px;
}

.close-btn {
    position: absolute;
    top: 1rem;
    right: 1.5rem;
    font-size: 1.5rem;
    cursor: pointer;
    opacity: 0.7;
    transition: opacity 0.2s;
}

.close-btn:hover {
    opacity: 1;
}

.result-value {
    margin-top: 1.5rem;
}

.result-value .label {
    display: block;
    font-size: 1.2rem;
    margin-bottom: 0.5rem;
    opacity: 0.8;
}

.result-value .value {
    display: block;
    font-size: 4rem;
    font-weight: 800;
    background: linear-gradient(to right, #c084fc, #f472b6);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@media (max-width: 600px) {
    .courses-header {
        display: none;
        /* Hide header on mobile for cleaner card look */
    }

    .course-item {
        grid-template-columns: 1fr;
        gap: 0.5rem;
    }

    .course-info {
        grid-column: 1 / -1;
    }

    .credit-hours {
        display: none;
        /* Hide simplified credits on mobile if confusing */
    }
}

/* Split Input Styles */
.grade-inputs-container {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.grade-input-group {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    justify-content: flex-end;
}

.input-label {
    font-size: 0.8rem;
    opacity: 0.7;
    white-space: nowrap;
}

.grade-input-group select {
    width: 120px;
}