:root {
    --bg-color: #f5f5f5;
    --container-bg: white;
    --text-color: #2c3e50;
    --text-secondary: #7f8c8d;
    --border-color: #eee;
    --input-bg: white;
    --input-border: #ddd;
    --hover-bg: #f8f9fa;
    --grade-bg: #f0f0f0;
    --results-bg: #f8f9fa;
    --tab-bg: #eee;
    --tab-active-bg: #3498db;
    --tab-active-color: white;
}

[data-theme="dark"] {
    --bg-color: #1a1a1a;
    --container-bg: #2d2d2d;
    --text-color: #ecf0f1;
    --text-secondary: #bdc3c7;
    --border-color: #404040;
    --input-bg: #3d3d3d;
    --input-border: #505050;
    --hover-bg: #363636;
    --grade-bg: #404040;
    --results-bg: #363636;
    --tab-bg: #404040;
    --tab-active-bg: #2980b9;
    --tab-active-color: white;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background-color: var(--bg-color);
    padding: 100px 20px 20px 20px;
    transition: background-color 0.3s ease;
}

.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: 80px;
    background-color: var(--container-bg);
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    display: flex;
    justify-content: flex-end;
    align-items: center;
    padding: 0 20px;
    z-index: 1000;
    transition: background-color 0.3s ease;
}

.logo {
    position: absolute;
    left: 20px;
    height: 60px;
    display: flex;
    align-items: center;
    background-color: transparent;
}

.logo img {
    height: 100%;
    object-fit: contain;
    transition: filter 0.3s ease;
    background-color: transparent;
}

[data-theme="dark"] .logo img {
    filter: brightness(0.9);
    background-color: transparent;
}

.theme-toggle {
    display: flex;
    align-items: center;
    margin-left: 20px;
}

#theme-toggle-btn {
    background: var(--container-bg);
    border: 2px solid var(--border-color);
    border-radius: 50%;
    width: 40px;
    height: 40px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 8px;
    transition: all 0.3s ease;
}

#theme-toggle-btn:hover {
    transform: scale(1.1);
}

#theme-toggle-btn svg {
    color: var(--text-color);
}

.sun-icon {
    display: none;
}

[data-theme="dark"] .sun-icon {
    display: block;
}

[data-theme="dark"] .moon-icon {
    display: none;
}

.container {
    max-width: 1000px;
    margin: 0 auto;
    background-color: var(--container-bg);
    padding: 30px;
    border-radius: 10px;
    box-shadow: 0 0 20px rgba(0, 0, 0, 0.1);
    transition: background-color 0.3s ease;
}

.semester-tabs {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
    justify-content: center;
}

.tab-btn {
    padding: 10px 20px;
    border: none;
    background-color: var(--tab-bg);
    color: var(--text-color);
    border-radius: 5px;
    cursor: pointer;
    font-size: 16px;
    transition: all 0.3s ease;
}

.tab-btn.active {
    background-color: var(--tab-active-bg);
    color: var(--tab-active-color);
}

.semester-container {
    display: none;
}

.semester-container.active {
    display: block;
}

h1 {
    text-align: center;
    color: var(--text-color);
    margin-bottom: 30px;
}

h2 {
    color: var(--text-color);
    margin-bottom: 20px;
    padding-bottom: 10px;
    border-bottom: 2px solid var(--border-color);
}

h3 {
    color: var(--text-secondary);
    margin: 15px 0;
}

.theory-section, .practical-section {
    margin-bottom: 30px;
}

.subject {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 15px;
    align-items: center;
    padding: 10px;
    border-bottom: 1px solid var(--border-color);
    transition: background-color 0.3s ease;
}

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

label {
    color: var(--text-color);
    font-weight: 500;
}

input[type="number"] {
    padding: 8px;
    border: 1px solid var(--input-border);
    border-radius: 4px;
    width: 100px;
    background-color: var(--input-bg);
    color: var(--text-color);
    transition: all 0.3s ease;
}

input[type="number"]:focus {
    outline: none;
    border-color: var(--tab-active-bg);
    box-shadow: 0 0 5px rgba(52, 152, 219, 0.3);
}

.grade, .grade-point {
    padding: 5px 10px;
    background-color: var(--grade-bg);
    border-radius: 4px;
    text-align: center;
    min-width: 50px;
    color: var(--text-color);
}

.results {
    margin-top: 30px;
    padding: 20px;
    background-color: var(--results-bg);
    border-radius: 8px;
    display: flex;
    justify-content: space-around;
}

.result-item {
    text-align: center;
}

.result-item h3 {
    margin: 0;
    color: var(--text-color);
}

#sgpa, #cgpa {
    font-size: 24px;
    font-weight: bold;
    color: #27ae60;
    display: block;
    margin-top: 10px;
}

.install-button {
    position: fixed;
    bottom: 20px;
    right: 20px;
    padding: 12px 20px;
    background-color: var(--tab-active-bg);
    color: white;
    border: none;
    border-radius: 50px;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 16px;
    font-weight: 500;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
    transition: all 0.3s ease;
    z-index: 1000;
}

.install-button:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 16px rgba(0, 0, 0, 0.2);
}

.install-button svg {
    width: 20px;
    height: 20px;
}

@media (max-width: 768px) {
    .subject {
        grid-template-columns: 1fr;
        gap: 10px;
    }
    
    .container {
        padding: 15px;
    }
    
    input[type="number"] {
        width: 100%;
    }
    
    .install-button {
        padding: 10px 16px;
        font-size: 14px;
    }
    
    .install-button svg {
        width: 18px;
        height: 18px;
    }
}