/* Clean Light Theme Styles */
:root {
    --primary-color: #e63946;
    --primary-hover: #d62828;
    --bg-main: #f8f9fa;
    --bg-card: #ffffff;
    --text-main: #1d3557;
    --text-muted: #6c757d;
    --border-color: #e9ecef;
    --card-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
    --font-heading: 'Oswald', sans-serif;
    --font-body: 'Roboto', sans-serif;
    --transition: all 0.25s ease;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-body);
    background-color: var(--bg-main);
    color: var(--text-main);
    line-height: 1.5;
    overflow-x: hidden;
}

.container {
    width: 100%;
    max-width: 1140px;
    margin: 0 auto;
    padding: 0 20px;
}

.section-padding {
    padding: 40px 0;
}

/* Header Navbar */
.navbar {
    position: sticky;
    top: 0;
    background-color: #ffffff;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.06);
    z-index: 1000;
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
}

.logo {
    font-family: var(--font-heading);
    font-size: 1.8rem;
    font-weight: 700;
    color: var(--text-main);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 8px;
}

.logo span {
    color: var(--primary-color);
}

.nav-links {
    display: flex;
    gap: 15px;
}

.nav-item {
    padding: 8px 16px;
    color: var(--text-muted);
    text-decoration: none;
    font-family: var(--font-heading);
    font-size: 1.1rem;
    border-radius: 6px;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 6px;
}

.nav-item.active,
.nav-item:hover {
    color: var(--primary-color);
    background-color: #fff5f5;
}

/* Title Section */
.page-title {
    text-align: center;
    margin-bottom: 30px;
}

.page-title h1 {
    font-family: var(--font-heading);
    font-size: 2.5rem;
    color: var(--text-main);
    margin-bottom: 8px;
}

.page-title p {
    color: var(--text-muted);
    font-size: 1.1rem;
}

/* Muscle & Tool Cards Grid */
.muscle-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
    gap: 20px;
    margin-bottom: 30px;
}

.muscle-card {
    background-color: var(--bg-card);
    border: 2px solid var(--border-color);
    border-radius: 12px;
    padding: 20px;
    text-align: center;
    cursor: pointer;
    box-shadow: var(--card-shadow);
    transition: var(--transition);
    -webkit-tap-highlight-color: transparent;
}

.muscle-card:hover {
    border-color: var(--primary-color);
    transform: translateY(-4px);
    box-shadow: 0 8px 20px rgba(230, 57, 70, 0.12);
}

.muscle-card.active {
    border-color: var(--primary-color);
    background-color: #fff5f5;
}

.muscle-img-wrapper {
    width: 100%;
    height: 120px;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: #f1f3f5;
    border-radius: 8px;
    margin-bottom: 12px;
    overflow: hidden;
}

.muscle-img-wrapper svg {
    max-width: 65px;
    max-height: 65px;
    transition: var(--transition);
}

.muscle-card:hover .muscle-img-wrapper svg {
    transform: scale(1.08);
}

.muscle-name {
    font-family: var(--font-heading);
    font-size: 1.3rem;
    color: var(--text-main);
    margin-bottom: 4px;
}

.muscle-count {
    color: var(--primary-color);
    font-weight: 700;
    font-size: 0.85rem;
}

/* Workout & Tool Workspace Section */
.workout-section {
    background-color: #ffffff;
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 25px;
    box-shadow: var(--card-shadow);
}

.workout-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 10px;
    margin-bottom: 20px;
    border-bottom: 2px solid var(--border-color);
    padding-bottom: 15px;
}

.workout-header h2 {
    font-family: var(--font-heading);
    font-size: 1.7rem;
    color: var(--text-main);
}

.exercise-list {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 20px;
}

.exercise-card {
    background-color: #f8f9fa;
    border: 1px solid var(--border-color);
    border-radius: 10px;
    padding: 20px;
    transition: var(--transition);
    display: flex;
    flex-direction: column;
    justify-content: space-between;
}

.exercise-card:hover {
    border-color: #cbd5e1;
    background-color: #ffffff;
    box-shadow: var(--card-shadow);
}

.exercise-name {
    font-family: var(--font-heading);
    font-size: 1.25rem;
    color: var(--text-main);
    margin-bottom: 6px;
}

.exercise-badge {
    display: inline-block;
    width: fit-content;
    background-color: rgba(230, 57, 70, 0.1);
    color: var(--primary-color);
    font-size: 0.8rem;
    font-weight: bold;
    padding: 4px 10px;
    border-radius: 4px;
    margin-bottom: 12px;
}

.exercise-info {
    color: var(--text-muted);
    font-size: 0.95rem;
    margin-bottom: 15px;
}

.exercise-tip {
    font-size: 0.85rem;
    color: #495057;
    background-color: #ffffff;
    border: 1px dashed #ced4da;
    padding: 10px;
    border-radius: 6px;
}

/* Tool Form & Result Styling */
.tool-form-box {
    max-width: 600px;
    margin: 0 auto;
}

.tool-form-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin-bottom: 25px;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.form-group label {
    font-weight: 500;
    color: var(--text-main);
    font-size: 0.95rem;
}

.form-group input, .form-group select {
    width: 100%;
    padding: 12px 14px;
    border: 1px solid #ced4da;
    border-radius: 8px;
    font-size: 1rem;
    color: var(--text-main);
    background-color: #f8f9fa;
    outline: none;
    transition: var(--transition);
}

.form-group input:focus, .form-group select:focus {
    border-color: var(--primary-color);
    background-color: #ffffff;
    box-shadow: 0 0 0 3px rgba(230, 57, 70, 0.15);
}

.btn-calc {
    width: 100%;
    padding: 14px;
    background-color: var(--primary-color);
    color: #ffffff;
    border: none;
    border-radius: 8px;
    font-family: var(--font-heading);
    font-size: 1.2rem;
    letter-spacing: 0.5px;
    cursor: pointer;
    transition: var(--transition);
}

.btn-calc:hover {
    background-color: var(--primary-hover);
}

.tool-result-box {
    margin-top: 25px;
    padding: 20px;
    border-radius: 8px;
    background-color: #f1f3f5;
    border-left: 4px solid var(--primary-color);
    text-align: center;
    word-break: break-word;
}

.result-value {
    font-family: var(--font-heading);
    font-size: 2.2rem;
    color: var(--primary-color);
    margin-bottom: 5px;
}

.result-desc {
    color: var(--text-main);
    font-size: 1.05rem;
}

/* Footer */
.footer {
    text-align: center;
    padding: 20px 0;
    color: var(--text-muted);
    font-size: 0.85rem;
    border-top: 1px solid var(--border-color);
    margin-top: 50px;
    background-color: #ffffff;
}

/* ==========================================================================
   RESPONSIVE BREAKPOINTS (Mobile, Tablet, Desktop)
   ========================================================================== */

@media (max-width: 768px) {
    .container {
        padding: 0 15px;
    }

    .section-padding {
        padding: 25px 0;
    }

    .nav-container {
        height: 60px;
    }

    .logo {
        font-size: 1.5rem;
    }

    .nav-item {
        padding: 6px 12px;
        font-size: 0.95rem;
    }

    .page-title {
        margin-bottom: 20px;
    }

    .page-title h1 {
        font-size: 1.8rem;
    }

    .page-title p {
        font-size: 0.95rem;
    }

    /* Grid collapses smoothly on tablet & mobile */
    .muscle-grid {
        grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
        gap: 12px;
        margin-bottom: 20px;
    }

    .muscle-card {
        padding: 12px 10px;
        border-radius: 10px;
    }

    .muscle-img-wrapper {
        height: 80px;
        margin-bottom: 8px;
    }

    .muscle-img-wrapper svg {
        max-width: 45px;
        max-height: 45px;
    }

    .muscle-name {
        font-size: 1.05rem;
    }

    .muscle-count {
        font-size: 0.75rem;
    }

    .workout-section {
        padding: 18px 15px;
        border-radius: 10px;
    }

    .workout-header h2 {
        font-size: 1.3rem;
    }

    .exercise-list {
        grid-template-columns: 1fr;
        gap: 15px;
    }

    .exercise-card {
        padding: 15px;
    }

    .tool-form-grid {
        grid-template-columns: 1fr;
        gap: 15px;
    }
}

@media (max-width: 420px) {
    .muscle-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .nav-links {
        gap: 5px;
    }

    .nav-item {
        padding: 5px 8px;
        font-size: 0.85rem;
    }
}