@import url('https://fonts.googleapis.com/css2?family=Roboto:wght@400;700&display=swap');

:root {
    /* Dark Mode (Default) */
    --primary-color: #38bdf8;
    --secondary-color: #94a3b8;
    --background-color: #0f172a;
    --text-color: #f1f5f9;
    --card-background: #1e293b;
    --form-background: rgba(30, 41, 59, 0.7);
    --shadow-color: rgba(0, 0, 0, 0.5);
    --glow-color: rgba(56, 189, 248, 0.4);
    --border-color: rgba(255, 255, 255, 0.1);
    --input-bg: #0f172a;
    --transition-speed: 0.3s;
}

[data-theme="light"] {
    --primary-color: #0284c7;
    --secondary-color: #64748b;
    --background-color: #f1f5f9;
    --text-color: #0f172a;
    --card-background: #ffffff;
    --form-background: rgba(255, 255, 255, 0.8);
    --shadow-color: rgba(0, 0, 0, 0.1);
    --glow-color: rgba(2, 132, 199, 0.2);
    --border-color: rgba(0, 0, 0, 0.1);
    --input-bg: #ffffff;
}

body {
    font-family: 'Roboto', sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    line-height: 1.6;
    margin: 0;
    padding: 20px;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    overflow-x: hidden;
    transition: background-color var(--transition-speed), color var(--transition-speed);
}

.background-glow {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: radial-gradient(circle at 50% 50%, var(--form-background) 0%, var(--background-color) 100%);
    z-index: -1;
    transition: background var(--transition-speed);
}

header {
    text-align: center;
    margin-bottom: 40px;
    animation: fadeInDown 0.8s ease-out;
    position: relative;
    width: 100%;
    max-width: 900px;
}

.theme-toggle {
    position: absolute;
    top: 0;
    right: 0;
    background: var(--form-background);
    border: 1px solid var(--border-color);
    color: var(--text-color);
    padding: 10px;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-speed);
    box-shadow: 0 4px 6px var(--shadow-color);
}

.theme-toggle:hover {
    transform: scale(1.1);
    background: var(--primary-color);
    color: #fff;
}

.logo {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 15px;
    margin-bottom: 10px;
}

.logo i {
    width: 48px;
    height: 48px;
    color: var(--primary-color);
    filter: drop-shadow(0 0 10px var(--glow-color));
}

h1 {
    font-size: 3em;
    margin: 0;
    background: linear-gradient(to right, var(--primary-color), #818cf8);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

main {
    width: 100%;
    max-width: 900px;
    display: flex;
    flex-direction: column;
    gap: 30px;
    animation: fadeInUp 0.8s ease-out;
}

#body-metrics, #workout-form {
    background: var(--form-background);
    backdrop-filter: blur(12px);
    padding: 30px 40px;
    border-radius: 24px;
    border: 1px solid var(--border-color);
    box-shadow: 0 25px 50px -12px var(--shadow-color);
    transition: background-color var(--transition-speed), border-color var(--transition-speed);
}

.metrics-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 20px;
    margin-bottom: 25px;
}

input[type="number"] {
    padding: 12px 16px;
    background: var(--input-bg);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    color: var(--text-color);
    font-size: 1em;
    transition: all var(--transition-speed);
}

input[type="number"]:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px var(--glow-color);
}

#calculate-btn {
    width: 100%;
    margin-bottom: 20px;
}

.hidden {
    display: none;
}

#metrics-results {
    margin-top: 20px;
    padding-top: 20px;
    border-top: 1px solid var(--border-color);
    animation: fadeIn 0.5s ease-out;
}

.result-cards {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
}

@media (max-width: 600px) {
    .result-cards {
        grid-template-columns: 1fr;
    }
}

.result-card {
    background: var(--card-background);
    padding: 20px;
    border-radius: 16px;
    border: 1px solid var(--border-color);
    text-align: center;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.result-label {
    font-size: 0.8em;
    color: var(--secondary-color);
    text-transform: uppercase;
    font-weight: 700;
}

.result-value {
    font-size: 2em;
    font-weight: 800;
    color: var(--primary-color);
}

.result-status {
    font-size: 0.9em;
    font-weight: 600;
    padding: 4px 12px;
    border-radius: 20px;
    background: var(--glow-color);
    width: fit-content;
    margin: 0 auto;
}

.result-unit {
    font-size: 0.8em;
    color: var(--secondary-color);
}

#workout-form {
    display: flex;
    flex-direction: column;
    gap: 25px;
}

.workout-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
}

@media (max-width: 768px) {
    #workout-form {
        grid-template-columns: 1fr;
    }
    .workout-grid {
        grid-template-columns: 1fr;
    }
    .theme-toggle {
        position: fixed;
        bottom: 20px;
        right: 20px;
        top: auto;
        z-index: 100;
    }
}

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

label {
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--secondary-color);
    font-size: 0.9em;
    text-transform: uppercase;
}

select {
    padding: 12px 16px;
    background: var(--input-bg);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    color: var(--text-color);
    font-size: 1em;
    cursor: pointer;
    transition: all var(--transition-speed);
}

select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px var(--glow-color);
}

button[type="submit"] {
    background: linear-gradient(135deg, var(--primary-color) 0%, #818cf8 100%);
    color: #fff;
    padding: 12px 24px;
    border: none;
    border-radius: 12px;
    cursor: pointer;
    font-size: 1em;
    font-weight: 700;
    transition: all 0.3s;
    box-shadow: 0 4px 15px var(--glow-color);
}

button[type="submit"]:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px var(--glow-color);
}

#workout-plan {
    margin-top: 50px;
}

#workout-plan h2 {
    text-align: center;
    margin-bottom: 30px;
}

#workout-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 25px;
}

workout-card {
    background-color: var(--card-background);
    border-radius: 16px;
    border: 1px solid var(--border-color);
    transition: all var(--transition-speed) ease;
}

workout-card:hover {
    transform: translateY(-5px);
    border-color: var(--primary-color);
    box-shadow: 0 10px 20px var(--shadow-color);
}

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

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