/* ===== CSS Variables for Easy Theming ===== */
:root {
    --primary-color: #4f46e5;
    --primary-hover: #4338ca;
    --success-color: #10b981;
    --success-hover: #059669;
    --bg-color: #f1f5f9;
    --card-bg: #ffffff;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --border-color: #e2e8f0;
    --shadow: 0 10px 40px rgba(0, 0, 0, 0.1);
    --menu-bg: #1e293b;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ===== Reset & Base ===== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 20px;
}

/* ===== Hamburger Menu Button ===== */
.hamburger {
    position: fixed;
    top: 20px;
    left: 20px;
    width: 45px;
    height: 45px;
    background: var(--card-bg);
    border-radius: 12px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    gap: 5px;
    cursor: pointer;
    z-index: 1000;
    box-shadow: var(--shadow);
    transition: var(--transition);
}

.hamburger:hover {
    transform: scale(1.05);
}

.hamburger span {
    display: block;
    width: 22px;
    height: 3px;
    background: var(--primary-color);
    border-radius: 2px;
    transition: var(--transition);
}

.hamburger.active span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
}

.hamburger.active span:nth-child(2) {
    opacity: 0;
}

.hamburger.active span:nth-child(3) {
    transform: rotate(-45deg) translate(6px, -6px);
}

/* ===== Side Menu ===== */
.menu-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
    z-index: 998;
}

.menu-overlay.active {
    opacity: 1;
    visibility: visible;
}

.menu-container {
    position: fixed;
    top: 0;
    left: 0;
    width: 280px;
    height: 100%;
    background: var(--menu-bg);
    transform: translateX(-100%);
    transition: var(--transition);
    z-index: 999;
    padding-top: 80px;
    overflow-y: auto;
}

.menu-container.open {
    transform: translateX(0);
}

.menu-header {
    padding: 0 25px 20px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    margin-bottom: 10px;
}

.menu-header h3 {
    color: #fff;
    font-size: 1.2rem;
    font-weight: 600;
}

.menu-header p {
    color: rgba(255, 255, 255, 0.6);
    font-size: 0.85rem;
    margin-top: 5px;
}

.menu a {
    display: flex;
    align-items: center;
    padding: 14px 25px;
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    font-size: 0.95rem;
    transition: var(--transition);
    border-left: 3px solid transparent;
}

.menu a:hover,
.menu a.active {
    background: rgba(255, 255, 255, 0.1);
    color: #fff;
    border-left-color: var(--primary-color);
}

.menu a.active {
    background: rgba(79, 70, 229, 0.3);
}

/* ===== Main Container ===== */
.container {
    background: var(--card-bg);
    padding: 40px 35px;
    border-radius: 24px;
    box-shadow: var(--shadow);
    width: 100%;
    max-width: 420px;
    animation: slideUp 0.5s ease;
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.container h2 {
    color: var(--text-primary);
    font-size: 1.75rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 30px;
    position: relative;
}

.container h2::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 50px;
    height: 4px;
    background: linear-gradient(90deg, var(--primary-color), var(--success-color));
    border-radius: 2px;
}

/* ===== Form Inputs ===== */
.form-group {
    margin-bottom: 16px;
}

.form-group label {
    display: block;
    color: var(--text-secondary);
    font-size: 0.85rem;
    font-weight: 600;
    margin-bottom: 6px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.form-group input {
    width: 100%;
    padding: 14px 16px;
    font-size: 1rem;
    border: 2px solid var(--border-color);
    border-radius: 12px;
    transition: var(--transition);
    background: var(--bg-color);
    color: var(--text-primary);
    font-weight: 500;
}

.form-group input:focus {
    outline: none;
    border-color: var(--primary-color);
    background: #fff;
    box-shadow: 0 0 0 4px rgba(79, 70, 229, 0.1);
}

.form-group input::placeholder {
    color: var(--text-secondary);
    font-weight: 400;
}

.form-group input.invalid {
    border-color: #ef4444;
    background: #fef2f2;
}

/* ===== Buttons ===== */
.btn {
    width: 100%;
    padding: 16px;
    font-size: 1rem;
    font-weight: 600;
    border: none;
    border-radius: 12px;
    cursor: pointer;
    transition: var(--transition);
    text-transform: uppercase;
    letter-spacing: 1px;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color), #6366f1);
    color: #fff;
    margin-top: 20px;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 20px rgba(79, 70, 229, 0.3);
}

.btn-primary:active {
    transform: translateY(0);
}

/* ===== Result Display ===== */
.result-section {
    margin-top: 30px;
    padding-top: 25px;
    border-top: 2px dashed var(--border-color);
    text-align: center;
}

.result-section p {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 10px;
}

.result-display {
    font-size: 3rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--primary-color), var(--success-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 20px;
    min-height: 60px;
    display: flex;
    justify-content: center;
    align-items: center;
}

.result-display.excellent {
    background: linear-gradient(135deg, #10b981, #059669);
    -webkit-background-clip: text;
    background-clip: text;
}

.result-display.good {
    background: linear-gradient(135deg, #3b82f6, #2563eb);
    -webkit-background-clip: text;
    background-clip: text;
}

.result-display.average {
    background: linear-gradient(135deg, #f59e0b, #d97706);
    -webkit-background-clip: text;
    background-clip: text;
}

.grade-badge {
    display: inline-block;
    padding: 8px 20px;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 600;
    margin-bottom: 20px;
}

.grade-badge.excellent {
    background: #d1fae5;
    color: #065f46;
}

.grade-badge.good {
    background: #dbeafe;
    color: #1e40af;
}

.grade-badge.average {
    background: #fef3c7;
    color: #92400e;
}

.grade-badge.poor {
    background: #fee2e2;
    color: #991b1b;
}

/* ===== Result Link ===== */
.result-link {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: linear-gradient(135deg, var(--success-color), #059669);
    color: #fff;
    padding: 14px 28px;
    border-radius: 12px;
    text-decoration: none;
    font-weight: 600;
    transition: var(--transition);
}

.result-link:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 20px rgba(16, 185, 129, 0.3);
}

.result-link svg {
    width: 18px;
    height: 18px;
}

/* ===== Toast Notification ===== */
.toast {
    position: fixed;
    bottom: 30px;
    left: 50%;
    transform: translateX(-50%) translateY(100px);
    background: var(--menu-bg);
    color: #fff;
    padding: 16px 30px;
    border-radius: 12px;
    font-weight: 500;
    box-shadow: var(--shadow);
    opacity: 0;
    transition: var(--transition);
    z-index: 2000;
}

.toast.show {
    transform: translateX(-50%) translateY(0);
    opacity: 1;
}

/* ===== Responsive ===== */
@media (max-width: 480px) {
    body {
        padding: 15px;
    }
    
    .container {
        padding: 30px 25px;
    }
    
    .container h2 {
        font-size: 1.5rem;
    }
    
    .menu-container {
        width: 260px;
    }
    
    .result-display {
        font-size: 2.5rem;
    }
}

/* ===== Scrollbar ===== */
::-webkit-scrollbar {
    width: 8px;
}

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

::-webkit-scrollbar-thumb {
    background: var(--primary-color);
    border-radius: 4px;
}