:root {
    --primary-color: #3498db;
    --secondary-color: #2ecc71;
    --background-color: #f4f4f6;
    --card-color: #ffffff;
    --text-color: #2c3e50;
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--background-color);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    line-height: 1.6;
    color: var(--text-color);
}

.container {
    width: 100%;
    max-width: 450px;
    padding: 20px;
}

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

.header h1 {
    font-size: 2.5rem;
    margin-bottom: 10px;
}

.subtitle {
    color: var(--text-color);
    opacity: 0.7;
}

.calculator-card {
    background-color: var(--card-color);
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.1);
    overflow: hidden;
}

.input-section {
    padding: 25px;
}

.input-group {
    margin-bottom: 20px;
}

.input-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
}

.input-wrapper {
    position: relative;
}

.input-wrapper i {
    position: absolute;
    left: 15px;
    top: 50%;
    transform: translateY(-50%);
    color: var(--primary-color);
    opacity: 0.6;
}

input {
    width: 100%;
    padding: 12px 12px 12px 40px;
    border: 2px solid #e0e0e0;
    border-radius: 10px;
    font-size: 16px;
    transition: all 0.3s ease;
}

input:focus {
    border-color: var(--primary-color);
    outline: none;
    box-shadow: 0 0 0 3px rgba(52, 152, 219, 0.2);
}

.operation-section {
    margin-bottom: 20px;
}

.toggle-buttons {
    display: flex;
    justify-content: space-between;
    gap: 10px;
}

.op-btn {
    flex: 1;
    padding: 10px;
    border: none;
    background-color: #f1f3f4;
    color: var(--text-color);
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    transition: all 0.3s ease;
}

.op-btn.active {
    background-color: var(--primary-color);
    color: white;
}

.op-btn i {
    font-size: 1rem;
}

.calculate-btn {
    width: 100%;
    padding: 15px;
    background-color: var(--secondary-color);
    color: white;
    border: none;
    border-radius: 10px;
    font-size: 1rem;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    transition: background-color 0.3s ease;
}

.calculate-btn:hover {
    background-color: #27ae60;
}

.result-section {
    background-color: #f8f9fa;
    padding: 20px;
    text-align: center;
}

.result-content {
    background-color: white;
    padding: 15px;
    border-radius: 10px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
}

.toast {
    position: fixed;
    bottom: 20px;
    left: 50%;
    transform: translateX(-50%);
    background-color: #333;
    color: white;
    padding: 15px 30px;
    border-radius: 5px;
    display: none;
    z-index: 1000;
}

.tutorial-link {
    display: block;
    text-align: center;
    color: var(--primary-color);
    text-decoration: none;
    margin-top: 10px;
    font-size: 0.9rem;
    transition: color 0.3s ease;
}

.tutorial-link:hover {
    color: var(--secondary-color);
}

.tutorial-popup {
    display: none;
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    overflow: auto;
    background-color: rgba(0,0,0,0.5);
    align-items: center;
    justify-content: center;
    padding: 20px;
}

.tutorial-content {
    background-color: white;
    padding: 30px;
    border-radius: 15px;
    width: 90%;
    max-width: 500px;
    position: relative;
    text-align: center;
    max-height: 90vh;
    overflow-y: auto;
    margin-top: env(safe-area-inset-top);
    margin-bottom: env(safe-area-inset-bottom);
}

.close-btn {
    position: absolute;
    top: 10px;
    right: 20px;
    font-size: 2rem;
    cursor: pointer;
    color: var(--text-color);
}

.tutorial-steps {
    margin-top: 20px;
}

.tutorial-step {
    display: flex;
    align-items: center;
    margin-bottom: 15px;
    background-color: #f4f4f4;
    padding: 15px;
    border-radius: 10px;
}

.tutorial-step i {
    margin-right: 15px;
    color: var(--primary-color);
    font-size: 1.5rem;
}

.got-it-btn {
    margin-top: 20px;
    background-color: var(--secondary-color);
    color: white;
    border: none;
    padding: 10px 20px;
    border-radius: 10px;
    cursor: pointer;
}

#confetti-container {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 9999;
}

.tutorial-example {
    background-color: #f0f4f8;
    border-radius: 10px;
    padding: 15px;
    margin-top: 20px;
}

.tutorial-example h3 {
    color: var(--primary-color);
    margin-bottom: 15px;
    text-align: center;
}

.example-case {
    background-color: white;
    border-radius: 10px;
    padding: 15px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
}

.example-step {
    display: flex;
    align-items: center;
    margin-bottom: 10px;
    background-color: #f4f4f4;
    padding: 10px;
    border-radius: 8px;
}

.example-step i {
    margin-right: 15px;
    color: var(--primary-color);
    font-size: 1.2rem;
}

.example-result {
    display: flex;
    align-items: center;
    background-color: var(--secondary-color);
    color: white;
    padding: 10px;
    border-radius: 8px;
}

.example-result i {
    margin-right: 15px;
    font-size: 1.2rem;
}

@media (max-width: 480px) {
    .toggle-buttons {
        flex-direction: column;
    }
}

@media (max-width: 480px) {
    .tutorial-content {
        width: 95%;
        padding: 20px;
        margin-top: max(20px, env(safe-area-inset-top));
    }

    .tutorial-steps, .tutorial-example {
        font-size: 0.9rem;
    }

    .tutorial-step i, .example-step i {
        font-size: 1.2rem;
    }
}