:root {
    --bg-primary: #0a0a0a;
    --bg-secondary: #111111;
    --bg-card: #151515;
    --text-primary: #ffffff;
    --text-secondary: #888888;
    --accent: #00d9ff;
    --accent-glow: rgba(0, 217, 255, 0.3);
    --success: #00ff88;
    --error: #ff3366;
    --border: #222222;
    --hover: #1a1a1a;
}

[data-theme="light"] {
    --bg-primary: #ffffff;
    --bg-secondary: #f5f5f5;
    --bg-card: #ffffff;
    --text-primary: #0a0a0a;
    --text-secondary: #666666;
    --accent: #0099ff;
    --accent-glow: rgba(0, 153, 255, 0.2);
    --border: #e0e0e0;
    --hover: #f0f0f0;
}

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

body {
    font-family: 'Space Grotesk', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    min-height: 100vh;
    overflow-x: hidden;
    position: relative;
}

/* Animated Background */
.background {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 0;
    pointer-events: none;
}

.grid-lines {
    position: absolute;
    inset: 0;
    background-image: 
        linear-gradient(rgba(0, 217, 255, 0.03) 1px, transparent 1px),
        linear-gradient(90deg, rgba(0, 217, 255, 0.03) 1px, transparent 1px);
    background-size: 50px 50px;
    animation: gridMove 20s linear infinite;
}

@keyframes gridMove {
    0% { transform: translateY(0); }
    100% { transform: translateY(50px); }
}

.glow-orb {
    position: absolute;
    border-radius: 50%;
    filter: blur(80px);
    opacity: 0.15;
    animation: float 20s ease-in-out infinite;
}

.orb-1 {
    width: 500px;
    height: 500px;
    background: var(--accent);
    top: -200px;
    right: -200px;
}

.orb-2 {
    width: 400px;
    height: 400px;
    background: #ff00ff;
    bottom: -150px;
    left: -150px;
    animation-delay: -10s;
}

@keyframes float {
    0%, 100% { transform: translate(0, 0) scale(1); }
    33% { transform: translate(50px, -50px) scale(1.1); }
    66% { transform: translate(-50px, 50px) scale(0.9); }
}

/* Container */
.container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 40px 20px;
    position: relative;
    z-index: 1;
}

/* Theme Toggle */
.theme-toggle {
    position: fixed;
    top: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background: var(--bg-card);
    border: 2px solid var(--accent);
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.3s ease;
    z-index: 1000;
    box-shadow: 0 0 20px var(--accent-glow);
}

.theme-toggle:hover {
    background: var(--accent);
    transform: rotate(180deg);
    box-shadow: 0 0 30px var(--accent-glow);
}

.theme-toggle svg {
    color: var(--accent);
    transition: color 0.3s ease;
}

.theme-toggle:hover svg {
    color: #000;
}

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

/* Header */
.header {
    text-align: center;
    margin-bottom: 60px;
}

.logo {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 15px;
    margin-bottom: 15px;
}

.logo-icon {
    font-size: 3rem;
    filter: drop-shadow(0 0 20px var(--accent-glow));
}

.header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    letter-spacing: -1px;
    background: linear-gradient(135deg, var(--text-primary), var(--accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.subtitle {
    font-size: 1rem;
    color: var(--text-secondary);
    margin-top: 10px;
}

/* Calculator Wrapper */
.calculator-wrapper {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 24px;
    overflow: hidden;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
}

/* Progress Tracker */
.progress-tracker {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 40px 50px;
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border);
}

.progress-step {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
    position: relative;
    z-index: 1;
}

.step-number {
    width: 45px;
    height: 45px;
    border-radius: 50%;
    background: var(--bg-card);
    border: 2px solid var(--border);
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 1.1rem;
    color: var(--text-secondary);
    transition: all 0.3s ease;
}

.progress-step.active .step-number {
    background: var(--accent);
    border-color: var(--accent);
    color: #000;
    box-shadow: 0 0 30px var(--accent-glow);
}

.progress-step.completed .step-number {
    background: var(--success);
    border-color: var(--success);
    color: #000;
}

.step-name {
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--text-secondary);
    font-weight: 600;
}

.progress-step.active .step-name {
    color: var(--accent);
}

.progress-line {
    flex: 1;
    height: 2px;
    background: var(--border);
    margin: 0 20px;
}

/* Step Container */
.step-container {
    padding: 50px;
    min-height: 500px;
}

.step {
    display: none;
    animation: fadeInUp 0.5s ease;
}

.step.active {
    display: block;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.step-title {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 10px;
    background: linear-gradient(135deg, var(--text-primary), var(--accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.step-desc {
    color: var(--text-secondary);
    margin-bottom: 40px;
    font-size: 1rem;
}

/* Form Elements */
.input-group {
    margin-bottom: 25px;
}

.input-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
    font-size: 0.9rem;
    color: var(--text-primary);
}

.input-field {
    width: 100%;
    padding: 16px 20px;
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: 12px;
    color: var(--text-primary);
    font-size: 1rem;
    font-family: inherit;
    transition: all 0.3s ease;
}

.input-field:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 3px var(--accent-glow);
}

.input-field::placeholder {
    color: var(--text-secondary);
}

/* Form Grids */
.form-grid {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 20px;
    margin-bottom: 30px;
}

.assignment-grid {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 15px;
    margin-bottom: 30px;
}

.exam-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
    margin-bottom: 30px;
}

/* Buttons */
.button-group {
    display: flex;
    gap: 15px;
    margin-top: 40px;
}

.btn {
    flex: 1;
    padding: 16px 32px;
    border: none;
    border-radius: 12px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    font-family: inherit;
}

.btn-primary {
    background: var(--accent);
    color: #000;
    box-shadow: 0 0 20px var(--accent-glow);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 30px var(--accent-glow);
}

.btn-secondary {
    background: var(--bg-secondary);
    color: var(--text-primary);
    border: 1px solid var(--border);
}

.btn-secondary:hover {
    background: var(--hover);
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

/* Course List */
.course-list {
    max-height: 350px;
    overflow-y: auto;
    margin-bottom: 20px;
}

.course-card {
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 20px;
    margin-bottom: 15px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: all 0.3s ease;
}

.course-card:hover {
    border-color: var(--accent);
}

.course-info h3 {
    font-size: 1.1rem;
    margin-bottom: 8px;
}

.course-details {
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.grade-pill {
    background: var(--accent);
    color: #000;
    padding: 6px 16px;
    border-radius: 20px;
    font-weight: 700;
    font-size: 1.2rem;
}

.delete-btn {
    background: transparent;
    border: none;
    color: var(--error);
    font-size: 1.5rem;
    cursor: pointer;
    padding: 5px 10px;
    border-radius: 6px;
    transition: all 0.3s ease;
}

.delete-btn:hover {
    background: rgba(255, 51, 102, 0.1);
}

/* Modal */
.modal {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.8);
    backdrop-filter: blur(10px);
    z-index: 2000;
    align-items: center;
    justify-content: center;
    padding: 20px;
}

.modal.active {
    display: flex;
}

.modal-content {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 24px;
    max-width: 800px;
    width: 100%;
    max-height: 90vh;
    overflow-y: auto;
    position: relative;
    animation: modalSlideIn 0.4s ease;
}

@keyframes modalSlideIn {
    from {
        opacity: 0;
        transform: scale(0.9) translateY(50px);
    }
    to {
        opacity: 1;
        transform: scale(1) translateY(0);
    }
}

.modal-close {
    position: absolute;
    top: 20px;
    right: 20px;
    width: 40px;
    height: 40px;
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: 50%;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-primary);
    transition: all 0.3s ease;
}

.modal-close:hover {
    background: var(--error);
    color: #fff;
}

.results-header {
    padding: 40px 40px 20px;
    text-align: center;
}

.results-header h2 {
    font-size: 2rem;
    background: linear-gradient(135deg, var(--text-primary), var(--accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* CGPA Showcase */
.cgpa-showcase {
    padding: 40px;
    text-align: center;
    background: linear-gradient(135deg, var(--accent), #00b8d4);
    margin: 20px 40px;
    border-radius: 20px;
}

.cgpa-label {
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 2px;
    color: rgba(0, 0, 0, 0.7);
    font-weight: 600;
}

.cgpa-value {
    font-size: 5rem;
    font-weight: 900;
    color: #000;
    margin: 10px 0;
    letter-spacing: -3px;
}

.cgpa-grade {
    font-size: 1.5rem;
    font-weight: 700;
    color: rgba(0, 0, 0, 0.8);
}

/* Stats Grid */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
    padding: 0 40px 30px;
}

.stat-box {
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 25px;
    text-align: center;
}

.stat-value {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--accent);
    margin-bottom: 5px;
}

.stat-label {
    font-size: 0.85rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 1px;
}

/* Results Table */
.results-table-container {
    padding: 0 40px 30px;
}

.results-table {
    width: 100%;
    border-collapse: collapse;
    background: var(--bg-secondary);
    border-radius: 12px;
    overflow: hidden;
}

.results-table th {
    background: var(--bg-primary);
    padding: 15px;
    text-align: left;
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--text-secondary);
}

.results-table td {
    padding: 15px;
    border-top: 1px solid var(--border);
}

.results-table tbody tr:hover {
    background: var(--hover);
}

/* Modal Actions */
.modal-actions {
    padding: 20px 40px 40px;
    display: flex;
    gap: 15px;
}

/* Empty State */
.empty-state {
    text-align: center;
    padding: 60px 20px;
    color: var(--text-secondary);
}

.empty-state-icon {
    font-size: 4rem;
    margin-bottom: 15px;
    opacity: 0.5;
}

/* Responsive */
@media (max-width: 768px) {
    .container {
        padding: 20px 15px;
    }

    .calculator-wrapper {
        border-radius: 16px;
    }

    .progress-tracker {
        padding: 30px 20px;
    }

    .step-container {
        padding: 30px 20px;
    }

    .form-grid,
    .exam-grid {
        grid-template-columns: 1fr;
    }

    .assignment-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .stats-grid {
        grid-template-columns: 1fr;
    }

    .cgpa-value {
        font-size: 3.5rem;
    }

    .button-group,
    .modal-actions {
        flex-direction: column;
    }

    .progress-line {
        margin: 0 10px;
    }

    .step-name {
        display: none;
    }
}