:root {
    /* Light Mode Colors */
    --primary-color: #2B4F81;
    --accent-color: #00BCD4;
    --background-color: #F8F9FB;
    --card-bg: #ffffff;
    --text-color: #1E1E1E;
    --border-color: #e0e0e0;
    --shadow-color: rgba(0, 0, 0, 0.1);
    --input-bg: #f5f5f5;
    --table-header-bg: #f0f4f8;
    --table-row-hover: #f5f9ff;
    --success-color: #4CAF50;
    --error-color: #F44336;
}

[data-theme="dark"] {
    /* Dark Mode Colors */
    --primary-color: #121212;
    --accent-color: #03DAC6;
    --background-color: #1E1E1E;
    --card-bg: #2d2d2d;
    --text-color: #E0E0E0;
    --border-color: #444444;
    --shadow-color: rgba(0, 0, 0, 0.3);
    --input-bg: #3d3d3d;
    --table-header-bg: #333333;
    --table-row-hover: #383838;
    --success-color: #81C784;
    --error-color: #E57373;
}

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

body {
    font-family: 'Roboto', sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    line-height: 1.6;
    transition: background-color 0.3s ease, color 0.3s ease;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

/* Header Styles */
header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 0;
    margin-bottom: 30px;
}

.logo-container {
    display: flex;
    align-items: center;
    gap: 15px;
}

.logo-icon {
    font-size: 2rem;
    color: var(--accent-color);
}

h1 {
    font-family: 'Poppins', sans-serif;
    font-size: 1.8rem;
    font-weight: 600;
    color: var(--primary-color);
}

#theme-toggle {
    background: none;
    border: none;
    cursor: pointer;
    font-size: 1.5rem;
    color: var(--text-color);
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background-color: var(--card-bg);
    box-shadow: 0 3px 10px var(--shadow-color);
    transition: all 0.3s ease;
}

#theme-toggle:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px var(--shadow-color);
}

#theme-toggle .fa-sun {
    display: none;
}

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

[data-theme="dark"] #theme-toggle .fa-sun {
    display: inline-block;
    color: #FFD700;
}

/* Card Styles */
.calculator-card, .result-card, .info-card {
    background-color: var(--card-bg);
    border-radius: 15px;
    box-shadow: 0 8px 30px var(--shadow-color);
    padding: 25px;
    margin-bottom: 30px;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.calculator-card:hover, .result-card:hover, .info-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 12px 40px var(--shadow-color);
}

h2 {
    font-family: 'Poppins', sans-serif;
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--primary-color);
    margin-bottom: 20px;
    padding-bottom: 10px;
    border-bottom: 2px solid var(--accent-color);
}

h3 {
    font-family: 'Poppins', sans-serif;
    font-size: 1.2rem;
    font-weight: 500;
    margin: 15px 0;
    color: var(--primary-color);
}

/* Form Styles */
.user-details {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
    margin-bottom: 25px;
}

.input-group {
    margin-bottom: 15px;
}

label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
}

input[type="text"], input[type="number"] {
    width: 100%;
    padding: 12px 15px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background-color: var(--input-bg);
    color: var(--text-color);
    font-size: 1rem;
    transition: border-color 0.3s ease, box-shadow 0.3s ease;
}

input[type="text"]:focus, input[type="number"]:focus {
    outline: none;
    border-color: var(--accent-color);
    box-shadow: 0 0 0 3px rgba(0, 188, 212, 0.2);
}

/* Table Styles */
.table-responsive {
    overflow-x: auto;
    margin-bottom: 20px;
}

table {
    width: 100%;
    border-collapse: collapse;
    margin-bottom: 20px;
    border-radius: 8px;
    overflow: hidden;
}

th, td {
    padding: 12px 15px;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

th {
    background-color: var(--table-header-bg);
    font-weight: 500;
    color: var(--primary-color);
}

tr:hover {
    background-color: var(--table-row-hover);
}

.marks-input {
    width: 80px;
    padding: 8px;
    border-radius: 5px;
}

.grade-display {
    font-weight: 500;
    text-align: center;
}

.optional-subject {
    opacity: 0.7;
}

/* Button Styles */
.action-buttons {
    display: flex;
    gap: 15px;
    margin-top: 25px;
    justify-content: center;
}

.primary-btn, .secondary-btn {
    padding: 12px 25px;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    gap: 8px;
}

.primary-btn {
    background-color: var(--primary-color);
    color: white;
    box-shadow: 0 4px 15px rgba(43, 79, 129, 0.3);
}

.primary-btn:hover {
    background-color: #1a3c68;
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(43, 79, 129, 0.4);
}

.secondary-btn {
    background-color: var(--card-bg);
    color: var(--text-color);
    border: 1px solid var(--border-color);
    box-shadow: 0 4px 10px var(--shadow-color);
}

.secondary-btn:hover {
    background-color: var(--input-bg);
    transform: translateY(-2px);
    box-shadow: 0 6px 15px var(--shadow-color);
}

/* Result Section Styles */
#result-section {
    display: none;
}

.result-content {
    padding: 15px;
}

.student-info {
    display: flex;
    flex-wrap: wrap;
    gap: 30px;
    margin-bottom: 20px;
    font-size: 1.1rem;
}

.sgpa-display {
    margin: 25px 0;
    text-align: center;
    font-size: 1.2rem;
}

.developer-credit {
    text-align: center;
    margin: 15px 0;
    padding: 10px;
    background-color: var(--primary-color);
    color: white;
    border-radius: 8px;
    font-weight: bold;
    letter-spacing: 1px;
    box-shadow: 0 4px 10px var(--shadow-color);
}

#sgpa-value {
    font-size: 2rem;
    font-weight: 700;
    color: var(--accent-color);
    background: linear-gradient(45deg, var(--primary-color), var(--accent-color));
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    padding: 10px 20px;
    display: inline-block;
}

#download-btn {
    margin: 0 auto;
    display: flex;
}

/* Grading Table Styles */
.grading-table {
    width: 100%;
    max-width: 500px;
    margin: 0 auto;
}

.formula-info {
    text-align: center;
    margin-top: 20px;
    padding: 15px;
    background-color: var(--input-bg);
    border-radius: 8px;
}

.formula-info p {
    font-size: 1.1rem;
    font-weight: 500;
    margin-top: 10px;
}

/* Footer Styles */
footer {
    text-align: center;
    padding: 20px 0;
    margin-top: 30px;
    border-top: 1px solid var(--border-color);
    font-size: 0.9rem;
    color: var(--text-color);
    opacity: 0.8;
}

/* Responsive Styles */
@media (max-width: 768px) {
    .container {
        padding: 15px;
    }

    header {
        flex-direction: column;
        text-align: center;
        gap: 15px;
    }

    h1 {
        font-size: 1.5rem;
    }

    .logo-container {
        flex-direction: column;
        gap: 10px;
    }

    .calculator-card, .result-card, .info-card {
        padding: 15px;
    }

    .action-buttons {
        flex-direction: column;
    }

    .student-info {
        flex-direction: column;
        gap: 10px;
    }

    #sgpa-value {
        font-size: 1.8rem;
    }
}

@media (max-width: 480px) {
    h1 {
        font-size: 1.3rem;
    }

    h2 {
        font-size: 1.3rem;
    }

    .primary-btn, .secondary-btn {
        width: 100%;
        justify-content: center;
    }
}

/* Animations */
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

.calculator-card, .result-card, .info-card {
    animation: fadeIn 0.5s ease-out forwards;
}

.result-card {
    animation-delay: 0.1s;
}

.info-card {
    animation-delay: 0.2s;
}

/* Tooltip for grade display */
.grade-display {
    position: relative;
}

.grade-display[data-grade]:not([data-grade="-"]):not([data-grade="Optional"]):hover::after {
    content: attr(data-grade-point) " points";
    position: absolute;
    bottom: 100%;
    left: 50%;
    transform: translateX(-50%);
    background-color: var(--primary-color);
    color: white;
    padding: 5px 10px;
    border-radius: 5px;
    font-size: 0.8rem;
    white-space: nowrap;
    z-index: 10;
    box-shadow: 0 3px 10px rgba(0, 0, 0, 0.2);
}

/* Custom scrollbar */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: var(--background-color);
}

::-webkit-scrollbar-thumb {
    background: var(--accent-color);
    border-radius: 10px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--primary-color);
}